[Docs] [txt|pdf] [draft-ietf-simple...] [Diff1] [Diff2]

PROPOSED STANDARD

Network Working Group                                        M. Lonnfors
Request for Comments: 5196                                       K. Kiss
Category: Standards Track                                          Nokia
                                                          September 2008


  Session Initiation Protocol (SIP) User Agent Capability Extension to
                Presence Information Data Format (PIDF)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   Presence Information Data Format (PIDF) defines a common presence
   data format for Common Profile for Presence (CPP) compliant presence
   protocols.  This memo defines a PIDF extension to represent SIP User
   Agent capabilities.




























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Table of Contents

   1. Introduction ....................................................3
      1.1. Motivation .................................................3
      1.2. Scope ......................................................4
   2. Conventions .....................................................4
   3. Extension for "Indicating User Agent Capabilities in the
      Session Initiation Protocol (SIP)" in PIDF Documents ............4
      3.1. Overview of Operation ......................................4
      3.2. Service capabilities .......................................5
           3.2.1. <servcaps> Element ..................................5
           3.2.2. <audio> Element .....................................5
           3.2.3. <application> Element ...............................5
           3.2.4. <data> Element ......................................6
           3.2.5. <control> Element ...................................6
           3.2.6. <video> Element .....................................6
           3.2.7. <text> Element ......................................6
           3.2.8. <message> Element ...................................7
           3.2.9. <type> Element ......................................7
           3.2.10. <automata> Element .................................7
           3.2.11. <class> Element ....................................7
           3.2.12. <duplex> Element ...................................8
           3.2.13. <description> Element ..............................8
           3.2.14. <event-packages> Element ...........................9
           3.2.15. <priority> Element .................................9
           3.2.16. <methods> Element .................................10
           3.2.17. <extensions> Element ..............................11
           3.2.18. <schemes> Element .................................11
           3.2.19. <actor> Element ...................................12
           3.2.20. <isfocus> Element .................................12
           3.2.21. <languages> Element ...............................13
      3.3. Device Capabilities .......................................13
           3.3.1. <devcaps> Element ..................................13
           3.3.2. <mobility> Element .................................14
           3.3.3. <description> Element ..............................14
   4. Usage Guidelines ...............................................15
      4.1. Use of <supported> and <notsupported> Elements ............15
   5. Examples .......................................................16
   6. XML Schema Definitions .........................................17
   7. IANA Considerations ............................................26
      7.1. URN Sub-Namespace Registration for ........................26
      7.2. Schema Registration for Schema ............................27
   8. Security Considerations ........................................27
   9. Acknowledgments ................................................27
   10. References ....................................................27
      10.1. Normative References .....................................27
      10.2. Informative References ...................................28




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1.  Introduction

   Common Profile for Presence (CPP) [RFC3859] and Common Profile for
   Instant Messaging (CPIM) [RFC3860] define common operations and
   formats that all presence and instant messaging services must agree
   upon so that basic interoperability is possible.  The actual base
   format for the presence is defined in the Presence Information
   Document Format (PIDF) [RFC3863].  The PIDF has been designed to
   reduce the need for gatewaying and to allow end-to-end security of
   presence information.  It has taken a very minimalistic approach to
   support such operations.  In order to make the PIDF usable by
   different presence applications, these applications usually must
   extend the basic PIDF by standard XML mechanisms as defined in PIDF
   [RFC3863].

   The aim of this memo is to introduce a SIP-specific extension
   mechanism to the PIDF that conveys the same SIP media feature tags as
   described in [RFC3840].  With this extension, presence applications
   based on SIP can have richer and more usable presence information
   compared to the baseline PIDF.

1.1.  Motivation

   The PIDF [RFC3863] defines a <contact> element that may appear once
   inside every <tuple> element.  The content of the <contact> element
   encodes the CONTACT ADDRESS and CONTACT MEANS as defined in
   [RFC2778].  The <contact> element is defined to be a URI of any
   scheme.  In some implementations, the URI scheme can uniquely
   identify the service the tuple intends to describe (e.g., im: URI
   scheme usually represents Instant Messaging service).  However, this
   may not be the case in all implementations.  For example in SIP, a
   SIP URI scheme can represent different kinds of services.  A SIP URI
   scheme can be used to contact voice services, video services, or
   messaging services.  If it is not known by other means, it might be
   hard for applications processing the presence information containing
   only a SIP URI contact addresses to know what particular service the
   tuple intends to describe.  Also, watchers receiving presence
   information would probably benefit from getting more descriptive
   information about what particular communication means or services are
   supported by the presentity.

   The User Agent Capabilities extension [RFC3840] defines a set of
   extensions that allow user agents to express preferences about
   request handling in SIP servers.  The same information can provide
   value to watchers as well so that they can make more rational
   decisions on how a presentity should be contacted if a presence
   document contained this information.




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1.2.  Scope

   This document defines a PIDF extension, which enables SIP presence
   implementations to represent User Agent Capabilities [RFC3840] within
   presence information.

   This extension does not replace media negotiation mechanisms defined
   for SIP (e.g., SDP [RFC4566]).  The purpose of this extension is for
   a presentity to give watchers hints about the presentity's
   preferences, willingness, and capabilities to communicate before
   watchers initiate communication with the presentity.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   This memo makes use of the vocabulary defined in [RFC2778] and
   [RFC3863].

3.  Extension for "Indicating User Agent Capabilities in the Session
    Initiation Protocol (SIP)" in PIDF Documents

   This section presents the extension elements, attributes, their
   values, and semantics.  This section also describes how this
   extension can be further extended.

