CIPID: Contact Information for the Presence Information Data Format
RFC 4482
Document | Type | RFC - Proposed Standard (July 2006) | |
---|---|---|---|
Author | Henning Schulzrinne | ||
Last updated | 2015-10-14 | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Additional resources | Mailing list discussion | ||
IESG | Responsible AD | Ted Hardie | |
Send notices to | (None) |
RFC 4482
quot;urn:ietf:params:xml:ns:pidf pidf.xsd urn:ietf:params:xml:ns:pidf:data-model data-model.xsd urn:ietf:params:xml:ns:pidf:cipid cipid.xsd urn:ietf:params:xml:ns:pidf:rpid rpid.xsd" entity="pres:someone@example.com"> <tuple id="bs35r9"> <status> <basic>open</basic> </status> <contact priority="0.8">im:someone@mobile.example.net</contact> <timestamp>2005-05-30T22:00:29Z</timestamp> </tuple> <tuple id="bs78"> <status> <basic>closed</basic> </status> <r:relationship><r:assistant/></r:relationship> <c:card>http://example.com/~assistant/card.vcd</c:card> <c:homepage>http://example.com/~assistant</c:homepage> <contact priority="0.1">im:assistant@example.com</contact> <timestamp>2005-05-30T22:00:29Z</timestamp> </tuple> <dm:person id="p1"> <c:card>http://example.com/~someone/card.vcd</c:card> <c:homepage>http://example.com/~someone</c:homepage> <c:icon>http://example.com/~someone/icon.gif</c:icon> Schulzrinne Standards Track [Page 5] RFC 4482 CIPID July 2006 <c:map>http://example.com/~someone/gml-map.xml</c:map> <c:sound>http://example.com/~someone/whoosh.wav</c:sound> <dm:timestamp>2005-05-30T22:02:44+05:00</dm:timestamp> </dm:person> </presence> 5. The XML Schema Definition The schema is shown below. <?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="urn:ietf:params:xml:ns:pidf:cipid" xmlns:cipid="urn:ietf:params:xml:ns:pidf:cipid" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:annotation> <xs:documentation> Describes CIPID tuple extensions for PIDF. </xs:documentation> </xs:annotation> <xs:element name="card" type="xs:anyURI"/> <xs:element name="display-name" type="xs:string"/> <xs:element name="homepage" type="xs:anyURI"/> <xs:element name="icon" type="xs:anyURI"/> <xs:element name="map" type="xs:anyURI"/> <xs:element name="sound" type="xs:anyURI"/> </xs:schema> Figure 1: CIPID schema Schulzrinne Standards Track [Page 6] RFC 4482 CIPID July 2006 6. IANA Considerations This document calls for IANA to register a new XML namespace URN and schema per [6]. 6.1. URN Sub-Namespace Registration for 'urn:ietf:params:xml:ns:pidf:cipid' URI: urn:ietf:params:xml:ns:pidf:cipid Description: This is the XML namespace for XML elements defined by RFC 4482 to describe contact information presence information extensions for the status element in the PIDF presence document format in the application/pidf+xml content type. Registrant Contact: IETF, SIMPLE working group, simple@ietf.org; Henning Schulzrinne, hgs@cs.columbia.edu 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>CIPID: Contact Information for the Presence Information Data Format</title> </head> <body> <h1>Namespace for contact information presence extension (status)</h1> <h2>urn:ietf:params:xml:ns:pidf:cipid</h2> <p>See <a href="http://www.rfc-editor.org/rfc/rfc4482.txt"> RFC4482</a>.</p> </body> </html> END 6.2. Schema Registration for Schema 'urn:ietf:params:xml:ns:pidf:cipid' URI: urn:ietf:params:xml:ns:pidf:cipid Registrant Contact: IESG XML: See Figure 1 Schulzrinne Standards Track [Page 7] RFC 4482 CIPID July 2006 7. Internationalization Considerations CIPID delivers only URLs, except for the <display-name> element. The resolution of the URLs can negotiate appropriate language and character sets within the URL-designated protocol. For the display name and to handle Internationalized Resource Identifiers (IRIs) [16], since CIPID is represented in XML, it provides native support for encoding information using the Unicode character set and its more compact representations including UTF-8. Conformant XML processors recognize both UTF-8 and UTF-16. Though XML includes provisions to identify and use other character encodings through use of an "encoding" attribute in an <?xml?> declaration, use of UTF-8 is RECOMMENDED in environments where parser encoding support incompatibility exists. The XML 'xml:lang' attribute can be used to identify the language and script for the <display-name> element. The specification allows multiple occurrences of this element so that the presentity can convey display names in multiple scripts and languages. If no 'xml: lang' attribute is provided, the default value is "i-default" [3]. 