SIMPLE WG M. Lonnfors Internet-Draft Nokia Research Center Expires: December 25, 2003 K. Kiss Nokia June 26, 2003 Device capability PIDF status extension draft-lonnfors-simple-prescaps-ext-01 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 25, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract Interoperation of Instant Messaging and Presence systems has been defined in IMPP Working Group. IMPP WG has come up with baseline interoperable operations and formats for Presence and Instant Messaging systems. However, these base formats might need standardized extensions in order to enable building rational applications using Presence and Instant Messaging. This memo proposes an extension to PIDF presence document format to represent SIP Caller preferences and Callee capabilities features to be used in SIMPLE based Presence systems but may also be applied to other protocols as well. Lonnfors & Kiss Expires December 25, 2003 [Page 1] Internet-Draft Device capability PIDF status extension June 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Support for Caller Preferences and Callee Capabilities . . . . 4 3.1 Extension overview . . . . . . . . . . . . . . . . . . . . . . 4 3.2 Handing of Caller Preferences and Callee Capabilities matching rules . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3 element . . . . . . . . . . . . . . . . . . . . . . 5 3.4 element . . . . . . . . . . . . . . . . . . . . . . 5 3.5 element . . . . . . . . . . . . . . . . . . . . . . . 6 3.6 Handling of Caller Preferences and Callee Capabilities priority feature tag . . . . . . . . . . . . . . . . . . . . . 6 4. Guidelines for using extension with PIDF document format . . . 6 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1 Basic extension in tuple level . . . . . . . . . . . . . . . . 7 5.2 Basic extension in status level . . . . . . . . . . . . . . . 7 5.3 Complex example in tuple level . . . . . . . . . . . . . . . . 8 6. XML schema definitions . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7.1 URN sub-namespace registration for 'urn:ietf:params:xml:ns:simple-prescaps-ext' . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 Normative references . . . . . . . . . . . . . . . . . . . . . 11 Informative references . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . 13 Lonnfors & Kiss Expires December 25, 2003 [Page 2] Internet-Draft Device capability PIDF status extension June 2003 1. Introduction Interoperation of Instant Messaging and Presence systems has been defined in IMPP Working Group. Working Group has defined a generic model for Presence and Instant Messaging [2] and also requirements for protocols implementing such a system [3]. Common Presence and Instant Messaging (CPP/CPIM) defines common operations and formats which all Presence and Instant Messaging services must agree upon so that basic interoperability would be possible [5], [6]. The actual base format for presence is being defined in [4]. The PIDF document format has been designed to reduce the need for gatewaying and to allow end-to-end security of presence data. It has taken very minimalistic approach to support such operations. In order to make the PIDF format usable by different presence applications, these applications usually must extend the basic PIDF format by standard XML mechanism as defined in [4]. The aim of this memo is to introduce SIP/SIMPLE specific extension mechanism for the PIDF document. With this extension SIMPLE based applications can have richer and usable formats compared to the baseline PIDF data format. Authors of this document believe that following items should be included into this extension: o Support for SIP Caller Preferences and Callee Capabilities [7] 1.1 Motivation The PIDF document format [4] defines a element which may appear once inside every element. The content of the element encodes the CONTACT ADDRESS and CONTACT MEANS as defined in [2]. The element is defined to be an URI. This URI can be of any URI type. In some implementations this URI can uniquely identify the application the tuple intends to describe (e.g. im: URIs). However, this may not be the case in all implementations. For example in SIP, a SIP URI can represent different kinds of applications. A SIP URI can be used to contact voice applications, video applications, or messaging applications. If it is not known by other means, it might be hard for applications processing the presence document containing only SIP URI contact addresses to know what particular application the tuple intends to describe. Also watchers receiving presence information would probably benefit for getting more descriptive information about what particular communication means or applications are supported by the presentity. Caller Preferences and Callee Capabilities document [7] defines a set of extensions which allow callers and callees to express preferences about request handling in SIP servers. The same information could Lonnfors & Kiss Expires December 25, 2003 [Page 3] Internet-Draft Device capability PIDF status extension June 2003 provide value also to presence watchers so that they could make more rational decisions on how presentity should be contacted if presence document would contain similar information as defined in Caller Preferences and Callee Capabilities extension. When the Caller Preferences and Callee Capabilities extension is used in this context (to represent presence information) there is no need for automated processing compared to the case when the Caller Preferences and Callee Capabilities extension is used by proxies or registrars. Because of this, it should be sufficient to introduce Caller Preferences and Callee Capabilities extension representation for presence without specifying similar processing rules as defined in [7]. 