   This extension is intended to be used within the PIDF [RFC3863] and
   that particular usage is described here.  This extension may also be
   used with other XML documents if appropriate.

3.1.  Overview of Operation

   This document defines how the features presented in [RFC3840] can be
   provided as part of presence information.  Additionally, this memo
   includes the "type" feature tag [RFC2913], "message" media type
   feature tag [RFC4569], and the "language" feature tag [RFC4646]
   definitions.  Adding these features to the PIDF means mapping them to
   an XML formatted structure.

   The presence data model [RFC4479] defines presence information
   consisting of three types of data elements: person, service, and
   device.  This memo follows this model so that one XML extension is
   defined to describe device capabilities and another one to describe
   service capabilities.





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   The namespace URIs for elements defined by this document are URNs
   using the namespace identifier 'ietf' defined by [RFC2648] and
   extended by [RFC3688].

   When these extension namespaces are congregated with the PIDF
   document, the combined document MUST follow the same general
   formatting rules as specified in Section 4.1 of [RFC3863].

3.2.  Service capabilities

   Elements belonging to service capabilities are used to describe
   dynamic characteristics of a service.  These capabilities are
   enclosed within the <servcaps> element which SHOULD be located in the
   PIDF document as a child element of urn:ietf:params:xml:ns:pidf
   namespace <tuple> [RFC3863] element.

   The namespace identifier for these elements is:

   urn:ietf:params:xml:ns:pidf:caps

3.2.1.  <servcaps> Element

   The root element of service capabilities is <servcaps>.  The root
   element always has to be present.  This element can contain the
   following child elements: <audio>, <application>, <data>, <control>,
   <video>, <text>, <message>, <type>, <automata>, <class>, <duplex>,
   <description>, <event-packages>, <priority>, <methods>, <extensions>,
   <schemes>, <actor>, <isfocus>, and <languages> followed by any number
   of optional extension elements from other namespaces.

   A <servcaps> element can contain any number of optional extension
   attributes from other namespaces.

3.2.2.  <audio> Element

   The <audio> element indicates that the service supports audio as a
   streaming media type as defined in [RFC3840].

   The <audio> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports audio
   media type, and the value 'false' indicates that service does not
   support audio media type.

3.2.3.  <application> Element

   The <application> element indicates that the service supports
   application as a streaming media type as defined in [RFC3840].




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   The <application> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports
   application media type, and the value 'false' indicates that service
   does not support application media type.

3.2.4.  <data> Element

   The <data> element indicates that the service supports data as a
   streaming media type as defined in [RFC3840].

   The <data> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports data
   media type, and the value 'false' indicates that service does not
   support data media type.

3.2.5.  <control> Element

   The <control> element indicates that the service supports control as
   a streaming media type as defined in [RFC3840].

   The <control> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports control
   media type, and the value 'false' indicates that service does not
   support control media type.

3.2.6.  <video> Element

   The <video> element indicates that the service supports video as a
   streaming media type as defined in [RFC3840].

   The <video> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports video
   media type, and the value 'false' indicates that service does not
   support video media type.

3.2.7.  <text> Element

   The <text> element indicates that the service supports text as a
   streaming media type as defined in [RFC3840].

   The <text> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports text
   media type, and the value 'false' indicates that service does not
   support text media type.







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3.2.8.  <message> Element

   The <message> element indicates that the service supports messaging
   as a streaming media type as defined in [RFC4569].

   The <message> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that service supports message
   media type, and the value 'false' indicates that service does not
   support message media type.

3.2.9.  <type> Element

   The <type> element indicates a MIME media content type (i.e., that
   appears in a 'Content-type:' header of the corresponding MIME-
   formatted data) as defined in [RFC2913].

   The <type> element is a string type and does not have any attributes.
   It MUST be a string of the form "type/subtype", where 'type' and
   'subtype' are defined by the MIME specification [RFC2045].  Only
   lowercase letters SHOULD be used.

3.2.10.  <automata> Element

   The <automata> element indicates whether the service represents an
   automaton (such as a voicemail server, conference server, or
   recording device) or a human as defined in [RFC3840].

   The <automata> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that the service represents
   an automaton, and the value 'false' indicates that it represents a
   human.

3.2.11.  <class> Element

   The <class> element indicates the setting, business or personal, in
   which a communications service is used as defined in [RFC3840].

   The <class> element can contain two elements: <supported> and
   <notsupported>.  Classes that are supported by the service can be
   listed under the <supported> element, and classes that are not
   supported by the service can be listed under the <notsupported>
   element.

   <supported> and <notsupported> elements can contain <business> and
   <personal> elements followed by any number of optional extension
   elements from other namespaces.  The semantics of business and
   personal are defined in [RFC3840] as:




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   o  <business>: The service is used for business communications.

   o  <personal>: The service is used for personal communications.

   Any value that is registered with IANA for the SIP media feature tag
   registration tree as a sip.class media feature tag can be used as a
   value of an extension element.  If the appropriate value is not
   registered, it SHOULD be registered as defined in [RFC3840].

3.2.12.  <duplex> Element

   The <duplex> element lists whether a communications service can
   simultaneously send and receive media ("full"), alternate between
   sending and receiving ("half"), only receive ("receive-only"), or
   only send ("send-only") as defined in [RFC3840].

   The <duplex> element can contain two elements: <supported> and
   <notsupported>.  Duplex modes that are supported by the service can
   be listed under the <supported> element, and duplex modes that are
   not supported by the service can be listed under the <notsupported>
   element.

