Network Working Group                                          J. Miller
Internet-Draft                                            P. Saint-Andre
Expires: June 6, 2003                         Jabber Software Foundation
                                                       December 06, 2002


                         XMPP Instant Messaging
                         draft-ietf-xmpp-im-00

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
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   Drafts.

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   This Internet-Draft will expire on June 6, 2003.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document describes the specific extensions to and applications
   of the eXtensible Messaging and Presence Protocol (XMPP) that are
   necessary to create a basic instant messaging and presence
   application.










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Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.1   Overview . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.2   Terminology  . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.3   Requirements . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.4   Conventions Used in this Document  . . . . . . . . . . . . .  4
   1.5   Discussion Venue . . . . . . . . . . . . . . . . . . . . . .  5
   1.6   Intellectual Property Notice . . . . . . . . . . . . . . . .  5
   2.    Registration . . . . . . . . . . . . . . . . . . . . . . . .  6
   2.1   Registration Data Flow . . . . . . . . . . . . . . . . . . .  6
   2.2   Cancellation Data Flow . . . . . . . . . . . . . . . . . . .  8
   3.    Authentication . . . . . . . . . . . . . . . . . . . . . . .  9
   4.    Authorizing a Resource . . . . . . . . . . . . . . . . . . . 10
   5.    Exchanging Messages  . . . . . . . . . . . . . . . . . . . . 11
   5.1   Specifying an Intended Recipient . . . . . . . . . . . . . . 11
   5.2   Specifying a Message Type  . . . . . . . . . . . . . . . . . 11
   5.3   Specifying a Message Subject . . . . . . . . . . . . . . . . 12
   5.4   Specifying a Message Thread  . . . . . . . . . . . . . . . . 12
   5.5   Specifying a Message Body  . . . . . . . . . . . . . . . . . 13
   5.6   Specifying Additional Information  . . . . . . . . . . . . . 13
   5.7   Message-Related Errors . . . . . . . . . . . . . . . . . . . 13
   6.    Exchanging Presence Information  . . . . . . . . . . . . . . 14
   6.1   Client and Server Responsibilities . . . . . . . . . . . . . 14
   6.2   Sending Initial Presence . . . . . . . . . . . . . . . . . . 14
   6.3   Specifying Availability Status . . . . . . . . . . . . . . . 15
   6.4   Specifying Detailed Status Information . . . . . . . . . . . 15
   6.5   Probing for Presence . . . . . . . . . . . . . . . . . . . . 15
   6.6   Sending Final Presence . . . . . . . . . . . . . . . . . . . 16
   6.7   Determining When a Contact Went Offline  . . . . . . . . . . 16
   7.    Managing Subscriptions . . . . . . . . . . . . . . . . . . . 17
   7.1   Requesting a Subscription  . . . . . . . . . . . . . . . . . 17
   7.2   Handling a Subscription Request  . . . . . . . . . . . . . . 17
   7.3   Cancelling a Subscription from Another Entity  . . . . . . . 18
   7.4   Unsubscribing from Another Entity's Presence . . . . . . . . 18
   8.    Blocking Communication . . . . . . . . . . . . . . . . . . . 19
   8.1   Retrieving One's Privacy Lists . . . . . . . . . . . . . . . 19
   8.2   Changing the Active List . . . . . . . . . . . . . . . . . . 20
   8.3   Editing a Privacy List . . . . . . . . . . . . . . . . . . . 20
   8.4   Removing a Privacy List  . . . . . . . . . . . . . . . . . . 21
   8.5   Blacklisted Entity Attempts to Communicate with User . . . . 21
   9.    Managing One's Roster  . . . . . . . . . . . . . . . . . . . 23
   9.1   Receiving One's Roster on Login  . . . . . . . . . . . . . . 23
   9.2   Adding a Roster Item . . . . . . . . . . . . . . . . . . . . 24
   9.3   Deleting a Roster Item . . . . . . . . . . . . . . . . . . . 25
   10.   Routing and Delivery Guidelines  . . . . . . . . . . . . . . 27
   11.   Security Considerations  . . . . . . . . . . . . . . . . . . 28
         References . . . . . . . . . . . . . . . . . . . . . . . . . 29



