SIMPLE WG                                                    M. Lonnfors
Internet-Draft                                                   K. Kiss
Expires: February 1, 2007                                          Nokia
                                                           July 31, 2006


  Session Initiation Protocol (SIP) User Agent Capability Extension to
                Presence Information Data Format (PIDF)
                   draft-ietf-simple-prescaps-ext-07

Status of this Memo

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   This Internet-Draft will expire on February 1, 2007.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

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





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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Motivation . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Extension for "Indicating User Agent Capabilities in the
       Session Initiation Protocol (SIP)" in PIDF documents . . . . .  5
     3.1.  Overview of operation  . . . . . . . . . . . . . . . . . .  5
     3.2.  Service capabilities . . . . . . . . . . . . . . . . . . .  6
       3.2.1.  <servcaps> element . . . . . . . . . . . . . . . . . .  6
       3.2.2.  <audio> element  . . . . . . . . . . . . . . . . . . .  6
       3.2.3.  <application> element  . . . . . . . . . . . . . . . .  6
       3.2.4.  <data> element . . . . . . . . . . . . . . . . . . . .  7
       3.2.5.  <control> element  . . . . . . . . . . . . . . . . . .  7
       3.2.6.  <video> element  . . . . . . . . . . . . . . . . . . .  7
       3.2.7.  <text> element . . . . . . . . . . . . . . . . . . . .  7
       3.2.8.  <message> element  . . . . . . . . . . . . . . . . . .  7
       3.2.9.  <type> element . . . . . . . . . . . . . . . . . . . .  8
       3.2.10. <automata> element . . . . . . . . . . . . . . . . . .  8
       3.2.11. <class> element  . . . . . . . . . . . . . . . . . . .  8
       3.2.12. <duplex> element . . . . . . . . . . . . . . . . . . .  9
       3.2.13. <description> element  . . . . . . . . . . . . . . . .  9
       3.2.14. <event-packages> element . . . . . . . . . . . . . . .  9
       3.2.15. <priority> element . . . . . . . . . . . . . . . . . . 10
       3.2.16. <methods> element  . . . . . . . . . . . . . . . . . . 11
       3.2.17. <extensions> element . . . . . . . . . . . . . . . . . 11
       3.2.18. <schemes> element  . . . . . . . . . . . . . . . . . . 12
       3.2.19. <actor> element  . . . . . . . . . . . . . . . . . . . 12
       3.2.20. <isfocus> element  . . . . . . . . . . . . . . . . . . 13
       3.2.21. <languages> element  . . . . . . . . . . . . . . . . . 13
     3.3.  Device capabilities  . . . . . . . . . . . . . . . . . . . 13
       3.3.1.  <devcaps> element  . . . . . . . . . . . . . . . . . . 14
       3.3.2.  <mobility> element . . . . . . . . . . . . . . . . . . 14
       3.3.3.  <priority> element . . . . . . . . . . . . . . . . . . 15
       3.3.4.  <description> element  . . . . . . . . . . . . . . . . 15
   4.  Usage guidelines . . . . . . . . . . . . . . . . . . . . . . . 16
   5.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
   6.  XML schema definitions . . . . . . . . . . . . . . . . . . . . 17
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 26
     7.1.  URN sub-namespace registration for
           'urn:ietf:params:xml:ns:pidf:caps' . . . . . . . . . . . . 26
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 26
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 27
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     10.1. Normative references . . . . . . . . . . . . . . . . . . . 27
     10.2. Informative references . . . . . . . . . . . . . . . . . . 28
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29



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   Intellectual Property and Copyright Statements . . . . . . . . . . 30


















































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1.  Introduction

   Common Profile for Presence (CPP) [1] and Common Profile for Instant
   Messaging (CPIM) [12] define common operations and formats which all
   presence and instant messaging services must agree upon so that basic
   interoperability would be possible.  The actual base format for the
   presence is defined in the Presence Information Document Format
   (PIDF) [4].  The PIDF has been designed to reduce the need for
   gatewaying and to allow end-to-end security of presence data.  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 [4].

   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 [5].  With this extension presence applications
   based on SIP can have richer and more usable presence data compared
   to the baseline PIDF.

