draft-ietf-ipp-notify-poll-00.txt   draft-ietf-ipp-notify-poll-01.txt 
INTERNET-DRAFT INTERNET-DRAFT Robert Herriot
<draft-ietf-ipp-notify-poll-00.txt> Carl-Uno Manros <draft-ietf-ipp-notify-poll-01.txt> Xerox Corp.
Tom Hastings Tom Hastings
Robert Herriot Xerox Corp.
Carl-Uno Manros
Xerox Corp. Xerox Corp.
Harry Lewis Harry Lewis
IBM, Corp. IBM, Corp.
March 8, 2000 July 7, 2000
Internet Printing Protocol (IPP): Internet Printing Protocol (IPP):
The 'ipp' Notification Polling Method The 'ipp-get' Delivery Method
Copyright (C) The Internet Society (2000). All Rights Reserved. Copyright (C) The Internet Society (2000). All Rights Reserved.
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of [rfc2026]. Internet-Drafts are working provisions of Section 10 of [rfc2026]. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, and documents of the Internet Engineering Task Force (IETF), its areas, and
its working groups. Note that other groups may also distribute working its working groups. Note that other groups may also distribute working
documents as Internet-Drafts. documents as Internet-Drafts.
skipping to change at page 1, line 37 skipping to change at page 1, line 38
or to cite them other than as "work in progress". or to cite them other than as "work in progress".
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed as The list of Internet-Draft Shadow Directories can be accessed as
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
The IPP notification specification [ipp-ntfy] is an OPTIONAL extension The notification extension document [ipp-ntfy] defines operations that a
to IPP/1.0 and IPP/1.1 that requires the definition of one or more client can perform in order to create Subscription Objects in a Printer
delivery methods for dispatching Event Notification reports to and carry out other operations on them. A Subscription Object represents
Notification Recipients. This document describes the semantics and a Subscription abstraction. The Subscription Object specifies that when
syntax of the 'ipp' event Notification delivery method. For this one of the specified Events occurs, the Printer sends an asynchronous
delivery method, the client uses an explicit IPP Get-Notifications Event Notification to the specified Notification Recipient via the
Printer operation in order to request (pull) Event Notifications from specified Delivery Method (i.e., protocol).
the IPP Printer.
When a Printer supports the 'ipp' delivery method, it holds each Event
Notification for a certain length of time. The amount of time is called
the "event-lease time".. A Printer may assign the same event-lease time
to each Event Notification or different times. If a Notification
Recipient does not want to miss Event Notifications, the time between
consecutive pollings of Subscription objects must be less than the
event-lease time of the events that occur between pollings. The Get-
Notifications request indicates whether the client wants to receive all
pending event Notifications for (1) any Subscription for which the
client is the owner, (2) any Subscription associated with a Job, (3) any
Subscription with a particular delivery-method URL, or (4) an identified
Expires: September 8, 2000 The notification extension document [ipp-ntfy] specifies that each
Delivery Method is defined in another document. This document is one
such document, and it specifies the 'ipp-get' delivery method.
set of Subscription objects. With the Get-Notifications operation, the The 'ipp-get' Delivery Method is a 'pull' Delivery Method. That is, the
Printer returns all existing Event Notifications along with two time Printer saves Event Notification for a period of time and expects the
intervals. One specifies the minimum time at which event-leases of Notification Recipient to fetch the Event Notifications.
future events of the type returned will begin to expire and the other
specifies the recommended interval for the client to wait before sending
the next Get-Notifications operation. The second time interval is less
than the first.
The Printer may keep the channel open if the recommended interval is When a Printer supports this Delivery Method, it holds each Event
sufficiently short, but in any case the client performs a new Get- Notification for an amount of time, called the Event Notification Lease
Notifications operation each time it wants more Event Notifications. Time.
Since the time interval between consecutive client requests is normally
less than the event-lease time, consecutive responses will normally
contain some Event Notifications that are identical. The youngest ones
in the previous response will become the oldest in the next response.
The client is expected to filter out these duplicates, which is easy to
do because of the sequence number in each Event Notification.
Expires: September 8, 2000 When a Notification Recipient wants to receive Event Notifications, it
performs an IPP operation called 'Get-Notifications', which this
document defines. This operation causes the Printer to return all Event
Notifications held for the Notification Recipient along with information
that tells the client when to perform this operation again.
The full set of IPP documents includes: The full set of IPP documents includes:
Design Goals for an Internet Printing Protocol [RFC2567] Design Goals for an Internet Printing Protocol [RFC2567]
Rationale for the Structure and Model and Protocol for the Internet Rationale for the Structure and Model and Protocol for the Internet
Printing Protocol [RFC2568] Printing Protocol [RFC2568]
Internet Printing Protocol/1.1: Model and Semantics [ipp-mod] Internet Printing Protocol/1.1: Model and Semantics [ipp-mod]
Internet Printing Protocol/1.1: Encoding and Transport [ipp-pro] Internet Printing Protocol/1.1: Encoding and Transport [ipp-pro]
Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig] Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig]
Mapping between LPD and IPP Protocols [RFC2569] Mapping between LPD and IPP Protocols [RFC2569]
Internet Printing Protocol/1.0 & 1.1: Event Notification Internet Printing Protocol/1.0 & 1.1: IPP Event Notification
Specification [ipp-ntfy] Specification [ipp-ntfy]
The "Design Goals for an Internet Printing Protocol" document takes a The "Design Goals for an Internet Printing Protocol" document takes a
broad look at distributed printing functionality, and it enumerates broad look at distributed printing functionality, and it enumerates
real-life scenarios that help to clarify the features that need to be real-life scenarios that help to clarify the features that need to be
included in a printing protocol for the Internet. It identifies included in a printing protocol for the Internet. It identifies
requirements for three types of users: end users, operators, and requirements for three types of users: end users, operators, and
administrators. It calls out a subset of end user requirements that are administrators. It calls out a subset of end user requirements that are
satisfied in IPP/1.0. A few OPTIONAL operator operations have been satisfied in IPP/1.0. A few OPTIONAL operator operations have been
added to IPP/1.1. added to IPP/1.1.
skipping to change at page 3, line 47 skipping to change at page 3, line 45
introduces a Printer and a Job object. The Job object optionally introduces a Printer and a Job object. The Job object optionally
supports multiple documents per Job. It also addresses security, supports multiple documents per Job. It also addresses security,
internationalization, and directory issues. internationalization, and directory issues.
