XEP-0001: XMPP Extension Protocols

This document defines the standards process followed by the Jabber Software Foundation.


NOTICE: This Procedural document defines a process or activity of the Jabber Software Foundation (JSF) that has been approved by the XMPP Council and/or the JSF Board of Directors. The JSF is currently following the process or activity defined herein and will do so until this document is deprecated or obsoleted.


XEP Information

Status: Active
Type: Procedural
Number: 0001
Version: 1.17
Last Updated: 2006-10-04
Publishing Organization: Jabber Software Foundation
Approving Body: JSF Board of Directors
Dependencies: None
Supersedes: None
Superseded By: None
Short Name: N/A
Wiki Page: <http://wiki.jabber.org/index.php/XMPP Extension Protocols (XEP-0001)>

Author Information

Peter Saint-Andre

Email: stpeter@jabber.org
JID: stpeter@jabber.org

Legal Notice

This XMPP Extension Protocol is copyright 1999 - 2006 by the Jabber Software Foundation (JSF) and is in full conformance with the JSF's Intellectual Property Rights Policy <http://www.xmpp.org/extensions/ipr-policy.shtml>. This material may be distributed only subject to the terms and conditions set forth in the Creative Commons Attribution License (<http://creativecommons.org/licenses/by/2.5/>).

Discussion Venue

The preferred venue for discussion of this document is the Standards-JIG discussion list: <http://mail.jabber.org/mailman/listinfo/standards-jig>.

Discussion by the membership of the JSF may also be appropriate (see <http://mail.jabber.org/mailman/listinfo/members> for details).


Table of Contents

1. Introduction
2. Objectives
3. XEP Types
3.1. Standards Track
3.2. Informational
3.3. Historical
3.4. Humorous
3.5. Procedural
4. Submission Process
5. Publication Process
6. Discussion Process
7. Proposal Process
8. Approval Process
8.1. Standards Track XEPs
8.2. Historical, Informational, and Procedural XEPs
9. Summary of XEP States
9.1. Experimental
9.2. Proposed
9.3. Draft
9.4. Final
9.5. Active
9.6. Deferred
9.7. Retracted
9.8. Rejected
9.9. Deprecated
9.10. Obsolete
10. Modification of Final and Active XEPs
11. Expiration Dates
12. Security Considerations
13. IANA Considerations
14. XMPP Registrar Considerations
15. XML Schema
Notes
Revision History


1. Introduction

The Jabber Software Foundation (JSF) [1] adheres to an open standards process that enables interested parties to document existing protocols used within the Jabber/XMPP developer community and to submit proposals that define new protocols; with a few exceptions, [2] such protocols can be considered extensions to the Extensible Messaging and Presence Protocol (XMPP) approved by the Internet Engineering Task Force (IETF) [3] in XMPP Core [4] and XMPP IM [5]. Advancement through the JSF's standards process is subject to open discussion on public discussion lists and approval by a technical steering committee elected by the members of the JSF. The focal point of the process is a series of protocol specifications called XMPP Extension Protocols or XEPs. [6] The nature of XMPP Extension Protocols and the mechanisms for managing and advancing them within the Jabber Software Foundation's standards process are canonically described in the current document, which represents the first document in the XEP series. [10]

2. Objectives

The Jabber Software Foundation was founded in the year 2001 to openly document, safeguard, manage, and extend the wire protocols used within the Jabber/XMPP developer community. The work of the Jabber Software Foundation has several objectives:

  1. To produce practical, technically excellent solutions to important problems of real-time communication based on the set of streaming XML technologies known as Jabber/XMPP.
  2. To document XMPP extensions in a clear, concise manner so that the task of implementing the protocols is straightforward.
  3. To ensure interoperability among the disparate technologies used on Jabber/XMPP networks.
  4. To guarantee that any person or entity may implement the protocols without encumbrance.
  5. To work in an fair, open, objective manner.

The standards process specified herein has been developed and refined in order to meet these objectives.

3. XEP Types

The five XEP types are described in the following sections.

The approving body for all Standards Track, Informational, Historical, and Humorous XEPs is the XMPP Council [11]; the approving body for Procedural XEPs may be either the JSF Board of Directors [12] or the XMPP Council.

This document focuses primarily on Standards Track XEPs since they are the vehicle for defining new protocols, but also discusses the other XEP types.

3.1 Standards Track

A Standards Track XEP defines one of the following:

  1. A wire protocol intended to be used as a standard part of Jabber/XMPP technologies. [13]
  2. A protocol suite that determines conformance requirements (e.g., Basic IM Protocol Suite [14]).

3.2 Informational

An Informational XEP defines one of the following:

  1. Best practices for protocol development (e.g., Service Discovery Extensions [15]).
  2. A usage profile for an existing protocol (e.g., Invisibility [16]).

3.3 Historical

An Historical XEP documents a protocol that was developed before the JSF's standards process was instituted, but that is still in use within the Jabber/XMPP developer community; such a XEP may or may not be obsoleted by a Standards Track XEP, or upgraded to Standards Track.

3.4 Humorous

A Humorous XEP attempts to be funny by defining a protocol that would never be used in the real world; such XEPs are usually published on April 1 and automatically have a status of Active.

3.5 Procedural

A Procedural XEP defines a process or activity to be followed by the JSF, including JIG charters as specified by Jabber Interest Groups [17].