   <supported> and <notsupported> elements can contain <full>, <half>,
   <receive-only>, and <send-only> elements followed by any number of
   optional extension elements from other namespaces.  The semantics of
   these elements are defined in [RFC3840] as:

   o  <full>: The service can simultaneously send and receive media.

   o  <half>: The service can alternate between sending and receiving
      media.

   o  <receive-only>: The service can only receive media.

   o  <send-only>: The service can only send media.

   Any value that is registered with IANA for the SIP media feature tag
   registration tree as a sip.duplex media feature tag can be used as a
   value of an extension element.  If the appropriate value is not
   registered, it SHOULD be registered as defined in [RFC3840].

3.2.13.  <description> Element

   The <description> element provides a textual description of the
   service as defined in [RFC3840].

   The <description> element is of string type and does not have any
   attributes.



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   The <description> element SHOULD be labeled with the 'xml:lang'
   attribute to indicate its language and script.  The specification
   allows multiple occurrences of this elements so that the presentity
   can convey <description> elements in multiple scripts and languages.
   If no 'xml:lang' attribute is provided, the default value is
   "i-default" as defined in [RFC2277].

3.2.14.  <event-packages> Element

   The <event-packages> element lists the event packages supported by a
   service.

   The <event-packages> element can contain two elements: <supported>
   and <notsupported>.  Event packages that are supported by the service
   can be listed under the <supported> element, and event packages that
   are not supported by the service can be listed under the
   <notsupported> element.

   The <supported> and <notsupported> elements can contain any values
   from the IANA SIP event types namespace registry followed by any
   number of optional extension elements from other namespaces.  As of
   this writing, the IANA SIP event types namespace registry includes
   the following packages: <conference>, <dialog>, <kpml>,
   <message-summary>, <poc-settings>, <presence>, <reg>, <refer>,
   <Siemens-RTP-Stats>, <spirits-INDPs>, <spirits-user-prof>, and
   <winfo>.

3.2.15.  <priority> Element

   The <priority> element indicates the call priorities the service is
   willing to handle as defined in [RFC3840].

   The <priority> element can contain two elements: <supported> and
   <notsupported>.  Priority values that are supported by the service
   can be listed under the <supported> element, and priority values that
   are not supported by the service can be listed under the
   <notsupported> element.

   The <supported> and <notsupported> elements can contain any number of
   <lowerthan>, <higherthan>, <equals>, and <range> elements followed by
   any number of optional extension elements from other namespaces.

3.2.15.1.  <lowerthan> Element

   The <lowerthan> element has a single attribute called "maxvalue".
   The "maxvalue" attribute is used to give the highest priority value
   that the service is willing to support.  All values equal and below
   that value are supported.



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3.2.15.2.  <higherthan> Element

   The <higherthan> element has a single attribute called "minvalue".
   The "minvalue" attribute is used to give the lowest priority value
   that the service is willing to support.  All values equal and above
   that value are supported.

3.2.15.3.  <equals> Element

   The <equals> element is used to indicate the exact priority value
   that the service is willing to handle.  The <equals> element has a
   single attribute called "value".  The "value" attribute is used to
   indicate the exact supported priority value.

3.2.15.4.  <range> Element

   The <range> element is used to indicate the priority range that the
   service is willing to handle.  The <range> element has two attributes
   called "minvalue" and "maxvalue".  The value of the "minvalue"
   attribute indicates the lowest priority value supported by the
   service, and the value of the "maxvalue" attribute indicates the
   highest priority value supported by the service.

3.2.16.  <methods> Element

   The <methods> element indicates the SIP methods supported by a
   service.  In this case, "supported" means that the service can
   receive requests with this method.  In that sense, it has the same
   connotation as the Allow header field as defined in [RFC3840].

   The <methods> element can contain two elements: <supported> and
   <notsupported>.  Methods that are supported by the service can be
   listed under the <supported> element, and methods that are not
   supported by the service can be listed under the <notsupported>
   element.

   The <supported> and <notsupported> elements can contain any values
   from the methods table of the IANA SIP parameters registry table
   followed by any number of optional extension elements from other
   namespaces.  As of this writing, the IANA SIP parameters registry
   includes the following methods:<ACK>, <BYE>, <CANCEL>, <INFO>,
   <INVITE>, <MESSAGE>, <NOTIFY>, <OPTIONS>, <PRACK>, <PUBLISH>,
   <REFER>, <REGISTER>, <SUBSCRIBE>, and <UPDATE>.








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3.2.17.  <extensions> Element

   The <extensions> element is a list of SIP extensions (each of which
   is defined by an option-tag registered with IANA) that are understood
   by the service.  Understood, in this context, means that the option
   tag would be included in a Supported header field in a request as
   defined in [RFC3840].

   The <extensions> element can contain two elements: <supported> and
   <notsupported>.  Extensions that are supported by the service can be
   listed under the <supported> element, and extensions that are not
   supported by the service can be listed under the <notsupported>
   element.

   The <supported> and <notsupported> elements can contain any values
   from the option tags table of the IANA SIP parameters registry table
   followed by any number of optional extension elements from other
   namespaces.  As of this writing, the IANA SIP parameters registry
   includes the following option tags: <rel100>, <early-session>,
   <eventlist>, <from-change>, <gruu>, <histinfo>, <join>, <norefersub>,
   <path>, <precondition>, <pref>, <privacy>, <recipient-list-invite>,
   <recipient-list-subscribe>, <replaces>, <resource-priority>, <sdp-
   anat>, <sec-agree>, <tdialog>, and <timer>.