The "Internet Printing Protocol/1.1: Encoding and Transport" document is The "Internet Printing Protocol/1.1: Encoding and Transport" document is
a formal mapping of the abstract operations and attributes defined in a formal mapping of the abstract operations and attributes defined in
the model document onto HTTP/1.1 [RFC2616]. It defines the encoding the model document onto HTTP/1.1 [RFC2616]. It defines the encoding
rules for a new Internet MIME media type called "application/ipp". This rules for a new Internet MIME media type called "application/ipp". This
document also defines the rules for transporting over HTTP a message document also defines the rules for transporting over HTTP a message
body whose Content-Type is "application/ipp". This document defines a body whose Content-Type is "application/ipp". This document defines a
new scheme named 'ipp' for identifying IPP printers and jobs. new scheme named 'ipp-get' for identifying IPP printers and jobs.
The "Internet Printing Protocol/1.1: Implementer's Guide" document gives The "Internet Printing Protocol/1.1: Implementer's Guide" document gives
insight and advice to implementers of IPP clients and IPP objects. It insight and advice to implementers of IPP clients and IPP objects. It
is intended to help them understand IPP/1.1 and some of the is intended to help them understand IPP/1.1 and some of the
considerations that may assist them in the design of their client and/or considerations that may assist them in the design of their client and/or
IPP object implementations. For example, a typical order of processing IPP object implementations. For example, a typical order of processing
requests is given, including error checking. Motivation for some of the requests is given, including error checking. Motivation for some of the
specification decisions is also included. specification decisions is also included.
The "Mapping between LPD and IPP Protocols" document gives some advice The "Mapping between LPD and IPP Protocols" document gives some advice
to implementers of gateways between IPP and LPD (Line Printer Daemon) to implementers of gateways between IPP and LPD (Line Printer Daemon)
implementations. implementations.
Expires: September 8, 2000 The "Event Notification Specification" document describes an extension
to the IPP/1.0, IPP/1.1, and future versions. This extension allows a
The "Event Notification Specification" document defines OPTIONAL client to subscribe to printing related Events. Subscriptions are
operations that allow a client to subscribe to printing related events. modeled as Subscription Objects. The Subscription Object specifies that
Subscriptions include "Per-Job subscriptions" and "Per-Printer when one of the specified Event occurs, the Printer sends an
subscriptions". Subscriptions are modeled as Subscription objects. asynchronous Event Notification to the specified Notification Recipient
Four other operations are defined for subscription objects: get via the specified Delivery Method (i.e., protocol). A client associates
attributes, get subscriptions, renew a subscription, and cancel a Subscription Objects with a particular Job by performing the Create-Job-
subscription. Subscriptions operation or by submitting a Job with subscription
information. A client associates Subscription Objects with the Printer
by performing a Create-Printer-Subscriptions operation. Four other
operations are defined for Subscription Objects: Get-Subscriptions-
Attributes, Get-Subscriptions, Renew-Subscription, and Cancel-
Subscription.
Expires: September 8, 2000
Table of Contents Table of Contents
1 Introduction......................................................6 1 Introduction......................................................6
2 Terminology.......................................................7 2 Terminology .......................................................6
3 Model and Operation...............................................7 3 Model and Operation...............................................7
4 Get-Notifications operation.......................................8 4 Get-Notifications operation.......................................8
4.1GET-NOTIFICATIONS REQUEST........................................9 4.1 GET-NOTIFICATIONS REQUEST.......................................11
4.2GET-NOTIFICATIONS RESPONSE......................................11 4.2GET-NOTIFICATIONS RESPONSE......................................11
5 Extension to Print-Job, Print-URI, Create-Job, Create-Printer- 5 Extensions to Print-Job, Print-URI, Create-Job, Create-Printer-
Subscription and Create-Printer-Subscription.........................12 Subscription and Create-Printer-Subscription.........................16
5.1RESPONSE........................................................12 5.1 RESPONSE........................................................16
6 Encoding.........................................................13
7 IANA Considerations..............................................13 6 Encoding .........................................................17
8 Internationalization Considerations..............................14 7 IANA Considerations ..............................................17
9 Security Considerations..........................................14 8 Internationalization Considerations ..............................17
10 References.......................................................14 9 Security Considerations ..........................................17
11 Authors' Addresses...............................................15 10 References .......................................................18
12 Full Copyright Statement.........................................15 11 Authors' Addresses ...............................................18
Expires: September 8, 2000 12 Full Copyright Statement .........................................19
1 Introduction 1 Introduction
IPP printers that support the OPTIONAL IPP notification extension [ipp- The notification extension document [ipp-ntfy] defines operations that a
ntfy] either a) accept, store, and use notification subscriptions to client can perform in order to create Subscription Objects in a Printer
generate Event Notification reports and implement one or more delivery and carry out other operations on them. A Subscription Object represents
methods for notifying interested parties, or b) support a subset of a Subscription abstraction. The Subscription Object specifies that when
these tasks and farm out the remaining tasks to a Notification Delivery one of the specified Events occurs, the Printer sends an asynchronous
Service. The 'ipp' Event Notification delivery method specified in this Event Notification to the specified Notification Recipient via the
document defines a Get-Notifications operation that may be used in a specified Delivery Method (i.e., protocol).
variety of notification scenarios. Its primary intended use is for
clients that want to be Notification Recipients. However, the Get-
Notifications operation may also be used by Notification Delivery
Services for subsequent distribution to the Ultimate Notification
Recipients.
When a Printer supports the 'ipp' delivery method, it holds each Event The notification extension document [ipp-ntfy] specifies that each
Notification for a certain length of time. The amount of time is called Delivery Method is defined in another document. This document is one
the "event-lease time". A Printer may assign the same event-lease time such document, and it specifies the 'ipp-get' delivery method.
to each event or different times. If a Notification Recipient does not
want to miss Event Notifications, the time between consecutive pollings
of Subscription objects must be less than the event-lease time of the
Event Notifications that occur between pollings. The Get-Notifications
request indicates whether the client wants to receive all pending Event
Notifications for (1) any Subscription for which the client is the
owner, (2) any Subscription associated with a particular Job, (3) any
Subscription with a particular notification recipient URL, or (4) an
identified set of Subscription objects. With the Get-Notifications
operation, the Printer returns all existing Event Notifications along
with two time intervals. One specifies the minimum time at which event-
leases of future events of the type returned will begin to expire and
the other specifies the recommended interval for the client to wait
before sending the next Get-Notifications operation. The second time
interval is less than the first.
