draft-ietf-iptel-cpl-06.txt   draft-ietf-iptel-cpl-07.txt 
Internet Engineering Task Force IPTEL WG Internet Engineering Task Force IPTEL WG
Internet Draft Lennox/Schulzrinne Internet Draft Lennox/Wu/Schulzrinne
draft-ietf-iptel-cpl-06.txt Columbia University Columbia University
January 15, 2002 draft-ietf-iptel-cpl-07.txt
Expires: July, 2002 August 1, 2003
Expires: February, 2004
CPL: A Language for User Control of Internet Telephony Services CPL: A Language for User Control of Internet Telephony Services
STATUS OF THIS MEMO STATUS OF THIS MEMO
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 46 skipping to change at page 1, line 47
be implementable on either network servers or user agent servers. It be implementable on either network servers or user agent servers. It
is meant to be simple, extensible, easily edited by graphical is meant to be simple, extensible, easily edited by graphical
clients, and independent of operating system or signalling protocol. clients, and independent of operating system or signalling protocol.
It is suitable for running on a server where users may not be allowed It is suitable for running on a server where users may not be allowed
to execute arbitrary programs, as it has no variables, loops, or to execute arbitrary programs, as it has no variables, loops, or
ability to run external programs. ability to run external programs.
This document is a product of the IP Telephony (IPTEL) working group This document is a product of the IP Telephony (IPTEL) working group
of the Internet Engineering Task Force. Comments are solicited and of the Internet Engineering Task Force. Comments are solicited and
should be addressed to the working group's mailing list at should be addressed to the working group's mailing list at
iptel@lists.research.bell-labs.com and/or the authors. iptel@ietf.org and/or the authors.
Table of Contents Table of Contents
1 Introduction ........................................ 4 1 Introduction ........................................ 4
1.1 Conventions of This Document ........................ 4 1.1 Conventions of This Document ........................ 4
2 Structure of CPL Scripts ............................ 4 2 Structure of CPL Scripts ............................ 5
2.1 High-level Structure ................................ 5 2.1 High-level Structure ................................ 5
2.2 Abstract Structure of a Call Processing Action ...... 5 2.2 Abstract Structure of a Call Processing Action ...... 5
2.3 Location Model ...................................... 6 2.3 Location Model ...................................... 6
2.4 XML Structure ....................................... 6 2.4 XML Structure ....................................... 6
3 Document Information ................................ 7 3 Script Structure: Overview .......................... 7
3.1 CPL Document Identifiers for XML .................... 7 4 Switches ............................................ 7
3.2 MIME Registration ................................... 8 4.1 Address Switches .................................... 9
4 Script Structure: Overview .......................... 9 4.1.1 Usage of "address-switch" with SIP .................. 12
5 Switches ............................................ 10 4.2 String Switches ..................................... 13
5.1 Address Switches .................................... 11 4.2.1 Usage of "string-switch" with SIP ................... 14
5.1.1 Usage of "address-switch" with SIP .................. 13 4.3 Language Switches ................................... 14
5.2 String Switches ..................................... 14 4.3.1 Usage of "language-switch" with SIP ................. 15
5.2.1 Usage of "string-switch" with SIP ................... 15 4.4 Time Switches ....................................... 15
5.3 Language Switches ................................... 15 4.4.1 iCalendar differences and implementation issues ..... 21
5.3.1 Usage of "language-switch" with SIP ................. 16 4.5 Priority Switches ................................... 22
5.4 Time Switches ....................................... 16 4.5.1 Usage of "priority-switch" with SIP ................. 23
5.4.1 iCalendar differences and implementation issues ..... 22 5 Location Modifiers .................................. 23
5.5 Priority Switches ................................... 23 5.1 Explicit Location ................................... 23
5.5.1 Usage of "priority-switch" with SIP ................. 24 5.1.1 Usage of "location" with SIP ........................ 24
6 Location Modifiers .................................. 24 5.2 Location Lookup ..................................... 24
6.1 Explicit Location ................................... 25 5.2.1 Usage of "lookup" with SIP .......................... 26
6.1.1 Usage of "location" with SIP ........................ 26 5.3 Location Removal .................................... 26
6.2 Location Lookup ..................................... 26 5.3.1 Usage of "remove-location" with SIP ................. 27
6.2.1 Usage of "lookup" with SIP .......................... 28 6 Signalling Operations ............................... 27
6.3 Location Removal .................................... 28 6.1 Proxy ............................................... 27
6.3.1 Usage of "remove-location" with SIP ................. 29 6.1.1 Usage of "proxy" with SIP ........................... 29
7 Signalling Operations ............................... 29 6.2 Redirect ............................................ 30
7.1 Proxy ............................................... 29 6.2.1 Usage of "redirect" with SIP ........................ 30
7.1.1 Usage of "proxy" with SIP ........................... 32 6.3 Reject .............................................. 30
7.2 Redirect ............................................ 32 6.3.1 Usage of "reject" with SIP .......................... 31
7.2.1 Usage of "redirect" with SIP ........................ 32 7 Non-signalling Operations ........................... 32
7.3 Reject .............................................. 33 7.1 Mail ................................................ 32
7.3.1 Usage of "reject" with SIP .......................... 33 7.1.1 Suggested Content of Mailed Information ............. 32
8 Non-signalling Operations ........................... 34 7.2 Log ................................................. 33
8.1 Mail ................................................ 34 8 Subactions .......................................... 34
8.1.1 Suggested Content of Mailed Information ............. 35 9 Ancillary Information ............................... 35
8.2 Log ................................................. 35 10 Default Behavior .................................... 35
9 Subactions .......................................... 36 11 CPL Extensions ...................................... 36
10 Ancillary Information ............................... 37 12 Examples ............................................ 38
11 Default Behavior .................................... 38 12.1 Example: Call Redirect Unconditional ................ 38
12 CPL Extensions ...................................... 39 12.2 Example: Call Forward Busy/No Answer ................ 38
13 Examples ............................................ 40 12.3 Example: Call Forward: Redirect and Default ......... 38
13.1 Example: Call Redirect Unconditional ................ 40 12.4 Example: Call Screening ............................. 39
13.2 Example: Call Forward Busy/No Answer ................ 40 12.5 Example: Priority and Language Routing .............. 39
13.3 Example: Call Forward: Redirect and Default ......... 40 12.6 Example: Outgoing Call Screening .................... 40
13.4 Example: Call Screening ............................. 42 12.7 Example: Time-of-day Routing ........................ 41
13.5 Example: Priority and Language Routing .............. 42 12.8 Example: Location Filtering ......................... 41
13.6 Example: Outgoing Call Screening .................... 42 12.9 Example: Non-signalling Operations .................. 42
13.7 Example: Time-of-day Routing ........................ 43 12.10 Example: Hypothetical Extensions .................... 43
13.8 Example: Location Filtering ......................... 44 12.11 Example: A Complex Example .......................... 43
13.9 Example: Non-signalling Operations .................. 44 13 Security Considerations ............................. 44
13.10 Example: Hypothetical Extensions .................... 45 14 IANA Considerations ................................. 44
13.11 Example: A Complex Example .......................... 45 14.1 URN Sub-Namespace Registration for
14 Security Considerations ............................. 48 urn:ietf:params:xml:ns:cpl ..................................... 46
15 IANA Considerations ................................. 49 14.2 MIME Registration ................................... 48
16 Acknowledgments ..................................... 49 15 Acknowledgments ..................................... 49
A An Algorithm for Resolving Time Switches ............ 49 A An Algorithm for Resolving Time Switches ............ 49
B Suggested Usage of CPL with H.323 ................... 51 B Suggested Usage of CPL with H.323 ................... 51
B.1 Usage of "address-switch" with H.323 ................ 51 B.1 Usage of "address-switch" with H.323 ................ 51
B.2 Usage of "string-switch" with H.323 ................. 53 B.2 Usage of "string-switch" with H.323 ................. 53
B.3 Usage of "language-switch" with H.323 ............... 53 B.3 Usage of "language-switch" with H.323 ............... 53
B.4 Usage of "priority-switch" with H.323 ............... 53 B.4 Usage of "priority-switch" with H.323 ............... 53
B.5 Usage of "location" with H.323 ...................... 53 B.5 Usage of "location" with H.323 ...................... 53
B.6 Usage of "lookup" with H.323 ........................ 53 B.6 Usage of "lookup" with H.323 ........................ 53
B.7 Usage of "remove-location" with H.323 ............... 54 B.7 Usage of "remove-location" with H.323 ............... 54
C The XML DTD for CPL ................................. 54 C The XML Schema for CPL .............................. 54
D Changes from Earlier Versions ....................... 60 D Changes from Earlier Versions ....................... 66
D.1 Changes from Draft -05 .............................. 60 D.1 Changes from Draft -06 .............................. 66
D.2 Changes from Draft -04 .............................. 61 D.2 Changes from Draft -05 .............................. 67
D.3 Changes from Draft -03 .............................. 62 D.3 Changes from Draft -04 .............................. 67
D.4 Changes from Draft -02 .............................. 62 D.4 Changes from Draft -03 .............................. 68
D.5 Changes from Draft -01 .............................. 63 D.5 Changes from Draft -02 .............................. 69
D.6 Changes from Draft -00 .............................. 65 D.6 Changes from Draft -01 .............................. 70
E Authors' Addresses .................................. 66 D.7 Changes from Draft -00 .............................. 71
F Bibliography ........................................ 66 E Authors' Addresses .................................. 72
F Normative References ................................ 73
G Informative References .............................. 74
1 Introduction 1 Introduction
The Call Processing Language (CPL) is a language that can be used to The Call Processing Language (CPL) is a language that can be used to
describe and control Internet telephony services. It is not tied to describe and control Internet telephony services. It is not tied to
any particular signalling architecture or protocol; it is anticipated any particular signalling architecture or protocol; it is anticipated
that it will be used with both SIP [1] and H.323 [2]. that it will be used with both the Session Initiation Protocol (SIP)
[1] and H.323 [16].
The CPL is powerful enough to describe a large number of services and CPL is powerful enough to describe a large number of services and
features, but it is limited in power so that it can run safely in features, but it is limited in power so that it can run safely in
Internet telephony servers. The intention is to make it impossible Internet telephony servers. The intention is to make it impossible
for users to do anything more complex (and dangerous) than describing for users to do anything more complex (and dangerous) than describing
Internet telephony services. The language is not Turing-complete, and Internet telephony services. The language is not Turing-complete, and
provides no way to write loops or recursion. provides no way to write loops or recursion.
The CPL is also designed to be easily created and edited by graphical CPL is also designed to be easily created and edited by graphical
tools. It is based on XML [3], so parsing it is easy and many tools. It is based on the Extensible Markup Language (XML) [2], so
parsers for it are publicly available. The structure of the language parsing it is easy and many parsers for it are publicly available.
maps closely to its behavior, so an editor can understand any valid The structure of the language maps closely to its behavior, so an
script, even ones written by hand. The language is also designed so editor can understand any valid script, even ones written by hand.
that a server can easily confirm scripts' validity at the time they The language is also designed so that a server can easily confirm
are delivered to it, rather that discovering them while a call is scripts' validity at the time they are delivered to it, rather that
being processed. discovering them while a call is being processed.
Implementations of the CPL are expected to take place both in Implementations of CPL are expected to take place both in Internet
Internet telephony servers and in advanced clients; both can usefully telephony servers and in advanced clients; both can usefully process
process and direct users' calls. This document primarily addresses and direct users' calls. This document primarily addresses the usage
the usage in servers. A mechanism will be needed to transport scripts in servers. A mechanism will be needed to transport scripts between
between clients and servers; this document does not describe such a clients and servers; this document does not describe such a
mechanism, but related documents will. mechanism, but related documents will.
The framework and requirements for the CPL architecture are described The framework and requirements for the CPL architecture are described
in RFC 2824, "Call Processing Language Framework and Requirements" in RFC 2824, "Call Processing Language Framework and Requirements"
[4]. [17].
1.1 Conventions of This Document 1.1 Conventions of This Document
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [5] and and "OPTIONAL" are to be interpreted as described in RFC 2119 [3] and
indicate requirement levels for compliant CPL implementations. indicate requirement levels for compliant CPL implementations.
Some paragraphs are indented, like this; they give Some paragraphs are indented, like this; they give
motivations of design choices, or questions for future motivations of design choices, advice to implementors, or
discussion in the development of the CPL, and are not thoughts on future development of or extensions to CPL.
essential to the specification of the language. They are not essential to the specification of the
language, and are non-normative.
2 Structure of CPL Scripts 2 Structure of CPL Scripts
2.1 High-level Structure 2.1 High-level Structure
A CPL script consists of two types of information: ancillary A CPL script consists of two types of information: ancillary
information about the script, and call processing actions. information about the script, and call processing actions.
A call processing action is a structured tree that describes the A call processing action is a structured tree that describes the
operations and decisions a telephony signalling server performs on a operations and decisions a telephony signalling server performs on a
call set-up event. There are two types of call processing actions: call set-up event. There are two types of call processing actions:
top-level actions and subactions. Top-level actions are actions that top-level actions and subactions. Top-level actions are actions that
are triggered by signalling events that arrive at the server. Two are triggered by signalling events that arrive at the server. Two
top-level action names are defined: "incoming", the action performed top-level actions are defined: "incoming", the action performed when
when a call arrives whose destination is the owner of the script; and a call arrives whose destination is the owner of the script; and
"outgoing", the action performed when a call arrives whose originator "outgoing", the action performed when a call arrives whose originator
is the owner of the script. Subactions are actions which can be is the owner of the script. Subactions are actions which can be
called from other actions. The CPL forbids subactions from being called from other actions. CPL forbids subactions from being called
called recursively: see Section 9. recursively: see Section 8.
Ancillary information is information which is necessary for a server Ancillary information is information which is necessary for a server
to correctly process a script, but which does not directly describe to correctly process a script, but which does not directly describe
any operations or decisions. Currently, no ancillary information is any operations or decisions. Currently, no ancillary information is
defined, but the section is reserved for use by extensions. defined, but the section is reserved for use by extensions.
2.2 Abstract Structure of a Call Processing Action 2.2 Abstract Structure of a Call Processing Action
Abstractly, a call processing action is described by a collection of Abstractly, a call processing action is described by a collection of
nodes, which describe operations that can be performed or decisions nodes, which describe operations that can be performed or decisions
which can be made. A node may have several parameters, which specify that can be made. A node may have several parameters, which specify
the precise behavior of the node; they usually also have outputs, the precise behavior of the node; they usually also have outputs,
which depend on the result of the decision or action. which depend on the result of the decision or action.
For a graphical representation of a CPL action, see Figure 1. Nodes For a graphical representation of a CPL action, see Figure 1. Nodes
and outputs can be thought of informally as boxes and arrows; the CPL and outputs can be thought of informally as boxes and arrows; CPL is
is designed so that actions can be conveniently edited graphically designed so that actions can be conveniently edited graphically using
using this representation. Nodes are arranged in a tree, starting at this representation. Nodes are arranged in a tree, starting at a
a single root node; outputs of nodes are connected to additional single root node; outputs of nodes are connected to additional nodes.
nodes. When an action is run, the action or decision described by the When an action is run, the action or decision described by the
action's top-level node is performed; based on the result of that action's top-level node is performed; based on the result of that
node, the server follows one of the node's outputs, and the node, the server follows one of the node's outputs, and the
subsequent node it points to is performed; this process continues subsequent node it points to is performed; this process continues
until a node with no specified outputs is reached. Because the graph until a node with no specified outputs is reached. Because the graph
is acyclic, this will occur after a bounded and predictable number of is acyclic, this will occur after a bounded and predictable number of
nodes are visited. nodes are visited.
If an output to a node does not point to another node, it indicates If an output to a node does not point to another node, it indicates
that the CPL server should perform a node- or protocol-specific that the CPL server should perform a node- or protocol-specific
action. Some nodes have specific default behavior associated with action. Some nodes have specific default behavior associated with
them; for others, the default behavior is implicit in the underlying them; for others, the default behavior is implicit in the underlying
signalling protocol, or can be configured by the administrator of the signalling protocol, or can be configured by the administrator of the
server. For further details on this, see Section 11. server. For further details on this, see Section 10.
_________________ ___________________ ________ busy _________________ ___________________ ________ busy
| Address-switch | | location | | proxy |--------\ | Address-switch | | location | | proxy |--------\
Call --->| field: origin | ->| url: sip:jones@ |--->|timeout:| timeout| Call-->| field: origin | ->| url: sip:jones@ |->|timeout:| timeout|
| subfield: host | / | example.com | | 10s |--------| | subfield: host | / | example.com | | 10s |--------|
|-----------------|/ |___________________| | | failure| |-----------------|/ |___________________| | | failure|
| subdomain-of: | |________|--------| | subdomain-of: | |________|--------|
| example.com | | | example.com | |
|-----------------| _____________________________________________/ |-----------------| ___________________________________________/
| otherwise | /.......................................... | otherwise | /........................................
| |\|. Voicemail . | |\|. Voicemail .
|_________________| \. ____________________ . |_________________| \. ____________________ .
->| location | __________ . ->| location | __________ .
. | url: sip:jones@ | | redirect | . . | url: sip:jones@ | | redirect | .
. | voicemail. |--->| | . . | voicemail. |->| | .
. | example.com | |__________| . . | example.com | |__________| .
. |____________________| . . |____________________| .
.......................................... ........................................
Figure 1: Sample CPL Action: Graphical Version Figure 1: Sample CPL Action: Graphical Version
2.3 Location Model 2.3 Location Model
For flexibility, one piece of information necessary for the function For flexibility, one piece of information necessary for CPL is not
of a CPL is not given as node parameters: the set of locations to given as node parameters: the set of locations to which a call is to
which a call is to be directed. Instead, this set of locations is be directed. Instead, this set of locations is stored as an implicit
stored as an implicit global variable throughout the execution of a global variable throughout the execution of a processing action (and
processing action (and its subactions). This allows locations to be its subactions). This allows locations to be retrieved from external
retrieved from external sources, filtered, and so forth, without sources, filtered, and so forth, without requiring general language
requiring general language support for such operations (which could support for such operations (which could harm the simplicity and
harm the simplicity and tractability of understanding the language). tractability of understanding the language). The specific operations
The specific operations which add, retrieve, or filter location sets which add, retrieve, or filter location sets are given in Section 5.
are given in Section 6.
For the incoming top-level call processing action, the location set For the incoming top-level call processing action, the location set
is initialized to the empty set. For the outgoing action, it is is initialized to the empty set. For the outgoing action, it is
initialized to the destination address of the call. initialized to the destination address of the call.
2.4 XML Structure 2.4 XML Structure
Syntactically, CPL scripts are represented by XML documents. XML is Syntactically, CPL scripts are represented by XML documents. XML is
thoroughly specified by [3], and implementors of this specification thoroughly specified by the XML specification [2], and implementors
should be familiar with that document, but as a brief overview, XML of this specification should be familiar with that document, but as a
consists of a hierarchical structure of tags; each tag can have a brief overview, XML consists of a hierarchical structure of tags;
number of attributes. It is visually and structurally very similar to each tag can have a number of attributes. It is visually and
HTML [6], as both languages are simplifications of the earlier and structurally very similar to HTML [18], as both languages are
larger standard SGML [7]. simplifications of the earlier and larger standard SGML [19].
See Figure 2 for the XML document corresponding to the graphical See Figure 2 for the XML document corresponding to the graphical
representation of the CPL script in Figure 1. Both nodes and outputs representation of the CPL script in Figure 1. Both nodes and outputs
in the CPL are represented by XML tags; parameters are represented by in CPL are represented by XML tags; parameters are represented by XML
XML tag attributes. Typically, node tags contain output tags, and tag attributes. Typically, node tags contain output tags, and vice-
vice-versa (with a few exceptions: see Sections 6.1, 6.3, 8.1, and versa (with a few exceptions: see Sections 5.1, 5.3, 7.1, and 7.2).
8.2).
The connection between the output of a node and another node is The connection between the output of a node and another node is
represented by enclosing the tag representing the pointed-to node represented by enclosing the tag representing the pointed-to node
inside the tag for the outer node's output. Convergence (several inside the tag for the outer node's output. Convergence (several
outputs pointing to a single node) is represented by subactions, outputs pointing to a single node) is represented by subactions,
discussed further in Section 9. discussed further in Section 8.
The higher-level structure of a CPL script is represented by tags The higher-level structure of a CPL script is represented by tags
corresponding to each piece of ancillary information, subactions, and corresponding to each piece of ancillary information, subactions, and
top-level actions, in order. This higher-level information is all top-level actions, in order. This higher-level information is all
enclosed in a special tag "cpl", the outermost tag of the XML enclosed in a special tag "cpl", the outermost tag of the XML
document. document.
A complete Document Type Declaration for the CPL is provided in A complete XML Schema for CPL is provided in Appendix C. The
Appendix C. The remainder of the main sections of this document remainder of the main sections of this document describe the
describe the semantics of the CPL, while giving its syntax semantics of CPL, while giving its syntax informally. For the formal
informally. For the formal syntax, please see the appendix. syntax, please see the appendix.
3 Document Information
This section gives information describing how CPL scripts are
identified.
3.1 CPL Document Identifiers for XML
A CPL script list which appears as a top-level XML document is 3 Script Structure: Overview
identified with the formal public identifier "-//IETF//DTD RFCxxxx
CPL 1.0//EN".
A CPL embedded as a fragment within another XML document is As mentioned, a CPL script consists of ancillary information,
identified with the XML namespace identifier "http://www.rfc- subactions, and top-level actions. The full syntax of the "cpl" node
editor.org/rfc/rfcxxxx.txt". is given in Figure 3.
<?xml version="1.0" ?> Call processing actions, both top-level actions and sub-actions,
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd"> consist of a tree of nodes and outputs. Nodes and outputs are both
described by XML tags. There are four categories of CPL nodes:
switches, which represent choices a CPL script can make; location
modifiers, which add or remove locations from the location set;
signalling operations, which cause signalling events in the
underlying protocol; and non-signalling operations, which trigger
behavior which does not effect the underlying protocol.
