SIMPLE J. Rosenberg Internet-Draft dynamicsoft Expires:
December 22, 2003 June 23,April 26, 2004 October 27, 2003 An Extensible Markup Language (XML) Configuration Access Protocol (XCAP) Usage for PresenceResource Lists draft-ietf-simple-xcap-list-usage-00draft-ietf-simple-xcap-list-usage-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 22, 2003.April 26, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document describes a usage of the Extensible Markup Language (XML) Configuration Access Protocol (XCAP) for manipulating lists of presentitiesresources. These lists can be used as presence lists (also known as buddy lists or rosters). Itrosters), but this specification does so by specifying an XML Schema that contains a list of presentities that a user is interested in watching.not restrict their usage to that. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Application Unique ID . . . . . . . . . . . . . . . . . . . 5 4. Structure of a PresenceResource List . . . . . . . . . . . . . . . . 6 5. Computed Data . . . . . .Resource Interdependencies . . . . . . . . . . . . . . . . . 8 6. Additional Constraints . . . . . . . . . . . . . . . . . . . 9 7. Naming Conventions . . . . . . . . . . . . . . . . . . . . . 10 8. Authorization Policies . . . . . . . . . . . . . . . . . . . 11 9. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 12 10. Example Document . . . . . . . . . . . . . . . . . . . . . . 1314 11. Security Considerations . . . . . . . . . . . . . . . . . . 1415 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 1516 12.1 XCAP Application Usage ID . . . . . . . . . . . . . . . . . 1516 12.2 application/presence-lists+xmlapplication/resource-lists+xml MIME Type . . . . . . . . . . 1516 12.3 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:presence-listsurn:ietf:params:xml:ns:resource-lists . . . . . . . . . . . 1617 Normative References . . . . . . . . . . . . . . . . . . . . 1718 Informative References . . . . . . . . . . . . . . . . . . . 1819 Author's Address . . . . . . . . . . . . . . . . . . . . . . 1819 Intellectual Property and Copyright Statements . . . . . . . 1920 1. Introduction TheIn many communications applications, it is neccesary for the network to have access to a list of resources that represent a group that the user would like to apply an action to. One such example is a presence list . These lists are used by Session Initiation Protocol (SIP) for Instant Messaging and Presence (SIMPLE) specifications allow a user, called a watcher, to subscribe to another user, called a presentity , in order to learn their presence information . In many cases, a watcher willResource List Servers (RLS)  for processing list subscriptions. Another example might be interested in not just a single presentity, but alist of presentities. Suchrecipients for an instant message, or a list of presentities is called a presence list. When a user wants to subscribeusers to their presence list, the procedures in  require the watcherinvite to create and managea subscription for each presentity in their list. For large lists, the bandwidth requiredconference bridge. Generally, these lists will need to do this canbe a problem, particularly for wireless networks. An extension to the SIP events framework  has been defined. The extension allows a watcher to subscribe to a list of resources, using a single subscription . This mechanism assumes that a server, calledmanipulated by the Resource List Server (RLS) has a copyend users of the presence list thatsystem, and used by servers in the user wishes to subscribe to. By using protocolsnetwork. To support such asmanipulations, the XML Configuration Access Protocol (XCAP) , a client can place this list on the server, and manipulate it as needed. has been defined. XCAP requires application usages to standardize several pieces of information, including an application unique ID (AUID), an XML schema, and various other pieces of information. This specification fulfills those requirements. The XML schema defined here has several other usages outside of XCAP: 1. A PC client application will need to know the users in the presence list, so that it can generate a subscription to each one. This information represents user provisioned data for the application. Typically, this information is stored on local disk in a proprietary file format. By defining a standard format, the same list can be used by a multiplicity of different client applications, providing portability across them. 2. It is common for users to share presence lists. As an example, user A may have three people in their list that they wish to tell user B about. User A would like to send an email to user B with an attachment describing these three people. Should user B open the attachment, the three people can be added to their own presence list. Doing this requires a standardized format for exchanging lists over email, instant messaging, and other communications protocols. 2. Terminology 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  and indicate requirement levels for compliant implementations. 3. Application Unique ID XCAP requires application usages to define a unique application usage ID (AUID) in either the IETF tree or a vendor tree. This specification defines the "presence-lists""resource-lists" AUID within the IETF tree, via the IANA registration in Section 12. 4. Structure of a PresenceResource List A presenceresource list is an XML  document that MUST be well-formed and SHOULD be valid. PresenceResource list documents MUST be based on XML 1.0 and MUST be encoded using UTF-8. This specification makes use of XML namespaces for identifying presenceresource list documents and document fragments. The namespace URI for elements defined by this specification is a URN , using the namespace identifier 'ietf' defined by  and extended by . This URN is: urn:ietf:params:xml:ns:presence-listsurn:ietf:params:xml:ns:resource-lists A presenceresource list document begins with the root element tag ``presence-lists''.