4. Submission Process

The JSF welcomes and encourages the submission of protocols to the JSF's standards process. [18] Any individual or group of individuals may author a proposal and submit it to the JSF for consideration as a XEP, and there is no requirement that a XEP author shall be an elected member of the JSF. However, proposals to define official JSF protocols must be presented in the XEP format and must follow the rules defined herein. The authoring and submission process is defined in Guidelines for Authors of XMPP Extension Protocols [19] (see also <http://www.xmpp.org/extensions/submit.shtml>). All inquiries related to the JSF's standards process, and all submissions, should be directed to the XMPP Extensions Editor [20].

Note well that XEP authors must transfer ownership of their protocols (but not implementations thereof) to the JSF. Refer to the JSF IPR Policy [21] for details. XEP authors must make sure that they have read, understood, and agreed to the JSF IPR Policy before submitting a proposal to the XMPP Extensions Editor!

All proposals submitted to the JSF for consideration as XEPs must contain the following information:

  1. Legal Notice -- the legal notice must be exactly that which is specified in the JSF IPR Policy

  2. Author Information -- first name, last name, email address, and Jabber ID are all required and must be provided for all authors

Finally, Standards Track, Informational, and Historical XEPs must conform to RFC 2119 [22] in the use of terminology regarding requirements levels.

5. Publication Process

The approving body for almost all XEPs is the XMPP Council; therefore, in order to be published as a XEP, a proposal must first be accepted by the XMPP Council (the only exceptions are certain kinds of Procedural XEPs, for which the approving body may be the JSF Board of Directors and which may be accepted for publication by the XMPP Extensions Editor in consultation with the Board). Upon receiving a proposal, the XMPP Extensions Editor shall do the following:

If no member of the XMPP Council objects to publication of the proposal within seven (7) days or at the next meeting of the Council, the XMPP Extensions Editor shall accept it as a XEP. If objections are raised by the Council on the Standards-JIG list or in its meeting, the XEP author is encouraged to address the feedback of the Council and to submit a revised version of the proposal and/or confer with the XMPP Extensions Editor or objecting Council member(s) regarding how to proceed.

If the proposal is accepted as a XEP, the XMPP Extensions Editor shall do the following:

Note well that no special criteria (other than acceptance by the XMPP Council and minimal formatting compliance) need to be met in order for a XEP to be granted a status of Experimental. The granting of Experimental status must not be construed as indicating any level of approval by the JSF, the XMPP Council, or the Jabber/XMPP developer community. Implementation of Experimental XEPs is encouraged in an exploratory fashion (e.g., in a proof of concept) in order to gain experience with and iteratively improve the protocol defined therein, but such implementations may not be appropriate for deployment in production systems.

6. Discussion Process

Once a XEP is published, it becomes available for public discussion within the Standards JIG and the broader Jabber/XMPP developer community. The XEP author is responsible for collecting feedback from the Jabber/XMPP developer community during the life of the XEP and for incorporating such feedback into the proposal. In order to fully participate in discussion of the proposal, the XEP author should be subscribed to the Standards-JIG list, which is the primary venue for discussion of XMPP Extension Protocols. Changes made based on feedback received by the XEP author must be captured in updated versions of the XEP (e.g., 0.2 after 0.1), each of which must be put under source control and subsequently published and announced by the XMPP Extensions Editor.

If an Experimental XEP is inactive (i.e., no updated versions are published) for a period of six (6) months, the XMPP Extensions Editor shall automatically change the status of the XEP to Deferred unless it is in the queue of XEPs under active consideration for advancement by the XMPP Council; upon submission of an updated version, the XMPP Extensions Editor shall change the status back to Experimental.

7. Proposal Process

Before an Experimental XEP may be proposed to the XMPP Council for advancement to Draft (Standards Track XEPs) or Active (Historical, Informational, and Procedural XEPs), the XMPP Council must agree that the XEP is ready to be considered for advancement. Once the Council so agrees, it shall instruct the XMPP Extensions Editor to (1) change the status of the XEP from Experimental to Proposed and (2) issue a Last Call for open discussion on the Standards JIG list. The Last Call shall expire not less than 10 days after the date of issue.

Once the consensus of the Standards JIG has been incorporated into the XEP and all issues of substance raised during the Last Call have been addressed by the XEP author, the XMPP Extensions Editor shall formally propose a specific revision of the XEP to the XMPP Council for its vote. If necessary, the XMPP Extensions Editor may, at his discretion and in consultation with the XMPP Council, extend the Last Call or issue a new Last Call if the XEP requires further discussion.

Last Calls regarding Procedural XEPs for which the approving body is the JSF Board of Directors may be issued directly by the XMPP Extensions Editor once instructed by the Board.

8. Approval Process

After a XEP has been proposed to the XMPP Council, any change in its status shall be determined by a vote of the XMPP Council. All members of the Council must vote, with the possible values being +1 (approve), 0 (neutral), or -1 (disapprove, with reasons). A XEP shall not be advanced to the next stage in the approval process so long as any Council Member continues to vote -1; that Council Member's written concerns must be addressed in order for the XEP to advance. A majority of Council members must vote +1 in order for a XEP to advance. (Additional voting policies, such as voting periods and defaults if a member does not vote, may be set by the XMPP Council.) A vote of the XMPP Council is final and binding, although a XEP author is free to address the concerns of the Council and to resubmit the XEP for future consideration.