<cpl> 4 Switches
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<subaction id="voicemail"> <subaction id="voicemail">
<location url="sip:jones@voicemail.example.com"> <location url="sip:jones@voicemail.example.com">
<redirect /> <redirect />
</location> </location>
</subaction> </subaction>
<incoming> <incoming>
<address-switch field="origin" subfield="host"> <address-switch field="origin" subfield="host">
<address subdomain-of="example.com"> <address subdomain-of="example.com">
<location url="sip:jones@example.com"> <location url="sip:jones@example.com">
<proxy timeout="10"> <proxy timeout="10">
<busy> <sub ref="voicemail" /> </busy> <busy> <sub ref="voicemail" /> </busy>
<noanswer> <sub ref="voicemail" /> </noanswer> <noanswer> <sub ref="voicemail" /> </noanswer>
<failure> <sub ref="voicemail" /> </failure> <failure> <sub ref="voicemail" /> </failure>
</proxy> </proxy>
</location> </location>
skipping to change at page 8, line 35 skipping to change at page 8, line 33
</address> </address>
<otherwise> <otherwise>
<sub ref="voicemail" /> <sub ref="voicemail" />
</otherwise> </otherwise>
</address-switch> </address-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 2: Sample CPL Script: XML Version Figure 2: Sample CPL Script: XML Version
[Note to RFC editor: please replace "xxxx" above with the
number of this RFC.]
Note that the URIs specifying XML namespaces are only
globally unique names; they do not have to reference any
particular actual object. The URI of a canonical source of
this specification meets the requirement of being globally
unique, and is also useful to document the format.
3.2 MIME Registration
As an XML type, CPL's MIME registration conforms with "XML Media
Types," RFC 3023 [8].
MIME media type name: application
MIME subtype name: cpl+xml
Mandatory parameters: none
Optional parameters: charset
As for application/xml in RFC 3023.
Encoding considerations: As for application/xml in RFC 3023.
Security considerations: See Section 14, and Section 10 of RFC
3023.
Interoperability considerations: Different CPL servers may use
incompatible address types. However, all potential
interoperability issues should be resolvable at the time a
script is uploaded; there should be no interoperability
issues which cannot be detected until runtime.
Published specification: This document.
Applications which use this media type: None publicly released
at this time, as far as the authors are aware.
Additional information:
Magic number: None
File extension: .cpl or .xml
Macintosh file type code: "TEXT"
Person and e-mail address for further information:
Jonathan Lennox <lennox@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
Intended usage: COMMON
Author/Change Controller: The IETF.
4 Script Structure: Overview
As mentioned, a CPL script consists of ancillary information,
subactions, and top-level actions. The full syntax of the "cpl" node
is given in Figure 3.
Tag: "cpl" Tag: "cpl"
Parameters: None Parameters: None
Sub-tags: "ancillary" See Section 10 Sub-tags: "ancillary" See Section 9
"subaction" See Section 9 "subaction" See Section 8
"outgoing" Top-level actions to take on this user's "outgoing" Top-level actions to take on this user's
outgoing calls outgoing calls
"incoming" Top-level actions to take on this user's "incoming" Top-level actions to take on this user's
incoming calls incoming calls
Figure 3: Syntax of the top-level "cpl" tag Figure 3: Syntax of the top-level "cpl" tag
Call processing actions, both top-level actions and sub-actions,
consist of a tree of nodes and outputs. Nodes and outputs are both
described by XML tags. There are four categories of CPL nodes:
switches, which represent choices a CPL script can make; location
modifiers, which add or remove locations from the location set;
signalling operations, which cause signalling events in the
underlying protocol; and non-signalling operations, which trigger
behavior which does not effect the underlying protocol.
5 Switches
Switches represent choices a CPL script can make, based on either Switches represent choices a CPL script can make, based on either
attributes of the original call request or items independent of the attributes of the original call request or items independent of the
call. call.
All switches are arranged as a list of conditions that can match a All switches are arranged as a list of conditions that can match a
variable. Each condition corresponds to a node output; the output variable. Each condition corresponds to a node output; the output
points to the next node to execute if the condition was true. The points to the next node to execute if the condition was true. The
conditions are tried in the order they are presented in the script; conditions are tried in the order they are presented in the script;
the output corresponding to the first node to match is taken. the output corresponding to the first node to match is taken.
There are two special switch outputs that apply to every switch type. There are two special switch outputs that apply to every switch type.
The output "not-present", which MAY occur anywhere in the list of The output "not-present", which MAY occur anywhere in the list of
outputs, is true if the variable the switch was to match was not outputs, is true if the variable the switch was to match was not
present in the original call setup request. (In this document, this present in the original call setup request. (In this document, this
is sometimes described by saying that the information is "absent".) is sometimes described by saying that the information is "absent".)
The output "otherwise", which MUST be the last output specified if it The output "otherwise", which MUST be the last output specified if it
is present, matches if no other condition matched. is present, matches if no other condition matched.
If no condition matches and no "otherwise" output was present in the If no condition matches and no "otherwise" output was present in the
script, the default script behavior is taken. See Section 11 for more script, the default script behavior is taken. See Section 10 for more
information on this. information on this.
Switches MAY contain no outputs. They MAY contain only an "otherwise" Switches MAY contain no outputs. They MAY contain only an "otherwise"
output. output.
Such switches are not particularly useful, but might be Such switches are not particularly useful, but might be
created by tools which automatically generate CPL scripts. created by tools which automatically generate CPL scripts.
5.1 Address Switches 4.1 Address Switches
Address switches allow a CPL script to make decisions based on one of Address switches allow a CPL script to make decisions based on one of
the addresses present in the original call request. They are the addresses present in the original call request. They are
summarized in Figure 4. summarized in Figure 4.
Node: "address-switch"
Outputs: "address" Specific addresses to match
Parameters: "field" "origin", "destination",
or "original-destination"
"subfield" "address-type", "user", "host", "port",
"tel", or "display"
(also: "password" and "alias-type")
Output: "address"
Parameters: "is" exact match
"contains" substring match (for "display" only)
"subdomain-of" sub-domain match (for "host", "tel" only)
Figure 4: Syntax of the "address-switch" node
Address switches have two node parameters: "field", and "subfield". Address switches have two node parameters: "field", and "subfield".
The mandatory "field" parameter allows the script to specify which The mandatory "field" parameter allows the script to specify which
address is to be considered for the switch: either the call's origin address is to be considered for the switch: either the call's origin
address (field "origin"), its current destination address (field address (field "origin"), its current destination address (field
"destination"), or its original destination (field "original- "destination"), or its original destination (field "original-
destination"), the destination the call had before any earlier destination"), the destination the call had before any earlier
forwarding was invoked. Servers MAY define additional field values. forwarding was invoked. Servers MAY define additional field values.
The optional "subfield" specifies what part of the address is to be The optional "subfield" specifies what part of the address is to be
considered. The possible subfield values are: "address-type", "user", considered. The possible subfield values are: "address-type", "user",
"host", "port", "tel", and "display". Additional subfield values MAY "host", "port", "tel", and "display". Additional subfield values MAY
be defined for protocol-specific values. (The subfield "password" is be defined for protocol-specific values. (The subfield "password" is
defined for SIP in Section 5.1.1; the subfield "alias-type" is Node: "address-switch"
Outputs: "address" Specific addresses to match
Parameters: "field" "origin", "destination",
or "original-destination"
"subfield" "address-type", "user", "host",
"port", "tel", or "display"
(also: "password" and "alias-type")
Output: "address"
Parameters: "is" Exact match
"contains" Substring match (for "display" only)
"subdomain-of" Sub-domain match (for "host", "tel")
Figure 4: Syntax of the "address-switch" node
defined for SIP in Section 4.1.1; the subfield "alias-type" is
defined for H.323 in Appendix B.1.) If no subfield is specified, the defined for H.323 in Appendix B.1.) If no subfield is specified, the
"entire" address is matched; the precise meaning of this is defined "entire" address is matched; the precise meaning of this is defined
for each underlying signalling protocol. Servers MAY define for each underlying signalling protocol. Servers MAY define
additional subfield values. additional subfield values.
The subfields are defined as follows: The subfields are defined as follows:
address-type This indicates the type of the underlying address; address-type This indicates the type of the underlying address;
i.e., the URI scheme, if the address can be represented by i.e., the URI scheme, if the address can be represented by
a URI. The types specifically discussed by this document a URI. The types specifically discussed by this document
skipping to change at page 12, line 21 skipping to change at page 10, line 41
case-sensitive. It has a value for all defined address case-sensitive. It has a value for all defined address
types. types.
user This subfield of the address indicates, for e-mail style user This subfield of the address indicates, for e-mail style
addresses, the user part of the address. For telephone addresses, the user part of the address. For telephone
number style address, it includes the subscriber number. number style address, it includes the subscriber number.
This subfield is case-sensitive; it may be absent. This subfield is case-sensitive; it may be absent.
host This subfield of the address indicates the Internet host host This subfield of the address indicates the Internet host
name or IP address corresponding to the address, in host name or IP address corresponding to the address, in host
name, IPv4, or IPv6 [9] textual representation format. name, IPv4, or IPv6 [4] textual representation format.
Host names are compared as strings. IP addresses are Host names are compared as strings. IP addresses are
compared numerically. (In particular, the presence or compared numerically. (In particular, the presence or
location of an IPv6 :: omitted-zero-bits block is not location of an IPv6 :: omitted-zero-bits block is not
significant for matching purposes.) Host names are never significant for matching purposes.) Host names are never
equal to IP addresses -- no DNS resolution is performed. equal to IP addresses -- no DNS resolution is performed.
IPv4 addresses are never equal to IPv6 addresses, even if IPv4 addresses are never equal to IPv6 addresses, even if
the IPv6 address is a v4-in-v6 embedding. the IPv6 address is a v4-in-v6 embedding. This subfield is
not case sensitive, and may be absent.
For host names only, subdomain matching is supported with For host names only, subdomain matching is supported with
the "subdomain-of" match operator. The "subdomain-of" the "subdomain-of" match operator. The "subdomain-of"
operator ignores leading dots in the hostname or match operator ignores leading dots in the hostname or match
pattern, if any. This subfield is not case sensitive, and pattern, if any.
may be absent.
port This subfield indicates the TCP or UDP port number of the port This subfield indicates the TCP or UDP port number of the
address, numerically in decimal format. It is not case address, numerically in decimal format. It is not case
sensitive, as it MUST only contain decimal digits. Leading sensitive, as it MUST only contain decimal digits. Leading
zeros are ignored. This subfield may be absent; however, zeros are ignored.
for address types with default ports, an absent port
matches the default port number.
tel This subfield indicates a telephone subscriber number, if tel This subfield indicates a telephone subscriber number, if
the address contains such a number. It is not case the address contains such a number. It is not case
sensitive (the telephone numbers may contain the symbols sensitive (the telephone numbers may contain the symbols
`A' `B' `C' and `D'), and may be absent. It may be matched `A' `B' `C' and `D'), and may be absent. It may be matched
using the "subdomain-of" match operator. Punctuation and using the "subdomain-of" match operator. Punctuation and
separator characters in telephone numbers are discarded. separator characters in telephone numbers are discarded.
display This subfield indicates a "display name" or user-visible display This subfield indicates a "display name" or user-visible
name corresponding to an address. It is a Unicode string, name corresponding to an address. It is a Unicode string,
and is matched using the case-insensitive algorithm and is matched using the case-insensitive algorithm
described in Section 5.2. The "contains" operator may be described in Section 4.2. The "contains" operator may be
applied to it. It may be absent. applied to it. It may be absent.
For any completely unknown subfield, the server MAY reject the script For any completely unknown subfield, the server MAY reject the script
at the time it is submitted with an indication of the problem; if a at the time it is submitted with an indication of the problem; if a
script with an unknown subfield is executed, the server MUST consider script with an unknown subfield is executed, the server MUST consider
the "not-present" output to be the valid one. the "not-present" output to be the valid one.
The "address" output tag may take exactly one of three possible The "address" output tag may take exactly one of three possible
parameters, indicating the kind of matching allowed. parameters, indicating the kind of matching allowed.
skipping to change at page 13, line 39 skipping to change at page 12, line 13
match exactly. In the case of the "tel" subfield, the match exactly. In the case of the "tel" subfield, the
output matches if the telephone number being matched has a output matches if the telephone number being matched has a
prefix that matches the argument of the match operator; prefix that matches the argument of the match operator;
subdomain-of="1212555" would match the telephone number "1 subdomain-of="1212555" would match the telephone number "1
212 555 1212." 212 555 1212."
contains This match operator applies only for the subfield contains This match operator applies only for the subfield
"display". The output matches if the display name being "display". The output matches if the display name being
matched contains the argument of the match as a substring. matched contains the argument of the match as a substring.
5.1.1 Usage of "address-switch" with SIP 4.1.1 Usage of "address-switch" with SIP
For SIP, the "origin" address corresponds to the address in the For SIP, the "origin" address corresponds to the address in the
"From" header; "destination" corresponds to the "Request-URI"; and "From" header; "destination" corresponds to the "Request-URI"; and
"original-destination" corresponds to the "To" header. "original-destination" corresponds to the "To" header.
The "display" subfield of an address is the display-name part of the The "display" subfield of an address is the display-name part of the
address, if it is present. Because of SIP's syntax, the "destination" address, if it is present. Because of SIP's syntax, the "destination"
address field will never have a "display" subfield. address field will never have a "display" subfield.
The "address-type" subfield of an address is the URI scheme of that The "address-type" subfield of an address is the URI scheme of that
address. Other address fields depend on that "address-type". address. Other address fields depend on that "address-type".
For sip URLs, the "user", "host", and "port" subfields correspond to For SIP URIs, the "user", "host", and "port" subfields correspond to
the "user," "host," and "port" elements of the URI syntax. The "tel" the "user," "host," and "port" elements of the URI syntax. (Note
subfield is defined to be the "user" part of the URI, with visual that, following the definitions of RFC 3261 [1], a SIP URI which does
separators stripped, if and only if the "user=phone" parameter is not specify a port is not the same as an explicit port 5060; the
given to the URI. An additional subfield, "password" is defined to former is indicated by an absent port subfield.)
correspond to the "password" element of the SIP URI, and is case-
sensitive. However, use of this field is NOT RECOMMENDED for general The "tel" subfield is defined to be the "user" part of the URI, with
security reasons. visual separators stripped, if the "user=phone" parameter is given to
the URI, or if the server is otherwise configured to recognize the
user part as a telephone number. An additional subfield, "password"
is defined to correspond to the "password" element of the SIP URI,
and is case-sensitive. However, use of this field is NOT RECOMMENDED
for general security reasons.
For tel URLs, the "tel" and "user" subfields are the subscriber name; For tel URLs, the "tel" and "user" subfields are the subscriber name;
in the former case, visual separators are stripped. The "host" and in the former case, visual separators are stripped. The "host" and
"port" subfields are both not present. "port" subfields are both not present.
For h323 URLs, subfields MAY be set according to the scheme described For h323 URLs, subfields MAY be set according to the scheme described
in Appendix B. in Appendix B.
For other URI schemes, only the "address-type" subfield is defined by For other URI schemes, only the "address-type" subfield is defined by
this specification; servers MAY set other pre-defined subfields, or this specification; servers MAY set other pre-defined subfields, or
MAY support additional subfields. MAY support additional subfields.
If no subfield is specified for addresses in SIP messages, the string If no subfield is specified for addresses in SIP messages, the string
matched is the URI part of the address. For "is" matches, standard matched is the URI part of the address. For "is" matches, standard
SIP URI matching rules are used; for "contains" matches, the URI is SIP URI matching rules are used; for "contains" matches, the URI is
used verbatim. used verbatim.
5.2 String Switches 4.2 String Switches
String switches allow a CPL script to make decisions based on free- String switches allow a CPL script to make decisions based on free-
form strings present in a call request. They are summarized in Figure form strings present in a call request. They are summarized in Figure
5. 5.
Node: "string-switch" Node: "string-switch"
Outputs: "string" Specific string to match Outputs: "string" Specific string to match
Parameters: "field" "subject", "organization", "user-agent", Parameters: "field" "subject", "organization",
or "display" "user-agent", or "display"
Output: "string" Output: "string"
Parameters: "is" exact match Parameters: "is" Exact match
"contains" substring match "contains" Substring match
Figure 5: Syntax of the "string-switch" node Figure 5: Syntax of the "string-switch" node
String switches have one node parameter: "field". The mandatory String switches have one node parameter: "field". The mandatory
"field" parameter specifies which string is to be matched. "field" parameter specifies which string is to be matched.
String switches are dependent on the call signalling protocol being String switches are dependent on the call signalling protocol being
used. used.
Five fields are defined, listed below. The value of each of these Five fields are defined, listed below. The value of each of these
skipping to change at page 15, line 26 skipping to change at page 14, line 5
"user-agent" The name of the program or device with which the "user-agent" The name of the program or device with which the
call request was made. call request was made.
"display" Free-form text associated with the call, intended to "display" Free-form text associated with the call, intended to
be displayed to the recipient, with no other semantics be displayed to the recipient, with no other semantics
defined by the signalling protocol. defined by the signalling protocol.
Strings are matched as case-insensitive Unicode strings, in the Strings are matched as case-insensitive Unicode strings, in the
following manner. First, strings are canonicalized to the following manner. First, strings are canonicalized to the
"Compatibility Composition" (KC) form, as specified in Unicode "Compatibility Composition" (KC) form, as specified in Unicode
Technical Report 15 [10]. Then, strings are compared using locale- Technical Report 15 [5]. Then, strings are compared using locale-
insensitive caseless mapping, as specified in Unicode Technical insensitive caseless mapping, as specified in Unicode Technical
Report 21 [11]. Report 21 [6].
Code to perform the first step, in Java and Perl, is Code to perform the first step, in Java and Perl, is
available; see the links from Annex E of UTR 15 [10]. The available; see the links from Annex E of UTR 15 [5]. The
case-insensitive string comparison in the Java standard case-insensitive string comparison in the Java standard
class libraries already performs the second step; other class libraries already performs the second step; other
Unicode-aware libraries should be similar. Unicode-aware libraries should be similar.
The output tags of string matching are named "string", and have a The output tag of string matching is named "string", and has a
mandatory argument, one of "is" or "contains", indicating whole- mandatory argument, one of "is" or "contains", indicating whole-
string match or substring match, respectively. string match or substring match, respectively.
5.2.1 Usage of "string-switch" with SIP 4.2.1 Usage of "string-switch" with SIP
For SIP, the fields "subject", "organization", and "user-agent" For SIP, the fields "subject", "organization", and "user-agent"
correspond to the SIP header fields with the same name. These are correspond to the SIP header fields with the same name. These are
used verbatim as they appear in the message. used verbatim as they appear in the message.
The field "display" is not used, and is never present. The field "display" is not used, and is never present.
5.3 Language Switches 4.3 Language Switches
Language switches allow a CPL script to make decisions based on the Language switches allow a CPL script to make decisions based on the
languages in which the originator of the call wishes to communicate. languages in which the originator of the call wishes to communicate.
They are summarized in Figure 6. They are summarized in Figure 6.
Node: "language-switch" Node: "language-switch"
Outputs: "language" Specific string to match Outputs: "language" Specific string to match
Parameters: None Parameters: None
Output: "language" Output: "language"
Parameters: "matches" Match if the given language matches a Parameters: "matches" Match if the given language matches a
language-range of the call. language-range of the call.
skipping to change at page 16, line 19 skipping to change at page 14, line 45
Parameters: None Parameters: None
Output: "language" Output: "language"
Parameters: "matches" Match if the given language matches a Parameters: "matches" Match if the given language matches a
language-range of the call. language-range of the call.
Figure 6: Syntax of the "language-switch" node Figure 6: Syntax of the "language-switch" node
Language switches take no parameters. Language switches take no parameters.
The "language" outputs take one parameter, "matches". The value of The "language" output takes one parameter, "matches". The value of
one of these parameters is a language-tag, as defined in RFC 3066 the parameter is a language-tag, as defined in RFC 3066 [7]. The
[12]. The caller may have specified a set of language-ranges, also as caller may have specified a set of language-ranges, also as defined
defined in RFC 3066. The CPL server checks each language-tag in RFC 3066. The CPL server checks each language-tag specified by the
specified by the script against the language-ranges specified in the script against the language-ranges specified in the request.
request.
See RFC 3066 for the details of how language-ranges match language- See RFC 3066 for the details of how language-ranges match language-
tags. Briefly, a language-range matches a language-tag if it exactly tags. Briefly, a language-range matches a language-tag if it exactly
equals the tag, or if it exactly equals a prefix of the tag such that equals the tag, or if it exactly equals a prefix of the tag such that
the first character following the prefix is "-". the first character following the prefix is "-".
If the caller specified the special language-range "*", it is ignored If the caller specified the special language-range "*", it is ignored
for the purpose of matching. Languages with a "q" value of 0 are for the purpose of matching. Languages with a "q" value of 0 are also
also ignored. ignored.
This switch MAY be not-present. This switch MAY be not-present.
5.3.1 Usage of "language-switch" with SIP 4.3.1 Usage of "language-switch" with SIP
The language-ranges for the "language-switch" switch are obtained The language-ranges for the "language-switch" switch are obtained
from the SIP "Accept-Language" header field. The switch is not- from the SIP "Accept-Language" header field. The switch is not-
present if the initial SIP request did not contain this header field. present if the initial SIP request did not contain this header field.
Note that because of CPL's first-match semantics in Note that because of CPL's first-match semantics in
switches, "q" values other than 0 of the "Accept-Language" switches, "q" values other than 0 of the "Accept-Language"
header fields are ignored. header fields are ignored.
5.4 Time Switches 4.4 Time Switches
Time switches allow a CPL script to make decisions based on the time Time switches allow a CPL script to make decisions based on the time
and/or date the script is being executed. They are summarized in and/or date the script is being executed. They are summarized in
Figure 7. Figure 7.
Time switches are independent of the underlying signalling protocol. Time switches are independent of the underlying signalling protocol.
Time switches are based closely on the specification of recurring
intervals of time in the Internet Calendaring and Scheduling Core
Object Specification (iCalendar COS), RFC 2445 [8].