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         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 29
   A.    vCards . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
   A.1   Retrieving One's vCard . . . . . . . . . . . . . . . . . . . 30
   A.2   Updating One's vCard . . . . . . . . . . . . . . . . . . . . 31
   A.3   Viewing Another User's vCard . . . . . . . . . . . . . . . . 32
   B.    Authentication Using jabber:iq:auth  . . . . . . . . . . . . 33
   C.    Formal Definitions . . . . . . . . . . . . . . . . . . . . . 35
   C.1   jabber:iq:last . . . . . . . . . . . . . . . . . . . . . . . 35
   C.1.1 DTD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
   C.1.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
   C.2   jabber:iq:privacy  . . . . . . . . . . . . . . . . . . . . . 35
   C.2.1 DTD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
   C.2.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
   C.3   jabber:iq:register . . . . . . . . . . . . . . . . . . . . . 37
   C.3.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 37
   C.3.2 DTD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
   C.3.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
   C.4   jabber:iq:roster . . . . . . . . . . . . . . . . . . . . . . 40
   C.4.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 40
   C.4.2 DTD  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
   C.4.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
   C.5   vcard-temp . . . . . . . . . . . . . . . . . . . . . . . . . 42
   D.    Revision History . . . . . . . . . . . . . . . . . . . . . . 50
   D.1   Changes from draft-miller-xmpp-im-02 . . . . . . . . . . . . 50
         Full Copyright Statement . . . . . . . . . . . . . . . . . . 51


























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1. Introduction

1.1 Overview

   The core features of the XMPP protocol are defined in XMPP Core [1].
   These features, specifically XML streams and the 'jabber:client' and
   'jabber:server' namespaces, provide the building blocks for many
   types of near-real-time applications, which may be layered on top of
   the core by sending XML stanzas that are scoped by specific XML
   namespaces.  This document describes the specific extensions to and
   applications of XMPP Core that are used to create the basic
   functionality expected of an instant messaging and presence
   application as defined in RFC 2779 [2].  Extended namespaces for many
   other functionality areas have been defined and continue to be
   defined by the Jabber Software Foundation [3], including service
   discovery, multi-user chat, search, remote procedure calls, data
   gathering and forms submission, encryption, feature negotiation,
   message composing events, message expiration, delayed delivery, and
   file transfer; however, such functionality is not described herein
   because it is not required by RFC 2779 [2].

1.2 Terminology

   This document inherits the terminology defined in XMPP Core [1].

1.3 Requirements

   For the purposes of this document, we stipulate that a basic instant
   messaging and presence application needs to enable a user to perform
   the following functionality by using a compliant client:

   o  Register an account with a server

   o  Authenticate with a server

   o  Exchange messages with other users

   o  Exchange presence information with other users

   o  Manage subscriptions to and from other users

   o  Manage the items in the user's contact list (called a "roster")


1.4 Conventions Used in this Document

   The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
   "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and



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   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [4].

1.5 Discussion Venue

   The authors welcome discussion and comments related to the topics
   presented in this document, preferably on the "xmppwg@jabber.org"
   mailing list (archives and subscription information are available at
   http://www.jabber.org/cgi-bin/mailman/listinfo/xmppwg/).

1.6 Intellectual Property Notice

   This document is in full compliance with all provisions of Section 10
   of RFC 2026.  Parts of this specification use the term "jabber" for
   identifying namespaces and other protocol syntax.  Jabber[tm] is a
   registered trademark of Jabber, Inc.  Jabber, Inc.  grants permission
   to the IETF for use of Jabber trademark in association with this
   specification and its successors, if any.

































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2. Registration

   Registering with a server is necessary in order for a user to engage
   in any desired functionality by means of a client.  Certainly such
   registration MAY (and frequently does) occur outside the context of
   an instant messaging and presence application.  However, XMPP also
   enables a user to register with a server within the context of an IM
   system.  This functionality is enabled by sending and receiving IQ
   stanzas in a request-response pattern, where the IQ stanzas contain
   <query/> elements in the 'jabber:iq:register' namespace.

2.1 Registration Data Flow

   Step 1: Client queries server regarding information that is required
   in order to register:

   <iq type="get"
       to="capulet.com"
       id="reg_1">
     <query xmlns="jabber:iq:register"/>
   </iq>

   Step 2: Server responds with the required registration fields:

   <iq type="result"
       from="capulet.com"
       id="reg_1">
     <query xmlns="jabber:iq:register">
       <instructions>
         Choose a username and password to register with this service.
       </instructions>
       <email/>
       <password/>
       <username/>
     </query>
   </iq>

   Note: the client is REQUIRED to provide information for all of the
   elements (other than <instructions/>) contained in the IQ result.
   (Note also that the XML stanza shown above does not include a 'to'
   attribute, since the connected socket does not yet have an account.)