If the XMPP Council does not complete voting on a XEP before the end of its term, the XMPP Extensions Editor shall issue a new Last Call on the Standards JIG list and the newly-elected Council shall vote anew on the XEP after completion of the Last Call. This provides an opportunity for any member of the previous Council who had voted -1 to voice his or her concerns in a public forum before the new Council votes on the XEP.

A vote of the XMPP Council applies only to the specific revision of the XEP that has been presented to it. Further revisions may need to be re-submitted for approval.

Any change in the status of a XEP must be announced on the Standards-JIG list by the XMPP Extensions Editor. If a XEP advances to a status of Final, it shall be so announced and also published as one of the official JSF protocols [26] on the website of the Jabber Software Foundation.

Approval of Procedural XEPs for which the approving body is the JSF Board of Directors shall occur upon approval by the Board in accordance with the rules defined in the JSF Bylaws [27].

More detailed information about the approval process is provided below, including criteria for Standards Track XEPs and for Historical, Informational, and Procedural XEPs.

8.1 Standards Track XEPs

The possible states for a Standards Track XEP are as follows:


     +--> Retracted
     |
     |
     +--> Deferred    +--> Rejected
     |                |
     |                |
Experimental ----> Proposed ----> Draft ----> Final
                                    |           |
                                    |           |
                                    +-----------+---> Deprecated ---> Obsolete
      

The ideal path is for a Standards Track XEP is to be advanced by the XMPP Council from Proposed to Draft to Final (the criteria for this advancement are described in the following paragraphs). However, an Experimental XEP shall be assigned a status of Deferred if it has not been updated in six (6) months (e.g., because of a lack of interest or because it depends on other specifications that have yet to move forward). In addition, rather than being advanced from Proposed to Draft, a Standards Track XEP may be voted to a status of Rejected if the XMPP Council deems it unacceptable. (Note that if a XEP is Deferred, the XMPP Extensions Editor may at some point re-assign it to Experimental status, and that, even if a XEP is Rejected, it is retained in source control and on the Jabber Software Foundation website for future reference.) Finally, a XEP author may voluntarily remove an Experimental XEP from further consideration, resulting in a status of Retracted.

In order for a Standards Track XEP to advance from Proposed to Draft, it must:

  1. fill known gaps in Jabber/XMPP technologies or deficiencies with existing protocols
  2. be clearly described and accurately documented so that it can be understood and implemented by interested and knowledgeable members of the Jabber/XMPP developer community
  3. document any known security considerations with the proposed technology
  4. be generally stable and appropriate for further field experience
  5. have achieved rough consensus (though not necessarily unanimity) within the Standards JIG
  6. be formally defined by an XML schema
  7. receive the requisite votes from the XMPP Council

Elevation to Draft status (version 1.0) is a major advancement for the XEP, indicating a strong sense on the part of the XMPP Council and Jabber/XMPP developer community that the specification will be of lasting value. Since a Draft standard must be well-understood and must be known to be reasonably stable, it is relatively safe to use it as the basis for implementations and production deployments. However, note that because a Draft standard may still require additional field experience and may be subject to change based on such experience, mission-critical or large-scale implementations of the Draft standard may not be advisable (although every effort shall be made to ensure that any changes to a Draft XEP will be backwards-compatible with the 1.0 version). Note also that any changes to a Draft XEP must be provisionally published at <http://www.xmpp.org/extensions/tmp/>, announced on the Standards-JIG mailing list, and formally approved by the XMPP Council before being officially published at the canonical URL for the XEP.

In order for a XEP to advance from Draft status to Final status (version 2.0), it must be shown to be stable and well-received by the Jabber/XMPP developer community. Before presenting a Draft standard to the XMPP Council for consideration as a Final standard, the XMPP Extensions Editor shall issue a Call for Experience on the Standards-JIG list so that feedback can be gathered from those who have implemented the Draft standard (the Call for Experience shall expire not less than 14 days after the date of issue, and shall not be issued until at least 60 days have passed since advancement to Draft). In addition, at least two implementations of the XEP must exist, at least one of which must be free software (in accordance with the The General Public License [28] or The Lesser General Public License [29]) or open-source software (in accordance with the definition provided by The Open Source Initiative [30]). Until two implementations are produced, a Standards Track XEP shall retain a status of Draft. Once (1) two implementations have been presented to the XMPP Council, (2) feedback provided during the Call for Experience has been incorporated into the XEP, and (3) the XEP has been fully checked for accuracy, the status of the XEP may be changed to Final upon a vote of the Council.

Finally, a Standards Track XEP that has been granted a status of Final may be superseded by a future XEP approved by the XMPP Council. In such cases, the status of the earlier XEP shall be changed to Deprecated, possibly with an expiration date assigned by the XMPP Council (see the Expiration Dates section below). After a reasonable period of time or upon the passing of the expiration date, the status of the XEP shall be changed to Obsolete.

8.2 Historical, Informational, and Procedural XEPs

The possible states for a Historical, Informational, or Procedural XEP are as follows:


     +--> Retracted
     |
     |
     +--> Deferred    +--> Rejected
     |                |
     |                |
Experimental ----> Proposed ----> Active
                                    |
                                    |
                                    +--> Deprecated --> Obsolete
    

Because such XEPs do not seek to define standard protocols, in general they are less controversial and tend to proceed from Proposed to Active without controversy on a vote of the XMPP Council. However, some of these XEPs may be remanded from the Council to the XEP author and/or XMPP Extensions Editor for revision in order to be suitable for advancement from Proposed to Active (e.g., documentation of protocols in use must be accurate and describe any existing security concerns). As with Standards Track XEPs, the XEP author may retract such a XEP when it is Experimental, and the Council may reject such a XEP when it is Proposed.