``resource-lists''. It consists of any number of ``list'' sub-elements, each of which is a presenceresource list. Other elements from different namespaces MAY be present for the purposes of extensibility; elements or attributes from unknown namespaces MUST be ignored. There are three attributes associated with this element. The first two,first, "name", and "subscribable"MUST be present: name: This attribute is a descriptive name for the list. It MUSTlist. It MUST be unique amongst all other list elements within the same parent element. Each list element will also have boolean attributes which indicate a specific action that may be made against that list. This specification defines a single attribute - subscribeable - which indicates that the list may be unique amongst all othersubscribed to using the SIP event list elementsspecification . Extensions to this application usage MAY define additional boolean elements, each within a different namespace, for the same parent element. subscribable: This booleanpurposes of indicating other actions that may be peformed. When an attribute indicates whether or notis absent, it implies that the listoperation is subscribable or not.not supported. The third other attribute, "uri" MAY be present: uri: This attributepresent. It provides a URI that can be used to subscribe toaccess the list, for example, using the SIP event notification extension for lists .. As a result, the URI MUST be either a SIP URI or a pres URI . [[OPEN ISSUE: Do we want this to be a comma separated list, so that a presence list can have any number of valid aliases?]] [[OPEN ISSUE: We also need to define policy about who is allowed to subscribe to the list. We can either integrate that into the list definition described here, or handle that as a separate policy specification. The SEACAP proposal kept them together. I believe now that they should be kept separate.]]. Each list element is composed of a sequence of entry elements orelements, list elements, external elements. The ability of a list element to contain other list elements means that a presenceresource list can be hierarchically structured. An entry element describes a single presentity that is part of the list. An external element contains a reference to a list stored on another server. A list element can also contain elements from other namespaces, for the purposes of extensibility. The entry element describes a single presentity.resource. The entry element has two attributes: name: This mandatory attribute is a unique identifier amongst all other entry elements of the same parent. uri: This optional attribute is a URI that is used to subscribe toaccess the presentity.resource. It MUST be either a SIP or pres URI. The entry element contains a sequence of other elements. Only one such element is defined at this time, which is the display-name. This element provides a UTF-8 encoded string, meant for consumption by the user, that describes the presentity.resource. Unlike the "name" attribute of the entry element, the display-name has no uniqueness requirements. [[OPEN ISSUE: Do we need this in addition to the name attribute?]].Other elements from other namespaces MAY be included. This is meant to support the inclusion of other information about the entry, such as a phone number or postal address. 5. Computed DataResource Interdependencies An XCAP server supporting this application usage need only worry about a single piece of computeddata interdependency - the "uri" attribute of the list element. If the "uri" attribute is absent in a document written to an XCAP server, but the "subscribable""subscribeable" flag is true, the XCAP server MUST allocate a URI for this list. This allocated URI MUST be globally unique, and MUST route to an RLS which will handle list subscriptions for the list defined by the document. The server MUST set the uri attribute of the document with this URI. A server MUST NOT delete the "uri" attribute, however, should a client change the subscribablesubscribeable flag to false after the server has allocated a URI. 6. Additional Constraints There are no constraints on the document beyond those described in the schema. 7. Naming Conventions There are no naming conventions that need to be defined for this application usage. A subscription to a presenceresource list will be to a specific URI. That URI will be one of the "uri" attributes defined in a list within one of the documents managed by an XCAP server. 8. Authorization Policies This application usage does not modify the default XCAP authorization policy, which is that only a user can read, write or modify their own documents. A server can allow priveleged users to modify documents that they don't own, but the establishment and indication of such policies is outside the scope of this document. It is anticipated that a future application usage will define which users are allowed to modify a list resource. 9. XML Schema The following is the XML schema definition of the presenceresource list: <?