The Printer may keep the channel open if the recommended interval is The 'ipp-get' Delivery Method is a 'pull' Delivery Method. That is, the
sufficiently short, but in any case the client performs a new Get- Printer saves Event Notification for a period of time and expects the
Notifications operation each time it wants more Notifications. Since the Notification Recipient to fetch the Event Notifications.
time interval between consecutive client requests is normally less than
the event-lease time, consecutive responses will normally contain some
events that are identical. The youngest ones in the previous response
will become the oldest in the next response. The client is expected to
filter out these duplicates, which is easy to do because of the sequence
number in each Notification. The reason for not removing the
Notifications from the Subscription object with every Get-Notifications
request, is so that multiple Notification Recipients can be polling the
same subscription object and so the Get-Notification operation satisfies
the rule of idempotency. The former is useful if someone is logged in
to several desktops at the same time and wants to see the same events at
both places. The latter is useful if the network loses the response.
Expires: September 8, 2000 When a Printer supports this Delivery Method, it holds each Event
Notification for an amount of time, called the Event Notification Lease
Time.
When a Notification Recipient wants to receive Event Notifications, it
performs an IPP operation called 'Get-Notifications', which this
document defines. This operation causes the Printer to return all Event
Notifications held for the Notification Recipient along with information
that tells the client when to perform this operation again.
2 Terminology 2 Terminology
This section defines the following additional terms that are used This section defines the following terms that are used throughout this
throughout this document: document:
REQUIRED: if an implementation supports the extensions described in Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT,
this document, it MUST support a REQUIRED feature. MAY, NEED NOT, and OPTIONAL, have special meaning relating to
OPTIONAL: if an implementation supports the extensions described in conformance to this specification. These terms are defined in [ipp-mod
this document, it MAY support an OPTIONAL feature. section 13.1 on conformance terminology, most of which is taken from RFC
Notification Recipient - See [ipp-ntfy] 2119 [RFC2119].
Subscription object - See [ipp-ntfy]
Ultimate Notification Recipient - See [ipp-ntfy] Event Notification Lease: The lease that is associated with an Event
Notification. When the lease expires, the Printer discards the
associated Event Notification.
Event Notification Lease Time: The expiration time assigned to a lease
that is associated with an Event Notification.
Event Notification Attributes Group: The attributes group in a response
that contains attributes that are part of an Event Notification.
For other capitalized terms that appear in this document, see [ipp-
ntfy].
3 Model and Operation 3 Model and Operation
In the IPP Notification Model [ipp-ntfy], one or more Per-Job In a Subscription Creation Operation, when the value of the "notify-
Subscriptions can be supplied in the Job Creation operation or recipient-uri" attributes has the scheme "ipp-get", the client is
OPTIONALLY as subsequent Create-Job-Subscription operations; one Per- requesting that the Printer use the 'ipp-get' Delivery Method for the
Printer Subscription can be supplied in the Create-Printer operation. Event Notifications associated with the new Subscription Object. The
The client that creates these Subscription objects becomes the owner of client MUST choose a value for the address part of the "notify-
the Subscription object. recipient-uri" attribute that uniquely identifies the Notification
Recipient.
When creating each Subscription object, the client supplies the "notify- When an Event occurs, the Printer MUST generate an Event Notification
recipient" (uri) attribute. The "notify-recipient" attribute specifies and MUST assign it an Event Notification Lease Time. The Printer MUST
both a single Notification Recipient that is to receive the hold an Event Notification for its assigned Event Notification Lease
Notifications when subsequent events occur and the method for Time and MUST discard it when its Event Notification Lease Time expires.
Notification delivery that the IPP Printer is to use. For the The Printer MAY assign the same Event Notification Lease Time to each
Notification delivery method defined in this document, the scheme of the Event Notification or it MAY assign a different time.
URL is 'ipp' and the host SHOULD be the client host's URL. In addition,
the URL MAY contains a path to allow for applications to have a unique
URL.
ISSUE 1: The 'ipp' is a convenient reuse of 'ipp', but does it imply the When a Notification Recipient wants to receive Event Notifications, it
existence of a print service at each client that is not a reality? performs the Get-Notifications operation, which causes the Printer to
return all unexpired Event Notifications held for the Notification
Recipient along with two time-intervals.
For most Notification delivery methods, a Printer sends Event The first returned time-interval is the suggested time a Notification
Notifications to the delivery URL and the Printer does not perform any Recipient should wait before performing the Get-Notifications operation
authentication or authorization with the receivers of the Event again. The second time-interval is the time that Event Notification
Notifications. For the Notification delivery method defined in this Leases begin to expire for Event Notifications created after the Get-
document, the client requests Event Notifications from the Printer via a Notifications operation. A Notification Recipient SHOULD perform this
Get-Notifications operation, and the Printer performs the same operation at the suggested time and somewhat before the Event
authentication and authorization as it does for the Get-Job-Attributes Notification Leases begin to expire.
operation. That is, a Printer MAY allow a client to perform a Get-
Notifications operation on any Subscription object or it MAY restrict
access as follows. Any client that is authenticated (1) as an operator
or administrator or (2) as the owner of the Subscription object can
initiate a Get-Notifications operation for that Subscription object.
Because a Printer has to wait for a client to request Event The Notification Recipient identifies its own Event Notifications with a
Notifications for the 'ipp' delivery method, any Printer that supports "notify-recipient-uri" Operation attribute in the request. It matches
the 'ipp' notification delivery method MUST hold each Event Notification any Event Notifications associated with a Subscription Object whose
at least for the event-lease time that it advertises to clients. With "notify-recipient-uri" attribute has the same value as the "notify-
this rule, a single user can login at different places, say his/her recipient-uri" Operation attribute of the request. To avoid getting
office, the lab, and/or several desktops in the same room, and receive Event Notification that belong to another Notification Recipient, a
client SHOULD pick values for the "notify-recipient-uri" attribute that
are unique, e.g. the client's host address.