Once approved, Historical, Informational, and Procedural XEPs will have a status of Active. Such a XEP may be replaced by a new XEP on the same or a similar topic, thus rendering the earlier XEP out of date; in such cases, the earlier XEP shall be assigned a status of Deprecated (and eventually Obsolete) with a note specifying the superseding XEP.

The XMPP Council may, at its discretion, decide to convert an Historical XEP into a Standards Track XEP if the protocol defined in the XEP has been in long use, is deemed stable and uncontroversial, and is unlikely to be superseded by a newer protocol. The Historical XEP shall be treated in the same way as a Standards Track XEP that has a status of Experimental, beginning with the Proposal Process. If after the Last Call and voting by the XMPP Council the XEP is approved for advancement on the standards track, its type shall be changed to Standards Track and its status shall be changed to Draft.

9. Summary of XEP States

The possible states for a XEP are summarized in the following sections.

9.1 Experimental

A XEP of any type is in the Experimental state after it has been accepted by the XMPP Council and published by the Jabber Software Foundation but before it has advanced within the standards process to a state of Active or Draft.

9.2 Proposed

A XEP of any type is in the Proposed state while it is in Last Call or under consideration by the XMPP Council for advancement from Experimental to Draft or Active.

9.3 Draft

A Standards Track XEP is in the Draft state after it has undergone extensive discussion and technical review on the Standards-JIG list and has been voted forward on the standards track by the XMPP Council.

9.4 Final

A Standards Track XEP is in the Final state after it has been in the Draft state for at least 60 days, has been implemented in at least two separate codebases, and has been voted forward on the standards track by the XMPP Council.

9.5 Active

A XEP of any type other than Standards Track is advanced to a status of Active after it has been voted forward from Experimental by the XMPP Council.

9.6 Deferred

An Experimental XEP of any type is changed to the Deferred state if it has not been updated in six (6) months.

9.7 Retracted

A XEP of any type is in the Retracted state if the authors have asked the XMPP Extensions Editor to remove the XEP from further consideration in the JSF's standards process.

9.8 Rejected

A XEP of any type is in the Rejected state if the XMPP Council has deemed it unacceptable and has voted to not move it forward within the standards process.

9.9 Deprecated

A XEP of any type is in the Deprecated state if the XMPP Council has determined that the protocol defined therein is out of date and that new implementations are no longer encouraged (e.g., because it has been superseded by a more modern protocol).

9.10 Obsolete

A XEP of any type is changed from Deprecated to Obsolete if the XMPP Council has determined that the protocol defined therein should no longer be implemented or deployed.

10. Modification of Final and Active XEPs

Sometimes it is necessary to modify XEPs that have received final approval by the XMPP Council or JSF Board of Directors (e.g., to correct errors, incorporate the lessons of experience, or document new security concerns). This section describes the process for doing so with regard to Standards Track XEPs that have achieved a status of Final and Historical, Informational, and Procedural XEPs that have achieved a status of Active.

With regard to Standards Track XEPs, the Jabber Software Foundation (in particular, the XMPP Council) strives to ensure that such XEPs are accurate, complete, and stable before advancing them to a status of Final (corresponding to document version 2.0 of the XEP). The Call for Experience and discussion within the Standards JIG help to ensure this result, but final responsibility rests with the XMPP Council. Despite the best efforts of all concerned, errors are sometimes discovered in Final XEPs (the individual who discovers such an error should inform the Council via the Standards-JIG mailing list or communicate directly with the XMPP Extensions Editor). Whereas other standards development organizations may issue errata while leaving the specification itself unchanged, the JSF makes changes to the Final XEP and publishes a revised document version (e.g., version 2.1). In general the changes are made by the XMPP Extensions Editor or XEP author in consultation with the XMPP Council, discussed within the Standards JIG if appropriate, and agreed upon by the full XMPP Council. Upon agreement regarding the exact changes, the XMPP Council shall instruct the XMPP Extensions Editor to publish a revised version of the XEP and announce the existence of the revised version through the normal channels (e.g., on the JSF website and to the Standards-JIG list). Naturally, if members of the Jabber/XMPP developer community have concerns regarding the changes made, they are free to discuss the matter in the relevant forum (usually the Standards-JIG list) before or after the revised version has been published.

The process is similar with regard to Historical and Informational XEPs that have achieved a status of Active (corresponding to document version 1.0 of the XEP): the XMPP Council agrees on the exact changes to be made and instructs the XMPP Extensions Editor to publish and announce a revised version (e.g., version 1.1). Here again the XMPP Council bears responsibility for any changes and public discussion is welcome.

Procedural XEPs may be modified more frequently as the Jabber Software Foundation gains experience with the processes defined therein. For example, XEP-0001 is modified periodically in order to document processes previously not made explicit or to modify existing processes based on experience with the JSF's standards process; similar changes are sometimes made to the XMPP Registrar [31] XEP and to various JIG-related XEPs. Changes to these XEPs are discussed by the XMPP Council, JSF Board of Directors, JSF membership, and Standards JIG as appropriate, and exact changes are agreed to by the relevant approving body (XMPP Council or JSF Board of Directors). The approving body then instructs the XMPP Extensions Editor to publish and announce the revised version as described above.