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="urn:ietf:params:xml:ns:resource-lists" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:ietf:params:xml:ns:resource-lists" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="presence-lists">name="resource-lists"> <xs:complexType> <xs:sequence> <xs:element name="list" type="listType" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> </xs:element> <xs:complexType name="listType"> <xs:sequence maxOccurs="unbounded"> <xs:choice> <xs:element name="list" type="listType"minOccurs="0" maxOccurs="unbounded"> <xs:complexType> <xs:complexContent> <xs:extension base="listType"/> </xs:complexContent> </xs:complexType> </xs:element> <xs:element name="external" type="xs:anyURI" minOccurs="0" maxOccurs="unbounded"/> <xs:element name="entry" type="entryType" minOccurs="0" maxOccurs="unbounded"/> <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> </xs:choice> </xs:sequence> <xs:attribute name="name" type="xs:string" use="required"/> <xs:attribute name="uri" type="xs:anyURI" use="optional"/> <xs:attribute name="subscribable"name="subscribeable" type="xs:boolean" use="required" />use="optional"/> <xs:anyAttribute namespace="##other"/> </xs:complexType> <xs:complexType name="entryType"> <xs:sequence> <xs:element name="display-name" type="display-nameType"/> <xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> <xs:attribute name="name" type="xs:string" use="required"/> <xs:attribute name="uri" type="xs:anyURI" use="optional"/> </xs:complexType> <xs:simpleType name="display-nameType"> <xs:restriction base="xs:string"/> </xs:simpleType> </xs:schema> 10. Example Document The following is an example of a document compliant to the schema: <?xml version="1.0" encoding="UTF-8"?> <presence-lists<resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <list name="friends" uri="sip:email@example.com" subscribable="true">subscribeable="true"> <entry name="Bill" uri="sip:firstname.lastname@example.org"> <display-name>Bill Doe</display-name> </entry> <list name="close-friends" uri="sip:email@example.com" subscribable="true">subscribeable="true"> <entry name="Joe" uri="sip:firstname.lastname@example.org"> <display-name>Joe Smith</display-name> </entry> <entry name="Nancy" uri="sip:email@example.com"> <display-name>Nancy Gross</display-name> </entry> <external>http://www.example.org/xcap/resource-lists/users/a/foo </external> </list> </list> </presence-lists></resource-lists> TODO: formally validate against schema. 11. Security Considerations The configuration information defined by this application usage is particularly sensitive. It represents the principle set of people with whom a user would like to communicate. As a result, clients SHOULD use TLS when contacting servers in order to fetch this information. Note that this does not represent a change in requirement strength from XCAP. 12. IANA Considerations There are several IANA considerations associated with this specification. 12.1 XCAP Application Usage ID This section registers a new XCAP Application Usage ID (AUID) according to the IANA procedures defined in .. Name of the AUID: presence-listsresource-lists Description: A presenceresource list application is a usage of the SIP events framework (RFC 3265)  along with its list extension , for subscribingany application that needs access to a list of presentities (RFC2778)  stored atresources, identified by a server.URI, to which operations, such as subscriptions, can be applied. 12.2 application/presence-lists+xmlapplication/resource-lists+xml MIME Type MIME media type name: application MIME subtype name: presence-lists+xmlresource-lists+xml Mandatory parameters: none Optional parameters: Same as charset parameter application/xml as specified in RFC 3023 . Encoding considerations: Same as encoding considerations of application/xml as specified in RFC 3023 . Security considerations: See Section 10 of RFC 3023  and Section 11 of this specification. Interoperability considerations: none. Published specification: This document. Applications which use this media type: This document type has been used to support subscriptions to lists of users  for SIP-based presence .. Additional Information: Magic Number: None File Extension: .pl.rl or .xml Macintosh file type code: "TEXT" Personal and email address for further information: Jonathan Rosenberg, firstname.lastname@example.org Intended usage: COMMON Author/Change controller: The IETF. 12.3 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:presence-listsurn:ietf:params:xml:ns:resource-lists This section registers a new XML namespace, as per the guidelines in  URI: The URI for this namespace is urn:ietf:params:xml:ns:presence-lists.urn:ietf:params:xml:ns:resource-lists. Registrant Contact: IETF, SIMPLE working group, (email@example.com),(firstname.lastname@example.org), Jonathan Rosenberg (email@example.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>Presence<title>Resource Lists Namespace</title> </head> <body> <h1>Namespace for PresenceResource Lists</h1> <h2>application/presence-lists+xml</h2><h2>application/resource-lists+xml</h2> <p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p> </body> </html> END Normative References  Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.  Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C REC REC-xml-20001006, October 2000.  Moats, R., "URN Syntax", RFC 2141, May 1997.  Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC 3023, January 2001.  Moats, R., "A URN Namespace for IETF Documents", RFC 2648, August 1999.  Mealling, M., "The IETF XML Registry", draft-mealling-iana-xmlns-registry-05 (work in progress), June 2003.  Rosenberg, J., "The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)", draft-ietf-simple-xcap-00 (work in progress), June 2003. Informative References  Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000.  Rosenberg, J., "A Presence Event Package for the Session Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work in progress), January 2003.  Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002.  Rosenberg, J., Roach, A.A., Rosenberg, J. and B. Campbell, "A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists", draft-ietf-simple-event-list-04 (work in progress), June 2003.  Peterson, J., "Common Profile for Presence (CPP)", draft-ietf-impp-pres-03draft-ietf-impp-pres-04 (work in progress), MayOctober 2003.  Rosenberg, J., "The Extensible Markup Language (XML) Configuration AccessJ. and M. Isomaki, "Requirements for Manipulation of Data Elements in Session Initiation Protocol (XCAP)", draft-rosenberg-simple-xcap-00(SIP) for Instant Messaging and Presence Leveraging Extensions (SIMPLE) Systems", draft-ietf-simple-data-req-03 (work in progress), MayJune 2003. 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