This allows CPL scripts to be generated automatically from
calendar books. It also allows us to re-use the extensive
existing work specifying time intervals.
If future standards-track documents are published that update or
obsolete RFC 2445, any changes or clarifications those documents make
to recurrence handling apply to CPL time-switches as well.
Node: "time-switch" Node: "time-switch"
Outputs: "time" Specific time to match Outputs: "time" Specific time to match
Parameters: "tzid" RFC 2445 Time Zone Identifier Parameters: "tzid" RFC 2445 Time Zone Identifier
"tzurl" RFC 2445 Time Zone URL "tzurl" RFC 2445 Time Zone URL
Output: "time" Output: "time"
Parameters: "dtstart" Start of interval (RFC 2445 DATE-TIME) Parameters: "dtstart" Start of interval (RFC 2445 DATE-TIME)
"dtend" End of interval (RFC 2445 DATE-TIME) "dtend" End of interval (RFC 2445 DATE-TIME)
"duration" Length of interval (RFC 2445 DURATION) "duration" Length of interval (RFC 2445 DURATION)
"freq" Frequency of recurrence (one of "secondly", "freq" Frequency of recurrence ("secondly",
"minutely", "hourly", "daily", "minutely", "hourly", "daily",
"weekly", "monthly", or "yearly") "weekly", "monthly", or "yearly")
"interval" How often the recurrence repeats "interval" How often the recurrence repeats
"until" Bound of recurrence (RFC 2445 DATE-TIME) "until" Bound of recurrence (RFC 2445 DATE-TIME)
"count" Number of occurrences of recurrence "count" Number of occurrences of recurrence
"bysecond" List of seconds within a minute "bysecond" List of seconds within a minute
"byminute" List of minutes within an hour "byminute" List of minutes within an hour
"byhour" List of hours of the day "byhour" List of hours of the day
"byday" List of days of the week "byday" List of days of the week
"bymonthday" List of days of the month "bymonthday" List of days of the month
"byyearday" List of days of the year "byyearday" List of days of the year
"byweekno" List of weeks of the year "byweekno" List of weeks of the year
"bymonth" List of months of the year "bymonth" List of months of the year
"wkst" First day of the work week "wkst" First day of the work week
"bysetpos" List of values within set of events specified "bysetpos" List of values within
set of events specified
Figure 7: Syntax of the "time-switch" node Figure 7: Syntax of the "time-switch" node
Time switches are based closely on the specification of recurring An algorithm to determine whether an instant falls within a given
intervals of time in the Internet Calendaring and Scheduling Core recurrence is given in Appendix A.
Object Specification (iCalendar COS), RFC 2445 [13].
This allows CPL scripts to be generated automatically from
calendar books. It also allows us to re-use the extensive
existing work specifying time intervals.
If future standards-track documents are published that update or
obsolete RFC 2445, any changes or clarifications those documents make
to recurrence handling apply to CPL time-switches as well.
An algorithm to whether an instant falls within a given recurrence is
given in Appendix A.
The "time-switch" tag takes two optional parameters, "tzid" and The "time-switch" tag takes two optional parameters, "tzid" and
"tzurl", both of which are defined in RFC 2445 (Sections 4.8.3.1 and "tzurl", both of which are defined in RFC 2445 (Sections 4.8.3.1 and
4.8.3.5 respectively). The TZID is the identifying label by which a 4.8.3.5 respectively). The "tzid" is the identifying label by which a
time zone definition is referenced. If it begins with a forward slash time zone definition is referenced. If it begins with a forward slash
(solidus), it references a to-be-defined global time zone registry; (solidus), it references a to-be-defined global time zone registry;
otherwise it is locally-defined at the server. The TZURL gives a otherwise it is locally-defined at the server. The "tzurl" gives a
network location from which an up-to-date VTIMEZONE definition for network location from which an up-to-date VTIMEZONE definition for
the timezone can be retrieved. the timezone can be retrieved.
While TZID labels that do not begin with a forward slash are locally While "tzid" labels that do not begin with a forward slash are
defined, it is RECOMMENDED that servers support at least the naming locally defined, it is RECOMMENDED that servers support at least the
scheme used by Olson Time Zone database [14]. Examples of timezone naming scheme used by Olson Time Zone database [9]. Examples of
databases that use the Olson scheme are the zoneinfo files on most timezone databases that use the Olson scheme are the zoneinfo files
Unix-like systems, and the standard Java TimeZone class. on most Unix-like systems, and the standard Java TimeZone class.
Servers SHOULD resolve TZID and TZURL references to time zone Servers SHOULD resolve "tzid" and "tzurl" references to time zone
definitions at the time the script is uploaded. They MAY periodically definitions at the time the script is uploaded. They MAY periodically
refresh these resolutions to obtain the most up-to-date definition of refresh these resolutions to obtain the most up-to-date definition of
a time zone. If a TZURL becomes invalid, servers SHOULD remember the a time zone. If a "tzurl" becomes invalid, servers SHOULD remember
most recent valid data retrieved from the URL. the most recent valid data retrieved from the URL.
If a script is uploaded with a "tzid" and "tzurl" which the CPL If a script is uploaded with a "tzid" and "tzurl" which the CPL
server does not recognize or cannot resolve, it SHOULD diagnose and server does not recognize or cannot resolve, it SHOULD diagnose and
reject this at script upload time. If neither "tzid" nor "tzurl" are reject this at script upload time. If neither "tzid" nor "tzurl" are
present, all non-UTC times within this time switch should be present, all non-UTC times within this time switch should be
interpreted as being "floating" times, i.e. that they are specified interpreted as being "floating" times, i.e. that they are specified
in the local timezone of the CPL server. in the local timezone of the CPL server.
Because of daylight-savings-time changes over the course of Because of daylight-savings-time changes over the course of
a year, it is necessary to specify time switches in a given a year, it is necessary to specify time switches in a given
skipping to change at page 19, line 11 skipping to change at page 17, line 38
of daylight-savings time. Note especially that some times may occur of daylight-savings time. Note especially that some times may occur
more than once when clocks are set back. The algorithm in Appendix A more than once when clocks are set back. The algorithm in Appendix A
is believed to handle this correctly. is believed to handle this correctly.
Time nodes specify a list of periods during which their output should Time nodes specify a list of periods during which their output should
be taken. They have two required parameters: "dtstart", which be taken. They have two required parameters: "dtstart", which
specifies the beginning of the first period of the list, and exactly specifies the beginning of the first period of the list, and exactly
one of "dtend" or "duration", which specify the ending time or the one of "dtend" or "duration", which specify the ending time or the
duration of the period, respectively. The "dtstart" and "dtend" duration of the period, respectively. The "dtstart" and "dtend"
parameters are formatted as iCalendar COS DATE-TIME values, as parameters are formatted as iCalendar COS DATE-TIME values, as
specified in Section 4.3.5 of RFC 2445 [13]. Because time zones are specified in Section 4.3.5 of RFC 2445 [8]. Because time zones are
specified in the top-level "time-switch" tag, only forms 1 or 2 specified in the top-level "time-switch" tag, only forms 1 or 2
(floating or UTC times) can be used. The "duration" parameter is (floating or UTC times) can be used. The "duration" parameter is
given as an iCalendar COS DURATION parameter, as specified in section given as an iCalendar COS DURATION parameter, as specified in section
4.3.6 of RFC 2445. Both the DATE-TIME and the DURATION syntaxes are 4.3.6 of RFC 2445. Both the DATE-TIME and the DURATION syntaxes are
subsets of the corresponding syntaxes from ISO 8601 [15]. subsets of the corresponding syntaxes from ISO 8601 [20].
For a recurring interval, the "duration" parameter MUST be small For a recurring interval, the "duration" parameter MUST be small
enough such that subsequent intervals do not overlap. For non- enough such that subsequent intervals do not overlap. For non-
recurring intervals, durations of any positive length are permitted. recurring intervals, durations of any positive length are permitted.
Zero-length and negative-length durations are not allowed. Zero-length and negative-length durations are not allowed.
If no other parameters are specified, a time node indicates only a If no other parameters are specified, a time node indicates only a
single period of time. More complicated sets periods intervals are single period of time. More complicated sets periods intervals are
constructed as recurrences. A recurrence is specified by including constructed as recurrences. A recurrence is specified by including
the "freq" parameter, which indicates the type of recurrence rule. No the "freq" parameter, which indicates the type of recurrence rule.
parameters other than "dtstart", "dtend", and "duration" SHOULD be Parameters other than "dtstart", "dtend", and "duration" SHOULD NOT
specified unless "freq" is present, though CPL servers SHOULD accept be specified unless "freq" is present, though CPL servers SHOULD
scripts with such parameters present, and ignore the other accept scripts with such parameters present, and ignore the other
parameters. parameters.
The "freq" parameter takes one of the following values: "secondly", The "freq" parameter takes one of the following values: "secondly",
to specify repeating periods based on an interval of a second or to specify repeating periods based on an interval of a second or
more; "minutely", to specify repeating periods based on an interval more; "minutely", to specify repeating periods based on an interval
of a minute or more; "hourly", to specify repeating periods based on of a minute or more; "hourly", to specify repeating periods based on
an interval of an hour or more; "daily", to specify repeating periods an interval of an hour or more; "daily", to specify repeating periods
based on an interval of a day or more; "weekly", to specify repeating based on an interval of a day or more; "weekly", to specify repeating
periods based on an interval of a week or more; "monthly", to specify periods based on an interval of a week or more; "monthly", to specify
repeating periods based on an interval of a month or more; and repeating periods based on an interval of a month or more; and
"yearly", to specify repeating periods based on an interval of a year "yearly", to specify repeating periods based on an interval of a year
or more. These values are not case-sensitive. or more. These values are not case-sensitive.
The "interval" parameter contains a positive integer representing how The "interval" parameter contains a positive integer representing how
often the recurrence rule repeats. The default value is "1", meaning often the recurrence rule repeats. The default value is "1", meaning
every day for a "daily" rule, every week for a "weekly" rule, every every second for a "secondly" rule, every minute for a "minutely"
month for a "monthly" rule and every year for a "yearly" rule. rule, every hour for an "hourly" rule, every day for a "daily" rule,
every week for a "weekly" rule, every month for a "monthly" rule and
every year for a "yearly" rule.
The "until" parameter defines an iCalendar COS DATE or DATE-TIME The "until" parameter defines an iCalendar COS DATE or DATE-TIME
value which bounds the recurrence rule in an inclusive manner. If the value which bounds the recurrence rule in an inclusive manner. If the
value specified by "until" is synchronized with the specified value specified by "until" is synchronized with the specified
recurrence, this date or date-time becomes the last instance of the recurrence, this date or date-time becomes the last instance of the
recurrence. If specified as a date-time value, then it MUST be recurrence. If specified as a date-time value, then it MUST be
specified in an UTC time format. If not present, and the "count" specified in an UTC time format. If not present, and the "count"
parameter is not also present, the recurrence is considered to repeat parameter is not also present, the recurrence is considered to repeat
forever. forever.
skipping to change at page 20, line 46 skipping to change at page 19, line 29
represents the tenth to the last day of the month. represents the tenth to the last day of the month.
The "byyearday" parameter specifies a comma-separated list of days of The "byyearday" parameter specifies a comma-separated list of days of
the year. Valid values are 1 to 366 or -366 to -1. For example, -1 the year. Valid values are 1 to 366 or -366 to -1. For example, -1
represents the last day of the year (December 31st) and -306 represents the last day of the year (December 31st) and -306
represents the 306th to the last day of the year (March 1st). represents the 306th to the last day of the year (March 1st).
The "byweekno" parameter specifies a comma-separated list of ordinals The "byweekno" parameter specifies a comma-separated list of ordinals
specifying weeks of the year. Valid values are 1 to 53 or -53 to -1. specifying weeks of the year. Valid values are 1 to 53 or -53 to -1.
This corresponds to weeks according to week numbering as defined in This corresponds to weeks according to week numbering as defined in
ISO 8601 [15]. A week is defined as a seven day period, starting on ISO 8601 [20]. A week is defined as a seven day period, starting on
the day of the week defined to be the week start (see "wkst"). Week the day of the week defined to be the week start (see "wkst"). Week
number one of the calendar year is the first week which contains at number one of the calendar year is the first week which contains at
least four (4) days in that calendar year. This parameter is only least four (4) days in that calendar year. This parameter is only
valid for "yearly" rules. For example, 3 represents the third week of valid for "yearly" rules. For example, 3 represents the third week of
the year. the year.
Note: Assuming a Monday week start, week 53 can only occur Note: Assuming a Monday week start, week 53 can only occur
when Thursday is January 1 or if it is a leap year and when Thursday is January 1 or if it is a leap year and
Wednesday is January 1. Wednesday is January 1.
The "bymonth" parameter specifies a comma-separated list of months of The "bymonth" parameter specifies a comma-separated list of months of
the year. Valid values are 1 to 12. the year. Valid values are 1 to 12.
The "wkst" parameter specifies the day on which the work week starts. The "wkst" parameter specifies the day on which the work week starts.
Valid values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU". This is Valid values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU". This is
significant when a "weekly" recurrence has an interval greater than significant when a "weekly" recurrence has an interval greater than
1, and a "byday" parameter is specified. This is also significant in 1, and a "byday" parameter is specified. This is also significant in
a "yearly" recurrence when a "byweekno" parameter is specified. The a "yearly" recurrence when a "byweekno" parameter is specified. The
default value is "MO", following ISO 8601 [15]. default value is "MO", following ISO 8601 [20].
The "bysetpos" parameter specifies a comma-separated list of values The "bysetpos" parameter specifies a comma-separated list of values
which corresponds to the nth occurrence within the set of events which corresponds to the nth occurrence within the set of events
specified by the rule. Valid values are 1 to 366 or -366 to -1. It specified by the rule. Valid values are 1 to 366 or -366 to -1. It
MUST only be used in conjunction with another byxxx parameter. For MUST only be used in conjunction with another byxxx parameter. For
example "the last work day of the month" could be represented as: example "the last work day of the month" could be represented as:
<time -timerange- freq="monthly" byday="MO,TU,WE,TH,FR" <time -timerange- freq="monthly" byday="MO,TU,WE,TH,FR"
bysetpos="-1"> bysetpos="-1">
skipping to change at page 22, line 11 skipping to change at page 20, line 41
If multiple Byxxx parameters are specified, then after evaluating the If multiple Byxxx parameters are specified, then after evaluating the
specified "freq" and "interval" parameters, the Byxxx parameters are specified "freq" and "interval" parameters, the Byxxx parameters are
applied to the current set of evaluated occurrences in the following applied to the current set of evaluated occurrences in the following
order: "bymonth", "byweekno", "byyearday", "bymonthday", "byday", order: "bymonth", "byweekno", "byyearday", "bymonthday", "byday",
"byhour", "byminute", "bysecond" and "bysetpos"; then "count" and "byhour", "byminute", "bysecond" and "bysetpos"; then "count" and
"until" are evaluated. "until" are evaluated.
Here is an example of evaluating multiple Byxxx parameters. Here is an example of evaluating multiple Byxxx parameters.
<time dtstart="19970105T083000" duration="10M" <time dtstart="19970105T083000" duration="10M"
freq="yearly" interval="2" bymonth="1" byday="SU" byhour="8,9" freq="yearly" interval="2" bymonth="1" byday="SU"
byminute="30"> byhour="8,9" byminute="30">
First, the interval="2" would be applied to freq="YEARLY" to arrive First, the interval="2" would be applied to freq="yearly" to arrive
at "every other year." Then, bymonth="1" would be applied to arrive at "every other year." Then, bymonth="1" would be applied to arrive
at "every January, every other year." Then, byday="SU" would be at "every January, every other year." Then, byday="SU" would be
applied to arrive at "every Sunday in January, every other year." applied to arrive at "every Sunday in January, every other year."
Then, byhour="8,9" would be applied to arrive at "every Sunday in Then, byhour="8,9" would be applied to arrive at "every Sunday in
January at 8 AM and 9 AM, every other year." Then, byminute="30" January at 8 AM and 9 AM, every other year." Then, byminute="30"
would be applied to arrive at "every Sunday in January at 8:30 AM and would be applied to arrive at "every Sunday in January at 8:30 AM and
9:30 AM, every other year." Then the second is derived from "dtstart" 9:30 AM, every other year." Then the second is derived from "dtstart"
to end up in "every Sunday in January from 8:30:00 AM to 8:40:00 AM, to end up in "every Sunday in January from 8:30:00 AM to 8:40:00 AM,
and from and 9:30:00 AM to 9:40:00 AM, every other year." Similarly, and from and 9:30:00 AM to 9:40:00 AM, every other year." Similarly,
if the "byminute", "byhour", "byday", "bymonthday" or "bymonth" if the "byminute", "byhour", "byday", "bymonthday" or "bymonth"
parameter were missing, the appropriate minute, hour, day or month parameter were missing, the appropriate minute, hour, day or month
would have been retrieved from the "dtstart" parameter. would have been retrieved from the "dtstart" parameter.
The iCalendar COS RDATE, EXRULE and EXDATE recurrence rules are not The iCalendar COS RDATE, EXRULE and EXDATE recurrence rules are not
specifically mapped to components of the time-switch node. Equivalent specifically mapped to components of the time-switch node. Equivalent
functionality to the exception rules can be attained by using the functionality to the exception rules can be attained by using the
ordering of switch rules to exclude times using earlier rules; ordering of switch rules to exclude times using earlier rules;
equivalent functionality to the additional-date RDATE rules can be equivalent functionality to the additional-date RDATE rules can be
attained by using "sub" nodes (see Section 9) to link multiple attained by using "sub" nodes (see Section 8) to link multiple
outputs to the same subsequent node. outputs to the same subsequent node.
The "not-present" output is never true for a time switch. However, it The "not-present" output is never true for a time switch. However, it
MAY be included, to allow switch processing to be more regular. MAY be included, to allow switch processing to be more regular.
5.4.1 iCalendar differences and implementation issues 4.4.1 iCalendar differences and implementation issues
(This sub-sub-section is non-normative.) (This sub-sub-section is non-normative.)
The specification of recurring events in this section is identical The specification of recurring events in this section is identical
(except for syntax and formatting issues) to that of RFC 2445 [13], (except for syntax and formatting issues) to that of RFC 2445 [8],
with only one additional restriction. That one restriction is that with only one additional restriction. That one restriction is that
consecutive instances of recurrence intervals may not overlap. consecutive instances of recurrence intervals may not overlap.
It was a matter of some debate, during the design of the CPL, whether It was a matter of some debate, during the design of CPL, whether the
the entire iCalendar COS recurrence specification should be included entire iCalendar COS recurrence specification should be included in
in CPL, or whether only a subset should be included. It was CPL, or whether only a subset should be included. It was eventually
eventually decided that compatibility between the two protocols was decided that compatibility between the two protocols was of primary
of primary importance. This imposes some additional implementation importance. This imposes some additional implementation issues on
issues on implementors of CPL servers. implementors of CPL servers.
It does not appear to be possible to determine, in constant time, It does not appear to be possible to determine, in constant time,
whether a given instant of time falls within one of the intervals whether a given instant of time falls within one of the intervals
defined by a full iCalendar COS recurrence. The primary concerns are defined by a full iCalendar COS recurrence. The primary concerns are
as follows: as follows:
o The "count" parameter cannot be checked in constant running o The "count" parameter cannot be checked in constant running
time, since it requires that the server enumerate all time, since it requires that the server enumerate all
recurrences from "dtstart" to the present time, in order to recurrences from "dtstart" to the present time, in order to
determine whether the current recurrence satisfies the determine whether the current recurrence satisfies the
skipping to change at page 23, line 50 skipping to change at page 22, line 35
to some extent pre-processing can help resolve this. to some extent pre-processing can help resolve this.
The algorithm given in Appendix A runs in constant time after these The algorithm given in Appendix A runs in constant time after these
pre-processing steps. pre-processing steps.
Servers ought to check that recurrence rules do not create any absurd Servers ought to check that recurrence rules do not create any absurd
run-time or memory requirements, and reject those that do, just as run-time or memory requirements, and reject those that do, just as
they ought to check that CPL scripts in general are not absurdly they ought to check that CPL scripts in general are not absurdly
large. large.
5.5 Priority Switches 4.5 Priority Switches
Priority switches allow a CPL script to make decisions based on the Priority switches allow a CPL script to make decisions based on the
priority specified for the original call. They are summarized in priority specified for the original call. They are summarized in
Figure 8. They are dependent on the underlying signalling protocol. Figure 8. They are dependent on the underlying signalling protocol.
Node: "priority-switch"
Outputs: "priority" Specific priority to match
Parameters: None
Output: "priority"
Parameters: "less" Match if priority is less than specified
"greater" Match if priority is greater than specified
"equal" Match if priority is equal to specified
Figure 8: Syntax of the "priority-switch" node
Priority switches take no parameters. Priority switches take no parameters.
The "priority" tags take one of the three parameters "greater", The "priority" tag takes one of the three parameters "greater",
"less", and "equal". The values of these tags are one of the "less", and "equal". The values of these parameters are one of the
following priorities: in decreasing order, "emergency", "urgent", following priorities: in decreasing order, "emergency", "urgent",
"normal", and "non-urgent". These values are matched in a case- "normal", and "non-urgent". These values are matched in a case-
insensitive manner. Outputs with the "less" parameter are taken if insensitive manner. Outputs with the "less" parameter are taken if
the priority of the call is less than the priority given in the the priority of the call is less than the priority given in the
argument; and so forth. argument; and so forth.
If no priority header is specified in a message, the priority is Node: "priority-switch"
considered to be "normal". If an unknown priority is specified in the Outputs: "priority" Specific priority to match
call, it is considered to be equivalent to "normal" for the purposes Parameters: None
of "greater" and "less" comparisons, but it is compared literally for
Output: "priority"
Parameters: "less" Match if priority is less
than that specified
"greater" Match if priority is greater
than that specified
"equal" Match if priority is equal
to that specified
Figure 8: Syntax of the "priority-switch" node
If no priority is specified in a message, the priority is considered
to be "normal". If an unknown priority is specified in the call, it
is considered to be equivalent to "normal" for the purposes of
"greater" and "less" comparisons, but it is compared literally for
"equal" comparisons. "equal" comparisons.