1.1.  Motivation

   The PIDF [4] defines a <contact> element which may appear once inside
   every <tuple> element.  The content of the <contact> element encodes
   the CONTACT ADDRESS and CONTACT MEANS as defined in RFC2778 [3].  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 document 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 for getting more descriptive information about what
   particular communication means or services are supported by the
   presentity.

   RFC3840 [5] defines a set of extensions which allow callees to
   express preferences about request handling in SIP servers.  The same
   information can provide value also to presence watchers so that they
   can make more rational decisions on how a presentity should be
   contacted if a presence document contained similar information.






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1.2.  Scope

   This document defines extensions to the PIDF which enables presence
   implementations based on SIP to utilize similar information in a
   presence information document as what RFC3840 [5] defines.

   This extension does not replace media negotiation mechanisms defined
   for SIP (e.g.  SDP [13]).  This extension is only aimed for
   presentities to give watchers hints about the presentity's
   preferences, willingness and capabilities to communicate before
   watchers initiate a 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 RFC 2119. [2].

   This memo makes use of the vocabulary defined in RFC2778 [3], and in
   RFC3863 [4].


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

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

   This extension is intended to be used within a PIDF [4] 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 [5] can
   be provided as a part of presence data.  Additionally, this memo
   includes the "type" feature tag [6], "message" media type feature tag
   [14] and the "language" feature tag [7] definitions.  Bringing these
   features in the PIDF means mapping them to an XML formatted
   structure.

   The presence data model [10] defines presence data consisting of
   three types of data elements: person, service, and device.  This memo
   follows this model so that one XML document 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 [8] and
   extended by RFC3688 [9].

   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 the RFC3863 [4].

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
   PIDF document as a child element of urn:ietf:params:xml:ns:pidf
   namespace <tuple> [4] element.

   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 has to be always present.  This element can contain following
   elements: <audio>, <application>, <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 does not have any attributes.

3.2.2.  <audio> element

   The <audio> element indicates that the service supports audio as a
   streaming media type as defined in RFC3840 [5].

   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 [5].

   The <application> element is a boolean type and does not have any



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   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 [5].

   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 [5].

   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 [5].

   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 [5].

   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.

3.2.8.  <message> element

   The <message> element indicates that the service supports message as
   a streaming media type as defined in [14].



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   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 [6].

   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 [11].  Only lower-
   case letters SHOULD be used.

3.2.10.  <automata> element

   The <automata> element indicates whether the service represents an
   automata (such as a voicemail server, conference server, IVR, or
   recording device) or a human as defined in RFC3840 [5].

   The <automata> element is a boolean type and does not have any
   attributes.  The value 'true' indicates that the service represents
   an automata 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 [5].

   The <class> element can contain two elements: <supported> and
   <notsupported>.  All classes that are supported by the service are
   listed under <supported> element and all classes that are not
   supported by the service are listed under <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 [5] as:

   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



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   value of an extension element.  If the appropriate value is not
   registered it SHOULD be registed as defined in RFC3840 [5].

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 [5].

   The <duplex> element can contain two elements: <supported> and
   <notsupported>.  All duplex modes that are supported by the service
   are listed under <supported> element and all duplex modes that are
   not supported by the service are listed under <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 [5] 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.class media feature tag can be used as a
   value of an extension element.  If the appropriate value is not
   registered it SHOULD be registed as defined in RFC3840 [5].

3.2.13.  <description> element

   The <description> element provides a textual description of the
   service as defined in RFC3840 [5].

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

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>



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   and <notsupported>.  All event packages that are supported by the
   service are listed under <supported> element and all event packages
   that are not supported by the service are listed under <notsupported>
   element.

   <supported> and <notsupported> elements can contain <presence>,
   <message-summary>, <reg>, <refer>, <winfo>, <spirits-user-prof>,
   <spirits-user-prof>, <spirits-INDPs>, and <Siemens-RTP-Stats>
   followed by any number of optional extension elements from other
   namespaces.

   Any value that is registered with IANA for the SIP Event types
   namespace registry can be used as a value of an extension element.

3.2.15.  <priority> element

   The <priority> element indicates the call priorities the service is
   willing to handle.

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

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



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   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 "min" and "max".  Value of the "min" attribute indicates
   lowest priority value supported by the service and the value of the
   "max" 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 [5].