11. Expiration Dates

In rare cases, a protocol enhancement may be accepted as an interim solution, especially when it is recognized that expected future improvements in technology or the underlying Jabber/XMPP protocols will make possible a much better solution to the problem at hand (e.g., a better protocol for user avatars may be contingent upon the development of a robust protocol for publish/subscribe functionality). In such cases, a XEP may be approved provisionally and be assigned an expiration date.

The exact form of such an expiration date shall be left up to the discretion of the XMPP Council. However, the preferred form is to assign an expiration date of six (6) months in the future, at which time the XMPP Council must re-affirm the status of the XEP and, if desired, extend the expiration date for another six (6) months. While this process may continue indefinitely (although that is unlikely), it has the virtue of forcing the XMPP Council and Jabber/XMPP developer community to re-examine the provisional protocol on a fairly regular basis in the light of technological changes. Alternatively, a XEP may be assigned a "soft" expiration date: that is, the XEP will expire when an expected future protocol comes into existence, whenever that may be. In either case, the status of the XEP shall be changed to Deprecated when it expires.

In addition, an expiration date may be assigned when the status of a XEP is changed from Final (or, potentially, Draft) to Deprecated. In this case, the expiration date applies to the date when the XEP is expected to change from Deprecated to Obsolete. These dates may be flexible; however it is expected that they will follow the same six-month rule as provisional protocol enhancements.

12. Security Considerations

Every XMPP Extension Protocol specification must contain a section entitled "Security Considerations", detailing security concerns or features related to the proposal; in particular, a Standards Track XEP should list the security threats that the protocol addresses and does not address, as well as security issues related to implementation of the protocol. XEP authors should refer to RFC 3552 [32] for helpful information about documenting security considerations and should also confer with the XMPP Extensions Editor and/or XMPP Council regarding this important task.

13. IANA Considerations

Some XMPP Extension Protocols may require interaction with the Internet Assigned Numbers Authority (IANA) [33]. The IANA acts as a clearinghouse to assign and coordinate the use of numerous Internet protocol parameters, such as MIME types and port numbers (e.g., the TCP ports 5222 and 5269 used by the Jabber/XMPP developer community are registered with the IANA). Whether or not a XEP requires registration of parameters with the IANA, that fact must be noted and explained in a distinct section of the XEP entitled "IANA Considerations". Registration with the IANA should not occur until a XEP advances to a status of Draft (Standards Track XEPs) or Active (Informational and Historical XEPs), and should be initiated by the XMPP Registrar in consultation with the XEP author, not by the XEP author directly with the IANA.

14. XMPP Registrar Considerations

The XMPP Registrar [34] performs a function similar to the IANA, although limited to the Jabber/XMPP developer community. It does so by reserving protocol namespaces and by uniquely assigning parameters for use in the context of Jabber/XMPP protocols (for example, the categories and types used in Service Discovery [35]).

Whether or not a XEP requires registration of protocol namespaces or parameters with the XMPP Registrar, that fact must be noted and explained in a distinct section of the XEP entitled "XMPP Registrar Considerations". Such registration should not occur until a XEP advances to a status of Draft (Standards Track XEPs) or Active (Informational and Historical XEPs). Registration of protocol namespaces is initiated by the XMPP Extensions Editor when a XEP advances to Draft or Active. Registration of particular parameters used within a specification may be initiated by a XEP author within the text of the XEP, or by an implementor of the XEP after it has advanced to Draft or Active. For details regarding the XMPP Registrar and its processes, refer to XMPP Registrar [36].

A XEP may also request that a new registry is to be created by the XMPP Registrar. The XEP author must clearly define the nature of the new registry as well as the process for submitting data to the registry, and must do so in collaboration with the Registrar.

15. XML Schema

XMPP Extension Protocol specifications that define official JSF protocols must include a schema that conforms to XML Schema Part 1 [37] and XML Schema Part 2 [38].

The schema for the XEP format itself is as follows:

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='http://www.xmpp.org/extensions'
    xmlns='http://www.xmpp.org/extensions'
    elementFormDefault='qualified'>

  <xs:element name='xep'>
    <xs:annotation>
      <xs:documentation>

        This schema defines the document format for XMPP Extension 
        Protocols (XEPs). For further information about XEPs, visit:

           http://www.xmpp.org/extensions/ 
        
        The canonical URL for this schema is:
        
           http://www.xmpp.org/extensions/xep.xsd

      </xs:documentation>
    </xs:annotation>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref='header'/>
        <xs:element ref='section1' maxOccurs='unbounded'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='header'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='title' type='xs:string'/>
        <xs:element name='abstract' type='xs:string'/>
        <xs:element name='legal' type='xs:string'/>
        <xs:element name='number' type='xs:byte'/>
        <xs:element ref='status'/>
        <xs:element ref='type'/> 
        <xs:element name='jig' type='xs:string'/>
        <xs:element name='approver' type='xs:string'/>
        <xs:element ref='dependencies'/>
        <xs:element ref='supersedes'/>
        <xs:element ref='supersededby'/>
        <xs:element name='shortname' type='xs:NCNAME'/>
        <xs:element ref='schemaloc' minOccurs='0' maxOccurs='unbounded'/> 
        <xs:element name='registry' type='empty' minOccurs='0'/> 
        <xs:element name='expires' type='xs:string'/>
        <xs:element ref='author' minOccurs='0' maxOccurs='unbounded'/> 
        <xs:element ref='revision' minOccurs='0' maxOccurs='unbounded'/> 
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='status'>
    <xs:simpleType>
      <xs:restriction base='xs:NCNAME'>
        <xs:enumeration value='Active'/>
        <xs:enumeration value='Deferred'/>
        <xs:enumeration value='Deprecated'/>
        <xs:enumeration value='Draft'/>
        <xs:enumeration value='Experimental'/>
        <xs:enumeration value='Final'/>
        <xs:enumeration value='Obsolete'/>
        <xs:enumeration value='Proposed'/>
        <xs:enumeration value='ProtoXEP'/>
        <xs:enumeration value='Rejected'/>
        <xs:enumeration value='Retracted'/>
      </xs:restriction>
    </xs:simpleType>
  </xs:element>