8. Security Considerations The security issues are similar to those for RPID [11]. Watchers need to restrict which content types of content pointed to by <icon>, <homepage>, <map>, <sound>, and <vcard> elements they render. Also, when a watcher accesses these URIs, the presentity may deduce that the watcher is currently using the presence application. Thus, a presence application concerned about leaking this information may want to cache these objects for later use. (A presentity could easily customize the URLs for each watcher, so that it can tell who is referencing the objects.) This caching behavior may cause the information to become stale, out-of-sync with the current data until the cache is refreshed. Fortunately, the elements in CIPID are expected to retain the same content for periods measured in days, so that privacy-conscious applications may well decide to perform caching over durations that reveal little current activity information. Presentities need to keep in mind that clients may cache the content referenced by URIs for long periods as they use their presence system to construct presence documents using this extension. If the referenced content needs to change frequently, the presentity could, for example, update the presence document with a new URI to encourage clients to notice. Schulzrinne Standards Track [Page 8] RFC 4482 CIPID July 2006 Icons and other URIs in this document could be used as a covert channel to convey messages to the watcher, outside the content monitoring that might be in place for instant messages or other communications channels. Thus, entities that worry about such channels may want to prohibit the usage of URLs pointing to resources outside their domain, for example. Implementors must take care to adhere to the mechanisms for verifying the identity in the referenced server's certificate against the URI. For instance, if the URI scheme is https, the requirements of RFC 2818 [5], section 3.1, must be met. In particular, the domain represented in the URI must match the subjectAltName in the certificate presented by the referenced server. If this identity check fails, the referenced content SHOULD NOT be retrieved and MUST NOT be used. 9. References 9.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Moats, R., "URN Syntax", RFC 2141, May 1997. [3] Alvestrand, H., "IETF Policy on Character Sets and Languages", BCP 18, RFC 2277, January 1998. [4] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, August 1999. [5] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [6] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [7] Maloney, M., Beech, D., Thompson, H., and N. Mendelsohn, "XML Schema Part 1: Structures Second Edition", W3C REC REC- xmlschema-1-20041028, October 2004. [8] Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes Second Edition", W3C REC REC-xmlschema-2-20041028, October 2004. [9] Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr, W., and J. Peterson, "Presence Information Data Format (PIDF)", RFC 3863, August 2004. Schulzrinne Standards Track [Page 9] RFC 4482 CIPID July 2006 [10] Yergeau, F., Paoli, J., Sperberg-McQueen, C., Bray, T., and E. Maler, "Extensible Markup Language (XML) 1.0 (Third Edition)", W3C REC REC-xml-20040204, February 2004. 9.2. Informative References [11] Schulzrinne, H., Gurbani, V., Kyzivat, P., and J. Rosenberg, "RPID: Rich Presence Extensions to the Presence Information Data Format (PIDF)", RFC 4480, July 2006. [12] Schulzrinne, H., "Timed Presence Extensions to the Presence Information Data Format (PIDF) to Indicate Status Information for Past and Future Time Intervals", RFC 4481, July 2006. [13] Rosenberg, J., "A Data Model for Presence", RFC 4479, July 2006. [14] Dawson, F. and T. Howes, "vCard MIME Directory Profile", RFC 2426, September 1998. [15] Good, G., "The LDAP Data Interchange Format (LDIF) - Technical Specification", RFC 2849, June 2000. [16] Duerst, M. and M. Suignard, "Internationalized Resource Identifiers (IRIs)", RFC 3987, January 2005. Acknowledgements This document is based on discussions within the IETF SIMPLE working group. Spencer Dawkins, Vijay Gurbani, Avshalom Houri, Hisham Khartabil, Paul Kyzivat, Eva Leppanen, Mikko Lonnfors, Aki Niemi, Jon Peterson, Jonathan Rosenberg, and Robert Sparks provided helpful comments. Author's Address Henning Schulzrinne Columbia University Department of Computer Science 450 Computer Science Building New York, NY 10027 US Phone: +1 212 939 7004 EMail: hgs+simple@cs.columbia.edu URI: http://www.cs.columbia.edu Schulzrinne Standards Track [Page 10] RFC 4482 CIPID July 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Schulzrinne Standards Track [Page 11]