1.2 Scope This document defines extension to the PIDF document format which enables presence implementations based on SIP protocol to utilize similar capabilities in presence document as what Caller Preferences and Callee Capabilities document [7] defines. The intension is only to allow representation of callee capabilities and not caller preferences. This extension does not replace media negotiation mechanisms defined for SIP (e.g. SDP [11]), therefore media negotiation (e.g. choose of voice and video codecs) MUST be performed according to [8]. This extension is only aimed to give the watchers hints about the presentity's preferences, willingness and capabilities to communicate before watchers would initiate SIP based communication with the presentity. 2. Conventions In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and indicate requirement levels for compliant implementations. 3. Support for Caller Preferences and Callee Capabilities This section presents Caller Preferences and Callee Capabilities extension namespace, its elements, their values, and semantics. This section also describes how this extension can be further extended. This extension is intended to be used with application/cpim-pidf+xml content type and that particular usage is described here. This extension may also be used with other content types if appropriate. 3.1 Extension overview Lonnfors & Kiss Expires December 25, 2003 [Page 4] Internet-Draft Device capability PIDF status extension June 2003 This extension adds most of the features presented in Caller Preferences and Callee Capabilities document [7] into PIDF presence document format. Features presented in [7] are added here without any change in their semantics. Bringing these features to PIDF presence document format basically means mapping them to XML structure. However, some Caller Preferences and Callee Capabilities features are not needed here because identical counterpart already exists in PIDF. These features are discussed in Section 3.6. Namespace identifier for this extension is: urn:ietf:params:xml:ns:simple-prescaps-ext When this extension namespace is congregated with base PIDF document, combined document must follow the same general formatting rules as specified in [4] in chapter 4.1. 3.2 Handing of Caller Preferences and Callee Capabilities matching rules Caller Preferences and Callee Capabilities document [7] defines a set of matching rules which can be used to determine if capabilities represented by two different URLs are equal. This extension is not aimed to provide these features i.e. this document does not provide means to compare two presence documents to determine whether capabilities represented by those documents match. 3.3 element Root element of this extension namespace is . The root element MUST be always present. This element MAY contain one or more elements as specified later in this document. element does not have any attributes and it MAY contain other namespace declarations for the extensions used in the presence XML document. 3.4 element The element can represent any feature tag as defined in Caller Preferences and Callee Capabilities [7] or any media feature tag registered through [14]. This element MAY appear under element one or several times. element has one mandatory attribute called name. This attribute represents the name of the feature tag. Each media feature tag (e.g. media, feature and etc.) SHOULD appear only once inside root element. If media feature tag has multiple values these values SHOULD be nested inside single element. The cannot be extended using other namespace declarations. Lonnfors & Kiss Expires December 25, 2003 [Page 5] Internet-Draft Device capability PIDF status extension June 2003 3.5 element The element represents the value of media feature tag. Each value element SHOULD contain only a single tag value. If contains multiple values then all these values should be presented in different elements. The element has optional attribute called negated. This attribute is of boolean type. It can be used to indicate whether feature value is supported or not supported. Value 'true' indicates that value is not supported and value 'false' indicates that value is supported. Default value is 'false'. element cannot be extended using other namespace declarations . 3.6 Handling of Caller Preferences and Callee Capabilities priority feature tag PIDF document format allows priority attribute to be used within element. Caller Preferences and Callee Capabilities priority feature tag can be mapped into this attribute and so there is no need to represent priority feature tag in inside XML structure. 