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   Step 3: Client provides required information:

   <iq type="set"
       to="capulet.com"
       id="reg_2">
     <query xmlns="jabber:iq:register">
       <email>juliet@capulet.com</email>
       <password>R0m30</password>
       <username>juliet</username>
     </query>
   </iq>

   Step 4: Server informs client of successful registration:

   <iq
       type="result"
       from="capulet.com"
       id="reg_2"/>

   Step 4 (alt 1): Server informs client of failed registration
   (required field not provided):

   <iq
       type="error"
       from="capulet.com"
       id="reg_2"/>
     <query xmlns="jabber:iq:register">
       <email>juliet@capulet.com</email>
       <password>R0m30</password>
     </query>
     <error code="406">Not Acceptable</error>
   </iq>



















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   Step 4 (alt 2): Client is already registered:

   <iq
       type="error"
       from="capulet.com"
       id="reg_2"/>
     <query xmlns="jabber:iq:register">
       <registered/>
       <email>juliet@capulet.com</email>
       <password>R0m30</password>
       <username>juliet</username>
     </query>
     <error code="400">Bad Request</error>
   </iq>


2.2 Cancellation Data Flow

   The 'jabber:iq:register' namespace also makes it possible for a user
   to cancel a registration with a server by sending a <remove/> element
   as shown below.

   Step 1: Client sends request to unregister:

   <iq type="set"
       to="capulet.com"
       id="unreg_1">
     <query xmlns="jabber:iq:register">
       <remove/>
     </query>
   </iq>

   Step 2: Server informs client of successful unregistration:

   <iq
       type="result"
       from="capulet.com"
       id="unreg_1"/>













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3. Authentication

   In order to gain access to the network of XMPP-compliant applications
   and thus engage in standard IM functionality such as exchanging
   messages and presence, a client must authenticate with a server.

   If a client is capable of authenticating with SASL, it MUST include a
   'version' attribute (set to a value of "1.0") within the opening
   <stream/> element with which it initiated communications with the
   server.  The protocol describing how a client authenticates with a
   server using SASL is defined XMPP Core [1].

   Earlier iterations of the Jabber protocol contained a client-server
   authentication protocol that was enforced after the stream was
   negotiated; this protocol, which uses the 'jabber:iq:auth' namespace,
   is described for the sake of completeness in Authentication Using
   jabber:iq:auth (Appendix B).


































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4. Authorizing a Resource

   Once a client has authenticated with a server using SASL, it MUST
   define a resource that the server can associate with the connection
   for purposes of authorization and addressing.  This is necessary
   because all stanzas sent to or received from the server within the
   context of an active session must use a "full JID" (user@host/
   resource) for addressing.  Authorizing a resource is accomplished by
   means of the 'jabber:iq:auth' namespace as described below.

   Step 1: Client queries server regarding information that is still
   required to begin a session:

   <iq type="get" id="res_1">
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
     </query>
   </iq>

   Step 2: Server responds with the required fields (in this case, only
   the username and authorized resource):

   <iq type="result" id="res_1">
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
       <resource/>
     </query>
   </iq>

   Step 3: Client sends name of authorized resource:

   <iq type="set" id="res_2">
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
       <resource>balcony</resource>
     </query>
   </iq>

   Step 4: Server informs client of successful session initiation:

   <iq type="result" id="res_2"/>










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5. Exchanging Messages

   Exchanging messages is simple within XMPP: using a message stanza, a
   user can send a message to any other user (or, more generally, any
   entity).

5.1 Specifying an Intended Recipient

   A client SHOULD specify an intended recipient for the message by
   providing an appropriate JID in the 'to' attribute of the <message/>
   element.  Normally, the value of the 'to' attribute specifies an
   entity other than the sending user (for exceptions, see the next
   paragraph).  The intended recipient MAY be any valid JID (e.g., a
   user on the same server, a user on a different server, the server
   itself, or another server).

   If no 'to' address is specified, it is implied that the message is
   addressed to the sending user itself (i.e., the user@domain sending
   the stanza); furthermore, a message explicitly or implicitly
   addressed to the sending user itself is processed by the server on
   behalf of that user.  A message addressed to a specific connected
   resource associated with the sending user is delivered to that
   user@domain/resource (which MAY be different from the connected
   resource that generated the message).

