SIMPLE WG M. Lonnfors Internet-Draft Nokia Research Center Expires: November 5, 2003 E. Leppanen H. Khartabil Nokia May 7, 2003 BINPIDF - External Object Extension to Presence Information Data Format draft-lonnfors-simple-binpidf-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 November 5, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This memo specifies a methodology whereby external content to a presence information document can be referenced in XML encoded presence information document (PIDF). The external content can be either transferred directly in the payload of messages or indirectly as an HTTP reference. The external part might contain binary data such as images. Lonnfors, et al. Expires November 5, 2003 [Page 1] Internet-Draft BINPIDF May 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Overview of Methodology . . . . . . . . . . . . . . . . . . . 3 4. BINPIDF Elements . . . . . . . . . . . . . . . . . . . . . . . 4 4.1 Namespace . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.2 'ObjLink' Element . . . . . . . . . . . . . . . . . . . . . . 4 5. How To Utilize this Specification . . . . . . . . . . . . . . 4 5.1 Direct Link to External Content . . . . . . . . . . . . . . . 4 5.2 Reference to Multipart where External Object is Embedded . . . 5 5.3 Reference to Multipart where Link and Another Information about the External Object is Found . . . . . . . . . . . . . . 5 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1 Binary Objects both Directly Embedded and Indirectly Referenced in Multiparts . . . . . . . . . . . . . . . . . . . 5 6.2 External Content Reference in Presence Information without MIME Multipart Definition . . . . . . . . . . . . . . . . . . 7 7. XML Schema Definition . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 10. Changes from the Version 00 . . . . . . . . . . . . . . . . . 8 References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . 11 Lonnfors, et al. Expires November 5, 2003 [Page 2] Internet-Draft BINPIDF May 2003 1. Introduction The Presence Information Data Format (PIDF) is described in [2]. It defines a generic XML encoded format to express a presentity's presence information. However, it does not specify any mechanism how external objects, e.g. pictures, as a part of presence information can be represented in such XML documents. The Content Indirection document [4] provides an extension to the URL MIME External-Body Access-Type [8] to allow any MIME part in a SIP message to be referred indirectly via a URL. In addition there is a need to specify an extension to PIDF in order to use the Content Indirection mechanism for the Presence in a way that the XML encoded presence information is carried directly in MIME message while external objects are referenced indirectly. Using the SIP Events [5] as transport for PIDF documents it is equally feasible to deliver the external objects in the payload of a SIP message, namely SIP NOTIFY. The MIME Multipart/Related content type [6] provides a tool for placing a reference to an external content as a MIME multipart. An extension to PIDF is needed for referencing the multiparts from a PIDF formatted presence information document. A similar kind of approach of utilizing the MIME Multipart/ Related with HTML can be found in [7]. 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. Overview of Methodology This section provides an overview for having references to the external objects (direct and indirect content) in presence information. The external object can be embedded as one part of a multipart payload of a MIME message, can be stored at an external location where the multipart payload includes a URL to external object using Content Indirection [4], or the PIDF XML part can directly contain a URL link to the content. The MIME Multipart/Related content type [6] is used for direct delivery of the external object. The presence information data format is extended with an object link (ObjLink) XML element. Each separate external content has its own ObjLink value within presence information. The value of the ObjLink Lonnfors, et al. Expires November 5, 2003 [Page 3] Internet-Draft BINPIDF May 2003 is URL (see more information about the syntax of URL from [9]). The value might be either the Content ID of the external object part in the multipart payload or a URL to the location of the external content. The application processing the PIDF document is able to discover the location of the content from the scheme of the URL (see more information about the reserved scheme names from [9] and [10]). The 'cid:' scheme [10] refers to a specific body part of a message. 