Expires: September 8, 2000 If a Notification Recipient performs the Get-Notifications operation
twice in quick succession, it will receive nearly the same Event
Notification both times. There are two possible differences. Some old
Event Notifications may not be present in the second response because
their Event Notification Leases have expired. Some new Event
Notifications may be present in the second response but not the first
response.
the same Event Notifications from a single Subscription object. In The Printer may keep the channel open if the suggested time-interval is
addition, a client that gets no response, perhaps because of a network sufficiently short, but in any case the client performs a new Get-
failure, can perform the Get-Notifications operations two or more times Notifications operation each time it wants more Event Notifications.
in quick succession and get the same results except for a few newly Since the time interval between consecutive client requests is normally
arrived Event Notifications and a few old Event Notifications whose less than the Event Notification Lease Time, consecutive responses will
event-leases have expired. normally contain some events that are identical. The youngest ones in
the previous response will become the oldest in the next response. The
client is expected to filter out these duplicates, which is easy to do
because of the sequence number in each Event Notification. The reason
for not removing the Event Notifications from the Printer with every
Get-Notifications request, is so that multiple Notification Recipients
can be polling the same Subscription Object and so the Get-Notification
operation satisfies the rule of idempotency. The former is useful if
someone is logged in to several desktops at the same time and wants to
see the same events at both places. The latter is useful if the network
loses the response.
The event-lease time assigned to Event Notifications MAY be different 4 General Information
for each implementation. Furthermore, a particular implementation MAY
assign different event-lease times to each Event Notification. If a
Printer assigns different event-lease times to each Event Notification,
the event-lease time returned with Get-Notifications MUST be a value
that ensures a client will not miss future Event Notifications.
The client issues a Get-Notifications Printer operation in order to According to the notification extension document [ipp-ntfy], this
initiate the delivery of the pending Notifications held by the Printer document MUST contain the following information:
for the Subscription objects requested. The client can indicate in the
Get-Notifications request whether it wants to receive all pending
Notifications for:
1) any existing Subscription objects for which the client is the 1.The URL scheme name for the Delivery Method is: 'ipp-get'
owner,
2) any existing Subscription objects whose notification-recipient is a 2.Printer support for this delivery method is OPTIONAL.
specified URL
3) any existing Subscription objects associated with a job-id or 3.For Event Notification content, a Printer MUST IPP with one new
operation.
4) particular Subscription object(s) (for which it MUST be the owner 4.Several Event Notifications MAY be combined into a compound Event
or have read-access rights). Notification. See section 5.
In any case, the Notifications are returned in a response to the Get- 5.The Notification Recipient MUST initiate the Delivery Method
Notifications request.
If the client requests a persistent channel, then the Printer MAY keep 6.The Delivery Method sends Machine Consumable Event Notifications.
the channel open. Either the client or the IPP Printer can disconnect
the HTTP connection.
4 Get-Notifications operation 7.The representation and encoding for each value MUST be the same as
for IPP (see section 5).
This REQUIRED operation allows the client to request that pending Event 8.In the Event Notification content, a Printer MUST send all attributes
Notifications be delivered as a response to this request. The client specified in section 5.
MUST be the owner or have read-access rights of the Subscription objects
that are involved and the delivery method specified when the
Subscription objects were created MUST be ipp'. When the Printer
creates a Subscription Object, either with a Job Creation operation or
with a Create-Printer-Subscription or Create-Job-Subscription operation
and a subscription object contains the 'ipp' value for the "notify-
recipient" operation attribute, the Printer returns the event-lease time
for Events and the recommended time interval before the client to
performs the next Get-Notifications operation. The client SHOULD
perform a Get-Notifications operation at about the recommended interval
Expires: September 8, 2000 9.Frequently occurring Events NEED NOT be moderated because the
Delivery Method is a 'pull' Delivery Method. An implementation of the
Get-Notifications operation SHOULD consider how often it recommends a
Notification Recipient to poll again.
and if the Printer receives the Get-Notifications before the event-lease 10. This Delivery Method has the same latency and reliability as the
time has elapsed, it MUST have all of the Notifications since the underlying HTTP transport.
previous Get-Notification operation or the Subscription object creation,
whichever was most recent.
Issue 2: Now that the Get-Notification operation does not affect the 11. This Delivery Method has the same security aspects as the
Event Notifications in the Printer, it should not require write access underlying HTTP transport.
to access them.
The IPP Printer MUST accept the request in any state (see [ipp-mod] 12. This Delivery Method has no content length restrictions.
13. There are no additional values that a Printer MUST send in a
Notification content.
14. There are no additional Subscription Template and/or Subscription
Description attributes.
15. There are no additional Printer Description attributes.
5 Get-Notifications operation
This operation causes the Printer to return all Event Notifications held
for the Notification Recipient along with information about when to
perform this operation again.
A Printer MUST support this operation.
When a Printer performs this operation, it MUST return all and only
those Event Notifications:
a)Whose associated Subscription Object's "notify-recipient-uri"
attribute equals the "notify-recipient-uri" Operation attribute
AND
b)Whose associated Subscription Object's "notify-recipient-uri"
attribute has a scheme value of 'ipp-get' AND
c)Whose Event Notification Lease Time has not yet expired AND
d)Where the Notification Recipient is the owner of or has read-
access rights to the associated Subscription Object.
When a Printer performs this operation, it MUST also return two time-
intervals:
a)the suggested time for a Notification Recipient to perform the
Get-Notifications operation again.
b)the time at which the Printer will begin to discard Event
Notifications that occur after this operation. This may be the
Event Notification Lease Time (see section 5.2 for details).
Note: the Subscription Creation Operations also return these two time-
intervals (see section 6).
The Printer MUST respond to this operation immediately with whatever
Event Notifications it currently holds. It MUST NOT wait for additional
Events to occur before sending a response.
The Printer MUST accept the request in any state (see [ipp-mod]
"printer-state" and "printer-state-reasons" attributes) and MUST remain "printer-state" and "printer-state-reasons" attributes) and MUST remain
in the same state with the same "printer-state-reasons". in the same state with the same "printer-state-reasons".
Access Rights: The authenticated user (see [ipp-mod] section 8.3) Access Rights: If the policy of the Printer is to allow all users to
performing this operation must either be the Subscription object owner access all Event Notifications, then the Printer MUST accept this
(as determined when the Subscription object was created by the Job operation from any user. Otherwise, the authenticated user (see [ipp-
Creation operation, Create-Job-Subscription, or Create-Printer- mod] section 8.3) performing this operation MUST either be the owner of
Subscription operations) or an operator or administrator of the Printer each Subscription Object identified by the "notify-recipient-uri"
object (see [ipp-mod] Sections 1 and 8.5). Otherwise, the IPP object Operation attribute (as determined during a Subscription Creation
MUST reject the operation and return: 'client-error-forbidden', 'client- Operation) or an operator or administrator of the Printer (see [ipp-mod]
error-not-authenticated', or 'client-error-not-authorized' as Sections 1 and 8.5). Otherwise, the IPP object MUST reject the
appropriate.