3.2.18.  <schemes> Element

   The <schemes> element provides the set of URI schemes that are
   supported by a service.  "Supported" implies, for example, that the
   service would know how to handle a URI of that scheme in the Contact
   header field of a redirect response as defined in [RFC3840].

   The <schemes> element can contain two elements: <supported> and
   <notsupported>.  Schemes that are supported by the service can be
   listed under the <supported> element, and schemes that are not
   supported by the service can be listed under the <notsupported>
   element.

   <supported> and <notsupported> elements can contain any number of <s>
   elements, which can be used to describe individual schemes supported
   by the service.

3.2.18.1.  <s> Element

   The <s> element is of string type and is used to describe an
   individual scheme supported by the service.  Values that can be used
   here are scheme names that are registered to the IANA URI scheme
   registry.




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3.2.19.  <actor> Element

   The <actor> element indicates the type of entity that is available at
   this URI as defined in [RFC3840].

   The <actor> element can contain two elements: <supported> and
   <notsupported>.  Actor types that are supported by the service can be
   listed under the <supported> element, and actor types that are not
   supported by the service can be listed under the <notsupported>
   element.

   The <supported> and <notsupported> elements can contain <principal>,
   <attendant>, <msg-taker>, and <information> elements followed by any
   number of optional extension elements from other namespaces.

   The semantics of these elements are defined in [RFC3840] as:

   o  <principal>: The service provides communication with the principal
      that is associated with the service.  Often this will be a
      specific human being, but it can be an automaton (for example,
      when calling a voice portal).

   o  <attendant>: The service provides communication with an automaton
      or a person that will act as an intermediary in contacting the
      principal associated with the service, or a substitute.

   o  <msg-taker>: The service provides communication with an automaton
      or a person that will take messages and deliver them to the
      principal.

   o  <information>: The service provides communication with an
      automaton or a person that will provide information about the
      principal.

   Any value that is registered with IANA for the SIP media feature tag
   registration tree as a sip.actor media feature tag can be used as a
   value of an extension element.  If the appropriate value is not
   registered, it SHOULD be registered as defined in [RFC3840].

3.2.20.  <isfocus> Element

   The <isfocus> element indicates that the service is a conference
   server, also known as a focus as defined in [RFC3840].

   The <isfocus> element is of boolean type and does not have any
   attributes.  The value 'true' indicates that service is a conference
   server and the value 'false' indicates that service does not support
   conferencing.



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3.2.21.  <languages> Element

   The <languages> element indicates the ability to display particular
   human languages as defined in [RFC4646].

   The <languages> element can contain two elements: <supported> and
   <notsupported>.  Languages that are supported by the service can be
   listed under the <supported> element, and languages that are not
   supported by the service can be listed under the <notsupported>
   element.

   <supported> and <notsupported> elements can contain any number of <l>
   elements which can be used to describe individual languages supported
   by the service.

3.2.21.1.  <l> Element

   The <l> element is of string type and is used to describe an
   individual language supported by the service.  Values that can be
   used here are language subtags that are registered to the IANA
   language subtag registry as per [RFC4646].

3.3.  Device Capabilities

   Elements belonging to device capabilities are used to describe
   dynamic characteristics of a device.  These capabilities are enclosed
   within the <devcaps> element, which SHOULD be located in the PIDF
   document as a child element of the
   urn:ietf:params:xml:ns:pidf:data-model namespace <device> element
   [RFC4479].

   The namespace identifier for these elements is urn:

   ietf:params:xml:ns:pidf:caps

3.3.1.  <devcaps> Element

   The root element of device capabilities is <devcaps>.  The root
   element always has to be present.  This element can contain the
   following child elements: <mobility> and <description> followed by
   any number of optional extension elements from other namespaces.

   A <devcaps> element can contain any number of optional extension
   attributes from other namespaces.







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3.3.2.  <mobility> Element

   The <mobility> element indicates whether the device is fixed (meaning
   that it is associated with a fixed point of contact with the network)
   or mobile (meaning that it is not associated with a fixed point of
   contact).  Note that cordless phones are fixed, not mobile, based on
   this definition as defined in [RFC3840].

   The <mobility> element can contain two elements: <supported> and
   <notsupported>.  Mobility modes that are supported by the device can
   be listed under the <supported> element and mobility modes that are
   not supported by the device can be listed under the <notsupported>
   element.

   The <supported> and <notsupported> elements can contain <fixed> and
   <mobile> elements followed by any number of optional extension
   elements from other namespaces.

   The semantics of these elements are defined in [RFC3840] as:

   o  <fixed>: The device is stationary.

   o  <mobile>: The device can move around with the user.

   Any value that is registered with IANA to the SIP media feature tag
   registration tree as sip.mobility media feature tag can be used as a
   value of an extension element.  If the appropriate value is not
   registered, it SHOULD be registered as defined in [RFC3840].

3.3.3.  <description> Element

   The <description> element provides a textual description of the
   device as defined in [RFC3840].

   The <description> element is of string type and does not have any
   attributes.

   The <description> element SHOULD be labeled with the 'xml:lang'
   attribute to indicate its language and script.  The specification
   allows multiple occurrences of this element so that the presentity
   can convey <description> elements in multiple scripts and languages.
   If no 'xml:lang' attribute is provided, the default value is
   "i-default" as defined in [RFC2277].