Since every message has a priority, the "not-present" output is never Since every message has a priority, the "not-present" output is never
true for a priority switch. However, it MAY be included, to allow true for a priority switch. However, it MAY be included, to allow
switch processing to be more regular. switch processing to be more regular.
5.5.1 Usage of "priority-switch" with SIP 4.5.1 Usage of "priority-switch" with SIP
The priority of a SIP message corresponds to the "Priority" header in The priority of a SIP message corresponds to the "Priority" header in
the initial "INVITE" message. the initial "INVITE" message.
6 Location Modifiers 5 Location Modifiers
The abstract location model of the CPL is described in Section 2.3. The abstract location model of CPL is described in Section 2.3. The
The behavior of several of the signalling operations (defined in behavior of several of the signalling operations (defined in Section
Section 7) is dependent on the current location set specified. 6) is dependent on the current location set specified. Location nodes
Location nodes add or remove locations from the location set. add or remove locations from the location set.
There are three types of location nodes defined. Explicit locations There are three types of location nodes defined. Explicit locations
add literally-specified locations to the current location set; add literally-specified locations to the current location set;
location lookups obtain locations from some outside source; and location lookups obtain locations from some outside source; and
location filters remove locations from the set, based on some location filters remove locations from the set, based on some
specified criteria. specified criteria.
6.1 Explicit Location 5.1 Explicit Location
Explicit location nodes specify a location literally. Their syntax is Explicit location nodes specify a location literally. Their syntax is
described in Figure 9. described in Figure 9.
Explicit location nodes are dependent on the underlying signalling Explicit location nodes are dependent on the underlying signalling
protocol. protocol.
Node: "location" Node: "location"
Outputs: None (next node follows directly) Outputs: None (Next node follows directly)
Next node: Any node Next node: Any node
Parameters: "url" URL of address to add to location set Parameters: "url" URL of address to add to location set
"priority" Priority of this location (0.0-1.0) "priority" Priority of this location (0.0-1.0)
"clear" Whether to clear the location set before adding "clear" Whether to clear the location set before
the new value adding the new value
Figure 9: Syntax of the "location" node Figure 9: Syntax of the "location" node
Explicit location nodes have three node parameters. The mandatory Explicit location nodes have three node parameters. The mandatory
"url" parameter's value is the URL of the address to add to the "url" parameter's value is the URL of the address to add to the
location set. Only one address may be specified per location node; location set. Only one address may be specified per location node;
multiple locations may be specified by cascading these nodes. multiple locations may be specified by cascading these nodes.
The optional "priority" parameter specifies a priority for the The optional "priority" parameter specifies a priority for the
location. Its value is a floating-point number between 0.0 and 1.0. location. Its value is a floating-point number between 0.0 and 1.0.
skipping to change at page 26, line 7 skipping to change at page 24, line 39
can be "yes" or "no", with "no" as the default. can be "yes" or "no", with "no" as the default.
Basic location nodes have only one possible result, since there is no Basic location nodes have only one possible result, since there is no
way that they can fail. (If a basic location node specifies a way that they can fail. (If a basic location node specifies a
location which isn't supported by the underlying signalling protocol, location which isn't supported by the underlying signalling protocol,
the script server SHOULD detect this and report it to the user at the the script server SHOULD detect this and report it to the user at the
time the script is submitted.) Therefore, their XML representations time the script is submitted.) Therefore, their XML representations
do not have explicit output tags; the <location> tag directly do not have explicit output tags; the <location> tag directly
contains another node. contains another node.
6.1.1 Usage of "location" with SIP 5.1.1 Usage of "location" with SIP
All SIP locations are represented as URLs, so the locations specified All SIP locations are represented as URLs, so the locations specified
in "location" tags are interpreted directly. in "location" tags are interpreted directly.
6.2 Location Lookup 5.2 Location Lookup
Locations can also be specified up through external means, through Locations can also be specified up through external means, through
the use of location lookups. The syntax of these tags is given in the use of location lookups. The syntax of these tags is given in
Figure 10. Figure 10.
Location lookup is dependent on the underlying signalling protocol. Location lookup is dependent on the underlying signalling protocol.
Node: "lookup" Node: "lookup"
Outputs: "success" Next node if lookup was successful Outputs: "success" Next node if lookup was successful
"notfound" Next node if lookup found no addresses "notfound" Next node if lookup found no addresses
"failure" Next node if lookup failed "failure" Next node if lookup failed
Parameters: "source" Source of the lookup Parameters: "source" Source of the lookup
"timeout" Time to try before giving up on the lookup "timeout" Time to try before giving up on the lookup
"use" Caller preferences fields to use "clear" Whether to clear the location set before
"ignore" Caller preferences fields to ignore adding the new values
"clear" Whether to clear the location set before adding
the new values
Output: "success" Output: "success"
Parameters: none Parameters: none
Output: "notfound" Output: "notfound"
Parameters: none Parameters: none
Output: "failure" Output: "failure"
Parameters: none Parameters: none
Figure 10: Syntax of the "lookup" node Figure 10: Syntax of the "lookup" node
Location lookup nodes have one mandatory parameter, and four optional Location lookup nodes have one mandatory parameter and two optional
parameters. The mandatory parameter is "source", the source of the parameters. The mandatory parameter is "source", the source of the
lookup. This can either be a URI, or a non-URI value. If the value of lookup. This can either be a URI, or a non-URI value. If the value of
"source" is a URI, it indicates a location which the CPL server can "source" is a URI, it indicates a location which the CPL server can
query to obtain an object with the text/uri-list media type (see the query to obtain an object with the text/uri-list media type (see the
IANA registration of this type, which also appears in RFC 2483 [16]). IANA registration of this type, which also appears in RFC 2483 [10]).
The query is performed verbatim, with no additional information (such The query is performed verbatim, with no additional information (such
as URI parameters) added. The server adds the locations contained in as URI parameters) added. The server adds the locations contained in
this object to the location set. this object to the location set.
CPL servers MAY refuse to allow URI-based sources for location CPL servers MAY refuse to allow URI-based sources for location
queries for some or all URI schemes. In this case, they SHOULD reject queries for some or all URI schemes. In this case, they SHOULD reject
the script at script upload time. the script at script upload time.
There has been discussion of having CPL servers add URI There has been discussion of having CPL servers add URI
parameters to the location request, so that (for instance) parameters to the location request, so that (for instance)
CGI scripts could be used to resolve them. However, the CGI scripts could be used to resolve them. However, the
consensus was that this should be a CPL extension, not a consensus was that this should be a CPL extension, not a
part of the base specification. part of the base specification.
Non-URL sources indicate a source not specified by a URL which the Non-URL sources indicate a source not specified by a URL which the
server can query for addresses to add to the location set. The only server can query for addresses to add to the location set. The only
non-URL source currently defined is "registration", which specifies non-URL source currently defined is "registration", which specifies
all the locations currently registered with the server. all the locations currently registered with the server.
The "lookup" node also has four optional parameters. The "timeout" The "lookup" node also has two optional parameters. The "timeout"
parameter specifies the time, as a positive integer number of parameter specifies the time, as a positive integer number of
seconds, the script is willing to wait for the lookup to be seconds, the script is willing to wait for the lookup to be
performed. If this is not specified, its default value is 30. The performed. If this is not specified, its default value is 30. The
"clear" parameter specifies whether the location set should be "clear" parameter specifies whether the location set should be
cleared before the new locations are added. cleared before the new locations are added. Lookup has three
outputs: "success", "notfound", and "failure". Notfound is taken if
The other two optional parameters affect the interworking of the CPL the lookup process succeeded but did not find any locations; failure
script with caller preferences and caller capabilities. By default, is taken if the lookup failed for some reason, including that
a CPL server SHOULD invoke the appropriate caller preferences specified timeout was exceeded. If a given output is not present,
filtering of the underlying signalling protocol, if the corresponding script execution terminates and the default behavior is performed.
information is available. The two parameters "use" and "ignore" allow
the script to modify how the script applies caller preferences
filtering. The specific meaning of the values of these parameters is
signalling-protocol dependent; see Section 6.2.1 for SIP and Appendix
B.6 for H.323.
Lookup has three outputs: "success", "notfound", and "failure".
Notfound is taken if the lookup process succeeded but did not find
any locations; failure is taken if the lookup failed for some reason,
including that specified timeout was exceeded. If a given output is
not present, script execution terminates and the default behavior is
performed.
Clients SHOULD specify the three outputs "success", "notfound", and
"failure" in that order, so their script complies with the DTD given
in Appendix C, but servers MAY accept them in any order.
6.2.1 Usage of "lookup" with SIP
Caller preferences for SIP are defined in "SIP Caller Preferences and
Callee Capabilities" [17]. By default, a CPL server SHOULD honor any
"Accept-Contact" and "Reject-Contact" headers of the original call
request, as specified in that document. The two parameters "use" and
"ignore" allow the script to modify the data input to the caller
preferences algorithm. These parameters both take as their arguments
comma-separated lists of caller preferences parameters. If "use" is
given, the server applies the caller preferences resolution algorithm
only to those preference parameters given in the "use" parameter, and
ignores all others; if the "ignore" parameter is given, the server
ignores the specified parameters, and uses all the others. Only one
of "use" and "ignore" can be specified.
The addr-spec part of the caller preferences is always applied, and 5.2.1 Usage of "lookup" with SIP
the script cannot modify it.
If a SIP server does not support caller preferences and callee For SIP, the "registration" lookup source corresponds to the
capabilities, if the call request does not contain any preferences, locations registered with the server using "REGISTER" messages.
or if the callee's registrations do not contain any capabilities, the
"use" and "ignore" parameters are ignored.
6.3 Location Removal 5.3 Location Removal
A CPL script can also remove locations from the location set, through A CPL script can also remove locations from the location set, through
the use of the "remove-location" node. The syntax of this node is the use of the "remove-location" node. The syntax of this node is
defined in Figure 11. defined in Figure 11.
The meaning of this node is dependent on the underlying signalling The meaning of this node is dependent on the underlying signalling
protocol. protocol.
Node: "remove-location" Node: "remove-location"
Outputs: None (next node follows directly) Outputs: None (Next node follows directly)
Next node: Any node Next node: Any node
Parameters: "location" Location to remove Parameters: "location" Location to remove
"param" Caller preference parameters to apply
"value" Value of caller preference parameters
Figure 11: Syntax of the "remove-location" node Figure 11: Syntax of the "remove-location" node
A "remove-location" node removes locations from the location set. It A "remove-location" node removes locations from the location set. It
is primarily useful following a "lookup" node. An example of this is is primarily useful following a "lookup" node. An example of this is
given in Section 13.8. given in Section 12.8.
The "remove-location" node has three optional parameters. The
parameter "location" gives the URL (or a signalling-protocol-
dependent URL pattern) of location or locations to be removed from
the set. If this parameter is not given, all locations, subject to
the constraints of the other parameters, are removed from the set.
If param and value are present, their values are comma-separated The "remove-location" node has one optional parameter. The parameter
lists of caller preferences parameters and corresponding values, "location" gives the URL (or a signalling-protocol-dependent URL
respectively. The nth entry in the param list matches the nth entry pattern) of location or locations to be removed from the set. If this
in the value list. There MUST be the same number of parameters as parameter is not given, all locations are removed from the set.
values specified. The meaning of these parameters is signalling-
protocol dependent.
The "remove-location" node has no explicit output tags. In the XML The "remove-location" node has no explicit output tags. In the XML
syntax, the XML "remove-location" tag directly encloses the next syntax, the XML "remove-location" tag directly encloses the next
node's tag. node's tag.
6.3.1 Usage of "remove-location" with SIP 5.3.1 Usage of "remove-location" with SIP
For SIP-based CPL servers, the "remove-location" node has the same
effect on the location set as a "Reject-Contact" header in caller
preferences [17]. The value of the "location" parameter is treated as
though it were the addr-spec field of a Reject-Contact header; thus,
an absent header is equivalent to an addr-spec of "*" in that
specification. The "param" and "value" parameters are treated as
though they appeared in the params field of a Reject-Location header,
as "; param=value" for each one.
If the CPL server does not support caller preferences and callee The location specified in the "location" parameter of the "remove-
capabilities, or if the callee did not supply any preferences, the location" node is matched against the location set using the standard
"param" and "value" parameters are ignored. rules for SIP URI matching (as are used, e.g., to match Contact
addresses when refreshing registrations).
7 Signalling Operations 6 Signalling Operations
Signalling operation nodes cause signalling events in the underlying Signalling operation nodes cause signalling events in the underlying
signalling protocol. Three signalling operations are defined: signalling protocol. Three signalling operations are defined:
"proxy," "redirect," and "reject." "proxy," "redirect," and "reject."
7.1 Proxy 6.1 Proxy
Proxy causes the triggering call to be forwarded on to the currently Proxy causes the triggering call to be forwarded on to the currently
specified set of locations. The syntax of the proxy node is given in specified set of locations. The syntax of the proxy node is given in
Figure 12. Figure 12.
The specific signalling events invoked by the "proxy" node are The specific signalling events invoked by the "proxy" node are
signalling-protocol-dependent, though the general concept should signalling-protocol-dependent, though the general concept should
apply to any signalling protocol. apply to any signalling protocol.
After a proxy operation has completed, the CPL server chooses the
"best" response to the call attempt, as defined by the signalling
protocol or the server's administrative configuration rules.
If the call attempt was successful, CPL execution terminates and the
server proceeds to its default behavior (normally, to allow the call
to be set up). Otherwise, the next node corresponding to one of the
"proxy" node's outputs is taken. The "busy" output is followed if the
call was busy; "noanswer" is followed if the call was not answered
before the "timeout" parameter expired; "redirection" is followed if
the call was redirected; and "failure" is followed if the call setup
failed for any other reason.
If one of the conditions above is true, but the corresponding output
was not specified, the "default" output of the "proxy" node is
followed instead. If there is also no "default" node specified, CPL
execution terminates and the server returns to its default behavior
Node: "proxy" Node: "proxy"
Outputs: "busy" Next node if call attempt returned "busy" Outputs: "busy" Next node if call attempt returned "busy"
"noanswer" Next node if call attempt was not answered "noanswer" Next node if call attempt was not
before timeout answered before timeout
"redirection" Next node if call attempt was redirected "redirection" Next node if call attempt was redirected
"failure" Next node if call attempt failed "failure" Next node if call attempt failed
"default" Default next node for unspecified outputs "default" Default next node for unspecified outputs
Parameters: "timeout" Time to try before giving up on the call attempt Parameters: "timeout" Time to try before giving up on the
"recurse" Whether to recursively look up redirections call attempt
"recurse" Whether to recursively look up
redirections
"ordering" What order to try the location set in. "ordering" What order to try the location set in.
Output: "busy" Output: "busy"
Parameters: none Parameters: none
Output: "noanswer" Output: "noanswer"
Parameters: none Parameters: none
Output: "redirection" Output: "redirection"
Parameters: none Parameters: none
Output: "failure" Output: "failure"
Parameters: none Parameters: none
Output: "default" Output: "default"
Parameters: none Parameters: none
Figure 12: Syntax of the "proxy" node Figure 12: Syntax of the "proxy" node
After a proxy operation has completed, the CPL server chooses the
"best" response to the call attempt, as defined by the signalling
protocol or the server's administrative configuration rules.
If the call attempt was successful, CPL execution terminates and the
server proceeds to its default behavior (normally, to allow the call
to be set up). Otherwise, the next node corresponding to one of the
"proxy" node's outputs is taken. The "busy" output is followed if the
call was busy; "noanswer" is followed if the call was not answered
before the "timeout" parameter expired; "redirection" is followed if
the call was redirected; and "failure" is followed if the call setup
failed for any other reason.
If one of the conditions above is true, but the corresponding output
was not specified, the "default" output of the "proxy" node is
followed instead. If there is also no "default" node specified, CPL
execution terminates and the server returns to its default behavior
(normally, to forward the best response upstream to the originator). (normally, to forward the best response upstream to the originator).
Note: CPL extensions to allow in-call or end-of-call Note: CPL extensions to allow in-call or end-of-call
operations will require an additional output, such as operations will require an additional output, such as
"success", to be added. "success", to be added.
If no locations were present in the set, or if the only locations in If no locations were present in the set, or if the only locations in
the set were locations to which the server cannot proxy a call (for the set were locations to which the server cannot proxy a call (for
example, "http" URLs), the "failure" output is taken. example, "http" URLs), the "failure" output is taken.
skipping to change at page 32, line 10 skipping to change at page 29, line 42
Once a proxy operation completes, if control is passed on to other Once a proxy operation completes, if control is passed on to other
nodes, all locations which have been used are cleared from the nodes, all locations which have been used are cleared from the
location set. That is, the location set is emptied of proxyable location set. That is, the location set is emptied of proxyable
locations if the "ordering" was "parallel" or "sequential"; the locations if the "ordering" was "parallel" or "sequential"; the
highest-priority item in the set is removed from the set if highest-priority item in the set is removed from the set if
"ordering" was "first-only". (In all cases, non-proxyable locations "ordering" was "first-only". (In all cases, non-proxyable locations
such as "http" URIs remain.) In the case of a "redirection" output, such as "http" URIs remain.) In the case of a "redirection" output,
the new addresses to which the call was redirected are then added to the new addresses to which the call was redirected are then added to
the location set. the location set.
7.1.1 Usage of "proxy" with SIP 6.1.1 Usage of "proxy" with SIP
For SIP, the best response to a "proxy" node is determined by the For SIP, the best response to a "proxy" node is determined by the
algorithm of the SIP specification. The node's outputs correspond to algorithm of the SIP specification. The node's outputs correspond to
the following events: the following events:
"busy" A 486 or 600 response was the best response received to "busy" A 486 or 600 response was the best response received to
the call request. the call request.
"redirection" A 3xx response was the best response received to "redirection" A 3xx response was the best response received to
the call request. the call request.
"failure" Any other 4xx, 5xx, or 6xx response was the best "failure" Any other 4xx, 5xx, or 6xx response was the best
response received to the call request. response received to the call request.
"no-answer" No final response was received to the call request "no-answer" No final response was received to the call request
before the timeout expired. before the timeout expired.
SIP servers SHOULD honor the "q" parameter of SIP registrations and SIP servers SHOULD honor the "q" parameter of SIP registrations when
the output of the caller preferences lookup algorithm when
determining location priority. determining location priority.
7.2 Redirect 6.2 Redirect
Redirect causes the server to direct the calling party to attempt to Redirect causes the server to direct the calling party to attempt to
place its call to the currently specified set of locations. The place its call to the currently specified set of locations. The
syntax of this node is specified in Figure 13. syntax of this node is specified in Figure 13.
The specific behavior the redirect node invokes is dependent on the The specific behavior the redirect node invokes is dependent on the
underlying signalling protocol involved, though its semantics are underlying signalling protocol involved, though its semantics are
generally applicable. generally applicable.
Node: "redirect"
Outputs: None (No node may follow)
Next node: None
Parameters: "permanent" Whether the redirection should be
considered permanent
Figure 13: Syntax of the "redirect" node
Redirect immediately terminates execution of the CPL script, so this Redirect immediately terminates execution of the CPL script, so this
node has no outputs and no next node. It has one parameter, node has no outputs and no next node. It has one parameter,
"permanent", which specifies whether the result returned should "permanent", which specifies whether the result returned should
indicate that this is a permanent redirection. The value of this indicate that this is a permanent redirection. The value of this
parameter is either "yes" or "no" and its default value is "no." parameter is either "yes" or "no" and its default value is "no."
7.2.1 Usage of "redirect" with SIP 6.2.1 Usage of "redirect" with SIP
The SIP server SHOULD send a 3xx class response to a call request The SIP server SHOULD send a 3xx class response to a call request
Node: "redirect"
Outputs: None (no node may follow)
Next node: None
Parameters: "permanent" Whether the redirection should be
considered permanent
Figure 13: Syntax of the "redirect" node
upon executing a "redirect" tag. If "permanent" was "yes", the server upon executing a "redirect" tag. If "permanent" was "yes", the server
SHOULD send the response "301 Moved permanently"; otherwise it SHOULD SHOULD send the response "301" (Moved permanently); otherwise it
send "302 Moved temporarily". SHOULD send "302" (Moved temporarily).
7.3 Reject
6.3 Reject
Reject nodes cause the server to reject the call attempt. Their Reject nodes cause the server to reject the call attempt. Their
syntax is given in Figure 14. The specific behavior they invoke is syntax is given in Figure 14. The specific behavior they invoke is
dependent on the underlying signalling protocol involved, though dependent on the underlying signalling protocol involved, though
their semantics are generally applicable. their semantics are generally applicable.
Node: "reject" Node: "reject"
Outputs: None (no node may follow) Outputs: None (No node may follow)
Next node: None Next node: None
Parameters: "status" Status code to return Parameters: "status" Status code to return
"reason" Reason phrase to return "reason" Reason phrase to return
Figure 14: Syntax of the "reject" node Figure 14: Syntax of the "reject" node
This immediately terminates execution of the CPL script, so this node A reject node immediately terminates the execution of a CPL script,
has no outputs and no next node. so this node has no outputs and no next node.
This node has two arguments: "status" and "reason". The "status" This node has two arguments: "status" and "reason". The "status"
argument is required, and can take one of the values "busy", argument is required, and can take one of the values "busy",
"notfound", "reject", and "error", or a signalling-protocol-defined "notfound", "reject", and "error", or a signalling-protocol-defined
status. status.
The "reason" argument optionally allows the script to specify a The "reason" argument optionally allows the script to specify a
reason for the rejection. reason for the rejection.
7.3.1 Usage of "reject" with SIP 6.3.1 Usage of "reject" with SIP
Servers which implement SIP SHOULD also allow the "status" field to Servers which implement SIP SHOULD also allow the "status" field to
be a numeric argument corresponding to a SIP status in the 4xx, 5xx, be a numeric argument corresponding to a SIP status in the 4xx, 5xx,
or 6xx range. or 6xx range.
They SHOULD send the "reason" parameter in the SIP reason phrase. They SHOULD send the "reason" parameter in the SIP reason phrase.