  <xs:element name='type'>
    <xs:simpleType>
      <xs:restriction base='xs:string'>
        <xs:enumeration value='Historical'/>
        <xs:enumeration value='Humorous'/>
        <xs:enumeration value='Informational'/>
        <xs:enumeration value='Organizational'/>
        <xs:enumeration value='Standards Track'/>
      </xs:restriction>
    </xs:simpleType>
  </xs:element>

  <xs:element name='dependencies'>
    <xs:complexType>
      <xs:sequence minOccurs='0' maxOccurs='unbounded'>
        <xs:element name='spec' type='xs:string'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='supersedes'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='spec' type='xs:string'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='supersededby'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='spec' type='xs:string'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='schemaloc'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='ns' type='xs:string' minOccurs='0'/>
        <xs:element name='url' type='xs:string'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='author'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='firstname' type='xs:string'/>
        <xs:element name='surname' type='xs:string'/>
        <xs:element name='authornote' type='empty' minOccurs='0'/>
        <xs:element name='org' type='xs:string' minOccurs='0'/>
        <xs:element name='email' type='xs:string'/>
        <xs:element name='jid' type='xs:string' minOccurs='0'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='revision'>
    <xs:complexType>
      <xs:sequence>
        <xs:element name='version' type='xs:string'/>
        <xs:element name='date' type='xs:dateTime'/>
        <xs:element name='initials' type='xs:NCName'/>
        <xs:element ref='remark'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='remark'>
    <xs:complexType>
      <xs:choice>
        <xs:element ref='p' minOccurs='0' maxOccurs='1'/>
        <xs:element ref='ul' minOccurs='0' maxOccurs='1'/>
      </xs:choice>
    </xs:complexType>
  </xs:element>

  <xs:element name='section1'>
    <xs:complexType>
      <xs:choice maxOccurs='unbounded'>
        <xs:element ref='div' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='p' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='section2' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='example' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='code' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ul' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ol' minOccurs='0' maxOccurs='unbounded'/>
      </xs:choice>
      <xs:attribute name='topic' type='xs:string' use='required'/>
      <xs:attribute name='anchor' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='section2'>
    <xs:complexType>
      <xs:choice maxOccurs='unbounded'>
        <xs:element ref='div' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='p' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='section3' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='example' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='code' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ul' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ol' minOccurs='0' maxOccurs='unbounded'/>
      </xs:choice>
      <xs:attribute name='topic' type='xs:string' use='required'/>
      <xs:attribute name='anchor' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='section3'>
    <xs:complexType>
      <xs:choice maxOccurs='unbounded'>
        <xs:element ref='div' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='p' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='section4' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='example' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element name='code' type='xs:string' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ul' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ol' minOccurs='0' maxOccurs='unbounded'/>
      </xs:choice>
      <xs:attribute name='topic' type='xs:string' use='required'/>
      <xs:attribute name='anchor' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='section4'>
    <xs:complexType>
      <xs:choice maxOccurs='unbounded'>
        <xs:element ref='div' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='p' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='example' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='code' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ul' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ol' minOccurs='0' maxOccurs='unbounded'/>
      </xs:choice>
      <xs:attribute name='topic' type='xs:string' use='required'/>
      <xs:attribute name='anchor' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='div'>
    <xs:complexType>
      <xs:choice maxOccurs='unbounded'>
        <xs:element ref='div' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='p' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='example' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='code' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ul' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='ol' minOccurs='0' maxOccurs='unbounded'/>
      </xs:choice>
      <xs:attribute name='class' type='xs:string' use='optional'/>
      <xs:attribute name='style' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='p' type='markup'/>

  <xs:element name='ul'>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref='li' minOccurs='1' maxOccurs='unbounded'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='ol'>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref='li' minOccurs='1' maxOccurs='unbounded'/>
      </xs:sequence>
      <xs:attribute name='start' type='xs:byte' use='optional'/>
      <xs:attribute name='type' type='xs:NCName' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='li' type='markup'/>

  <xs:element name='img'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='empty'>
          <xs:attribute name='source' use='required'/> 
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name='link'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='xs:string'>
          <xs:attribute name='url' use='required'/> 
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name='note' type='markup'/>

  <xs:element name='example'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='xs:string'>
          <xs:attribute name='caption' use='optional'/> 
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name='code'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='xs:string'>
          <xs:attribute name='caption' use='optional'/> 
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name='table'>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref='tr' minOccurs='1' maxOccurs='unbounded'/>
      </xs:sequence>
      <xs:attribute name='caption' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:element name='tr'>
    <xs:complexType>
      <xs:choice>
        <xs:element ref='th' minOccurs='0' maxOccurs='unbounded'/>
        <xs:element ref='td' minOccurs='0' maxOccurs='unbounded'/>
      </xs:choice>
    </xs:complexType>
  </xs:element>