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4.  Usage Guidelines

   The User Agent Capabilities extension [RFC3840] recommends that a UA
   provides complete information in its contact predicate.  However, it
   may be that the presentity is not willing to publish presence
   information that would be consistent with actual device or service
   capabilities (e.g., presentity may not want to indicate that he/she
   supports voice when the service actually is able to support it).
   Authorization rules or policies in the presence server may limit or
   modify the presence information published by the presentity.  Also,
   combining presence information from multiple sources may result in
   loss or mismatch of information.

   It is RECOMMENDED that Presence User Agents (PUAs) using this
   extension provide as complete presence information as they can.  If
   the PUA is publishing sensitive information using this extension, it
   SHOULD obtain permission from the presentity.  PUAs can indicate the
   explicitly supported capabilities using the <supported> element, and
   the capabilities that are explicitly not supported using the
   <notsupported> element.

   It is not mandated that presence information be consistent with
   actual service or device capabilities.  However, it is in the
   presentity's best interest to avoid publishing false presence
   information and provide accurate information to help minimize
   unsuccessful communication invitations.  Otherwise, watchers may
   conclude that communication cannot be established with the
   presentity, but in reality it would be possible; or watchers may
   conclude that certain communication capabilities are available, but
   in reality a communication establishment attempt would fail using
   those capabilities.  In any case, watchers should not expect the
   presence information represented by this extension to be fully
   aligned with the actual presentity's service or device capabilities.
   As explained in Section 1.2, presence of this extension does not
   replace the use of SIP signaling for capability negotiation.

4.1.  Use of <supported> and <notsupported> Elements

   PUAs should add information under <supported> and <notsupported>
   elements only when they believe it may affect the decision making in
   the watcher's end, i.e., information should be relevant and valuable
   for the watcher.  Listing all possible information under <supported>
   and <notsupported> is rarely needed.

   For example, if the PUA wants to advertise a message service that
   supports the MESSAGE method, it should add it under the <supported>
   element in the <methods> element.  Even if the service does not




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   support other methods, it is unlikely that listing all the methods
   not supported under the <notsupported> element would provide any
   value to the watcher.

   In case of conflicting information, i.e., the same child element
   appears under the <supported> and <notsupported> elements with the
   same value, the watcher can safely assume that the listed capability
   is supported regardless of the inclusion of the capability under the
   <notsupported> element.

5.  Examples

   <?xml version="1.0" encoding="UTF-8"?>
   <presence xmlns="urn:ietf:params:xml:ns:pidf"
         xmlns:caps="urn:ietf:params:xml:ns:pidf:caps"
         xmlns:mod="urn:ietf:params:xml:ns:pidf:data-model"
         entity="pres:someone@example.com">

     <tuple id="joi9877866786ua9">
       <status>
         <basic>open</basic>
       </status>
       <caps:servcaps>
         <caps:audio>true</caps:audio>
         <caps:description xml:lang="en">
            Example service
         </caps:description>
         <caps:description xml:lang="hu">
            Pe'lda szolga'ltata's
         </caps:description>
         <caps:duplex>
           <caps:supported>
             <caps:full/>
           </caps:supported>
         </caps:duplex>
         <caps:message>true</caps:message>
         <caps:methods>
           <caps:supported>
             <caps:ACK/>
             <caps:BYE/>
             <caps:INVITE/>
             <caps:MESSAGE/>
           </caps:supported>
         </caps:methods>
         <caps:priority>
           <caps:supported>
             <caps:lowerthan maxvalue="10"/>
           </caps:supported>



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         </caps:priority>
         <caps:schemes>
           <caps:supported>
             <caps:s>sip</caps:s>
           </caps:supported>
         </caps:schemes>
         <caps:video>false</caps:video>
       </caps:servcaps>
       <contact>sip:someone@example.com</contact>
     </tuple>
     <mod:device id="hgt67">
       <caps:devcaps>
         <caps:mobility>
           <caps:supported>
             <caps:mobile/>
           </caps:supported>
         </caps:mobility>
       </caps:devcaps>
       <mod:deviceID
        >urn:uuid:d27459b7-8213-4395-aa77-ed859a3e5b3a</mod:deviceID>
     </mod:device>
   </presence>

6.  XML Schema Definitions

   This section gives the XML schema definitions for the extensions
   defined in this document.  The namespace identifier for this schema
   is urn:ietf:params:xml:ns:pidf:caps.

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:tns="urn:ietf:params:xml:ns:pidf:caps"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  targetNamespace="urn:ietf:params:xml:ns:pidf:caps"
  elementFormDefault="qualified"
  attributeFormDefault="unqualified">

<!-- This import brings in the XML language
     attribute xml:lang-->

 <xs:import namespace="http://www.w3.org/XML/1998/namespace"
  schemaLocation="http://www.w3.org/2001/xml.xsd"/>

<!-- ROOT -->
 <xs:element name="servcaps" type="tns:servcapstype"/>
 <xs:complexType name="servcapstype">
  <xs:sequence>
   <xs:element name="actor" type="tns:actortype"
    minOccurs="0"/>