4. BINPIDF Elements 4.1 Namespace The namespace declaration to the PIDF extension specified in this document is 'urn:ietf:params:xml:ns:pidf-ext-cont'. 4.2 'ObjLink' Element The 'ObjLink' XML element contains a URL reference [9] to the external object. The scheme of the URL specifies how the value of the ObjLink element is processed. The value of the ObjLink might correspond to the Content ID [10] parameter of the multipart made according to MIME Multipart/Related content type [6], or to the 'external' location of the content. The ObjLink element MAY have a ContentType attribute. The ContentType should be used when the URL references directly to an external location. The value of the attribute describes the content (see description of entity headers from [11]). 5. How To Utilize this Specification This chapter describes how the payload of a SIP message is composed when there is a need to convey external objects to XML encoded presence information document between the client and presence server. The following methods for delivering the external object are explained later in their own subchapters: a direct link to the external content within a PIDF based XML document and a reference to a multipart having either the content of the external object embedded or a URL (and other information) to an external location where the content is stored. 5.1 Direct Link to External Content The ObjLink XML element is included in PIDF to point to the location where the external content is stored. The used content type in the SIP message is one of the normal content type(s) of presence service. Lonnfors, et al. Expires November 5, 2003 [Page 4] Internet-Draft BINPIDF May 2003 5.2 Reference to Multipart where External Object is Embedded The content type of the SIP message and the multiparts of the payload are composed according to [6] (MIME Multipart/Related). The XML encoded presence information in PIDF is the 'root' of the body part. The ObjLink XML element is used within presence information in PIDF to reference to the multipart where the content of the external object is found. 5.3 Reference to Multipart where Link and Another Information about the External Object is Found The content type of the SIP message and the multiparts of the payload are composed according to [6] (MIME Multipart/Related). The XML encoded presence information in PIDF is the 'root' of the body part. The ObjLink XML element is used within presence information in PIDF to reference the part in the multipart payload where the additional information (e.g., URL) of the external object is found. The multipart of the external object is composed according to [4]. 6. Examples 6.1 Binary Objects both Directly Embedded and Indirectly Referenced in Multiparts Presence information subscription from client to server: SUBSCRIBE sip:john@pres.example.com SIP/2.0 Via: SIP/2.0/TCP xxxxx;branch=z9hG4bKwYb6QREiCL Max-Forwards: 70 To: From: ;tag=ie4hbb8t Call-ID: cdB34qLToC@terminal.example.com CSeq: 322723822 SUBSCRIBE Contact: xxxx Event: presence Expires: 7200 Accept: application/cpim-pidf+xml Accept: multipart/related Accept: message/external-body, text/html, text/plain, image/* Content-Length: 0 (200 OK are omitted) The NOTIFY looks like: NOTIFY sip:terminal.example.com SIP/2.0 Via: SIP/2.0/TCP pres.example.com;branch=z9hG4bKMgRenTETmm Lonnfors, et al. Expires November 5, 2003 [Page 5] Internet-Draft BINPIDF May 2003 Max-Forwards: 70 From: ;tag=zpNctbZq To: ;tag=ie4hbb8t Call-ID: cdB34qLToC@terminal.example.com CSeq: 997935768 NOTIFY Contact: Event: presence Subscription-State: active;expires=7200 Content-Type: multipart/related;type="application/cpim-pidf+xml"; start="";boundary="50UBfW7LSCVLtggUPe5z" Content-Length: xxx --50UBfW7LSCVLtggUPe5z Content-Transfer-Encoding: 8bit Content-ID: Content-Type: application/cpim-pidf+xml;charset="UTF-8" open sip:john@im.example.com At home cid:own_photo@example.com cid:image1@example.com --50UBfW7LSCVLtggUPe5z Content-Type: image/jpeg Content-ID: Content-Transfer-Encoding: binary Content-Description: Own photo (encoded jpeg image) --50UBfW7LSCVLtggUPe5z Content-Type: message/external-body Content-ID: Content-Disposition: render Content-Description: Group photo Content-Type: message/external-body; Lonnfors, et al. Expires November 5, 2003 [Page 6] Internet-Draft BINPIDF May 2003 access-type="URL"; expiration="Mon, 24 June 200x 09:00:00 GMT"; URL="http://www.ex.com/company_party/image1.png" size=234422 --50UBfW7LSCVLtggUPe5z 6.2 External Content Reference in Presence Information without MIME Multipart Definition Presence information subscription from client to server: SUBSCRIBE sip:john@pres.example.com SIP/2.0 Via: SIP/2.0/TCP xxxxx;branch=z9hG4bKwYb6QREiCL Max-Forwards: 70 To: From: ;tag=ie4hbb8t Call-ID: cdB34qLToC@terminal.example.com CSeq: 322723822 SUBSCRIBE Contact: xxxx Event: presence Expires: 7200 Accept: application/cpim-pidf+xml Accept: image/* Content-Length: 0 Notification having a link to the picture: NOTIFY sip:terminal.example.com SIP/2.0 Via: SIP/2.0/TCP pres.example.com;branch=z9hG4bKMgRenTETmm Max-Forwards: 70 From: ;tag=zpNctbZq To: ;tag=ie4hbb8t Call-ID: cdB34qLToC@terminal.example.com CSeq: 997935768 NOTIFY Contact: Event: presence Subscription-State: active;expires=7200 Content-Type: application/cpim-pidf+xml Content-Length: xxx Lonnfors, et al. Expires November 5, 2003 [Page 7] Internet-Draft BINPIDF May 2003 open sip:john@im.example.com At home http://www.example.com/own_photo.jpg 7. XML Schema Definition 8. Security Considerations All security conciderations defined in [5] and [4] apply this document. 9. Acknowledgements The authors would like to thank Aki Niemi for his valuable input. 10. Changes from the Version 00 o Two XML extension elements (ExtLink and CId) were combined together and named as ObjLink. o Optional ContentType attribute was added to the ObjLink element. o References to the syntax of URL and pre-defined scemes were added. o Content type negotiation related texts were removed from the Lonnfors, et al. Expires November 5, 2003 [Page 8] Internet-Draft BINPIDF May 2003 Section 5. o Some editorial corrections. References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Sugano, H., "CPIM Presence Information Data Format", draft-ietf-impp-cpim-pidf-07.txt, December 2002. [3] Campbell, B., "SIMPLE Presence Publication Mechanism", draft-olson-simple-publish-02.txt, February 2003. [4] Olson, S., "A Mechanism for Content Indirection in Session Initiation Protocol (SIP) Messages", draft-ietf-sip-content-indirect-mech-01, February 2003. [5] Rosenberg, J., "Session Initiation Protocol (SIP) Extensions for Presence", draft-ietf-simple-presence-10.txt, January 2003. [6] Levinson, E., "The MIME Multipart/Related Content Type", RFC 2387, August 1998. [7] Palme, J., "MIME Encapsulation of Aggregate Documents", RFC 2557, March 1999. [8] Freed, N., "Definition of the URL MIME External-Body Access-Type", RFC 2017, October 1996. [9] Berners-Lee, T., "Uniform Resource Locators (URL)", RFC 1738, December 1994. [10] Levinson, E., "Content-ID and Message-ID Uniform Resource Locators", RFC 2392, August 1998. [11] Freed, N., "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. Lonnfors, et al. Expires November 5, 2003 [Page 9] Internet-Draft BINPIDF May 2003 Authors' Addresses Mikko Lonnfors Nokia Research Center Itamerenkatu 00180 Helsinki Finland Phone: + 358 50 4836402 EMail: mikko.lonnfors@nokia.com Eva Leppanen Nokia P.O BOX 785 Tampere Finland Phone: +358 7180 77066 EMail: eva-maria.leppanen@nokia.com Hisham Khartabil Nokia P.O. Box 321 Helsinki Finland Phone: +358 7180 76161 EMail: hisham.khartabil@nokia.com Lonnfors, et al. Expires November 5, 2003 [Page 10] Internet-Draft BINPIDF May 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. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. 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