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

   The <supported> and <notsupported> elements can contain <ACK>, <BYE>,
   <CANCEL>, <INFO>, <INVITE>, <MESSAGE>, <NOTIFY>, <OPTIONS>, <PRACK>,
   <PUBLISH>, <REFER>, <REGISTER>, <SUBSCRIBE>, and <UPDATE> elements
   followed by any number of optional extension elements from other
   namespaces.

   Any value that is registered with IANA for the SIP methods namespace
   registry can be used as a value of an extension element.

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 [5].

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

   The <supported> and <notsupported> elements can contain <rel100>,
   <join>, <path>, <precondition>, <pref>, <privacy>, <replaces>,
   <histinfo> and <sec-agree> elements followed by any number of



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   optional extension elements from other namespaces.

   Any value that is defined in IANA SIP parameters registry option tags
   table can be used as a value of an extension element.

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 [5].

   The <schemes> element can contain two elements: <supported> and
   <notsupported>.  All schemes that are supported by the service are
   listed under <supported> element and all schemes that are not
   supported by the service are listed under <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 it is used to describe
   individual scheme supported by the service.  Values that can be used
   here are scheme names that are registered to IANA URI scheme
   registry.

3.2.19.  <actor> element

   The <actor> element indicates the type of entity that is available at
   this URI as defined in RFC3840 [5].

   The <actor> element can contain two elements: <supported> and
   <notsupported>.  All actor types that are supported by the service
   are listed under <supported> element and all actor types that are not
   supported by the service are listed under <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 [5] 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 automata (for example, when
      calling a voice portal).



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   o  <attendant>: The service provides communication with an automata
      or 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 automata
      or person that will take messages and deliver them to the
      principal.

   o  <information>: The service provides communication with an automata
      or 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.class media feature tag can be used as a
   value of an extension element.  If the appropriate value is not
   registered it SHOULD be registed as defined in RFC3840 [5].

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 [5].

   The <isfocus> element is of boolean type and does not have any
   attributes.

3.2.21.  <languages> element

   The <languages> element indicates the ability to display particular
   human languages as defined in RFC2987 [7].

   The <languages> element can contain two elements: <supported> and
   <notsupported>.  All languages that are supported by the service are
   listed under <supported> element and all languages that are not
   supported by the service are listed under <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 it is used to describe
   individual language supported by the service.  Values that can be
   used here are language names that are registered to IANA as per
   RFC2987 [7].

3.3.  Device capabilities

   Elements belonging to service capabilities are used to describe



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   dynamic characteristics of a service.  These capabilities are
   enclosed within the <devcaps> element which SHOULD be located in the
   PIDF document as a child element of
   urn:ietf:params:xml:ns:pidf:data-model namespace <device> element
   [10].

   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 has to be always present.  This element can contain following
   elements: <mobility>, <priority>, and <description> followed by any
   number of optional extension elements from other namespaces.

   A <devcaps> element does not have any attributes.

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 [5].

   The <mobility> element can contain two elements: <supported> and
   <notsupported>.  All mobility modes that are supported by the device
   are listed under <supported> element and all mobility modes that are
   not supported by the device are listed under <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 [5] as:

   o  <fixed>: The device is stationary.

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

   Any value that is register to IANA to 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 registed as defined in RFC3840 [5].





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3.3.3.  <priority> element

   The <priority> element indicates the call priorities the device is
   willing to handle.

   The <priority> element can contain two elements: <supported> and
   <notsupported>.  All priority values that are supported by the device
   are listed under <supported> element and all priority values that are
   not supported by the device are listed under <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.

3.3.3.1.  <lowerthan> element

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

3.3.3.2.  <higherthan> element

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

3.3.3.3.  <equals> element

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

3.3.3.4.  <range> element

   The <range> element is used to indicate the priority range that the
   device is willing to handle.  The <range> element has two attributes
   called "min" and "max".  Value of the "min" attribute indicates
   lowest priority value supported by the device and the value of the
   "max" attribute indicates the highest priority value supported by the
   device.

3.3.4.  <description> element

   The <description> element provides a textual description of the
   device as defined in RFC3840 [5].



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


4.  Usage guidelines

   In RFC3840 [5] it is recommended that a UA provides complete
   information in its contact predicate.  However, it may be that
   presentity is not willing to publish presence information which 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).  Also authorization
   rules or policies in presence server may limit or modify the
   published presence information in a way that all published presence
   information may not end up to all possible watchers.