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   <xs:element name="application" type="tns:applicationtype"
    minOccurs="0"/>
   <xs:element name="audio" type="tns:audiotype" minOccurs="0"/>
   <xs:element name="automata" type="tns:automatatype"
    minOccurs="0"/>
   <xs:element name="class" type="tns:classtype"
    minOccurs="0"/>
   <xs:element name="control" type="tns:controltype"
    minOccurs="0"/>
   <xs:element name="data" type="tns:datatype"
    minOccurs="0"/>
   <xs:element name="description" type="tns:descriptiontype"
    minOccurs="0" maxOccurs="unbounded"/>
   <xs:element name="duplex" type="tns:duplextype"
    minOccurs="0"/>
   <xs:element name="event-packages" type="tns:event-packagestype"
    minOccurs="0"/>
   <xs:element name="extensions" type="tns:extensionstype"
    minOccurs="0"/>
   <xs:element name="isfocus" type="tns:isfocustype"
    minOccurs="0"/>
   <xs:element name="message" type="tns:messagetype"
    minOccurs="0"/>
   <xs:element name="methods" type="tns:methodstype"
    minOccurs="0"/>
   <xs:element name="languages" type="tns:languagestype"
    minOccurs="0"/>
   <xs:element name="priority" type="tns:prioritytype"
    minOccurs="0"/>
   <xs:element name="schemes" type="tns:schemestype"
    minOccurs="0"/>
   <xs:element name="text" type="tns:texttype"
    minOccurs="0"/>
   <xs:element name="type" type="tns:typetype"
    minOccurs="0" maxOccurs="unbounded"/>
   <xs:element name="video" type="tns:videotype"
    minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0" maxOccurs="unbounded"/>
  </xs:sequence>
 <xs:anyAttribute namespace="##any" processContents="lax"/>
 </xs:complexType>

 <xs:element name="devcaps" type="tns:devcaps"/>
 <xs:complexType name="devcaps">
  <xs:sequence>
   <xs:element name="description" type="tns:descriptiontype"
    minOccurs="0" maxOccurs="unbounded"/>



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   <xs:element name="mobility" type="tns:mobilitytype"
    minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0" maxOccurs="unbounded"/>
  </xs:sequence>
 <xs:anyAttribute namespace="##any" processContents="lax"/>
 </xs:complexType>

 <!-- AUDIO -->
 <xs:simpleType name="audiotype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- APPLICATION -->
 <xs:simpleType name="applicationtype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- DATA -->
 <xs:simpleType name="datatype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- CONTROL -->
 <xs:simpleType name="controltype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- VIDEO -->
 <xs:simpleType name="videotype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- TEXT -->
 <xs:simpleType name="texttype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- MESSAGE -->
 <xs:simpleType name="messagetype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- TYPE -->
 <xs:simpleType name="typetype">
  <xs:restriction base="xs:string"/>
 </xs:simpleType>




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 <!-- AUTOMATA -->
 <xs:simpleType name="automatatype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- CLASS -->
 <xs:complexType name="classtype">
  <xs:sequence>
   <xs:element name="supported" type="tns:classtypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:classtypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="classtypes">
  <xs:sequence>
   <xs:element name="business" type="xs:string"
    minOccurs="0"/>
   <xs:element name="personal" type="xs:string"
    minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0"
    maxOccurs="unbounded"/>
  </xs:sequence>
 </xs:complexType>

 <!-- DUPLEX -->
 <xs:complexType name="duplextype">
  <xs:sequence>
   <xs:element name="supported" type="tns:duplextypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:duplextypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="duplextypes">
  <xs:sequence>
   <xs:element name="full" type="xs:string"
    minOccurs="0"/>
   <xs:element name="half" type="xs:string"
    minOccurs="0"/>
   <xs:element name="receive-only" type="xs:string"
    minOccurs="0"/>
   <xs:element name="send-only" type="xs:string"
    minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0" maxOccurs="unbounded"/>
  </xs:sequence>



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 </xs:complexType>

 <!-- DESCRIPTION -->
 <xs:complexType name="descriptiontype">
  <xs:simpleContent>
   <xs:extension base="xs:string">
    <xs:attribute ref="xml:lang"/>
   </xs:extension>
  </xs:simpleContent>
 </xs:complexType>

 <!-- EVENT-PACKAGES -->
 <xs:complexType name="event-packagestype">
  <xs:sequence>
   <xs:element name="supported" type="tns:eventtypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:eventtypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="eventtypes">
  <xs:sequence>
   <xs:element name="conference" type="xs:string"
    minOccurs="0"/>
   <xs:element name="dialog" type="xs:string"
    minOccurs="0"/>
   <xs:element name="kpml" type="xs:string"
    minOccurs="0"/>
   <xs:element name="message-summary" type="xs:string"
    minOccurs="0"/>
   <xs:element name="poc-settings" type="xs:string"
    minOccurs="0"/>
   <xs:element name="presence" type="xs:string"
    minOccurs="0"/>
   <xs:element name="reg" type="xs:string"
    minOccurs="0"/>
   <xs:element name="refer" type="xs:string"
    minOccurs="0"/>
   <xs:element name="Siemens-RTP-Stats"
    type="xs:string" minOccurs="0"/>
   <xs:element name="spirits-INDPs"
    type="xs:string" minOccurs="0"/>
   <xs:element name="spirits-user-prof"
    type="xs:string" minOccurs="0"/>
   <xs:element name="winfo" type="xs:string"
    minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0" maxOccurs="unbounded"/>



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  </xs:sequence>
 </xs:complexType>