A suggested mapping of the named statuses is as follows. Servers MAY A suggested mapping of the named statuses is as follows. Servers MAY
use a different mapping, though similar semantics SHOULD be use a different mapping, though similar semantics SHOULD be
preserved. preserved.
"busy": 486 Busy Here "busy": 486 Busy Here
"notfound": 404 Not Found "notfound": 404 Not Found
"reject": 603 Decline "reject": 603 Decline
"error": 500 Internal Server Error "error": 500 Internal Server Error
8 Non-signalling Operations 7 Non-signalling Operations
In addition to the signalling operations, the CPL defines several In addition to the signalling operations, CPL defines several
operations which do not affect and are not dependent on the telephony operations which do not affect and are not dependent on the telephony
signalling protocol. signalling protocol.
8.1 Mail 7.1 Mail
The mail node causes the server to notify a user of the status of the The mail node causes the server to notify a user of the status of the
CPL script through electronic mail. Its syntax is given in Figure 15. CPL script through electronic mail. Its syntax is given in Figure 15.
Node: "mail" Node: "mail"
Outputs: None (next node follows directly) Outputs: None (Next node follows directly)
Next node: Any node Next node: Any node
Parameters: "url" Mailto url to which the mail should be sent Parameters: "url" Mailto url to which the mail should be sent
Figure 15: Syntax of the "mail" node Figure 15: Syntax of the "mail" node
The "mail" node takes one argument: a mailto URL giving the address, The "mail" node takes one argument: a "mailto" URL giving the
and any additional desired parameters, of the mail to be sent. The address, and any additional desired parameters, of the mail to be
server sends the message containing the content to the given url; it sent. The server sends the message containing the content to the
SHOULD also include other status information about the original call given url; it SHOULD also include other status information about the
request and the CPL script at the time of the notification. original call request and the CPL script at the time of the
notification.
Using a full mailto URL rather than just an e-mail address Using a full "mailto" URL rather than just an e-mail
allows additional e-mail headers to be specified, such as address allows additional e-mail headers to be specified,
<mail such as <mail
url="mailto:jones@example.com?subject=lookup%20failed" />. url="mailto:jones@example.com?subject=Lookup%20failed" />.
Mail nodes have only one possible result, since failure of e-mail A mail node has only one possible result, since failure of e-mail
delivery cannot reliably be known in real-time. Therefore, its XML delivery cannot reliably be known in real-time. Therefore, its XML
representation does not have output tags: the <mail> tag directly representation does not have output tags: the <mail> tag directly
contains another node tag. contains another node tag.
Note that the syntax of XML requires that ampersand characters, "&", Note that the syntax of XML requires that ampersand characters, "&",
which are used as parameter separators in "mailto" URLs, be quoted as which are used as parameter separators in "mailto" URLs, be quoted as
"&amp;" inside parameter values (see Section C.12 of [3]). "&amp;" inside parameter values (see Section C.12 of the XML
specification [2]).
8.1.1 Suggested Content of Mailed Information 7.1.1 Suggested Content of Mailed Information
This section presents suggested guidelines for the mail sent as a This section presents suggested guidelines for the mail sent as a
result of the "mail" node, for requests triggered by SIP. The message result of the "mail" node, for requests triggered by SIP. The message
mailed (triggered by any protocol) SHOULD contain all this mailed (triggered by any protocol) SHOULD contain all this
information, but servers MAY elect to use a different format. information, but servers MAY elect to use a different format.
1. If the "mailto" URI did not specify a subject header, the 1. If the "mailto" URI did not specify a subject header, the
subject of the e-mail is "[CPL]" followed by the subject subject of the e-mail is "[CPL]" followed by the subject
header of the SIP request. If the URI specified a subject header of the SIP request. If the URI specified a subject
header, it is used instead. header, it is used instead.
skipping to change at page 35, line 47 skipping to change at page 33, line 32
4. If the "mailto" URI specifies a body, it is used. If none 4. If the "mailto" URI specifies a body, it is used. If none
was specified, the body SHOULD contain at least the was specified, the body SHOULD contain at least the
identity of the caller (both the caller's display name and identity of the caller (both the caller's display name and
address), the date and time of day, the call subject, and address), the date and time of day, the call subject, and
if available, the call priority. if available, the call priority.
The server SHOULD honor the user's requested languages, and send the The server SHOULD honor the user's requested languages, and send the
mail notification using an appropriate language and character set. mail notification using an appropriate language and character set.
8.2 Log 7.2 Log
The Log node causes the server to log information about the call to The Log node causes the server to log information about the call to
non-volatile storage. Its syntax is specified in Figure 16. non-volatile storage. Its syntax is specified in Figure 16.
Node: "log" Node: "log"
Outputs: None (next node follows directly) Outputs: None (Next node follows directly)
Next node: Any node Next node: Any node
Parameters: "name" Name of the log file to use Parameters: "name" Name of the log file to use
"comment" Comment to be placed in log file "comment" Comment to be placed in log file
Figure 16: Syntax of the "log" node Figure 16: Syntax of the "log" node
Log takes two arguments, both optional: "name", which specifies the Log takes two arguments, both optional: "name", which specifies the
name of the log, and "comment", which gives a comment about the name of the log, and "comment", which gives a comment about the
information being logged. Servers SHOULD also include other information being logged. Servers SHOULD also include other
information in the log, such as the time of the logged event, information in the log, such as the time of the logged event,
skipping to change at page 36, line 35 skipping to change at page 34, line 23
the log file name is server defined, as is a mechanism to access the log file name is server defined, as is a mechanism to access
these logs. The CPL server SHOULD NOT directly map log names these logs. The CPL server SHOULD NOT directly map log names
uninterpreted onto local file names, for security reasons, lest a uninterpreted onto local file names, for security reasons, lest a
security-critical file be overwritten. security-critical file be overwritten.
A correctly operating CPL server SHOULD NOT ever allow the "log" A correctly operating CPL server SHOULD NOT ever allow the "log"
event to fail. As such, log nodes can have only one possible result, event to fail. As such, log nodes can have only one possible result,
and their XML representation does not have explicit output tags. A and their XML representation does not have explicit output tags. A
CPL <log> tag directly contains another node tag. CPL <log> tag directly contains another node tag.
9 Subactions 8 Subactions
XML syntax defines a tree. To allow more general call flow diagrams, XML syntax defines a tree. To allow more general call flow diagrams,
and to allow script re-use and modularity, we define subactions. and to allow script re-use and modularity, we define subactions.
Two tags are defined for subactions: subaction definitions and Two tags are defined for subactions: subaction definitions and
subaction references. Their syntax is given in Figure 17. subaction references. Their syntax is given in Figure 17.
Subactions are defined through "subaction" tags. These tags are
placed in the CPL after any ancillary information (see Section 10)
but before any top-level tags. They take one argument: "id", a token
indicating a script-chosen name for the subaction. The "id" value for
every "subaction" tag in a script MUST be unique within that script.
Tag: "subaction" Tag: "subaction"
Subtags: Any node Subtags: Any node
Parameters: "id" Name of this subaction Parameters: "id" Name of this subaction
Pseudo-node: "sub" Pseudo-node: "sub"
Outputs: None in XML tree Outputs: None in XML tree
Parameters: "ref" Name of subaction to execute Parameters: "ref" Name of subaction to execute
Figure 17: Syntax of subactions and "sub" pseudo-nodes Figure 17: Syntax of subactions and "sub" pseudo-nodes
Subactions are defined through "subaction" tags. These tags are
placed in CPL after any ancillary information (see Section 9) but
before any top-level tags. They take one argument: "id", a token
indicating a script-chosen name for the subaction. The "id" value for
every "subaction" tag in a script MUST be unique within that script.
Subactions are called from "sub" tags. The "sub" tag is a "pseudo- Subactions are called from "sub" tags. The "sub" tag is a "pseudo-
node": it can be used anyplace in a CPL action that a true node could node": it can be used anyplace in a CPL action that a true node could
be used. It takes one parameter, "ref", the name of the subaction to be used. It takes one parameter, "ref", the name of the subaction to
be called. The "sub" tag contains no outputs of its own; control be called. The "sub" tag contains no outputs of its own; control
instead passes to the subaction. instead passes to the subaction.
References to subactions MUST refer to subactions defined before the References to subactions MUST refer to subactions defined before the
current action. A "sub" tag MUST NOT refer to the action which it current action. A "sub" tag MUST NOT refer to the action which it
appears in, or to any action defined later in the CPL script. Top- appears in, or to any action defined later in the CPL script. Top-
level actions cannot be called from "sub" tags, or through any other level actions cannot be called from "sub" tags, or through any other
skipping to change at page 37, line 41 skipping to change at page 35, line 29
non-terminating or non-decidable CPL scripts, a possibility non-terminating or non-decidable CPL scripts, a possibility
our requirements specifically excluded. our requirements specifically excluded.
Every sub MUST refer to a subaction ID defined within the same CPL Every sub MUST refer to a subaction ID defined within the same CPL
script. No external links are permitted. script. No external links are permitted.
Subaction IDs are case sensitive. Subaction IDs are case sensitive.
If any subsequent version or extension defines external If any subsequent version or extension defines external
linkages, it should probably use a different tag, perhaps linkages, it should probably use a different tag, perhaps
XLink [18]. Ensuring termination in the presence of XLink [21]. Ensuring termination in the presence of
external links is a difficult problem. external links is a difficult problem.
10 Ancillary Information 9 Ancillary Information
No ancillary information is defined in the base CPL specification. If No ancillary information is defined in the base CPL specification. If
ancillary information, not part of any operation, is found to be ancillary information, not part of any operation, is found to be
necessary for a CPL extension, it SHOULD be placed within this tag. necessary for a CPL extension, it SHOULD be placed within this tag.
The (trivial) definition of the ancillary information tag is given in The (trivial) definition of the ancillary information tag is given in
Figure 18. Figure 18.
It may be useful to include timezone definitions inside CPL It may be useful to include timezone definitions inside CPL
scripts directly, rather than referencing them externally scripts directly, rather than referencing them externally
with "tzid" and "tzurl" parameters. If it is, an extension with "tzid" and "tzurl" parameters. If it is, an extension
could be defined to include them here. could be defined to include them here.
10 Default Behavior
Tag: "ancillary" Tag: "ancillary"
Parameters: None Parameters: None
Subtags: None Subtags: None
Figure 18: Syntax of the "ancillary" tag Figure 18: Syntax of the "ancillary" tag
11 Default Behavior
When a CPL node reaches an unspecified output, either because the When a CPL node reaches an unspecified output, either because the
output tag is not present, or because the tag is present but does not output tag is not present, or because the tag is present but does not
contain a node, the CPL server's behavior is dependent on the current contain a node, the CPL server's behavior is dependent on the current
state of script execution. This section gives the operations that state of script execution. This section gives the operations that
should be taken in each case. should be taken in each case.
no location modifications or signalling operations performed, no location modifications or signalling operations performed,
location set empty: Look up the user's location through location set empty: Look up the user's location through
whatever mechanism the server would use if no CPL script whatever mechanism the server would use if no CPL script
were in effect. Proxy, redirect, or send a rejection were in effect. Proxy, redirect, or send a rejection
skipping to change at page 39, line 17 skipping to change at page 36, line 46
unspecified, and no timeout parameter was given to the unspecified, and no timeout parameter was given to the
proxy node, the call should be allowed to ring for the proxy node, the call should be allowed to ring for the
maximum length of time allowed by the server (or the maximum length of time allowed by the server (or the
request, if the request specified a timeout). request, if the request specified a timeout).
proxy operation previously taken: Return whatever the "best" proxy operation previously taken: Return whatever the "best"
response is of all accumulated responses to the call to response is of all accumulated responses to the call to
this point, according to the rules of the underlying this point, according to the rules of the underlying
signalling protocol. signalling protocol.
12 CPL Extensions 11 CPL Extensions
Servers MAY support additional CPL features beyond those listed in Servers MAY support additional CPL features beyond those listed in
this document. Some of the extensions which have been suggested are a this document. Some of the extensions which have been suggested are a
means of querying how a call has been authenticated; richer control means of querying how a call has been authenticated; richer control
over H.323 addressing; end-system or administrator-specific features; over H.323 addressing; end-system or administrator-specific features;
regular-expression matching for strings and addresses; mid-call or regular-expression matching for strings and addresses; and mid-call
end-of-call controls; and the parts of iCalendar COS recurrence rules or end-of-call controls. CPL extensions are indicated by XML
omitted from time switches. namespaces [11]. Every extension MUST have an appropriate XML
namespace assigned to it. All XML tags and attributes that are part
CPL extensions are indicated by XML namespaces [19]. Every extension of the extension MUST be appropriately qualified so as to place them
MUST have an appropriate XML namespace assigned to it. All XML tags within that namespace.
and attributes that are part of the extension MUST be appropriately
qualified so as to place them within that namespace.
Tags or attributes in a CPL script which are in the global namespace Tags or attributes in a CPL script which are in the global namespace
(i.e., not associated with any namespace) are equivalent to tags and (i.e., not associated with any namespace) are equivalent to tags and
attributes in the CPL namespace "http://www.rfc- attributes in the CPL namespace "urn:ietf:params:xml:ns:cpl".
editor.org/rfc/rfcxxxx.txt".
A CPL script SHOULD NOT specify any namespaces it does not use. For
compatibility with non-namespace-aware parsers, a CPL script MAY omit
the base CPL namespace for a script which does not use any
extensions.
A CPL server MUST reject any script which contains a reference to a A CPL server MUST reject any script which contains a reference to a
namespace which it does not understand. It MUST reject any script namespace which it does not understand. It MUST reject any script
which contains an extension tag or attribute which is not qualified which contains an extension tag or attribute which is not qualified
to be in an appropriate namespace. to be in an appropriate namespace.
A CPL script SHOULD NOT specify any namespaces it does not use. For
compatibility with non-namespace-aware parsers, a CPL script SHOULD
NOT specify the base CPL namespace for a script which does not use
any extensions.
A syntax such as A syntax such as
<extension-switch> <extension-switch>
<extension has="http://www.example.com/foo"> <extension has="http://www.example.com/foo">
[extended things] [extended things]
</extension> </extension>
<otherwise> <otherwise>
[non-extended things] [non-extended things]
</otherwise> </otherwise>
</extension-switch> </extension-switch>
was suggested as an alternate way of handling extensions. was suggested as an alternate way of handling extensions.
skipping to change at page 40, line 17 skipping to change at page 37, line 44
</extension> </extension>
<otherwise> <otherwise>
[non-extended things] [non-extended things]
</otherwise> </otherwise>
</extension-switch> </extension-switch>
was suggested as an alternate way of handling extensions. was suggested as an alternate way of handling extensions.
This would allow scripts to be uploaded to a server without This would allow scripts to be uploaded to a server without
requiring a script author to somehow determine which requiring a script author to somehow determine which
extensions a server supports. However, experience extensions a server supports. However, experience
developing other languages, notably Sieve [20], was that developing other languages, notably Sieve [22], was that
this added excessive complexity to languages. The this added excessive complexity to languages. The
"extension-switch" tag could, of course, itself be defined "extension-switch" tag could, of course, itself be defined
in a CPL extension. in a CPL extension.
It is unfortunately true that XML DTDs, such as the CPL DTD In the XML schema of CPL, we introduce three abstract elements,
given in Appendix C, are not powerful enough to encompass namely `toplevelaction', `switch', and `action', which accordingly
namespaces, since the base XML specification (which defines have the abstract type `TopLevelActionType', `SwitchType', and
DTDs) predates the XML namespace specification. XML schemas `ActionType'. Any top-level action in a CPL extension MUST be defined
[21] are a work in progress to define a namespace-aware as the substitutionGroup of the abstract `toplevelaction' element,
method for validating XML documents, as well as improving and has the type extended from the `TopLevelActionType'. Any switch
upon DTDs' expressive power in many other ways. in a CPL extension MUST be defined as the substitutionGroup of the
abstract `switch' element, and has the type extended from the
`SwitchType'. Any action in a CPL extension MUST be defined as the
substitutionGroup of the abstract `action' element, and has the type
extended from the `ActionType'.
13 Examples 12 Examples
13.1 Example: Call Redirect Unconditional 12.1 Example: Call Redirect Unconditional
The script in Figure 19 is a simple script which redirects all calls The script in Figure 19 is a simple script which redirects all calls
to a single fixed location. to a single fixed location.
13.2 Example: Call Forward Busy/No Answer <?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
The script in Figure 20 illustrates some more complex behavior. We xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
see an initial proxy attempt to one address, with further operations xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
if that fails. We also see how several outputs take the same action
subtree, through the use of subactions.
13.3 Example: Call Forward: Redirect and Default
The script in Figure 21 illustrates further proxy behavior. The
server initially tries to proxy to a single address. If this attempt
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl>
<incoming> <incoming>
<location url="sip:smith@phone.example.com"> <location url="sip:smith@phone.example.com">
<redirect /> <redirect />
</location> </location>
</incoming> </incoming>
</cpl> </cpl>
Figure 19: Example Script: Call Redirect Unconditional Figure 19: Example Script: Call Redirect Unconditional
<?xml version="1.0" ?> 12.2 Example: Call Forward Busy/No Answer
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl> The script in Figure 20 illustrates some more complex behavior. We
see an initial proxy attempt to one address, with further operations
if that fails. We also see how several outputs take the same action
subtree, through the use of subactions.
12.3 Example: Call Forward: Redirect and Default
The script in Figure 21 illustrates further proxy behavior. The
server initially tries to proxy to a single address. If this attempt
is redirected, a new redirection is generated using the locations
returned. In all other failure cases for the proxy node, a default
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<subaction id="voicemail"> <subaction id="voicemail">
<location url="sip:jones@voicemail.example.com" > <location url="sip:jones@voicemail.example.com" >
<proxy /> <proxy />
</location> </location>
</subaction> </subaction>
<incoming> <incoming>
<location url="sip:jones@jonespc.example.com"> <location url="sip:jones@jonespc.example.com">
<proxy timeout="8"> <proxy timeout="8">
<busy> <busy>
<sub ref="voicemail" /> <sub ref="voicemail" />
</busy> </busy>
<noanswer> <noanswer>
<sub ref="voicemail" /> <sub ref="voicemail" />
</noanswer> </noanswer>
</proxy> </proxy>
skipping to change at page 41, line 43 skipping to change at page 39, line 29
<noanswer> <noanswer>
<sub ref="voicemail" /> <sub ref="voicemail" />
</noanswer> </noanswer>
</proxy> </proxy>
</location> </location>
</incoming> </incoming>
</cpl> </cpl>
Figure 20: Example Script: Call Forward Busy/No Answer Figure 20: Example Script: Call Forward Busy/No Answer
is redirected, a new redirection is generated using the locations
returned. In all other failure cases for the proxy node, a default
operation -- forwarding to voicemail -- is performed. operation -- forwarding to voicemail -- is performed.
<?xml version="1.0" ?> 12.4 Example: Call Screening
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl> The script in Figure 22 illustrates address switches and call
rejection, in the form of a call screening script. Note also that
because the address-switch lacks an "otherwise" clause, if the
initial pattern did not match, the script does not define any
operations. The server therefore proceeds with its default behavior,
which would presumably be to contact the user.
12.5 Example: Priority and Language Routing
The script in Figure 23 illustrates service selection based on a
call's priority value and language settings. If the call request had
a priority of "urgent" or higher, the default script behavior is
performed. Otherwise, the language field is checked for the language
"es" (Spanish). If it is present, the call is proxied to a Spanish-
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<incoming> <incoming>
<location url="sip:jones@jonespc.example.com"> <location url="sip:jones@jonespc.example.com">
<proxy> <proxy>
<redirection> <redirection>
<redirect /> <redirect />
</redirection> </redirection>
<default> <default>
<location url="sip:jones@voicemail.example.com" > <location url="sip:jones@voicemail.example.com" >
<proxy /> <proxy />
</location> </location>
</default> </default>
</proxy> </proxy>
</location> </location>
</incoming> </incoming>
</cpl> </cpl>
Figure 21: Example Script: Call Forward: Redirect and Default Figure 21: Example Script: Call Forward: Redirect and Default
13.4 Example: Call Screening <?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
The script in Figure 22 illustrates address switches and call xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
rejection, in the form of a call screening script. Note also that xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
because the address-switch lacks an "otherwise" clause, if the
initial pattern did not match, the script does not define any
operations. The server therefore proceeds with its default behavior,
which would presumably be to contact the user.
13.5 Example: Priority and Language Routing
The script in Figure 23 illustrates service selection based on a
call's priority value and language settings. If the call request had
a priority of "urgent" or higher, the default script behavior is
performed. Otherwise, the language field is checked for the language
"es" (Spanish). If it is present, the call is proxied to a Spanish-
speaking operator; other calls are proxied to an English-speaking
operator.
13.6 Example: Outgoing Call Screening
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl>
<incoming> <incoming>
<address-switch field="origin" subfield="user"> <address-switch field="origin" subfield="user">
<address is="anonymous"> <address is="anonymous">
<reject status="reject" <reject status="reject" reason="I reject anonymous calls"/>
reason="I don't accept anonymous calls" />
</address> </address>
</address-switch> </address-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 22: Example Script: Call Screening Figure 22: Example Script: Call Screening
The script in Figure 24 illustrates a script filtering outgoing speaking operator; other calls are proxied to an English-speaking
calls, in the form of a script which prevent 1-900 (premium) calls operator.
from being placed. This script also illustrates subdomain matching.
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl>
<outgoing>
<address-switch field="original-destination" subfield="tel">
<address subdomain-of="1900">
<reject status="reject"
reason="Not allowed to make 1-900 calls." />
</address>
</address-switch>
</outgoing>
</cpl>
Figure 24: Example Script: Outgoing Call Screening
13.7 Example: Time-of-day Routing
Figure 25 illustrates time-based conditions and timezones.