Issue 3: Is it possible for this operation to have an option that causes operation and return: 'client-error-forbidden', 'client-error-not-
it to delay completing its response? It would initially returns all authenticated', or 'client-error-not-authorized' as appropriate.
existing Event Notifications. Then it would return additional
notifications as they occur for some period of time. The client would
receive these Event Notifications as they occur. The question is
whether http servers or proxies would behave in this manner so that the
client would get the Event Notifications without delay after they are
sent by the http server? It has been suggested that the Printer send
each burst of Event Notifications be in a separate message body where
each message body is part of a multipart MIME content-type.
4.1 Get-Notifications Request 5.1 Get-Notifications Request
The following groups of attributes are part of the Get-Notifications The following groups of attributes are part of the Get-Notifications
Request: Request:
Group 1: Operation Attributes Group 1: Operation Attributes
Natural Language and Character Set: Natural Language and Character Set:
The "attributes-charset" and "attributes-natural-language" The "attributes-charset" and "attributes-natural-language"
attributes as described in [ipp-mod] section 3.1.4.1. attributes as described in [ipp-mod] section 3.1.4.1.
Target: Target:
The "printer-uri" (uri) operation attribute which is the target for The "printer-uri" (uri) operation attribute which is the target for
this operation as described in [ipp-mod] section 3.1.5. this operation as described in [ipp-mod] section 3.1.5.
Requesting User Name: Requesting User Name:
The "requesting-user-name" (name(MAX)) attribute SHOULD be supplied The "requesting-user-name" (name(MAX)) attribute SHOULD be supplied
by the client as described in [ipp-mod] section 8.3. by the client as described in [ipp-mod] section 8.3.
Expires: September 8, 2000 "notify-recipient-uri" (url):
"notification-recipient" (url): The client MUST supply this attribute. The Printer object MUST
The client OPTIONALLY supplies this attribute. The Printer object support this attribute. The Printer matches the value of this
MUST support this attribute. It is a URL that identifies one or attribute (byte for byte with no case conversion) against the value
more Subscription objects for which Event Notifications are being of the "notify-recipient-uri" in each Subscription Object in the
requested. If the client supplies this attribute, but no Printer. If there are no matches, the IPP Printer MUST return the
notification-recipients are found, the IPP Printer MUST return the 'client-error-not-found' status code. For each matched
'client-error-not-found' status code. If some are found and others Subscription Object, the IPP Printer MUST return all unexpired
are not, the ones that are not found are return in the Unsupported Event Notifications associated with it.
Attributes. By definition, if a notification-recipient URL
exists, there must be at least one Subscription object.
Note: this attribute allows a subscribing client to pick URLs that Note: this attribute allows a subscribing client to pick URLs that
are unique, e.g. the client's own URL or a friend's URL, which in are unique, e.g. the client's own URL or a friend's URL, which in
both cases is likely the URL of the person's host. An application both cases is likely the URL of the person's host. An application
could make a URL unique for each application if it wants. If a could make a URL unique for each application.
client uses such a URL as the value of this attribute, the client
gets event Notifications for all Subscription objects whose
"notification-recipient" is the specified URL. This mechanism is
more general than getting all subscriptions owned by a client. It
allows clients who didn't subscribe to get Event Notifications
without knowing job-ids or subscription-ids.
ISSUE 4: The "notification-recipient" option allows a client to group
multiple Subscription-ids with a single URL. A client might decide to
use the same URL for all subscriptions for a user, or it might have a
separate URL for each client program. In addition a client might use an
URL belonging to some other known user and let that user access Event
Notifications using that URL. Is the above option useful?
"subscription-ids" (1setOf integer(1:MAX)):
The client OPTIONALLY supplies this attribute. The Printer object
MUST support this attribute. It is an integer value that identifies
one or more Subscription objects for which Event Notifications are
being requested. If the client supplies this attribute, but none
of the Subscription objects are found, the IPP Printer MUST return
the 'client-error-not-found' status code. If some are found and
others are not, the ones that are not found are return in the
Unsupported Attributes.
"job-ids" (1setOf integer(1:MAX)):
The client OPTIONALLY supplies this attribute. The Printer object
MUST support this attribute. It is an integer value that identifies
one or more job-ids. These job-ids identify the Subscription
objects for which Event Notifications are being requested. If the
client supplies this attribute, but no Jobs are found, the IPP
Printer MUST return the 'client-error-not-found' status code. If
some are found and others are not, the ones that are not found are
returned in the Unsupported Attributes. It is not an error if
there are no Subscription objects for a Job.
Expires: September 8, 2000
If the client supplies none of the last three attributes described
for this operation, then the IPP Printer returns Event
Notifications for all Subscription objects for which the client is
the owner and the "notify-recipients" attribute is 'ipp'. It is
not an error if there are currently no Subscription objects for
this client; the response then contains no Notifications.
ISSUE 5: Does the mechanism described in the above paragraph describe a
useful option that "notification-recipient" alone cannot do? Should this
case be an error instead?
If a client supplies more than one of the last three attributes
described for this operation, the Printer returns Event
Notifications for all Subscription objects specified by all
attributes. If these attributes describe duplicate Event
Notifications, the Printer MAY remove them.
ISSUE 6: Is it better if "notification-recipient" is the only way to
request Event Notification? If so, this behaves more like other
notification delivery methods where a recipient receives those and only
those events with its delivery URL. Furthermore, if there is a single
mechanism of "notification-recipient" for a client to specify Event
Notifications, a Printer can better optimize event-leases because it
knows which events will be accessed together. If client can specify
subscription-ids, each request can contain a different mix of
subscription-ids.
4.2 Get-Notifications Response 5.2 Get-Notifications Response
The Printer object returns either an immediate error response or a The following groups of attributes are part of the Get-Notifications
successful response with status code: 'successful-ok' when the first Response:
event occurs, i.e., when the Printer delivers the first Event
Notification.