 <!-- PRIORITY -->
 <xs:complexType name="prioritytype">
  <xs:sequence>
   <xs:element name="supported" type="tns:prioritytypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:prioritytypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="prioritytypes">
  <xs:sequence>
   <xs:element name="equals" type="tns:equalstype"
    minOccurs="0" maxOccurs="unbounded"/>
   <xs:element name="higherhan" type="tns:higherthantype"
    minOccurs="0" maxOccurs="unbounded"/>
   <xs:element name="lowerthan" type="tns:lowerthantype"
    minOccurs="0" maxOccurs="unbounded"/>
   <xs:element name="range" type="tns:rangetype"
    minOccurs="0" maxOccurs="unbounded"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0" maxOccurs="unbounded"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="lowerthantype">
  <xs:attribute name="maxvalue" type="xs:integer"
   use="required"/>
 </xs:complexType>
 <xs:complexType name="higherthantype">
  <xs:attribute name="minvalue" type="xs:integer"
   use="required"/>
 </xs:complexType>
 <xs:complexType name="equalstype">
  <xs:attribute name="value" type="xs:integer"
   use="required"/>
 </xs:complexType>
 <xs:complexType name="rangetype">
  <xs:attribute name="minvalue" type="xs:integer"
   use="required"/>
  <xs:attribute name="maxvalue" type="xs:integer"
   use="required"/>
 </xs:complexType>

 <!-- METHODS -->
 <xs:complexType name="methodstype">
  <xs:sequence>



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   <xs:element name="supported" type="tns:methodtypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:methodtypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="methodtypes">
  <xs:sequence>
   <xs:element name="ACK" type="xs:string" minOccurs="0"/>
   <xs:element name="BYE" type="xs:string" minOccurs="0"/>
   <xs:element name="CANCEL" type="xs:string" minOccurs="0"/>
   <xs:element name="INFO" type="xs:string" minOccurs="0"/>
   <xs:element name="INVITE" type="xs:string" minOccurs="0"/>
   <xs:element name="MESSAGE" type="xs:string" minOccurs="0"/>
   <xs:element name="NOTIFY" type="xs:string" minOccurs="0"/>
   <xs:element name="OPTIONS" type="xs:string" minOccurs="0"/>
   <xs:element name="PRACK" type="xs:string" minOccurs="0"/>
   <xs:element name="PUBLISH" type="xs:string" minOccurs="0"/>
   <xs:element name="REFER" type="xs:string" minOccurs="0"/>
   <xs:element name="REGISTER" type="xs:string" minOccurs="0"/>
   <xs:element name="SUBSCRIBE" type="xs:string" minOccurs="0"/>
   <xs:element name="UPDATE" type="xs:string" minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax" minOccurs="0"
    maxOccurs="unbounded"/>
  </xs:sequence>
 </xs:complexType>

 <!-- EXTENSIONS -->
 <xs:complexType name="extensionstype">
  <xs:sequence>
   <xs:element name="supported" type="tns:extensiontypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:extensiontypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="extensiontypes">
  <xs:sequence>
   <xs:element name="rel100" type="xs:string" minOccurs="0"/>
   <xs:element name="early-session" type="xs:string" minOccurs="0"/>
   <xs:element name="eventlist" type="xs:string" minOccurs="0"/>
   <xs:element name="from-change" type="xs:string" minOccurs="0"/>
   <xs:element name="gruu" type="xs:string" minOccurs="0"/>
   <xs:element name="hist-info" type="xs:string" minOccurs="0"/>
   <xs:element name="join" type="xs:string" minOccurs="0"/>
   <xs:element name="norefersub" type="xs:string" minOccurs="0"/>
   <xs:element name="path" type="xs:string" minOccurs="0"/>
   <xs:element name="precondition" type="xs:string" minOccurs="0"/>



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   <xs:element name="pref" type="xs:string" minOccurs="0"/>
   <xs:element name="privacy" type="xs:string" minOccurs="0"/>
   <xs:element name="recipient-list-invite" type="xs:string"
    minOccurs="0"/>
   <xs:element name="recipient-list-subscribe" type="xs:string"
    minOccurs="0"/>
   <xs:element name="replaces" type="xs:string" minOccurs="0"/>
   <xs:element name="resource-priority" type="xs:string" minOccurs="0"/>
   <xs:element name="sdp-anat" type="xs:string" minOccurs="0"/>
   <xs:element name="sec-agree" type="xs:string" minOccurs="0"/>
   <xs:element name="tdialog" type="xs:string" minOccurs="0"/>
   <xs:element name="timer" type="xs:string" minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax"
    minOccurs="0" maxOccurs="unbounded"/>
  </xs:sequence>
 </xs:complexType>

 <!-- SCHEMES -->
 <xs:complexType name="schemestype">
  <xs:sequence>
   <xs:element name="supported" minOccurs="0">
    <xs:complexType>
     <xs:sequence>
      <xs:element name="s" type="xs:string" maxOccurs="unbounded"/>
     </xs:sequence>
    </xs:complexType>
   </xs:element>
   <xs:element name="notsupported" minOccurs="0">
    <xs:complexType>
     <xs:sequence>
      <xs:element name="s" type="xs:string" maxOccurs="unbounded"/>
     </xs:sequence>
    </xs:complexType>
   </xs:element>
  </xs:sequence>
 </xs:complexType>

 <!-- ACTOR -->
 <xs:complexType name="actortype">
  <xs:sequence>
   <xs:element name="supported" type="tns:actortypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:actortypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="actortypes">
  <xs:sequence>



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   <xs:element name="attendant" type="xs:string" minOccurs="0"/>
   <xs:element name="information" type="xs:string" minOccurs="0"/>
   <xs:element name="msg-taker" type="xs:string" minOccurs="0"/>
   <xs:element name="principal" type="xs:string" minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax" minOccurs="0"
    maxOccurs="unbounded"/>
  </xs:sequence>
 </xs:complexType>

 <!-- ISFOCUS -->
 <xs:simpleType name="isfocustype">
  <xs:restriction base="xs:boolean"/>
 </xs:simpleType>