5.2 Specifying a Message Type

   As mentioned in XMPP Core [1], there are several defined types of
   messages (specified by means of a 'type' attribute within the
   <message/> element).  In the context of an instant messaging
   application, a client MAY include a message type in order to capture
   the conversational context of the message, thus providing a hint
   regarding presentation (e.g., in a GUI).  If included, the 'type'
   attribute SHOULD have one of the following values (any other value
   MAY be ignored):

   o  chat -- The message is sent in the context of a one-to-one chat
      conversation.

   o  groupchat -- The message is sent in the context of a multi-user
      chat environment.

   o  headline -- The message is generated by an automated service that
      delivers content (news, sports, market information, etc.).

   o  error - A message returned to a sender specifying an error
      associated with a previous message sent by the sender (for a full
      list of error messages, see XMPP Core [1])



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5.3 Specifying a Message Subject

   A message stanza MAY contain a child element specifying the subject
   of the message.  The subject MUST NOT contain mixed content.

   A message with a subject:

   <message to="romeo@montague.net" from="juliet@capulet.com/balcony">
     <subject>Imploring</subject>
     <body>Wherefore art thou, Romeo?</body>
   </message>


5.4 Specifying a Message Thread

   A message stanza MAY contain a child element specifying the thread of
   the message for the purpose of tracking a conversation thread.  The
   content of the <thread/> element is a random string that is generated
   by the sender; this string MAY be copied back to the sender in
   subsequent replies.  If included, the <thread/> element MUST have no
   attributes and MUST NOT contain mixed content.

   A simple threaded conversation:

   <message
       to="romeo@montague.net/orchard"
       from="juliet@capulet.com/balcony"
       type="chat">
     <body>Art thou not Romeo, and a Montague?</body>
     <thread>283461923759234</thread>
   </message>

   <message
       to="juliet@capulet.com/balcony"
       from="romeo@montague.net/orchard"
       type="chat">
     <body>Neither, fair saint, if either thee dislike.</body>
     <thread>283461923759234</thread>
   </message>

   <message
       to="romeo@montague.net/orchard"
       from="juliet@capulet.com/balcony"
       type="chat">
     <body>How cam'st thou hither, tell me, and wherefore?</body>
     <thread>283461923759234</thread>
   </message>




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5.5 Specifying a Message Body

   A message stanza MAY (and usually will) contain a child element
   specifying the body of the message.  The body MUST NOT contain mixed
   content.  If it is necessary to provide the message body in an
   alternate form (e.g., encrypted using the public key infrastructure
   or formatted using XHTML), the alternate form SHOULD be contained in
   an appropriately-namespaced child of the message stanza other than
   the <body/> element.

5.6 Specifying Additional Information

   A message stanza MAY house an element containing content that extends
   the meaning of the message (e.g., an encrypted form of the message
   body).  In common usage this child element is often the <x/> element
   but MAY be any element, as long as the 'xmlns' namespace declaration
   is something other than the streams namespace and the default
   namespace; this extended namespace defines all elements contained
   within the child element.

5.7 Message-Related Errors

   If a message sent by a sender cannot be delivered, a server SHOULD
   return that message to the sender in a message stanza of type "error"
   along with an appropriate error message (for a list of error
   messages, see XMPP Core [1]).

   A message-related error:

   <message
       to="juliet@capulet.com"
       from="romeo@montague.net">
     <body>Sleep dwell upon thine eyes</body>
   </message>

   <message
       to="romeo@montague.net"
       from="juliet@capulet.com"
       type="error">
     <body>Sleep dwell upon thine eyes</body>
     <error code="404">No Such JID</error>
   </message>









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6. Exchanging Presence Information

   Exchanging presence information is made relatively simple within XMPP
   by using presence stanzas.  However, we see here a contrast to the
   handling of messages: although a client MAY send directed presence
   information to another entity, in general presence information is
   sent from a client to a server and then broadcasted by the server to
   any entities that are subscribed to the presence of the sending
   entity.  (Note: in the terminology of RFC 2778 [5], the only watchers
   in XMPP are subscribers.)

6.1 Client and Server Responsibilities

   When a client connects to a server, it SHOULD send an initial
   presence stanza to the server to express default availability.  This
   presence stanza MUST have no type.