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl> 12.6 Example: Outgoing Call Screening
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<incoming> <incoming>
<priority-switch> <priority-switch>
<priority greater="urgent" /> <priority greater="urgent" />
<otherwise> <otherwise>
<language-switch> <language-switch>
<language matches="es"> <language matches="es">
<location url="sip:spanish@operator.example.com"> <location url="sip:spanish@operator.example.com">
<proxy /> <proxy />
</location> </location>
</language> </language>
skipping to change at page 44, line 32 skipping to change at page 41, line 31
</location> </location>
</otherwise> </otherwise>
</language-switch> </language-switch>
</otherwise> </otherwise>
</priority-switch> </priority-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 23: Example Script: Priority and Language Routing Figure 23: Example Script: Priority and Language Routing
13.8 Example: Location Filtering The script in Figure 24 illustrates a script filtering outgoing
calls, in the form of a script which prevent 1-900 (premium) calls
from being placed. This script also illustrates subdomain matching.
12.7 Example: Time-of-day Routing
Figure 25 illustrates time-based conditions and timezones.
12.8 Example: Location Filtering
Figure 26 illustrates filtering operations on the location set. In Figure 26 illustrates filtering operations on the location set. In
this example, we assume that version 0.9beta2 of the "Inadequate this example, we assume that version 0.9beta2 of the "Inadequate
Software SIP User Agent" mis-implements some features, and so we must Software SIP User Agent" mis-implements some features, and so we must
work around its problems. We assume, first, that the value of its work around its problems. We know that it cannot talk successfully to
"feature" parameter in caller preferences is known to be unreliable, one particular mobile device we may have registered, so we remove
so we ignore it; we also know that it cannot talk successfully to one that location from the location set. Once this operation has been
particular mobile device we may have registered, so we remove that <?xml version="1.0" encoding="UTF-8"?>
location from the location set. Once these two operations have been <cpl xmlns="urn:ietf:params:xml:ns:cpl"
completed, call setup is allowed to proceed normally. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
13.9 Example: Non-signalling Operations <outgoing>
<address-switch field="original-destination" subfield="tel">
<address subdomain-of="1900">
<reject status="reject"
reason="Not allowed to make 1-900 calls."/>
</address>
</address-switch>
</outgoing>
</cpl>
Figure 27 illustrates non-signalling operations; in particular, Figure 24: Example Script: Outgoing Call Screening
alerting a user by electronic mail if the lookup server failed. The
primary motivation for having the "mail" node is to allow this sort
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl> <?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<incoming> <incoming>
<time-switch tzid="America/New_York" <time-switch tzid="America/New_York"
tzurl="http://zones.example.com/tz/America/New_York"> tzurl="http://zones.example.com/tz/America/New_York">
<time dtstart="20000703T090000" duration="PT8H" <time dtstart="20000703T090000" duration="PT8H" freq="weekly"
freq="weekly" byday="MO,TU,WE,TH,FR"> byday="MO,TU,WE,TH,FR">
<lookup source="registration"> <lookup source="registration">
<success> <success>
<proxy /> <proxy />
</success> </success>
</lookup> </lookup>
</time> </time>
<otherwise> <otherwise>
<location url="sip:jones@voicemail.example.com"> <location url="sip:jones@voicemail.example.com">
<proxy /> <proxy />
</location> </location>
</otherwise> </otherwise>
</time-switch> </time-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 25: Example Script: Time-of-day Routing Figure 25: Example Script: Time-of-day Routing
of out-of-band notification of error conditions, as the user might completed, call setup is allowed to proceed normally.
otherwise be unaware of any problem.
13.10 Example: Hypothetical Extensions
The example in Figure 28 shows a hypothetical extension which
implements distinctive ringing. The XML namespace
"http://www.example.com/distinctive-ring" specifies a new node named
"ring".
The example in Figure 29 implements a hypothetical new attribute for
address switches, to allow regular-expression matches. It defines a
new attribute "regex" for the standard "address" node. In this
example, the global namespace is not specified.
13.11 Example: A Complex Example
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl> <?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<incoming> <incoming>
<string-switch field="user-agent"> <string-switch field="user-agent">
<string is="Inadequate Software SIP User Agent/0.9beta2"> <string is="Inadequate Software SIP User Agent/0.9beta2">
<lookup source="registration" ignore="feature"> <lookup source="registration">
<success> <success>
<remove-location location="sip:me@mobile.provider.net"> <remove-location location="sip:me@mobile.provider.net">
<proxy /> <proxy />
</remove-location> </remove-location>
</success> </success>
</lookup> </lookup>
</string> </string>
</string-switch> </string-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 26: Example Script: Location Filtering Figure 26: Example Script: Location Filtering
<?xml version="1.0" ?> Figure 27 illustrates non-signalling operations; in particular,
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd"> alerting a user by electronic mail if the lookup server failed. The
primary motivation for having the "mail" node is to allow this sort
of out-of-band notification of error conditions, as the user might
otherwise be unaware of any problem.
<cpl> 12.10 Example: Hypothetical Extensions
The example in Figure 12.10 shows a hypothetical extension which
implements distinctive ringing. The XML namespace
"http://www.example.com/distinctive-ring" specifies a new node named
"ring".
The example in Figure 29 implements a hypothetical new attribute for
address switches, to allow regular-expression matches. It defines a
new attribute "regex" for the standard "address" node.
12.11 Example: A Complex Example
Finally, Figure 30 is a complex example which shows the sort of
sophisticated behavior which can be achieved by combining CPL nodes.
In this case, the user attempts to have his calls reach his desk; if
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<incoming> <incoming>
<lookup <lookup
source="http://www.example.com/cgi-bin/locate.cgi?user=jones" source="http://www.example.com/cgi-bin/locate.cgi?user=mary"
timeout="8"> timeout="8">
<success> <success>
<proxy /> <proxy />
</success> </success>
<failure> <failure>
<mail url="mailto:jones@example.com?subject=lookup%20failed" /> <mail url="mailto:mary@example.com?subject=Lookup%20failed"/>
</failure> </failure>
</lookup> </lookup>
</incoming> </incoming>
</cpl> </cpl>
Figure 27: Example Script: Non-signalling Operations Figure 27: Example Script: Non-signalling Operations
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl xmlns="http://www.rfc-editor.org/rfc/rfcXXXX.txt" he does not answer within a small amount of time, calls from his boss
xmlns:dr="http://www.example.com/distinctive-ring"> are forwarded to his mobile phone, and all other calls are directed
to voicemail. If the call setup failed, no operation is specified,
so the server's default behavior is performed.
13 Security Considerations
CPL is designed to allow services to be specified in a manner which
prevents potentially hostile or mis-configured scripts from launching
security attacks, including denial-of-service attacks. Because script
runtime is strictly bounded by acyclicity, and because the number of
possible script operations are strictly limited, scripts should not
be able to inflict damage upon a CPL server.
Because scripts can direct users' telephone calls, the method by
which scripts are transmitted from a client to a server MUST be
strongly authenticated. Such a method is not specified in this
document.
Script servers SHOULD allow server administrators to control the
details of what CPL operations are permitted.
14 IANA Considerations
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://www.example.com/distinctive-ring"
xmlns="http://www.example.com/distinctive-ring"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:CPL="urn:ietf:params:xml:ns:cpl"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:import namespace="urn:ietf:params:xml:ns:cpl"
schemaLocation="cpl.xsd"/>
<xs:complexType name="DRingAction">
<xs:complexContent>
<xs:extension base="CPL:ActionType">
<xs:attribute name="ringstyle" type="xs:string"
use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="ring" type="DRingAction"
substitutionGroup="CPL:action"/>
</xs:schema>
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:dr="http://www.example.com/distinctive-ring"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd
http://www.example.com/distinctive-ring distinctive-ring.xsd">
<incoming> <incoming>
<address-switch field="origin"> <address-switch field="origin">
<address is="sip:boss@example.com"> <address is="sip:boss@example.com">
<dr:ring ringstyle="warble" /> <dr:ring ringstyle="warble" />
</address> </address>
</address-switch> </address-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 28: Example Script: Hypothetical Distinctive-Ringing Extension Figure 28: Example Schema and Script: Hypothetical Distinctive-
Ringing Extension
<?xml version="1.0" ?> This document registers a new MIME type, application/cpl+xml, and a
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd"> new URN per RFC 2141 [12], RFC 2648 [13], and RFC YYYY [14].
<cpl> <?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<incoming> <incoming>
<address-switch field="origin" subfield="user" <address-switch field="origin" subfield="user"
xmlns:re="http://www.example.com/regex"> xmlns:re="http://www.example.com/regex">
<address re:regex="(.*.smith|.*.jones)"> <address re:regex="(.*.smith|.*.jones)">
<reject status="reject" <reject status="reject"
reason="I don't want to talk to Smiths or Joneses" /> reason="I don't want to talk to Smiths or Joneses" />
</address> </address>
</address-switch> </address-switch>
</incoming> </incoming>
</cpl> </cpl>
Figure 29: Example Script: Hypothetical Regular-Expression Extension Figure 29: Example Script: Hypothetical Regular-Expression Extension
Finally, Figure 30 is a complex example which shows the sort of [Note to RFC Editor: please replace "YYYY" above with the
sophisticated behavior which can be achieved by combining CPL nodes. RFC number of draft-mealling-iana-xmlns-registry, which is
In this case, the user attempts to have his calls reach his desk; if currently in the RFC Editor's queue, when it is published
he does not answer within a small amount of time, calls from his boss as an RFC.]
are forwarded to his mobile phone, and all other calls are directed
to voicemail. If the call setup failed, no operation is specified,
so the server's default behavior is performed.
<?xml version="1.0" ?> 14.1 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:cpl
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl> URI: urn:ietf:params:xml:ns:cpl
Registrant Contact: Jonathan Lennox <lennox@cs.columbia.edu>
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML:
<?xml version="1.0" encoding="UTF-8"?>
<cpl xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:cpl cpl.xsd ">
<subaction id="voicemail"> <subaction id="voicemail">
<location url="sip:jones@voicemail.example.com"> <location url="sip:jones@voicemail.example.com">
<redirect /> <redirect />
</location> </location>
</subaction> </subaction>
<incoming> <incoming>
<location url="sip:jones@phone.example.com"> <location url="sip:jones@phone.example.com">
<proxy timeout="8"> <proxy timeout="8">
<busy> <busy>
<sub ref="voicemail" /> <sub ref="voicemail" />
</busy> </busy>
<noanswer> <noanswer>
<address-switch field="origin"> <address-switch field="origin">
<address is="sip:boss@example.com"> <address is="sip:boss@example.com">
<location url="tel:+19175551212"> <location url="tel:+19175551212">
skipping to change at page 48, line 40 skipping to change at page 47, line 39
</otherwise> </otherwise>
</address-switch> </address-switch>
</noanswer> </noanswer>
</proxy> </proxy>
</location> </location>
</incoming> </incoming>
</cpl> </cpl>
Figure 30: Example Script: A Complex Example Figure 30: Example Script: A Complex Example
14 Security Considerations BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Call Processing Language Namespace</title>
</head>
<body>
<h1>Namespace for Call Processing Language</h1>
<h2>application/cpl+xml</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
The CPL is designed to allow services to be specified in a manner [Note to RFC Editor: please replace "[[[URL of published
which prevents potentially hostile or mis-configured scripts from RFC]]]" above with the official URL of this RFC at rfc-
launching security attacks, including denial-of-service attacks. editor.org, and "XXXX" above with the number of this RFC.]
Because script runtime is strictly bounded by acyclicity, and because
the number of possible script operations are strictly limited,
scripts should not be able to inflict damage upon a CPL server.
Because scripts can direct users' telephone calls, the method by 14.2 MIME Registration
which scripts are transmitted from a client to a server MUST be
strongly authenticated. Such a method is not specified in this
document.
Script servers SHOULD allow server administrators to control the As an XML type, CPL's MIME registration conforms with "XML Media
details of what CPL operations are permitted. Types," RFC 3023 [15].
15 IANA Considerations MIME media type name: application
This document registers the MIME type application/cpl+xml. See MIME subtype name: cpl+xml
Section 3.2.
16 Acknowledgments Mandatory parameters: none
Optional parameters: charset
As for application/xml in RFC 3023.
Encoding considerations: As for application/xml in RFC 3023.
Security considerations: See Section 13, and Section 10 of RFC
3023.
Interoperability considerations: Different CPL servers may use
incompatible address types. However, all potential
interoperability issues should be resolvable at the time a
script is uploaded; there should be no interoperability
issues which cannot be detected until runtime.
Published specification: This document.
Applications which use this media type: A number of Internet
telephony servers, mostly using SIP. Specifically, the
authors of this specification have implemented it in their
SIP proxy server (part of the CINEMA project).
Additional information:
Magic number: None
File extension: .cpl or .xml
Macintosh file type code: "TEXT"
Person and e-mail address for further information:
Jonathan Lennox <lennox@cs.columbia.edu>
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
Intended usage: COMMON
Author/Change Controller: The IETF.
15 Acknowledgments
This document was reviewed and commented upon by IETF IP Telephony This document was reviewed and commented upon by IETF IP Telephony
Working Group. We specifically acknowledge the following people for Working Group. We specifically acknowledge the following people for
their help: their help:
The outgoing call screening script was written by Kenny Hom. The outgoing call screening script was written by Kenny Hom.
Paul E. Jones contributed greatly to the mappings of H.323 addresses. Paul E. Jones contributed greatly to the mappings of H.323 addresses.
The text of the time-switch section was taken (lightly modified) from The text of the time-switch section was taken (lightly modified) from
RFC 2445 [13], by Frank Dawson and Derik Stenerson. RFC 2445 [8], by Frank Dawson and Derik Stenerson.
We drew a good deal of inspiration, notably the language's lack of We drew a good deal of inspiration, notably the language's lack of
Turing-completeness and the syntax of string matching, from the Turing-completeness and the syntax of string matching, from the
specification of Sieve [20], a language for user filtering of specification of Sieve [22], a language for user filtering of
electronic mail messages. electronic mail messages.
Thomas F. La Porta and Jonathan Rosenberg had many useful Thomas F. La Porta and Jonathan Rosenberg had many useful
discussions, contributions, and suggestions. discussions, contributions, and suggestions.
Richard Gumpertz performed a very useful last-minute technical and Richard Gumpertz performed a very useful last-minute technical and
editorial review of the specification. editorial review of the specification.
A An Algorithm for Resolving Time Switches A An Algorithm for Resolving Time Switches
The following algorithm determines whether a given instant falls The following algorithm determines whether a given instant falls
within a repetition of a "time-switch" recurrence. If the pre- within a repetition of a "time-switch" recurrence. If the pre-
processing described in Section 5.4.1 has been done, it operates in processing described in Section 4.4.1 has been done, it operates in
constant time. Open-source Java code implementing this algorithm is constant time. Open-source Java code implementing this algorithm is
available on the world wide web at available on the world wide web at
<http://www.cs.columbia.edu/~lennox/Cal-Code/> <http://www.cs.columbia.edu/~lennox/Cal-Code/>.
This algorithm is believed to be correct, but this section is non- This algorithm is believed to be correct, but this section is non-
normative. Section 5.4, and RFC 2445 [13], are the definitive normative. Section 4.4, and RFC 2445 [8], are the definitive
definitions of recurrences. definitions of recurrences.
1. Compute the time of the call, in the timezone of the time 1. Compute the time of the call, in the timezone of the time
switch. switch.
2. If the call time is earlier than "dtstart", fail NOMATCH. 2. If the call time is earlier than "dtstart", fail NOMATCH.
3. If the call time is less than "duration" after dtstart, 3. If the call time is less than "duration" after dtstart,
succeed MATCH. succeed MATCH.
skipping to change at page 51, line 16 skipping to change at page 51, line 20
time matches one of the options specified by that "byxxx" time matches one of the options specified by that "byxxx"
rule. If so, succeed MATCH. rule. If so, succeed MATCH.
9. Calculate a previous candidate start time. Repeat until the 9. Calculate a previous candidate start time. Repeat until the
difference between the candidate start time and the call difference between the candidate start time and the call
time is more than the duration. If no candidate start time time is more than the duration. If no candidate start time
has been validated, fail NOMATCH. has been validated, fail NOMATCH.
B Suggested Usage of CPL with H.323 B Suggested Usage of CPL with H.323
This appendix gives a suggested usage of CPL with H.323 [2]. Study This appendix gives a suggested usage of CPL with H.323 [16]. Study
Group 16 of the ITU, which developed H.323, is proposing to work on Group 16 of the ITU, which developed H.323, is proposing to work on
official CPL mappings for that protocol. This section is therefore official CPL mappings for that protocol. This section is therefore
not normative. not normative.
B.1 Usage of "address-switch" with H.323 B.1 Usage of "address-switch" with H.323
Address switches are specified in Section 5.1. This section specifies Address switches are specified in Section 4.1. This section specifies
the mapping between H.323 messages and the fields and subfields of the mapping between H.323 messages and the fields and subfields of
address-switches address-switches
For H.323, the "origin" address corresponds to the alias addresses in For H.323, the "origin" address corresponds to the alias addresses in
the "sourceAddress" field of the "Setup-UUIE" user-user information the "sourceAddress" field of the "Setup-UUIE" user-user information
element, and to the Q.931 [22] information element "Calling party element, and to the Q.931 [23] information element "Calling party
number." If both fields are present, or if multiple aliases addresses number." If both fields are present, or if multiple aliases addresses
for "sourceAddress" are present, which one has priority is a matter for "sourceAddress" are present, which one has priority is a matter
of local server policy; the server SHOULD use the same resolution as of local server policy; the server SHOULD use the same resolution as
it would use for routing decisions in this case. Similarly, the it would use for routing decisions in this case. Similarly, the
"destination" address corresponds to the alias addresses of the "destination" address corresponds to the alias addresses of the
"destinationAddress" field, and to the Q.931 information element "destinationAddress" field, and to the Q.931 information element
"Called party number." "Called party number."
The "original-destination" address corresponds to the "Redirecting The "original-destination" address corresponds to the "Redirecting
number" Q.931 information element, if it is present; otherwise it is number" Q.931 information element, if it is present; otherwise it is
skipping to change at page 52, line 8 skipping to change at page 52, line 12
"transportID", "email-ID", "partyNumber", "mobileUIM", and "Q.931IE". "transportID", "email-ID", "partyNumber", "mobileUIM", and "Q.931IE".
If future versions of the H.323 specification define additional types If future versions of the H.323 specification define additional types
of alias addresses, those names MAY also be used. of alias addresses, those names MAY also be used.
In versions of H.323 prior to version 4, "dialedDigits" was known as In versions of H.323 prior to version 4, "dialedDigits" was known as
"e164". The two names SHOULD be treated as synonyms. "e164". The two names SHOULD be treated as synonyms.
The value of the "address-type" subfield for H.323 messages is "h323" The value of the "address-type" subfield for H.323 messages is "h323"
unless the alias type is "url-ID" and the URL scheme is something unless the alias type is "url-ID" and the URL scheme is something
other than h323; in this case the address-type is the URL scheme, as other than h323; in this case the address-type is the URL scheme, as
specified in Section 5.1.1 for SIP. specified in Section 4.1.1 for SIP.
An H.323-aware CPL server SHOULD map the address subfields from the An H.323-aware CPL server SHOULD map the address subfields from the
primary alias used for routing. It MAY also map subfields from other primary alias used for routing. It MAY also map subfields from other
aliases, if subfields in the primary address are not present. aliases, if subfields in the primary address are not present.
The following mappings are used for H.323 alias types: The following mappings are used for H.323 alias types:
dialedDigits, partyNumber, mobileUIM, and Q.931IE: the "tel" and dialedDigits, partyNumber, mobileUIM, and Q.931IE: the "tel" and
"user" subfields are the string of digits, as is the "user" subfields are the string of digits, as is the
"entire-address" form. The "host" and "port" subfields are "entire-address" form. The "host" and "port" subfields are
not present. not present.
url-ID: the same mappings are used as for SIP, in Section 5.1.1. url-ID: the same mappings are used as for SIP, in Section 4.1.1.
h323-ID: the "user" field is the string of characters, as is the h323-ID: the "user" field is the string of characters, as is the
"entire-address" form. All other subfields are not present. "entire-address" form. All other subfields are not present.
email-ID: the "user" and "host" subfields are set to the email-ID: the "user" and "host" subfields are set to the
corresponding parts of the e-mail address. The "port" and corresponding parts of the e-mail address. The "port" and
"tel" subfields are not present. The "entire-address" form "tel" subfields are not present. The "entire-address" form
corresponds to the entire e-mail address. corresponds to the entire e-mail address.
transportID: if the TransportAddress is of type "ipAddress," transportID: if the TransportAddress is of type "ipAddress,"
"ipSourceRoute," or "ip6Address," the "host" subfield is "ipSourceRoute," or "ip6Address," the "host" subfield is
set to the "ip" element of the sequence, translated into set to the "ip" element of the sequence, translated into
the standard IPv4 or IPv6 textual representation, and the the standard IPv4 or IPv6 textual representation, and the
"port" subfield is set to the "port" element of the "port" subfield is set to the "port" element of the
sequence represented in decimal. The "tel" and "user" sequence represented in decimal. The "tel" and "user"
fields are not present. The "entire-address" form is not fields are not present. The "entire-address" form is not
defined. The representation and mapping of transport defined. The representation and mapping of transport
addresses is not defined for non-IP addresses. addresses is not defined for non-IP addresses.
H.323 version 4 [2] defines an "h323" URI scheme. This appendix H.323 version 4 [16] defines an "h323" URI scheme. This appendix
defines a mapping for these URIs onto the CPL "address-switch" defines a mapping for these URIs onto the CPL "address-switch"
subfields, as given in Section 5.1. This definition is also subfields, as given in Section 4.1. This definition is also
available as RFC YYYY [23], which is an excerpt from the H.323 available as RFC 3508 [24], which is an excerpt from the H.323
specification. [Note to RFC Editor: "RFC YYYY" indicates the specification.
publication as an RFC of draft-levin-iptel-h323-url-scheme-04, which
is currently in the RFC Editor's Queue.]
For h323 URIs, the the "user", "host", and "port" subfields are set For h323 URIs, the "user", "host", and "port" subfields are set to
to the corresponding parts of the H.323 URL. The "tel" subfield is the corresponding parts of the H.323 URL. The "tel" subfield is not
not present. The "entire-address" form corresponds to the entire URI. present. The "entire-address" form corresponds to the entire URI.