4. Guidelines for using extension with PIDF document format This section presents guidelines how extension can be used with PIDF document format. PIDF format allows use of extension XML namespaces inside , , and elements. element is intended to describe presentity as a whole. Prescaps extension is related to Contact Address defined by PIDF to which this extension is applied to. These Contact Addresses can only appear inside elements. The use of this extension in element level is NOT RECOMMENDED for this purpose. It is up to the applications using this extension to decide if they want to include extension inside or inside element. The semantics of the extension remains same regardless where it is placed inside PIDF document format. Root element MUST NOT appear more than once inside a single element but can appear multiple times in PIDF document format inside different elements. 5. Examples This section presents various examples how this extension can be used with base PIDF document format. Lonnfors & Kiss Expires December 25, 2003 [Page 6] Internet-Draft Device capability PIDF status extension June 2003 5.1 Basic extension in tuple level open voice message sip:someone@example.com 5.2 Basic extension in status level open voice message sip:someone@example.com Lonnfors & Kiss Expires December 25, 2003 [Page 7] Internet-Draft Device capability PIDF status extension June 2003 5.3 Complex example in tuple level open voice mobile voicemail false business full sip:someone@example.com 6. XML schema definitions This section gives the XML Schema Definition for the extension defined in this document which can be used in the context of "application/cpim-pidf+xml" content type. Lonnfors & Kiss Expires December 25, 2003 [Page 8] Internet-Draft Device capability PIDF status extension June 2003 Figure 4 7. IANA Considerations This memo calls for IANA to register a new XML namespace URN as defined in [12] 7.1 URN sub-namespace registration for 'urn:ietf:params:xml:ns:simple-prescaps-ext' Lonnfors & Kiss Expires December 25, 2003 [Page 9] Internet-Draft Device capability PIDF status extension June 2003 URI: urn:ietf:params:xml:ns:simple-prescaps-ext Description: This is the XML namespace for XML elements defined by [RFCXXXX] to describe communication means extension for CPIM-PIDF presence document format in application/cpim-pidf+xml content type. Registrant Contact: IETF, SIMPLE working group, Mikko Lonnfors, XML: BEGIN SIMPLE PIDF presence capabilities extension

Namespace for SIMPLE presence capabilities extension

application/cpim-pidf+xml

See RFCXXXX.

END 8. Security Considerations All security considerations specified in CPIM [5] and in PIDF [4] documents apply also to this document. For clarity some of the security considerations are repeated here. 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. 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. Lonnfors & Kiss Expires December 25, 2003 [Page 10] Internet-Draft Device capability PIDF status extension June 2003 9. Acknowledgements Authors of this document would like to thank following people for their contributions and valuable comments: Paul Kyzivat, Markus Isomaki, and Hisham Khartabil. Normative references [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000. [3] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "Instant Messaging / Presence Protocol Requirements", RFC 2779, February 2000. [4] Sugano, H., Fujimoto, S., Klyne, G. and A. Bateman, "Common Presence and Instant Messaging (CPIM) Presence Information Data Format", draft-ietf-impp-cpim-pidf-08, May 2002. [5] Peterson, J., "Common Profile for Presence (CPP)", draft-ietf-impp-pres-03, May 2003. [6] Peterson, J., "Common Profile for Instant Messaging (CPIM)", draft-ietf-impp-im-03, May 2003. Informative references [7] Schulzrinne, H., "Session Initiation Protocol (SIP) Caller Preferences and Callee Capabilities", draft-ietf-sip-callerprefs-08, July 2002. [8] Rosenberg, J., "SIP: Session Initiation Protocol", RFC 3261, June 2002. [9] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [10] Rosenberg, J., "Session Initiation Protocol (SIP) Extensions for Presence", draft-ietf-simple-presence-10.txt, May 2002. [11] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [12] Mealling, M., "The IETF XML Registry", draft-mealling-iana-xmlns-registry-04, June 2002. Lonnfors & Kiss Expires December 25, 2003 [Page 11] Internet-Draft Device capability PIDF status extension June 2003 [13] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) part two: Media Types", RFC 2046, November 1996. [14] Holtman, K., Mutz, A. and T. Hardie, "Media Feature Tag Registration Procedure", RFC 2046, March 1999. Authors' Addresses Mikko Lonnfors Nokia Research Center Itamerenkatu 11-13 00180 Helsinki Finland Phone: +358 50 4836402 EMail: mikko.lonnfors@nokia.com Krisztian Kiss Nokia P.O BOX 100 33721 Tampere Finland Phone: +358 50 4835363 EMail: krisztian.kiss@nokia.com Lonnfors & Kiss Expires December 25, 2003 [Page 12] Internet-Draft Device capability PIDF status extension June 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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