Group 1: Operation Attributes Group 1: Operation Attributes
Status Message: Status Message:
In addition to the REQUIRED status code returned in every response, In addition to the REQUIRED status code returned in every response,
the response OPTIONALLY includes a "status-message" (text(255)) the response OPTIONALLY includes a "status-message" (text(255))
and/or a "detailed-status-message" (text(MAX)) operation attribute and/or a "detailed-status-message" (text(MAX)) operation attribute
as described in [ipp-mod] sections 13 and 3.1.6. as described in [ipp-mod] sections 13 and 3.1.6.
The Printer can return any status codes defined in [ipp-mod]. The
following is a description of the important status codes:
successful-ok: the response contains all Event Notification
associated with the specified "notify-recipient-uri". If the
specified Subscription Objects have no associated Event
Notification, the response MUST contain zero Event
Notifications.
client-error-not-found: The Printer has no Subscription Object's
whose "notify-recipient-uri" attribute equals the "notify-
recipient-uri" Operation attribute.
Natural Language and Character Set: Natural Language and Character Set:
The "attributes-charset" and "attributes-natural-language" The "attributes-charset" and "attributes-natural-language"
attributes as described in [ipp-mod] section 3.1.4.2. attributes as described in [ipp-mod] section 3.1.4.2.
"recommended-time-interval" (integer(0:MAX)): The Printer MUST use the values of "notify-charset" and "notify-
The value of this attribute is the recommended number of seconds natural-language", respectively, from one Subscription Object
that SHOULD elapse before the client performs this operation again associated with the Event Notifications in this response.
for these Subscription objects. A client MAY perform this operation
Expires: September 8, 2000 Normally, there is only one matched Subscription Object, or the
at any time, and a Printer MUST respond with all existing value of the "notify-charset" and "notify-natural-language"
Notifications. A client observes this value in order to be a "good attributes is the same in all Subscription Objects. If not, the
network citizen". The value that a Printer returns for this Printer MUST pick one Subscription Object from which to obtain the
attribute MUST NOT exceed 80% of the "event-lease-time-interval" in value of these attributes. The algorithm for picking the
order to give a client plenty of time to perform another Get- Subscription Object is implementation dependent. The choice of
Notifications operation before the event-lease of the oldest Event natural language is not critical because 'text' and 'name' values
Notifications expire. can override the "attributes-natural-language" Operation attribute.
The Printer's choice of charset is critical because a bad choice
may leave it unable to send some 'text' and 'name' values
accurately.
"event-lease-time-interval" (integer(0:MAX)): "suggested-ask-again-time-interval" (integer(0:MAX)):
The value of this attribute is the minimum number of seconds until The value of this attribute is the suggested number of seconds that
the event-lease expiration time for all future Event Notifications SHOULD elapse before the client performs the Get-Notifications
associated with the Subscription objects generating the requested operation again for these Subscription Objects. A client MAY
Event Notifications. Thus this number is the maximum number of perform the Get-Notifications operation at any time, and a Printer
seconds that elapses before this client SHOULD issue this operation MUST respond with all unexpired Event Notifications. A Notification
again for these Subscription objects. A Printer MUST preserve all Recipient waits until this time interval has elapsed in order to be
Notifications that occur for the number of seconds specified by a "good network citizen". It is RECOMMENDED that the value of this
this attribute starting at the time it is sent in a response. A attribute be 80% of the "begin-to-expire-time-interval" (see the
client MAY perform this operation at any time, and a Printer MUST next attribute) in order to give a Notification Recipient plenty of
respond with all existing Event Notifications. If a Printer time to perform the Get-Notifications operation again before new
receives this operation after this time interval, it MAY have Event Notifications expire.
discarded some Notifications since the last response.
"begin-to-expire-time-interval" (integer(0:MAX)):
The value of this attribute is the minimum number of seconds that
MUST elapse before Event Notification Leases begin to expire on
Event Notifications produced by matching Subscriptions Objects
after the Printer sends the Get-Notifications response. The Printer
MUST discard an Event Notification when its Event Notification
Lease has expired. That is, if the Printer performs the Get-
Notifications operation before the time specified by the "begin-to-
expire-time-interval" attribute returned in the previous operation,
the Printer MUST still have all of the Event Notifications that
have occurred since the previous operation. If the Printer assigns
the same Event Notification Lease Time to all Event Notifications,
the value of this attribute MUST equal the Event Notification Lease
Time. If a Notification Recipient waits until after this time or
even slightly less than this time, the Notification Recipient MUST
expect to lose some Event Notifications.
"printer-up-time" (integer(0:MAX)):
The value of this attribute is the Printer's "printer-up-time"
attribute at the time the Printer sends this response. Because each
Event Notification also contains the value of this attribute when
the event occurred, the value of this attribute lets a Notification
Recipient know when each Event Notification occurred relative to
the time of this response.
Group 2: Unsupported Attributes Group 2: Unsupported Attributes
See [ipp-mod] section 3.1.7 for details on returning Unsupported See [ipp-mod] section 3.1.7 for details on returning Unsupported
Attributes. Attributes.
If the "subscription-ids" attribute contained subscription-ids that If the "subscription-ids" attribute contained subscription-ids that
do not exist, the Printer returns them in this group as value of do not exist, the Printer returns them in this group as value of
the "subscription-ids" attribute. the "subscription-ids" attribute.
Group 3 through N: Notification Attributes Group 3 through N: Event Notification Attributes
The Printer object responds with one Event Notification per Group The Printer responds with one Event Notification Attributes Group
for each Notification that meets the criteria specified by the per matched Event Notification. The matched Event Notifications are
request.(see [ipp-ntfy]). all un-expired Event Notification associated with the matched
Subscription Objects. Each Event Notification Group MUST start with
an 'event-notification-attributes-tag' (see the section "Encodings
of Additional Attribute Tags" in [ipp-ntfy]).
5 Extension to Print-Job, Print-URI, Create-Job, Create-Printer- Each attribute is encoded using the IPP rules for encoding
Subscription and Create-Printer-Subscription attributes [ipp-pro] and may be encoded in any order. Note: the
Get-Jobs response in [ipp-mod] acts as a model for encoding
multiple groups of attributes.
5.1 Response Each Event Notification Group MUST contain all of attributes
specified in section 9.1 ("Content of Machine Consumable Event
Notifications") of [ipp-ntfy] with exceptions denoted by asterisks
in the tables below.
When Print-Job, Print-URI or Create-Job contains a "job-notify" The tables below are copies of the tables in section 9.1 ("Content
attribute and the "notify-recipient" is 'ipp', the response contains two of Machine Consumable Event Notifications") of [ipp-ntfy] except
additional Operation Attributes that pertain to subscriptions. that each cell in the "Sends" column is a "MUST".