This mapping MAY be used both for h323 URIs in an h323 "url-ID" This mapping MAY be used both for h323 URIs in an h323 "url-ID"
address alias, and for h323 URIs in SIP messages. address alias, and for h323 URIs in SIP messages.
B.2 Usage of "string-switch" with H.323 B.2 Usage of "string-switch" with H.323
For H.323, the "string-switch" node (see Section 5.2) is used as For H.323, the "string-switch" node (see Section 4.2) is used as
follows. The field "display" corresponds to the Q.931 information follows. The field "display" corresponds to the Q.931 information
element of the same name, copied verbatim. The fields "subject", element of the same name, copied verbatim. The fields "subject",
"organization", and "user-agent" are not used and are never present. "organization", and "user-agent" are not used and are never present.
The "display" IE is conventionally used for Caller-ID The "display" IE is conventionally used for Caller-ID
purposes, so arguably it should be mapped to the "display" purposes, so arguably it should be mapped to the "display"
subfield of an "address-match" with the field "originator". subfield of an "address-match" with the field "originator".
However, since a) it is a message-level information However, since a) it is a message-level information
element, not an address-level one, and b) the Q.931 element, not an address-level one, and b) the Q.931
specification [22] says only that "[t]he purpose of the specification [23] says only that "[t]he purpose of the
Display information element is to supply display Display information element is to supply display
information that may be displayed by the user," it seems to information that may be displayed by the user," it seems to
be more appropriate to allow it to be matched in a be more appropriate to allow it to be matched in a
"string-switch" instead. "string-switch" instead.
B.3 Usage of "language-switch" with H.323 B.3 Usage of "language-switch" with H.323
The language-ranges for the "language-switch" switch are obtained The language-ranges for the "language-switch" switch are obtained
from the H.323 UUIE "language". The switch is not-present if the from the H.323 UUIE "language". The switch is not-present if the
initial message did not contain this UUIE. initial message did not contain this UUIE.
B.4 Usage of "priority-switch" with H.323 B.4 Usage of "priority-switch" with H.323
All H.323 messages are considered to have priority "normal" for the All H.323 messages are considered to have priority "normal" for the
purpose of a priority switch (see Section 5.5). purpose of a priority switch (see Section 4.5).
B.5 Usage of "location" with H.323 B.5 Usage of "location" with H.323
Locations in explicit location nodes (Section 6.1) are specified as Locations in explicit location nodes (Section 5.1) are specified as
URLs. Therefore, all locations added in this manner are interpreted URLs. Therefore, all locations added in this manner are interpreted
as being of alias type "url-ID" in H.323. as being of alias type "url-ID" in H.323.
Specifications of other H.323 address alias types will require a CPL Specifications of other H.323 address alias types will require a CPL
extension (see Section 12). extension (see Section 11).
B.6 Usage of "lookup" with H.323 B.6 Usage of "lookup" with H.323
For location lookup nodes (Section 5.2), the "registration" lookup
For location lookup nodes (Section 6.2), the "registration" lookup
source corresponds to the locations registered with the server using source corresponds to the locations registered with the server using
"RAS" messages. "RAS" messages.
As H.323 currently has no counterpart of SIP caller preferences and
callee capabilities, the "use" and "ignore" parameters of the
"lookup" node are ignored.
B.7 Usage of "remove-location" with H.323 B.7 Usage of "remove-location" with H.323
For location removal nodes (Section 6.3), only literal URLs can be Location removal nodes (Section 5.3) remove addresses with alias type
removed. No URL patterns are defined. "url-ID" using verbatim string matching on the URLs. If a "tel" URL
is specified as the location, matching addresses (ignoring visual
As H.323 currently has no counterpart of SIP caller preferences and separators) with alias types "dialedDigits" ("e164"), "partyNumber",
callee capabilities, the "param" and "value" parameters of the "mobileUIM", or "Q.931IE" are also removed. No mechanism is provided
"remove-location" node are ignored. to remove other alias types.
C The XML DTD for CPL C The XML Schema for CPL
This section includes a full DTD describing the XML syntax of the This section includes a full XML Schema describing the XML syntax of
CPL. Every script submitted to a CPL server SHOULD comply with this CPL. Every script submitted to a CPL server SHOULD comply with this
DTD. However, CPL servers MAY allow minor variations from it, XML Schema. When parsing scripts comply with the CPL DTD in earlier
particularly in the ordering of the outputs of nodes. Note that drafts, the DOCTYPE lines in the scripts should be ignored. Note that
compliance with this DTD is not a sufficient condition for compliance with this schema is not a sufficient condition for
correctness of a CPL script, as many of the conditions described in correctness of a CPL script, as many of the conditions described in
this specification are not expressible in DTD syntax. this specification are not expressible in schema syntax. Figure B.4
shows the structure of the schema. `incoming' and `outgoing' are
<?xml version="1.0" encoding="US-ASCII" ?> defined as the substitutionGroup of the `toplevelaction'. All the
switches are defined as the substitutionGroup of the `switch'
<!-- Nodes. --> element. All the actions are defined as the substitutionGroup of the
<!-- Switch nodes --> `action' element.
<!ENTITY % Switch 'address-switch|string-switch|language-switch|
time-switch|priority-switch' >
<!-- Location nodes -->
<!ENTITY % Location 'location|lookup|remove-location' >
<!-- Signalling action nodes -->
<!ENTITY % SignallingAction 'proxy|redirect|reject' >
<!-- Other actions -->
<!ENTITY % OtherAction 'mail|log' >
<!-- Links to subactions -->
<!ENTITY % Sub 'sub' >
<!-- Nodes are one of the above four categories, or a subaction.
This entity (macro) describes the contents of an output.
Note that a node can be empty, implying default action. -->
<!ENTITY % Node '(%Location;|%Switch;|%SignallingAction;|
%OtherAction;|%Sub;)?' >
<!-- Switches: choices a CPL script can make. -->
<!-- All switches can have an 'otherwise' output. -->
<!ELEMENT otherwise ( %Node; ) >
<!-- All switches can have a 'not-present' output. -->
<!ELEMENT not-present ( %Node; ) >
<!-- Address-switch makes choices based on addresses. -->
<!ELEMENT address-switch ( address*, (not-present, address*)?,
otherwise? ) >
<!-- <not-present> must appear at most once -->
<!ATTLIST address-switch
field CDATA #REQUIRED
subfield CDATA #IMPLIED
>
<!ELEMENT address ( %Node; ) >
<!ATTLIST address
is CDATA #IMPLIED
contains CDATA #IMPLIED
subdomain-of CDATA #IMPLIED
> <!-- Exactly one of these three attributes must appear -->
<!-- String-switch makes choices based on strings. -->
<!ELEMENT string-switch ( string*, (not-present, string*)?,
otherwise? ) >
<!-- <not-present> must appear at most once -->
<!ATTLIST string-switch
field CDATA #REQUIRED
>
<!ELEMENT string ( %Node; ) >
<!ATTLIST string
is CDATA #IMPLIED
contains CDATA #IMPLIED
> <!-- Exactly one of these two attributes must appear -->
<!-- Language-switch makes choices based on the originator's preferred
languages. -->
<!ELEMENT language-switch ( language*, (not-present, language*)?,
otherwise? ) >
<!-- <not-present> must appear at most once -->
<!ELEMENT language ( %Node; ) >
<!ATTLIST language
matches CDATA #REQUIRED
>
<!-- Time-switch makes choices based on the current time. -->
<!ELEMENT time-switch ( time*, (not-present, time*)?, otherwise? ) >
<!ATTLIST time-switch
tzid CDATA #IMPLIED
tzurl CDATA #IMPLIED
>
<!ELEMENT time ( %Node; ) >
<!-- Exactly one of the two attributes "dtend" and "duration"
must occur. -->
<!-- The value of "freq" is (daily|weekly|monthly|yearly). It is
case-insensitive, so it is not given as a DTD switch. -->
<!-- None of the attributes following freq are meaningful unless freq
appears. -->
<!-- The value of "wkst" is (MO|TU|WE|TH|FR|SA|SU). It is
case-insensitive, so it is not given as a DTD switch. -->
<!ATTLIST time
dtstart CDATA #REQUIRED
dtend CDATA #IMPLIED
duration CDATA #IMPLIED
freq CDATA #IMPLIED
until CDATA #IMPLIED
count CDATA #IMPLIED
interval CDATA "1"
bysecond CDATA #IMPLIED
byminute CDATA #IMPLIED
byhour CDATA #IMPLIED
byday CDATA #IMPLIED
bymonthday CDATA #IMPLIED
byyearday CDATA #IMPLIED
byweekno CDATA #IMPLIED
bymonth CDATA #IMPLIED
wkst CDATA "MO"
bysetpos CDATA #IMPLIED
>
<!-- Priority-switch makes choices based on message priority. -->
<!ELEMENT priority-switch ( priority*, (not-present, priority*)?,
otherwise? ) >
<!-- <not-present> must appear at most once -->
<!ENTITY % PriorityVal '(emergency|urgent|normal|non-urgent)' >
<!ELEMENT priority ( %Node; ) >
<!-- Exactly one of these three attributes must appear -->
<!ATTLIST priority
less %PriorityVal; #IMPLIED
greater %PriorityVal; #IMPLIED
equal CDATA #IMPLIED
>
<!-- Locations: ways to specify the location a subsequent action
(proxy, redirect) will attempt to contact. -->
<!ENTITY % Clear 'clear (yes|no) "no"' >
<!ELEMENT location ( %Node; ) >
<!ATTLIST location
url CDATA #REQUIRED
priority CDATA #IMPLIED
%Clear;
>
<!-- priority is in the range 0.0 - 1.0. Its default value SHOULD
be 1.0 -->
<!ELEMENT lookup ( success?,notfound?,failure? ) >
<!ATTLIST lookup
source CDATA #REQUIRED
timeout CDATA "30"
use CDATA #IMPLIED
ignore CDATA #IMPLIED
%Clear;
>
<!ELEMENT success ( %Node; ) >
<!ELEMENT notfound ( %Node; ) >
<!ELEMENT failure ( %Node; ) >
<!ELEMENT remove-location ( %Node; ) >
<!ATTLIST remove-location
param CDATA #IMPLIED
value CDATA #IMPLIED
location CDATA #IMPLIED
>
<!-- Signalling Actions: call-signalling actions the script can
take. -->
<!ELEMENT proxy ( busy?,noanswer?,redirection?,failure?,default? ) >
<!-- The default value of timeout is "20" if the <noanswer> output
exists. -->
<!ATTLIST proxy
timeout CDATA #IMPLIED
recurse (yes|no) "yes"
ordering (parallel|sequential|first-only) "parallel"
>
<!ELEMENT busy ( %Node; ) >
<!ELEMENT noanswer ( %Node; ) >
<!ELEMENT redirection ( %Node; ) >
<!-- "failure" repeats from lookup, above. -->
<!ELEMENT default ( %Node; ) >
<!ELEMENT redirect EMPTY >
<!ATTLIST redirect
permanent (yes|no) "no"
>
<!-- Statuses we can return -->
<!ELEMENT reject EMPTY >
<!-- The value of "status" is (busy|notfound|reject|error), or a SIP
4xx-6xx status. -->
<!ATTLIST reject
status CDATA #REQUIRED
reason CDATA #IMPLIED
>
<!-- Non-signalling actions: actions that don't affect the call -->
<!ELEMENT mail ( %Node; ) >
<!ATTLIST mail
url CDATA #REQUIRED
>
<!ELEMENT log ( %Node; ) > +---------+ +------+ +--address
<!ATTLIST log +-+ancillary| |switch|** +--------------+ | +-not-present
name CDATA #IMPLIED | +---------+ +---+--+ **|address-switch+-+-+-address
comment CDATA #IMPLIED | | * +--------------+ +--otherwise
> | +---------+ +----+ | * +--language
+-+subaction+-+Node| | * +---------------+ | +-not-present
| +---------+ +----+ | **|language-switch|-+-+-language
| | * +---------------+ +--otherwise
| | * +--priority
| | * +---------------+ | +-not-present
| | **|proiroty-switch|-+-+-priority
| | * +---------------+ +--otherwise
| | * +--string
cpl-+ | * +-------------+ | +-not-present
| | **|string-switch|-+ +-string
| | * +-------------+ +--otherwise
| | * +--time
| +--------------+ +-+--+ * +-----------+ | +-not-present
+-+toplevelaction+-+Node| *|time-switch|-+-+-time
+-----*--------+ +-+--+ +-----------+ +--otherwise
* | +--------+ +----+
* | +-+location+-|Node|
* | +--------+ | +--------+ +----+
* +--------+ |-+Location+-| +------+ +-success-Node
**|incoming| | +--------+ +-+lookup+-+-notfound-Node
* +--------+ | | +------+ +-failure-Node
* | +---+ | +---------------+ +----+
* +--------+ +-+Sub+-sub +-+remove-location+-+Node|
*|outgoing| | +---+ +---------------+ +----+
+--------+ | +---+
| **|log+-Node
| * +---+
| * +----+
| +------+ **|mail+-Node
+-+action|** +----+ +-busy-Node
---- contains +------+ * +-----+ |
**|proxy+----+-noanswer-Node
**** substitutes * +-----+ |
* +--------+ +-failure-Node
**|redirect| |
* +--------+ +-redirection-Node
* +------+ |
*|reject| +-default-Node
+------+
<!-- Calls to subactions. --> Figure 31: The structure of the XML schema for CPL
<xs:schema targetNamespace="urn:ietf:params:xml:ns:cpl"
xmlns="urn:ietf:params:xml:ns:cpl"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:complexType name="TopLevelActionType" abstract="true">
<xs:group ref="Node"/>
</xs:complexType>
<xs:element name="toplevelaction" type="TopLevelActionType"/>
<xs:complexType name="ActionType" abstract="true"/>
<xs:element name="action" type="ActionType"/>
<xs:complexType name="SwitchType" abstract="true"/>
<xs:element name="switch" type="SwitchType"/>
<xs:group name="Location">
<xs:choice>
<xs:element name="location" type="LocationType"/>
<xs:element name="lookup" type="LookupType"/>
<xs:element name="remove-location" type="RemoveLocationType"/>
</xs:choice>
</xs:group>
<xs:group name="Sub">
<xs:all>
<xs:element name="sub" type="SubAction"/>
</xs:all>
</xs:group>
<xs:group name="Node">
<xs:choice>
<xs:element ref="switch" minOccurs="0" maxOccurs="1"/>
<xs:group ref="Location" minOccurs="0" maxOccurs="1"/>
<xs:group ref="Sub" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="action" minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
</xs:group>
<xs:complexType name="OtherwiseAction">
<xs:group ref="Node"/>
</xs:complexType>
<xs:complexType name="NotPresentAction">
<xs:group ref="Node"/>
</xs:complexType>
<xs:simpleType name="YesNoType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="yes"/>
<xs:enumeration value="no"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="StatusType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="busy"/>
<xs:pattern value="notfound"/>
<xs:pattern value="reject"/>
<xs:pattern value="error"/>
<xs:pattern value="[4-6][0-9][0-9]"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="OrderingType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="parallel"/>
<xs:enumeration value="sequential"/>
<xs:enumeration value="first-only"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="DirectionType">
<xs:restriction base="xs:string">
<xs:enumeration value="incoming"/>
<xs:enumeration value="outgoing"/>
<xs:enumeration value="both"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="AddressFieldType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="origin"/>
<xs:enumeration value="destination"/>
<xs:enumeration value="original-destination"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="AddressSubfieldType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="address-type"/>
<xs:enumeration value="user"/>
<xs:enumeration value="host"/>
<xs:enumeration value="port"/>
<xs:enumeration value="tel"/>
<xs:enumeration value="display"/>
<xs:enumeration value="password"/>
<xs:enumeration value="alias-type"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="AddressType">
<xs:annotation>Exactly one of the three attributes must
appear</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="is" type="xs:string" use="optional"/>
<xs:attribute name="contains" type="xs:string" use="optional">
<xs:annotation>for "display" only</xs:annotation>
</xs:attribute>
<xs:attribute name="subdomain-of" type="xs:string"
use="optional">
<xs:annotation>for "host", "tel" only</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="AddressSwitchType">
<xs:sequence>
<xs:element name="address" type="AddressType" minOccurs="0"
maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="address" type="AddressType" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction"
minOccurs="0"/>
</xs:sequence>
<xs:attribute name="field" type="AddressFieldType"
use="required"/>
<xs:attribute name="subfield" type="AddressSubfieldType"
use="optional"/>
</xs:complexType>
<xs:element name="address-switch" type="AddressSwitchType"
substitutionGroup="switch"/>
<xs:simpleType name="StringFieldType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="subject"/>
<xs:enumeration value="organization"/>
<xs:enumeration value="user-agent"/>
<xs:enumeration value="display"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="StringType">
<xs:group ref="Node"/>
<xs:attribute name="is" type="xs:string" use="optional"/>
<xs:attribute name="contains" type="xs:string" use="optional"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="StringSwitchType">
<xs:sequence>
<xs:element name="string" type="StringType" minOccurs="0"
maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="string" type="StringType" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction"
minOccurs="0"/>
</xs:sequence>
<xs:attribute name="field" type="StringFieldType"
use="required">
<xs:annotation>Strings are matched as case-insensitive Unicode
strings.</xs:annotation>
</xs:attribute>
</xs:complexType>
<xs:element name="string-switch" type="StringSwitchType"
substitutionGroup="switch"/>
<xs:complexType name="LanguageType">
<xs:group ref="Node"/>
<xs:attribute name="matches" type="xs:string" use="required">
<xs:annotation>The value of one of these parameters is a
language-tag, as defined in RFC 3066.</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="LanguageSwitchType">
<xs:sequence>
<xs:element name="language" type="LanguageType" minOccurs="0"
maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="language" type="LanguageType" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="language-switch" type="LanguageSwitchType"
substitutionGroup="switch"/>
<xs:simpleType name="FreqType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[s|S][e|E][c|C][o|O][n|N][d|D][l|L][y|Y]"/>
<xs:pattern value="[m|M][i|I][n|N][u|U][t|T][e|E][l|L][y|Y]"/>
<xs:pattern value="[h|H][o|O][u|U][r|R][l|L][y|Y]"/>
<xs:pattern value="[d|D][a|A][i|I][l|L][y|Y]"/>
<xs:pattern value="[w|W][e|E][e|E][k|K][l|L][y|Y]"/>
<xs:pattern value="[m|M][o|N][n|N][t|T][h|H][l|L][y|Y]"/>
<xs:pattern value="[y|Y][e|E][a|A][r|R][l|L][y|Y]"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="YearDayType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="-366"/>
<xs:maxInclusive value="-1"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="1"/>
<xs:maxExclusive value="366"/>
</xs:restriction>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:simpleType name="DayType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[m|M][o|O]"/>
<xs:pattern value="[t|T][u|U]"/>
<xs:pattern value="[w|W][e|E]"/>
<xs:pattern value="[t|T][h|H]"/>
<xs:pattern value="[f|F][r|R]"/>
<xs:pattern value="[s|S][a|A]"/>
<xs:pattern value="[s|S][u|U]"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="TimeType">
<xs:annotation>Exactly one of the two attributes "dtend" and
"duration" must occur. None of the attributes following freq
are meaningful unless freq appears. </xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="dtstart" type="xs:string" use="required">
<xs:annotation>RFC 2445 DATE-TIME</xs:annotation>
</xs:attribute>
<xs:attribute name="dtend" type="xs:string" use="optional">
<xs:annotation>RFC 2445 DATE-TIME</xs:annotation>
</xs:attribute>
<xs:attribute name="duration" type="xs:string" use="optional">
<xs:annotation>RFC 2445 DURATION</xs:annotation>
</xs:attribute>
<xs:attribute name="freq" type="FreqType" use="optional"/>
<xs:attribute name="interval" type="xs:positiveInteger"
default="1"/>
<xs:attribute name="until" type="xs:string" use="optional">
<xs:annotation>RFC 2445 DATE-TIME</xs:annotation>
</xs:attribute>
<xs:attribute name="count" type="xs:positiveInteger"
use="optional"/>
<xs:attribute name="bysecond" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of seconds within a minute.
Valid values are 0 to 59.</xs:annotation>
</xs:attribute>
<xs:attribute name="byminute" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of minutes within an hour.
Valid values are 0 to 59.</xs:annotation>
</xs:attribute>
<xs:attribute name="byhour" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of hours of the day. Valid
values are 0 to 23.</xs:annotation>
</xs:attribute>
<xs:attribute name="byday" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of days of the week. Valid
values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU".
These values are not case-sensitive. Each can be preceded
by a positive (+n) or negative (-n)
integer.</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonthday" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of days of the month. Valid
values are 1 to 31 or -31 to -1.</xs:annotation>
</xs:attribute>
<xs:attribute name="byyearday" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of days of the year. Valid
values are 1 to 366 or -366 to -1.</xs:annotation>
</xs:attribute>
<xs:attribute name="byweekno" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of ordinals specifying
weeks of the year. Valid values are 1 to 53 or -53 to
-1.</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonth" type="xs:string" use="optional">
<xs:annotation>Comma-separated list of months of the year.