   It is RECOMMENTED 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 a permission from a user.  PUAs can indicate all the
   explicitly supported capabilities using the <supported> element and
   all the explicitly not supported capabilities using the
   <notsupported> element, where appropriate.

   However, it is not mandated that this presence information should be
   consistent with actual device capabilities.  Also, watchers should
   not expect that the presence information represented by this
   extension fully represents the actual presentity's device
   capabilities.


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>
                 Example service
         </caps:description>



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         <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:supported>
         </caps:methods>
         <caps:priority>
           <caps:supported>
             <caps:lowerthan maxvalue="10"/>
           </caps:supported>
         </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.  Namespace identifier for this schema is
   urn:ietf:params:xml:ns:pidf:caps.

   <?xml version="1.0" encoding="UTF-8"?>



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   <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"/>
      <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"/>
      <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"



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       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:complexType>

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



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     <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>

    <!-- 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"



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       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>
    </xs:complexType>

    <!-- DESCRIPTION -->
    <xs:simpleType name="descriptiontype">
     <xs:restriction base="xs:string"/>
    </xs:simpleType>

    <!-- 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="message-summary" type="xs:string"
       minOccurs="0"/>
      <xs:element name="presence" type="xs:string"
       minOccurs="0"/>
      <xs:element name="refer" type="xs:string"
       minOccurs="0"/>
      <xs:element name="reg" 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"/>



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      <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"/>
     </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"



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      use="required"/>
    </xs:complexType>

    <!-- METHODS -->
    <xs:complexType name="methodstype">
     <xs:sequence>
      <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="join" type="xs:string" minOccurs="0"/>
      <xs:element name="path" type="xs:string" minOccurs="0"/>
      <xs:element name="precondition" type="xs:string" minOccurs="0"/>
      <xs:element name="pref" type="xs:string" minOccurs="0"/>



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      <xs:element name="privacy" type="xs:string" minOccurs="0"/>
      <xs:element name="rel100" type="xs:string" minOccurs="0"/>
      <xs:element name="replaces" type="xs:string" minOccurs="0"/>
      <xs:element name="sec-agree" 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>
      <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>



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

   Figure 2




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7.  IANA Considerations

   This memo calls for IANA to register one new XML namespace URNs as
   defined in RFC3688 [9].

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 [[[RFCXXXX]]]
   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="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
    </body>
    </html>
   END


8.  Security Considerations

   All security considerations specified in RFC3859 [1] and in RFC3863
   [4] apply to this document.  Compared to PIDF [4] this presence
   document format may reveal additional information about user's
   service and device capabilities.  Thus, the PUA SHOULD always obtain



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   permission from the user when publishing sensitive information using
   this extension.

   Because presence is very privacy-sensitive information, the transport
   protocol for the presence information SHOULD have capabilities to
   protect protocol messages from possible threats, such as
   eavesdropping, corruption, tamper and replay attacks.  If such
   security measures are not used, eavesdroppers can learn sensitive
   information about the user.  It may be possible for a third party to
   modify the user's presence information.  This can lead to a situation
   that users receiving presentity's presence information can take
   incorrect actions based on false information.  The protocols SHOULD
   be able to use security mechanisms which are standardized or being
   standardized in IETF.  However, it depends on the actual transport
   protocols which security mechanisms should be used, and it is beyond
   the scope of this memo.


9.  Acknowledgments

   Authors of this document would like to thank 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

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

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

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

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

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

   [6]   Klyne, G., "MIME Content Types in Media Feature Expressions",



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         RFC 2913, September 2000.

   [7]   Hoffman, P., "Registration of Charset and Languages Media
         Features Tags", RFC 2987, November 2000.

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

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

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

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

10.2.  Informative references

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

   [13]  Handley, M. and V. Jacobson, "SDP: Session Description
         Protocol", RFC 2327, April 1998.

   [14]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
         Extensions (MIME) part two: Media Types", RFC 2046,
         November 1996.






















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Authors' Addresses

   Mikko Lonnfors
   Nokia
   P.O. Box 321
   Helsinki
   Finland

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


   Krisztian Kiss
   Nokia
   12278 Scripps Summit Drive
   San Diego, CA 92131
   USA

   Phone: +18583357341
   Email: krisztian.kiss@nokia.com































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