When Create-Job-Subscription or Create-Printer-Subscription operation For an Event Notification for all Events, the Printer includes the
contains a "notify-recipient" that is 'ipp', the response contains two following attributes.
additional Operation Attributes that pertain to subscriptions.
Table 1 - Attributes in Event Notification Content
Source Value Sends Source Object
notify-subscription-id (integer(1:MAX)) MUST Subscription
notify-printer-uri (uri) MUST Subscription
notify-subscribed-event (type2 keyword) MUST Event
Notification
printer-up-time (integer(MIN:MAX)) MUST Printer
printer-current-time (dateTime)* MUST Printer
notify-sequence-number (integer (0:MAX)) MUST Subscription
notify-charset (charset) MUST Subscription
notify-natural-language (naturalLanguage) MUST Subscription
notify-user-data (octetString(63)) ** MUST Subscription
notify-text (text) MUST Event
Notification
attributes from the "notify-attributes" MUST Printer
attribute ***
attributes from the "notify-attributes" MUST Job
attribute ***
attributes from the "notify-attributes" MUST Subscription
attribute ***
* The Printer MUST send "printer-current-time" if and only if it
supports the "printer-current-time" attribute on the Printer
object.
** If the associated Subscription Object does not contain a
"notify-user-data" attribute, the Printer MUST send an octet-string
of length 0.
*** If the "notify-attributes" attribute is present on the
Subscription Object, the Printer MUST send all attributes specified
by the "notify-attributes" attribute. Note: if the Printer doesn't
support the "notify-attributes" attribute, it is not present on the
associated Subscription Object.
For Event Notifications for Job Events, the Printer includes the
following additional attributes.
Table 2 - Additional Attributes in Event Notification Content for
Job Events
Source Value Sends Source Object
job-id (integer(1:MAX)) MUST Job
job-state (type1 enum) MUST Job
job-state-reasons (1setOf type2 keyword) MUST Job
job-impressions-completed MUST Job
(integer(0:MAX)) *
* The Printer MUST send the "job-impressions-completed" attribute
in an Event Notification only for the combinations of Events and
Subscribed Events shown in Table 3.
Table 3 - Combinations of Events and Subscribed Events for "job-
impressions-completed"
Job Event Subscribed Job Event
'job-progress' 'job-progress'
'job-completed' 'job-completed'
'job-completed' 'job-state-changed'
For Event Notification for Printer Events, the Printer includes the
following additional attributes.
Table 4 - Additional Attributes in Event Notification Content for
Printer Events
Source Value Sends Source Object
printer-state (type1 enum) MUST Printer
printer-state-reasons (1setOf type2 MUST Printer
keyword)
printer-is-accepting-jobs (boolean) MUST Printer
6 Extensions to Subscription Creation Operations
6.1 Response
When a Subscription Creation Operation contains a "notify-recipient-uri"
attribute and the scheme in its value is 'ipp-get', the response MUST
contain two additional Operation Attributes that pertain to this
Delivery Method. Note: Subscription Creation Operations include: Print-
Job, Print-URI, Create-Job, Create-Job-Subscriptions and Create-Printer-
Subscriptions.
Group 1: Operation Attributes Group 1: Operation Attributes
Expires: September 8, 2000 "suggested-ask-again-time-interval" (integer(0:MAX)):
"recommended-time-interval" (integer(0:MAX)): This attribute has the same meaning as the "suggested-ask-again-
The value of this attribute is the recommended number of seconds time-interval" attribute in the Get-Notifications operation except
that SHOULD elapse before the client SHOULD perform the Get- that it suggests when to perform the Get-Notifications operation
Notification operation for the first time with any Subscription for the first time on all Subscription Objects in the response
objects returned with this job. A client MAY perform the Get- whose "notify-recipient-uri" scheme is 'ipp-get'.
Notification operation at any time, and a Printer MUST respond with
all existing Notifications. A client observes this value in order
to be a "good network citizen". The value that a Printer returns
for this attribute MUST NOT exceed 80% of the "event-lease-time-
interval" in order to give a client plenty of time to perform
another Get-Notifications operation before the event-lease of the
oldest events expire.
"event-lease-time-interval" (integer(0:MAX)): "begin-to-expire-time-interval" (integer(0:MAX)):
The value of this attribute is the minimum number of seconds until This attribute has the same meaning as the "begin-to-expire-time-
the event-lease expiration time for all future Event Notifications interval" attribute in the Get-Notifications operation except that
associated with the Subscription objects generating the requested it indicates when the Event Notification Lease begins to expire for
Event Notifications. Thus this number is the maximum number of all Subscription Objects in the response whose "notify-recipient-
seconds that elapses before a client SHOULD perform the Get- uri" scheme is 'ipp-get'.
Notification operation for the first time with any Subscription
objects returned with this job. A Printer MUST preserve all
Notifications that occur for the number of seconds specified by
this attribute starting at the time it is sent in a response. A
client MAY perform the Get-Notification operation at any time, and
a Printer MUST respond with all existing Event Notifications. If a
Printer receives a Get-Notification operation after this time
interval, it may have discarded some Notifications since the last
response.
6 Encoding 7 Encoding
The operation-id assigned for the Get-Notification operation is: The operation-id assigned for the Get-Notifications operation is:
0x00?? 0x001C
and should be added to the next version of [ipp-mod] section 4.4.15 and should be added to the next version of [ipp-mod] section 4.4.15
"operations-supported". "operations-supported".
This notification delivery method uses the IPP transport and encoding This notification delivery method uses the IPP transport and encoding
[ipp-pro] for the Get-Notifications operation with one extension: [ipp-pro] for the Get-Notifications operation with one extension:
notification-attributes-tag = %x07 ; tag of 7 notification-attributes-tag = %x07 ; tag of
7
7 IANA Considerations 8 IANA Considerations
There is nothing to register. There is nothing to register.
Expires: September 8, 2000 9 Internationalization Considerations
8 Internationalization Considerations The IPP Printer MUST localize the "notify-text" attribute as specified
in section 14 of [ipp-ntfy].