 <!-- LANGUAGES -->
 <xs:complexType name="languagestype">
  <xs:sequence>
   <xs:element name="supported" minOccurs="0">
    <xs:complexType>
     <xs:sequence>
      <xs:element name="l" type="xs:string" maxOccurs="unbounded"/>
     </xs:sequence>
    </xs:complexType>
   </xs:element>
   <xs:element name="notsupported" minOccurs="0">
    <xs:complexType>
     <xs:sequence>
      <xs:element name="l" type="xs:string" maxOccurs="unbounded"/>
     </xs:sequence>
    </xs:complexType>
   </xs:element>
  </xs:sequence>
 </xs:complexType>

 <!-- MOBILITY -->
 <xs:complexType name="mobilitytype">
  <xs:sequence>
   <xs:element name="supported" type="tns:mobilitytypes"
    minOccurs="0"/>
   <xs:element name="notsupported" type="tns:mobilitytypes"
    minOccurs="0"/>
  </xs:sequence>
 </xs:complexType>
 <xs:complexType name="mobilitytypes">
  <xs:sequence>
   <xs:element name="fixed" type="xs:string"
    minOccurs="0"/>
   <xs:element name="mobile" type="xs:string"



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    minOccurs="0"/>
   <xs:any namespace="##other" processContents="lax" minOccurs="0"
    maxOccurs="unbounded"/>
  </xs:sequence>
 </xs:complexType>
</xs:schema>

7.  IANA Considerations

   IANA has registered one new XML namespace URN and one schema as
   defined in [RFC3688].

7.1.  URN Sub-Namespace Registration for
      'urn:ietf:params:xml:ns:pidf:caps'

   URI:
   urn:ietf:params:xml:ns:pidf:caps

   Description:
   This is the XML namespace for XML elements defined by RFC 5196 to
   describe service and device capabilities in application/pidf+xml
   content type.

   Registrant Contact:
   IETF, SIMPLE working group, <simple@ietf.org>
   Mikko Lonnfors, <mikko.lonnfors@nokia.com>

   XML:

   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>Namespace for PIDF user agent capability
               extension</title>
   </head>
   <body>
       <h1>Namespace for PIDF service capability extension</h1>
       <h2>urn:ietf:params:xml:ns:pidf:caps</h2>
       <p>
         See <a href="http://www.rfc-editor.org/rfc/rfc5196.txt">RFC
         5196</a>.
       </p>
    </body>



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    </html>
   END

7.2.  Schema Registration for Schema
      'urn:ietf:params:xml:schema:pidf:caps'

   URI:
   urn:ietf:params:xml:schema:pidf:caps

   Registrant Contact:
   IESG

   XML:
   See Section 6

8.  Security Considerations

   All security considerations specified in [RFC3859] and [RFC3863]
   apply to this document.  Compared to PIDF [RFC3863], this presence
   document format may reveal additional information about user's
   service and device capabilities.  Thus, the PUA SHOULD always obtain
   permission from the presentity when publishing sensitive information
   using this extension.

9.  Acknowledgments

   Authors of this document would like to thank the following people for
   their contributions and valuable comments: Paul Kyzivat, Jonathan
   Rosenberg, Markus Isomaki, Eva Leppanen, Miguel Garcia, Jari
   Urpalainen, and Hisham Khartabil.

10.  References

10.1.  Normative References

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) part one: Format of Internet Message
              Bodies", RFC 2045, November 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and
              Languages", BCP 18, RFC 2277, January 1998.

   [RFC2913]  Klyne, G., "MIME Content Types in Media Feature
              Expressions", RFC 2913, September 2000.




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   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC3840]  Schulzrinne, H., Rosenberg, J., and P. Kyzivat,
              "Indicating User Agent Capabilities in the Session
              Initiation Protocol (SIP)", RFC 3840, August 2004.

   [RFC3859]  Peterson, J., "Common Profile for Presence (CPP)",
              RFC 3859, August 2004.

   [RFC3863]  Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr,
              W., and J. Peterson, "Presence Information Data Format
              (PIDF)", RFC 3863, August 2004.

   [RFC4479]  Rosenberg, J., "A Data Model for Presence", RFC 4479,
              July 2006.

   [RFC4646]  Phillips, A. and M. Davis, "Tags for Identifying
              Languages", BCP 47, RFC 4646, September 2006.

10.2.  Informative References

   [RFC2648]  Moats, R., "A URN namespace for IETF documents", RFC 2648,
              August 1999.

   [RFC2778]  Day, M., Rosenberg, J., and H. Sugano, "A Model for
              Presence and Instant Messaging", RFC 2778, February 2000.

   [RFC3860]  Peterson, J., "Common Profile for Instant Messaging
              (CPIM)", RFC 3860, August 2004.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC4569]  Camarillo, G., "Internet Assigned Numbers Authority (IANA)
              Registration of the Message Media Feature Tag", RFC 4569,
              July 2006.














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RFC 5196         User Agent Capability Presence Status    September 2008


Authors' Addresses

   Mikko Lonnfors
   Nokia
   P.O. Box 321
   Helsinki
   Finland

   Phone: +358 71 8008000
   EMail: mikko.lonnfors@nokia.com


   Krisztian Kiss
   Nokia
   313 Fairchild Dr
   Mountain View, CA 94043
   US

   Phone: +1 650 391 5969
   EMail: krisztian.kiss@nokia.com































Lonnfors & Kiss             Standards Track                    [Page 29]

RFC 5196         User Agent Capability Presence Status    September 2008


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