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Network Working GroupP. Saint-Andre
Internet-DraftJabber Software Foundation
Expires: August 6, 2004February 6, 2004

XMPP URI Format
draft-saintandre-xmpp-uri-01

Status of this Memo

This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026.

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This Internet-Draft will expire on August 6, 2004.

Copyright Notice

Copyright (C) The Internet Society (2004). All Rights Reserved.

Abstract

This document defines a URI scheme for use in addressing generic entities that can communicate via the Extensible Messaging and Presence Protocol (XMPP).



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Table of Contents




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1. Introduction

The Extensible Messaging and Presence Protocol (XMPP)[XMPP-CORE] has been adapted by the XMPP WG from the open protocol originally developed by the Jabber community. Currently the Jabber/XMPP network contains tens of thousands of servers and millions of other entities. Within the context of the streaming XML technology that forms the foundation of XMPP, the addresses of XMPP entities are not specified as full URIs. However, many applications external to the existing network would like to address XMPP entities as full URIs in compliance with RFC 2396[URI].

Many types of application can be built using XMPP. The best-known such application is instant messaging (IM) and presence (as described in [IMP-MODEL] and [IMP-REQS] and defined for XMPP in [XMPP-IM]). Therefore it might seem appropriate to use the im: and pres: URI schemes specified by Common Profile for Instant Messaging (CPIM)[CPIM] and Common Profile for Presence (CPP)[CPP], rather than to define an XMPP-specific URI scheme. However, while the im: and pres: URI schemes are appropriate for instant messaging and presence applications and are therefore specified in [XMPP-IM], they may not be appropriate for all XMPP applications. Because XMPP is a technology for near-real-time messaging, presence, and request-response services using streaming XML, XMPP applications may not be IM and presence applications (i.e., they may conform to [XMPP-CORE] but not [XMPP-IM]). Indeed, XMPP is already used in applications quite distinct from IM and presence, including network management, workflow applications, generic publish-subscribe, remote procedure calls, content syndication, gaming, and middleware. These applications require an addressing scheme that is not tied to the particular semantics of the im: and pres: URI schemes. Therefore, this document defines a generic URI scheme that will enable applications to address as a URI any entity that can communicate via XMPP (not merely instant messaging and presence entities).

On the XMPP network itself, entities are addressed as <[node@]domain[/resource]> (i.e., without a URI scheme) rather than as <xmpp:[node@]domain[/resource]>. However, some interfaces to XMPP services may be provided by non-native applications (e.g., web browsers), and other applications (e.g., databases) may want to refer to XMPP entities using addresses that are full URIs. The xmpp: URI format is provided for the sake of such interfaces and applications, and MUST NOT be used by native applications for addressing of XML stanzas sent over the XMPP network itself.

The xmpp: URI is opaque rather than hierarchical, and thus is similar to a mailto: URI as specified by RFC 2368[MAILTO]. Because an xmpp: URI is opaque, it SHOULD contain only the node identifier (optional) and domain identifier (required) portions of a JID as defined in Section 3 of [XMPP-CORE] (including by reference all relevant stringprep profiles). An xmpp: URI MAY include the resource identifier portion of a JID if the XMPP entity must be addressed as such, but this is not recommended since the delimiter used before a resource identifier in XMPP addresses is the slash character ("/"), which is discouraged by [URI] in opaque URIs.

If an xmpp: URI is presented in an end-user application that provides an non-native interface to an XMPP service (e.g., in a web browser), interacting with such a URI SHOULD trigger the application to present a user with an appropriate interface to complete an action such as sending a message, sending presence, managing a subscription, sending an information request (IQ get), or updating relevant information (IQ set).

This memo conforms to the requirements in Registration Procedures for URL Scheme Names[URL-REG]. This memo also follows the recommendations in Guidelines for new URL Schemes[URL-GUIDE].

1.1 Terminology

This document inherits terminology described in [XMPP-CORE].

The capitalized 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[TERMS].

1.2 Discussion Venue

The author welcomes discussion and comments related to the topics presented in this document. The preferred forum is the <xmppwg@jabber.org> mailing list, for which archives and subscription information are available at <http://www.jabber.org/cgi-bin/mailman/listinfo/xmppwg/>.



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2. xmpp: URI IANA Registration

This section provides the information required to register the xmpp: URI scheme.

2.1 URI Scheme Name

xmpp

2.2 URI Scheme Syntax

The syntax for an xmpp: URI is defined below using Augmented Backus-Naur Form as specified by [ABNF]. The jid rule is defined in [XMPP-CORE].

XMPP-URI = "xmpp:" jid 
          

2.3 Character Encoding Considerations

Representation of non-ASCII character sets in local-part strings is limited to the standard methods provided as extensions to RFC 2822[IMF].

2.4 Intended usage

The xmpp: URI is intended to be used by interfaces to the XMPP network from non-native user agents such as web browsers, as well as by applications that need to address XMPP entities as full URIs.

2.5 Security considerations

See Security Considerations of this document.

2.6 Relevant publications

[XMPP-CORE], [XMPP-IM]

2.7 Person and email address to contact for further information

Peter Saint-Andre [mailto:stpeter@jabber.org]

2.8 Author/Change controller

This scheme is registered under the IETF tree. As such, the IETF maintains change control.

2.9 Applications and/or protocols which use this URI scheme name

Applications that provide an interface to XMPP services or that need to address XMPP entities as full URIs.



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3. IANA Considerations

This entire document addresses IANA considerations.



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4. Security Considerations

Detailed security considerations for XMPP are given in [XMPP-CORE]. Providing an interface to XMPP services from non-native applications introduces new security concerns. For example, the ability to interact with XMPP entities via a web browser may expose sensitive information to attacks that are not possible or unlikely on a native XMPP network. Due care must be taken in deciding what information is appropriate for representing in xmpp: URIs; in particular, passwords MUST NOT be represented.



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Normative References

[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997.
[IMF] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[TERMS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[URI] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
[URL-GUIDE] Masinter, L., Alvestrand, H., Zigmond, D. and R. Petke, "Guidelines for new URL Schemes", RFC 2718, November 1999.
[URL-REG] Petke, R. and I. King, "Registration Procedures for URL Scheme Names", BCP 35, RFC 2717, November 1999.
[XMPP-CORE] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Core", draft-ietf-xmpp-core-22 (work in progress), January 2004.
[XMPP-IM] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence", draft-ietf-xmpp-im-21 (work in progress), January 2004.


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Informative References

[CPIM] Peterson, J., "Common Profile for Instant Messaging (CPIM)", draft-ietf-impp-im-04 (work in progress), August 2003.
[CPP] Peterson, J., "Common Profile for Presence (CPP)", draft-ietf-impp-pres-04 (work in progress), August 2003.
[IMP-MODEL] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000.
[IMP-REQS] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging / Presence Protocol Requirements", RFC 2779, February 2000.
[MAILTO] Hoffman, P., Masinter, L. and J. Zawinski, "The mailto URL scheme", RFC 2368, July 1998 (TXT, HTML, XML).


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Author's Address

  Peter Saint-Andre
  Jabber Software Foundation
EMail:  stpeter@jabber.org


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Appendix A. Revision History

Note to RFC Editor: please remove this entire appendix, and the corresponding entries in the table of contents, prior to publication.

A.1 Changes from draft-saintandre-xmpp-uri-00



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Intellectual Property Statement

Full Copyright Statement

Acknowledgment