Valid values are 1 to 12.</xs:annotation>
</xs:attribute>
<xs:attribute name="wkst" type="DayType" default="MO"/>
<xs:attribute name="bysetpos" type="YearDayType"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:simpleType name="TZIDType">
<xs:restriction base="xs:string"/>
</xs:simpleType>
<xs:simpleType name="TZURLType">
<xs:restriction base="xs:anyURI"/>
</xs:simpleType>
<xs:complexType name="TimeSwitchType">
<xs:sequence>
<xs:element name="time" type="TimeType" minOccurs="0"
maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="time" type="TimeType" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction"
minOccurs="0"/>
</xs:sequence>
<xs:attribute name="tzid" type="TZIDType"/>
<xs:attribute name="tzurl" type="TZURLType"/>
</xs:complexType>
<xs:element name="time-switch" type="TimeSwitchType"
substitutionGroup="switch"/>
<xs:simpleType name="PriorityValues">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern
value="[e|E][m|M][e|E][r|R][g|G][e|E][n|N][c|C][y|Y]"/>
<xs:pattern value="[u|U][r|R][g|G][e|E][n|N][t|T]"/>
<xs:pattern value="[n|N][o|O][r|R][m|M][a|A][l|L]"/>
<xs:pattern
value="[n|N][o|O][n|N]-[u|U][r|R][g|G][e|E][n|N][t|T]"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="PriorityType">
<xs:annotation>Exactly one of the three attributes must appear
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="less" type="PriorityValues"/>
<xs:attribute name="greater" type="PriorityValues"/>
<xs:attribute name="equal" type="xs:string">
<xs:annotation>case-insensitive</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="PrioritySwitchType">
<xs:sequence>
<xs:element name="priority" type="PriorityType" minOccurs="0"
maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="priority" type="PriorityType" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="priority-switch" type="PrioritySwitchType"
substitutionGroup="switch"/>
<xs:simpleType name="LocationPriorityType">
<xs:restriction base="xs:float">
<xs:minInclusive value="0.0"/>
<xs:maxInclusive value="1.0"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="LocationType">
<xs:group ref="Node"/>
<xs:attribute name="url" type="xs:anyURI" use="required"/>
<xs:attribute name="priority" type="LocationPriorityType"
use="optional" default="1.0"/>
<xs:attribute name="clear" type="YesNoType" default="no"/>
</xs:complexType>
<xs:complexType name="LookupType">
<xs:all>
<xs:element name="success" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="notfound" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="source" type="xs:string" use="required"/>
<xs:attribute name="timeout" type="xs:positiveInteger"
default="30"/>
<xs:attribute name="clear" type="YesNoType" default="no"/>
</xs:complexType>
<xs:complexType name="RemoveLocationType">
<xs:group ref="Node"/>
<xs:attribute name="location" type="xs:string" use="optional"/>
</xs:complexType>
<xs:complexType name="LogAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="name" type="xs:string" use="optional"/>
<xs:attribute name="comment" type="xs:string"
use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="log" type="LogAction"
substitutionGroup="action"/>
<xs:complexType name="IncomingType">
<xs:complexContent>
<xs:extension base="TopLevelActionType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="incoming" type="IncomingType"
substitutionGroup="toplevelaction"/>
<xs:complexType name="OutgoingType">
<xs:complexContent>
<xs:extension base="TopLevelActionType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="outgoing" type="OutgoingType"
substitutionGroup="toplevelaction"/>
<xs:complexType name="ProxyAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:all>
<xs:element name="busy" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="redirection" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="default" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:positiveInteger"
use="optional" default="20"/>
<xs:attribute name="recursive" type="YesNoType"
use="optional" default="yes"/>
<xs:attribute name="ordering" type="OrderingType"
use="optional" default="parallel"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="proxy" type="ProxyAction"
substitutionGroup="action"/>
<xs:complexType name="RedirectAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:attribute name="permanent" type="YesNoType"
default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="redirect" type="RedirectAction"
substitutionGroup="action"/>
<xs:complexType name="RejectAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:attribute name="status" type="StatusType"
use="required"/>
<xs:attribute name="reason" type="xs:string"
use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="reject" type="RejectAction"
substitutionGroup="action"/>
<xs:complexType name="MailAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="url" type="xs:anyURI" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="mail" type="MailAction"
substitutionGroup="action"/>
<xs:complexType name="SubAction">
<xs:attribute name="ref" type="xs:string" use="required"/>
</xs:complexType>
<xs:complexType name="AncillaryType"/>
<xs:complexType name="SubactionType">
<xs:group ref="Node"/>
<xs:attribute name="id" use="required"/>
</xs:complexType>
<xs:element name="cpl">
<xs:complexType>
<xs:sequence>
<xs:element name="ancillary" type="AncillaryType"
minOccurs="0"/>
<xs:element name="subaction" type="SubactionType"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="toplevelaction" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
<!ELEMENT sub EMPTY > D Changes from Earlier Versions
<!ATTLIST sub
ref IDREF #REQUIRED
>
<!-- Ancillary data --> [Note to RFC Editor: please remove this appendix before
publication as an RFC.]
<!ENTITY % Ancillary 'ancillary?' > D.1 Changes from Draft -06
<!ELEMENT ancillary EMPTY > The changebars in the Postscript and PDF versions of this document
indicate significant changes from this version.
<!-- Subactions --> o Added Xiaotao Wu as a co-author.
<!ENTITY % Subactions 'subaction*' > o Converted CPL DTD to CPL XML Schema.
<!ELEMENT subaction ( %Node; )>
<!ATTLIST subaction
id ID #REQUIRED
>
<!-- Top-level actions --> o Dropped all features dependent on caller preferences and
callee capabilities.
<!ENTITY % TopLevelActions 'outgoing?,incoming?' > o Added an XML namespace URN urn:ietf:params:xml:ns:cpl and
registration information for it.
<!ELEMENT outgoing ( %Node; )> o Separated normative and informative references.
<!ELEMENT incoming ( %Node; )> o Updated some references; most notably, updated SIP reference
to RFC 3261. Updated text to reflect changes in these
references.
<!-- The top-level element of the script. --> o Allowed servers more flexibility about recognizing SIP
addresses as telephone numbers.
<!ELEMENT cpl ( %Ancillary;,%Subactions;,%TopLevelActions; ) > o Restored some text, in the definition of "interval",
accidentally omitted when sub-day recurrences were re-added in
draft -05.
D Changes from Earlier Versions o Clarified the usages of "lookup" and "remove-location" with
SIP, and "remove-location" with H.323.
[Note to RFC Editor: please remove this appendix before o Updated address of the IPTel working group's mailing list.
publication as an RFC.]
D.1 Changes from Draft -05 o Improved wording, cleaned up formatting, and corrected typos.
The changebars in the Postscript and PDF versions of this document D.2 Changes from Draft -05
indicate significant changes from this version.
o Clarified that switch nodes are allowed to be degenerate -- o Clarified that switch nodes are allowed to be degenerate --
they can have no outputs, and they can have only an they can have no outputs, and they can have only an
"otherwise" output. "otherwise" output.
o Clarified the (non-) usage of the special language-range "*". o Clarified the (non-) usage of the special language-range "*".
o Clarified that the Candidate Start Time can be equal to the o Clarified that the Candidate Start Time can be equal to the
call time. call time.
skipping to change at page 61, line 9 skipping to change at page 67, line 39
o Added DTD entries for the "time-switch" attributes re-added in o Added DTD entries for the "time-switch" attributes re-added in
draft -05. draft -05.
o Updated the reference to ISO 8601 to cite 8601:2000. o Updated the reference to ISO 8601 to cite 8601:2000.
o Updated all H.323 references to cite H.323v4. o Updated all H.323 references to cite H.323v4.
o Corrected some spelling errors. o Corrected some spelling errors.
D.2 Changes from Draft -04 D.3 Changes from Draft -04
o Broke out language switches into their own switch node. o Broke out language switches into their own switch node.
o Restored the full iCalendar COS recurrence specification. o Restored the full iCalendar COS recurrence specification.
Added text describing the consequences of this for Added text describing the consequences of this for
implementors, and expanded somewhat on the recurrence implementors, and expanded somewhat on the recurrence
algorithm. algorithm.
o Clarified when time zones are resolved. o Clarified when time zones are resolved.
skipping to change at page 62, line 5 skipping to change at page 68, line 35
can trigger a default action, just like anything else. can trigger a default action, just like anything else.
o Clarified that the time-switch resolution algorithm is non- o Clarified that the time-switch resolution algorithm is non-
normative. normative.
o Updated references to previously-unpublished RFCs, now o Updated references to previously-unpublished RFCs, now
published. published.
o Thanked Richard Gumpertz. o Thanked Richard Gumpertz.
D.3 Changes from Draft -03 D.4 Changes from Draft -03
o Removed an obsolete reference to a usage in examples which o Removed an obsolete reference to a usage in examples which
wasn't actually used anywhere. wasn't actually used anywhere.
o Added forward references to "remove-location", "mail" and o Added forward references to "remove-location", "mail" and
"log", as well as "location", in the XML syntax as examples of "log", as well as "location", in the XML syntax as examples of
nodes that don't have explicit output tags. nodes that don't have explicit output tags.
o Made the usage of some terminology more consistent: "output" o Made the usage of some terminology more consistent: "output"
vs. "next node"; "action" vs. "operation" vs. "behavior"; vs. "next node"; "action" vs. "operation" vs. "behavior";
skipping to change at page 62, line 51 skipping to change at page 69, line 33
extensions only. extensions only.
o Expunged some references to sub-daily recurrences which had o Expunged some references to sub-daily recurrences which had
accidentally been left in the text. accidentally been left in the text.
o Updated bibliography to refer to the latest versions of the o Updated bibliography to refer to the latest versions of the
cited documents. cited documents.
o Fixed a number of typographical errors. o Fixed a number of typographical errors.
D.4 Changes from Draft -02 D.5 Changes from Draft -02
o Reduced time-switches from the full iCal recurrence to an iCal o Reduced time-switches from the full iCal recurrence to an iCal
subset. Added an appendix giving an algorithm to resolve subset. Added an appendix giving an algorithm to resolve
time-switches. time-switches.
o Added the extension mechanism. o Added the extension mechanism.
o Made explicit how each node is dependent on protocol handling. o Made explicit how each node is dependent on protocol handling.
Separated out protocol-specific information -- for SIP in Separated out protocol-specific information -- for SIP in
subsections of the main text, for H.323 in a non-normative subsections of the main text, for H.323 in a non-normative
appendix. appendix.
o Clarified some address mapping rules for H.323. o Clarified some address mapping rules for H.323.
o Corrected the name of the "Redirecting number" in Q.931. o Corrected the name of the "Redirecting number" in Q.931.
o Clarified that address matching on the "password" subfield is o Clarified that address matching on the "password" subfield is
case-sensitive. case-sensitive.
o Added a recommendation that TZID labels follow the usage of o Added a recommendation that "tzid" labels follow the usage of
the Olson database. the Olson database.
o Added the "priority" parameter to "location" nodes. o Added the "priority" parameter to "location" nodes.
o Added the "default" output to the "proxy" node. o Added the "default" output to the "proxy" node.
o Made the meaning of the "proxy" node's outputs explicit. o Made the meaning of the "proxy" node's outputs explicit.
o Added suggested content for the e-mail generated by "mail" o Added suggested content for the e-mail generated by "mail"
nodes. nodes.
skipping to change at page 63, line 46 skipping to change at page 70, line 29
o Pointed out that log names are logical names, and should not o Pointed out that log names are logical names, and should not
be interpreted as verbatim filenames. be interpreted as verbatim filenames.
o Added some examples. o Added some examples.
o Clarified some wording. o Clarified some wording.
o Fixed some typographical errors. o Fixed some typographical errors.
D.5 Changes from Draft -01 D.6 Changes from Draft -01
o Completely re-wrote changes to time switches: they are now o Completely re-wrote changes to time switches: they are now
based on iCal rather than on crontab. based on iCal rather than on crontab.
o Timezone references are now defined within time switches o Timezone references are now defined within time switches
rather than in the ancillary section. The ancillary section is rather than in the ancillary section. The ancillary section is
now empty, but still defined for future use. To facilitate now empty, but still defined for future use. To facilitate
this, an explicit "ancillary" tag was added. this, an explicit "ancillary" tag was added.
o Added XML document type identifiers (the public identifier and o Added XML document type identifiers (the public identifier and
skipping to change at page 65, line 7 skipping to change at page 71, line 37
servers. servers.
o Updated reference to RFC 2824 now that it has been published. o Updated reference to RFC 2824 now that it has been published.
o Added explanatory text to the introduction to types of nodes. o Added explanatory text to the introduction to types of nodes.
o Numerous minor clarifications and wording changes. o Numerous minor clarifications and wording changes.
o Fixed copy-and-paste errors, typos. o Fixed copy-and-paste errors, typos.
D.6 Changes from Draft -00 D.7 Changes from Draft -00
o Added high-level structure; script doesn't just start at a o Added high-level structure; script doesn't just start at a
first action. first action.
o Added a section giving a high-level explanation of the o Added a section giving a high-level explanation of the
location model. location model.
o Added informal syntax specifications for each tag so people o Added informal syntax specifications for each tag so people
don't have to try to understand a DTD to figure out the don't have to try to understand a DTD to figure out the
syntax. syntax.
skipping to change at page 66, line 22 skipping to change at page 72, line 51
E Authors' Addresses E Authors' Addresses
Jonathan Lennox Jonathan Lennox
Dept. of Computer Science Dept. of Computer Science
Columbia University Columbia University
1214 Amsterdam Avenue, MC 0401 1214 Amsterdam Avenue, MC 0401
New York, NY 10027 New York, NY 10027
USA USA
electronic mail: lennox@cs.columbia.edu electronic mail: lennox@cs.columbia.edu
Xiaotao Wu
Dept. of Computer Science
Columbia University
1214 Amsterdam Avenue, MC 0401
New York, NY 10027
USA
electronic mail: xiaotaow@cs.columbia.edu
Henning Schulzrinne Henning Schulzrinne
Dept. of Computer Science Dept. of Computer Science
Columbia University Columbia University
1214 Amsterdam Avenue, MC 0401 1214 Amsterdam Avenue, MC 0401
New York, NY 10027 New York, NY 10027
USA USA
electronic mail: schulzrinne@cs.columbia.edu electronic mail: schulzrinne@cs.columbia.edu
F Bibliography F Normative References
[1] M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg, "SIP:
session initiation protocol," Request for Comments 2543, Internet
Engineering Task Force, Mar. 1999.
[2] International Telecommunication Union, "Packet based multimedia [1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. R. Johnston, J.
communication systems," Recommendation H.323, Telecommunication Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session
Standardization Sector of ITU, Geneva, Switzerland, Nov. 2000. initiation protocol," RFC 3261, Internet Engineering Task Force, June
2002.
[3] T. Bray, J. Paoli, and C. M. Sperberg-McQueen, "Extensible markup [2] T. Bray, J. Paoli, and C. M. Sperberg-McQueen, "Extensible markup
language (XML) 1.0 (second edition)," W3C Recommendation REC-xml- language (XML) 1.0 (second edition)," W3C Recommendation REC-xml-
20001006, World Wide Web Consortium (W3C), Oct. 2000. Available at 20001006, World Wide Web Consortium (W3C), Oct. 2000. Available at
http://www.w3.org/XML/. http://www.w3.org/XML/.
[4] J. Lennox and H. Schulzrinne, "Call processing language framework [3] S. Bradner, "Key words for use in RFCs to indicate requirement
and requirements," Request for Comments 2824, Internet Engineering levels," RFC 2119, Internet Engineering Task Force, Mar. 1997.
Task Force, May 2000.
[5] S. Bradner, "Key words for use in RFCs to indicate requirement
levels," Request for Comments 2119, Internet Engineering Task Force,
Mar. 1997.
[6] D. Raggett, A. Le Hors, and I. Jacobs, "HTML 4.01 specification,"
W3C Recommendation REC-html401-19991224, World Wide Web Consortium
(W3C), Dec. 1999. Available at http://www.w3.org/TR/html4/.
[7] ISO (International Organization for Standardization),
"Information processing -- text and office systems -- standard
generalized markup language (SGML)," ISO Standard ISO 8879:1986(E),
International Organization for Standardization, Geneva, Switzerland,
Oct. 1986.
[8] M. Murata, S. S. Laurent, and D. Kohn, "XML media types," Request
for Comments 3023, Internet Engineering Task Force, Jan. 2001.
[9] R. Hinden and S. Deering, "IP version 6 addressing architecture," [4] R. Hinden and S. E. Deering, "IP version 6 addressing
Request for Comments 2373, Internet Engineering Task Force, July architecture," RFC 2373, Internet Engineering Task Force, July 1998.
1998.
[10] M. Davis and M. Duerst, "Unicode normalization forms," Unicode [5] M. F. Davis and M. Duerst, "Unicode normalization forms," Unicode
Technical Report 15, Unicode Consortium, Aug. 2000. Revision 19; Technical Report 15, Unicode Consortium, Aug. 2000. Revision 19;
part of Unicode 3.0.1. Available at part of Unicode 3.0.1. Available at
http://www.unicode.org/unicode/reports/tr15/. http://www.unicode.org/unicode/reports/tr15/.
[11] M. Davis, "Case mappings," Unicode Technical Report 21, Unicode [6] M. F. Davis, "Case mappings," Unicode Technical Report 21,
Consortium, Oct. 2000. Revision 4.3. Available at Unicode Consortium, Oct. 2000. Revision 4.3. Available at
http://www.unicode.org/unicode/reports/tr21/. http://www.unicode.org/unicode/reports/tr21/.
[12] H. Alvestrand, "Tags for the identification of languages," [7] H. Alvestrand, "Tags for the identification of languages," RFC
Request for Comments 3066, Internet Engineering Task Force, Jan. 3066, Internet Engineering Task Force, Jan. 2001.
2001.
[13] F. Dawson and D. Stenerson, "Internet calendaring and scheduling [8] F. Dawson and D. Stenerson, "Internet calendaring and scheduling
core object specification (icalendar)," Request for Comments 2445, core object specification (icalendar)," RFC 2445, Internet
Internet Engineering Task Force, Nov. 1998. Engineering Task Force, Nov. 1998.
[14] P. Eggert, "Sources for time zone and daylight saving time [9] P. Eggert, "Sources for time zone and daylight saving time data."
data." Available at http://www.twinsun.com/tz/tz-link.htm. Available at http://www.twinsun.com/tz/tz-link.htm.
[15] ISO (International Organization for Standardization), "Data [10] M. Mealling and R. W. Daniel, "URI resolution services necessary
for URN resolution," RFC 2483, Internet Engineering Task Force, Jan.
1999.
[11] T. Bray, D. Hollander, and A. Layman, "Namespaces in XML," W3C
Recommendation REC-xml-names-19900114, World Wide Web Consortium
(W3C), Jan. 1999. Available at http://www.w3.org/TR/REC-xml-names/.
[12] R. Moats, "URN syntax," RFC 2141, Internet Engineering Task
Force, May 1997.
[13] R. Moats, "A URN namespace for IETF documents," RFC 2648,
Internet Engineering Task Force, Aug. 1999.
[14] M. Mealling, "The IETF XML registry," internet draft, Internet
Engineering Task Force, June 2003. Work in progress.
[15] M. Murata, S. S. Laurent, and D. Kohn, "XML media types," RFC
3023, Internet Engineering Task Force, Jan. 2001.
G Informative References
[16] International Telecommunication Union, "Packet based multimedia
communication systems," Recommendation H.323, Telecommunication
Standardization Sector of ITU, Geneva, Switzerland, Nov. 2000.
[17] J. Lennox and H. Schulzrinne, "Call processing language
framework and requirements," RFC 2824, Internet Engineering Task
Force, May 2000.
[18] D. Raggett, A. Le Hors, and I. Jacobs, "HTML 4.01
specification," W3C Recommendation REC-html401-19991224, World Wide
Web Consortium (W3C), Dec. 1999. Available at
http://www.w3.org/TR/html4/.
[19] ISO (International Organization for Standardization),
"Information processing -- text and office systems -- standard
generalized markup language (SGML)," ISO Standard ISO 8879:1986(E),
International Organization for Standardization, Geneva, Switzerland,
Oct. 1986.
[20] ISO (International Organization for Standardization), "Data
elements and interchange formats -- information interchange -- elements and interchange formats -- information interchange --
representation of dates and times," ISO Standard ISO 8601:2000(E), representation of dates and times," ISO Standard ISO 8601:2000(E),
International Organization for Standardization, Geneva, Switzerland, International Organization for Standardization, Geneva, Switzerland,
Dec. 2000. Dec. 2000.
[16] M. Mealling and R. Daniel, "URI resolution services necessary [21] S. DeRose, E. Maler, D. Orchard, and B. Trafford, "XML linking
for URN resolution," Request for Comments 2483, Internet Engineering
Task Force, Jan. 1999.
[17] H. Schulzrinne and J. Rosenberg, "SIP caller preferences and
callee capabilities," Internet Draft, Internet Engineering Task
Force, Nov. 2001. Work in progress.
[18] S. DeRose, E. Maler, D. Orchard, and B. Trafford, "XML linking
language (XLink) version 1.0," W3C Candidate Recommendation CR- language (XLink) version 1.0," W3C Candidate Recommendation CR-
xlink-20000703, World Wide Web Consortium (W3C), July 2000. xlink-20000703, World Wide Web Consortium (W3C), July 2000.
Available at http://www.w3.org/TR/xlink/. Available at http://www.w3.org/TR/xlink/.
[19] T. Bray, D. Hollander, and A. Layman, "Namespaces in XML," W3C [22] T. Showalter, "Sieve: A mail filtering language," RFC 3028,
Recommendation REC-xml-names-19900114, World Wide Web Consortium Internet Engineering Task Force, Jan. 2001.
(W3C), Jan. 1999. Available at http://www.w3.org/TR/REC-xml-names/.
[20] T. Showalter, "Sieve: A mail filtering language," Request for
Comments 3028, Internet Engineering Task Force, Jan. 2001.
[21] D. C. Fallside, "XML schema part 0: Primer," W3C Candidate
Recommendation CR-xmlschema-0-20001024, World Wide Web Consortium
(W3C), Oct. 2000. Available at http://www.w3.org/TR/xmlschema-0/.
[22] International Telecommunication Union, "Digital subscriber [23] International Telecommunication Union, "Digital subscriber
signalling system no. 1 (dss 1) - isdn user-network interface layer 3 signalling system no. 1 (DSS 1) - ISDN user-network interface layer 3
specification for basic call control," Recommendation Q.931, specification for basic call control," Recommendation Q.931,
Telecommunication Standardization Sector of ITU, Geneva, Switzerland, International Telecommunication Union, Geneva, Switzerland, Mar.
Mar. 1993. 1993.
[23] O. Levin, "H.323 URL scheme definition," Internet Draft, [24] O. Levin, "H.323 uniform resource locator (URL) scheme
Internet Engineering Task Force, Nov. 2001. Work in progress. registration," RFC 3508, Internet Engineering Task Force, Apr. 2003.
Full Copyright Statement Full Copyright Statement
Copyright (c) The Internet Society (2002). All Rights Reserved. Copyright (c) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/