  <xs:element name='th'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='xs:string'>
          <xs:attribute name='colspan' use='optional'/> 
          <xs:attribute name='rowspan' use='optional'/> 
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:element name='td'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='xs:string'>
          <xs:attribute name='colspan' use='optional'/> 
          <xs:attribute name='rowspan' use='optional'/> 
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:complexType name='markup' type='mixed'>
    <xs:choice minOccurs='0' maxOccurs='unbounded'>
      <xs:element name='cite' type='xs:token'/>
      <xs:element name='em' type='xs:token'/>
      <xs:element ref='img'/>
      <xs:element ref='link'/>
      <xs:element ref='note'/>
      <xs:element name='span' type='xs:token'/>
      <xs:element name='strong' type='xs:token'/>
      <xs:element name='tt' type='xs:token'/>
    </xs:choice>
    <xs:attribute name='class' type='xs:string' use='optional'/>
    <xs:attribute name='style' type='xs:string' use='optional'/>
  </xs:complexType>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>
  


Notes

1. The Jabber Software Foundation (JSF) is an independent, non-profit organization that develops open extensions to the IETF's Extensible Messaging and Presence Protocol (XMPP). For further information, see <http://www.jabber.org/jsf/>.

2. Effectively the only such exceptions are protocols that were superseded by RFC 3920 and RFC 3921.

3. The Internet Engineering Task Force is the principal body engaged in the development of new Internet standard specifications, best known for its work on standards such as HTTP and SMTP. For further information, see <http://www.ietf.org/>.

4. RFC 3920: Extensible Messaging and Presence Protocol (XMPP): Core <http://www.ietf.org/rfc/rfc3920.txt>.

5. RFC 3921: Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence <http://www.ietf.org/rfc/rfc3921.txt>.

6. The JEP (now XEP) concept as exemplified in version 1.0 of this document (approved in July of 2001) was borrowed from the Python community (see PEP-1). Subsequent revisions have been based on the Jabber/XMPP developer community's experience with this standards process, as well as insights gleaned from the standards processes followed by the IETF (RFC 2026 [7]), the World Wide Web Consortium (W3C) [8] (W3C Process Document [9]), and other standards development organizations.

7. RFC 2026: The Internet Standards Process <http://www.ietf.org/rfc/rfc2026.txt>.

8. The World Wide Web Consortium defines data formats and markup languages (such as HTML and XML) for use over the Internet. For further information, see <http://www.w3.org/>.

9. W3C Process Document <http://www.w3.org/Consortium/Process-20010719/process.html>.

10. The term "XEP" is normally pronounced "zepp".

11. The XMPP Council is a technical steering committee, authorized by the JSF Board of Directors and elected by JSF members, that approves of new XMPP Extensions Protocols and oversees the JSF's standards process. For further information, see <http://www.xmpp.org/council/>.

12. The JSF Board of Directors is an elected body that possesses overall responsibility for the affairs of the Jabber Software Foundation. For further information, see <http://www.jabber.org/board/>.

13. Note well that a protocol defined in a Standards Track XEP is not considered a full standard of the Jabber Software Foundation until it achieves a status of Final within the standards process defined herein (a Standards Track XEP that has achieved a status of Draft may be referred to as a Draft Standard; a Standards Track XEP that has a status of Experimental must not be referred to as a standard, but instead should be referred to as a work in progress).

14. XEP-0073: Basic IM Protocol Suite <http://www.xmpp.org/extensions/xep-0073.html>.

15. XEP-0128: Service Discovery Extensions <http://www.xmpp.org/extensions/xep-0128.html>.

16. XEP-0126: Invisibility <http://www.xmpp.org/extensions/xep-0126.html>.

17. XEP-0002: Jabber Interest Groups <http://www.xmpp.org/extensions/xep-0002.html>.

18. It is important to understand that private extensions to XMPP are also allowed. The JSF does not, and cannot, require such private extensions to be added to the public, official set of protocols recognized by the JSF. The processes and procedures in this document apply only to protocols that are submitted to the JSF, not to private protocol extensions used for custom functionality in particular applications. However, such private extensions must not be considered part of the protocols recognized by the JSF.

19. XEP-0143: Guidelines for Authors of XMPP Extension Protocols <http://www.xmpp.org/extensions/xep-0143.html>.

20. The XMPP Extensions Editor is the individual appointed by the JSF Board of Directors to handle protocol submissions and provide day-to-day management of the JSF's standards process. For further information, see <http://www.xmpp.org/extensions/editor.shtml>.

21. The JSF IPR Policy defines the Jabber Software Foundation's official policy regarding intellectual property rights (IPR) as they pertain to XMPP Extension Protocols (XEPs). For further information, see <http://www.xmpp.org/extensions/ipr-policy.shtml>.

22. RFC 2119: Key words for use in RFCs to Indicate Requirement Levels <http://www.ietf.org/rfc/rfc2119.txt>.

23. The Standards JIG is a standing Jabber Interest Group devoted to development of XMPP Extension Protocols. The discussion list of the Standards JIG is the primary venue for discussion of Jabber/XMPP protocols, as well as for announcements by the XMPP Extensions Editor and XMPP Registrar. To subscribe to the list or view the list archives, visit <http://mail.jabber.org/mailman/listinfo/standards-jig/>.