With the 'ipp' method defined in this document, the client cannot In addition, when the client receives the Get-Notifications response, it
request the Human Consumable form by supplying the "notify-format" is expected to localize the attributes that have the 'keyword' attribute
operation attribute (see [ipp-ntfy]). The only supported value for this syntax according to the charset and natural language requested in the
delivery method is "application/ipp". Therefore, the IPP Printer does Get-Notifications request.
not have to perform any localization with this notification delivery
method. However, the client when it receives the Get-Notifications
response is expected to localize the attributes that have the 'keyword'
attribute syntax according to the charset and natural language requested
in the Get-Notifications request.
9 Security Considerations 10 Security Considerations
The IPP Model and Semantics document [ipp-mod] discusses high level The IPP Model and Semantics document [ipp-mod] discusses high-level
security requirements (Client Authentication, Server Authentication and security requirements (Client Authentication, Server Authentication and
Operation Privacy). Client Authentication is the mechanism by which the Operation Privacy). Client Authentication is the mechanism by which the
client proves its identity to the server in a secure manner. Server client proves its identity to the server in a secure manner. Server
Authentication is the mechanism by which the server proves its identity Authentication is the mechanism by which the server proves its identity
to the client in a secure manner. Operation Privacy is defined as a to the client in a secure manner. Operation Privacy is defined as a
mechanism for protecting operations from eavesdropping. mechanism for protecting operations from eavesdropping.
Unlike other Event Notification delivery methods in which the IPP Unlike other Event Notification delivery methods in which the IPP
Printer initiates the Event Notification, with the method defined in Printer initiates the Event Notification, with the method defined in
this document, the Notification Recipient is the client who issues the this document, the Notification Recipient is the client who s the Get-
Get-Notifications operation. Therefore, there is no chance of "spam" Notifications operation. Therefore, there is no chance of "spam"
notifications with this method. Furthermore, such a client can close notifications with this method. Furthermore, such a client can close
down the HTTP channel at any time, and so can avoid future unwanted down the HTTP channel at any time, and so can avoid future unwanted
Event Notifications at any time. Event Notifications at any time.
10 References 11 References
[ipp-mod] [ipp-mod]
R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell, R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
"Internet Printing Protocol/1.1: Model and Semantics", <draft-ietf- "Internet Printing Protocol/1.1: Model and Semantics", <draft-ietf-
ipp-model-v11-06.txt>, March 1, 2000. ipp-model-v11-06.txt>, March 1, 2000.
[ipp-ntfy] [ipp-ntfy]
Isaacson, S., Martin, J., deBry, R., Hastings, T., Shepherd, M., R. Herriot, Hastings, T., Isaacson, S., Martin, J., deBry, R.,
Bergman, R., "Internet Printing Protocol/1.1: IPP Event Shepherd, M., Bergman, R., "Internet Printing Protocol/1.1: IPP
Notification Specification", <draft-ietf-ipp-not-spec-02.txt>, Event Notification Specification", <draft-ietf-ipp-not-spec-
March 8, 2000. 04.txt>, June 30, 2000.
[ipp-pro] [ipp-pro]
Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing
Protocol/1.1: Encoding and Transport", draft-ietf-ipp-protocol-v11- Protocol/1.1: Encoding and Transport", draft-ietf-ipp-protocol-v11-
05.txt, March 1, 2000. 05.txt, March 1, 2000.
[rfc2026] [rfc2026]
S. Bradner, "The Internet Standards Process -- Revision 3", RFC S. Bradner, "The Internet Standards Process -- Revision 3", RFC
2026, October 1996. 2026, October 1996.
Expires: September 8, 2000
[RFC2616] [RFC2616]
R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P.
Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1", Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
RFC 2616, June 1999. RFC 2616, June 1999.
11 Authors' Addresses 12 Authors' Addresses
Carl-Uno Manros Robert Herriot
Xerox Corporation Xerox Corp.
701 Aviation Blvd. 3400 Hill View Ave, Building 1
El Segundo, CA 90245 Palo Alto, CA 94304
Phone: 310-333- Phone: 650-813-7696
Fax: 310-333-5514 Fax: 650-813-6860
e-mail: manros@cp10.es.xerox.com e-mail: robert.herriot@pahv.xerox.com
Tom Hastings Tom Hastings
Xerox Corporation Xerox Corporation
737 Hawaii St. ESAE 231 737 Hawaii St. ESAE 231
El Segundo, CA 90245 El Segundo, CA 90245
Phone: 310-333-6413 Phone: 310-333-6413
Fax: 310-333-5514 Fax: 310-333-5514
e-mail: hastings@cp10.es.xerox.com e-mail: hastings@cp10.es.xerox.com
Robert Herriot Carl-Uno Manros
Xerox Corp. Xerox Corporation
3400 Hill View Ave, Building 1 701 Aviation Blvd.
Palo Alto, CA 94304 El Segundo, CA 90245
Phone: 650-813-7696 Phone: 310-333-
Fax: 650-813-6860 Fax: 310-333-5514
e-mail: robert.herriot@pahv.xerox.com e-mail: manros@cp10.es.xerox.com
Harry Lewis Harry Lewis
IBM IBM
P.O. Box 1900 P.O. Box 1900
Boulder, CO 80301-9191 Boulder, CO 80301-9191
Phone: (303) 924-5337 Phone: (303) 924-5337
FAX: FAX:
e-mail: harryl@us.ibm.com e-mail: harryl@us.ibm.com
12 Full Copyright Statement 13 Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved. Copyright (C) The Internet Society (2000). 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 or others, and derivative works that comment on or otherwise explain it or
assist in its implementation may be prepared, copied, published and assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind, distributed, in whole or in part, without restriction of any kind,
Expires: September 8, 2000
provided that the above copyright notice and this paragraph are included provided that the above copyright notice and this paragraph are included
on all such copies and derivative works. However, this document itself on all such copies and derivative works. However, this document itself
may not be modified in any way, such as by removing the copyright notice may not be modified in any way, such as by removing the copyright notice
or references to the Internet Society or other Internet organizations, or references to the Internet Society or other Internet organizations,
except as needed for the purpose of developing Internet standards in except as needed for the purpose of developing Internet standards in
which case the procedures for copyrights defined in the Internet which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into Standards process must be followed, or as required to translate it into
languages other than English. languages other than English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
skipping to change at page 16, line 22 skipping to change at page 20, line 4
which case the procedures for copyrights defined in the Internet which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into Standards process must be followed, or as required to translate it into
languages other than English. languages other than English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an "AS This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE. FITNESS FOR A PARTICULAR PURPOSE.
Expires: September 8, 2000
 End of changes. 

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