24. XEPs are kept under source control in the 'xmpp' module and 'extensions' directory of the CVS repository maintained at the jabberstudio.org service. Instructions for accessing these files can be found at <http://www.jabberstudio.org/cvs.php>, and a web interface to these files is available at <http://www.jabberstudio.org/cgi-bin/viewcvs.cgi/xmpp/extensions/>.

25. The canonical URL for accessing XMPP Extensions is <http://www.xmpp.org/extensions/>.

26. A list of official JSF protocols is maintained at <http://www.xmpp.org/protocol>.

27. The Bylaws of the Jabber Software Foundation (JSF) define the legal basis and operating procedures of the JSF. For further information, see <http://www.jabber.org/jsf/bylaws.shtml>.

28. The General Public License is the primary code license for free software as defined by the Free Software Foundation. For further information, see <http://www.gnu.org/licenses/gpl.txt>.

29. The Lesser General Public License is a secondary code license for free software as defined by the Free Software Foundation. For further information, see <http://www.gnu.org/licenses/lgpl.txt>.

30. The Open Source Initiative defines the term 'open source' and maintains a list of a open-source code licenses. For further information, see <http://www.opensource.org/>.

31. XEP-0053: XMPP Registrar <http://www.xmpp.org/extensions/xep-0053.html>.

32. RFC 3552: Guidelines for Writing RFC Text on Security Considerations <http://www.ietf.org/rfc/rfc3552.txt>.

33. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>.

34. The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the Jabber Software Foundation. For further information, see <http://www.xmpp.org/registrar/>.

35. XEP-0030: Service Discovery <http://www.xmpp.org/extensions/xep-0030.html>.

36. XEP-0053: XMPP Registrar <http://www.xmpp.org/extensions/xep-0053.html>.

37. XML Schema Part 1: Structures <http://www.w3.org/TR/xmlschema-1/>.

38. XML Schema Part 2: Datatypes <http://www.w3.org/TR/xmlschema-2/>.


Revision History

Version 1.17 (2006-10-04)

As approved by the members of the Jabber Software Foundation, changed Jabber Enhancement Proposal to XMPP Extension Protocol.

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Version 1.16 (2006-06-23)

Clarified and simplified the state charts based on implementation experience; summarized state definitions.

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Version 1.15 (2004-11-02)

Specified that a Standards Track specification defines either (1) a wire protocol or (2) a protocol suite.

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Version 1.14 (2004-09-28)

Defined Procedural type as the union of JIG Formation type and certain Informational specifications in order to clarify the categories; added Modifications to Approved Specifications section in order to make explicit existing Council practices regarding Active and Final specifications; specified that documents on which voting was not complete at the end of a Council term shall undergo a second Last Call and subsequent vote by the new Council; modified Proposal Process to specify that the Jabber Council shall issue Last Calls on documents for which it is the approving body, with all discussion to occur on the Standards-JIG list; updated the schema.

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Version 1.13 (2004-08-24)

Further specified the goals of the standards process; mentioned Board-approved specifications.

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Version 1.11 (2004-07-14)

Specified the procedure for changing a XEP from Historical to Standards Track.

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Version 1.10 (2004-03-24)

Specified the procedure for acceptance of a proposal as a XEP; clarified the XEP types; completed editorial review.

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Version 1.9 (2003-12-22)

Added rule about automatic deferral of inactive specifications.

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Version 1.8 (2003-10-06)

Clarified the definition of informational specification.

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Version 1.7 (2003-04-11)

Added status of Retracted; corrected several errors related to the XMPP Registrar.

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Version 1.6 (2003-01-08)

Further clarified the proposal process per discussion on the JSF members list.

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Version 1.5 (2002-10-29)

Major revision based on experience. In addition to a reorganization of the content to improve the clarity of the presentation, changes include: (1) no anonymous authors; (2) proposal must be seconded by at least 5% of JSF members before being proposed for a Council vote; (3) clarification that the Council votes only on a particular revision of a specification (e.g., version 1.3 when proceeding from Draft to Final); (4) added information about the "Call for Experience" phase before proceeding from Draft to Final; (5) added reference to RFC 2119; (6) added sections for security considerations, IANA considerations, and XMPP Registrar considerations. Approved by the JSF Board and Jabber Council on 2002-11-20.

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Version 1.4 (2002-01-16)

Added information about the new "Experimental" state for Standards Track specifications and made appropriate changes to the standards process.

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Version 1.3.1 (2002-01-11)

Added link to DTD.

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Version 1.3 (2001-10-23)

(1) Added information about the "cooling off" period before a Standards Track specification may be advanced from Draft to Final; (2) Added a link to the template file; (3) Performed several minor fixes.

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Version 1.2 (2001-09-27)

(1) Added information about expiration dates; (2) Added a status of Deprecated to Standards Track specifications.

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Version 1.1 (2001-09-09)

(1) Changed "Jabber Foundation" to "Jabber Software Foundation"; (2) Changed "JIG Proposal" to "JIG Formation"; (3) Removed reference to the Secretary of the Jabber Software Foundation in connection with the role of Editor; (4) Clarified the possible states of acceptance of each kind of specification and described in greater detail the criteria for advancement from one state to another.

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Version 1.0 (2001-07-09)

Changed status to Active.

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Version 0.1 (2001-06-28)

Initial release -- a simplified and updated version of Rahul Dave's Jabberization of the process and format for Python Enhancement Proposals

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END