   Upon receiving initial presence from a client, the server sends
   presence probes to any remote entities that are subscribed to the
   associated user's presence (as represented in the user's roster) in
   order to determine if they are available.  (The remote server is
   responsible for responding to the presence probe only when (1) the
   probing entity has been allowed to access the probed entity's
   presence, e.g., by server rules or user subscriptions, and (2) the
   probed entity is available; the probing entity's server then informs
   the probing entity of the probed entity's last known available
   presence, for all of the probed entity's resources if applicable.)
   The server then sends the user's initial presence stanza to any
   subscribed entities that are available.

   Throughout the active session of a connected resource associated with
   the client, the server is responsible for broadcasting any changes in
   the availability status of the connected resource to the subscribed
   entities that are available, so that such entities are apprised of
   availability changes.

   Finally, the server MUST notify all of the subscribed and available
   entities when a connected resource becomes unavailable.

6.2 Sending Initial Presence

   Upon authenticating, a client SHOULD send initial presence to its
   server indicating that the connected resource is available for
   communications.  This presence stanza MUST have no type.







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   Initial presence sent from client to server:

   <presence/>


6.3 Specifying Availability Status

   A client MAY provide further information about its availability
   status by using the <show/> element.  As defined in XMPP Core [1],
   the recognized values for the show element are "away", "chat", "xa",
   and "dnd".

   Availability status:

   <presence>
     <show>away</show>
   </presence>


6.4 Specifying Detailed Status Information

   In conjunction with the  <show/> element, a client MAY provide
   detailed status information by using the <status/> element.  The
   content of this element is a natural-language description of the
   client's current availability status.

   Detailed status information:

   <presence>
     <show>dnd</show>
     <status>Busy fighting the Romans</status>
   </presence>


6.5 Probing for Presence

   A client or a server MAY probe for the current presence of another
   entity.  A user probing for the presence of another user MUST have
   permission to view the presence of the probed user.

   Presence probe:

   <presence type="probe" to="romeo@montague.net"/>








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6.6 Sending Final Presence

   Upon ending its session with a server, a client SHOULD send a final
   presence stanza that is explicitly of type unavailable.

   Sending final presence to express unavailable state:

   <presence type="unavailable"/>

   Optionally, final presence MAY contain one or more <status/> elements
   specifying the reason why the user is no longer available.

6.7 Determining When a Contact Went Offline

   The server SHOULD maintain a record of the time at which a user sent
   final presence.  An authorized subscriber to that user's presence MAY
   determine the time of last activity by sending an IQ stanza to the
   user's user@host address containing an empty <query/> element scoped
   by the 'jabber:iq:last' namespace:

   Requesting the last active time of a user:

   <iq type='get' to='user@domain'>
     <query xmlns='jabber:iq:last'/>
   </iq>

   The server MUST return an IQ stanza of type 'result' with the number
   of seconds since the user was last active:

   Returning the last active time of a user:

   <iq from='user@domain' type='result' to='subscriber@domain/resource'>
     <query seconds='76490' xmlns='jabber:iq:last'/>
   </iq>

   If the entity requesting the time of last activity is not an
   authorized subscriber to the user's presence, the server MUST return
   an IQ stanza of type 'error' with an error code of 403 (Forbidden):

   Requester is forbidden to view the last active time of a user:

   <iq from='user@domain' type='result' to='subscriber@domain/resource'>
     <query xmlns='jabber:iq:last'/>
     <error code='403'>Forbidden</error>
   </iq>






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7. Managing Subscriptions

   In order to protect the privacy of instant messaging users and any
   other entities, presence and availability information is made
   available only to other entities that the user has approved.  When a
   user has agreed that another entity may view its presence, the entity
   is said to have a subscription to the user's presence information.
   Note well that a subscription lasts across sessions; indeed, it lasts
   until the subscriber unsubscribes or the subscribee cancels the
   previously-granted subscription.  Subscriptions are completed within
   XMPP by sending presence stanzas containing specially-defined
   attributes.

7.1 Requesting a Subscription

   A request to subscribe to another entity's presence is made by
   sending a presence stanza of type "subscribe".

   Sending a subscription request:

   <presence
       to="juliet@capulet.com"
       from="romeo@montague.net"
       type="subscribe"/>


7.2 Handling a Subscription Request

   When a client receives a subscription request from another entity, it
   MAY accept the request by sending a presence stanza of type
   "subscribed" or decline the request by sending a presence stanza of
   type "unsubscribed".

   Accepting a subscription request:

   <presence
       to="romeo@montague.net"
       from="juliet@capulet.com"
       type="subscribed"/>












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   Denying a presence subscription request:

   <presence
       to="romeo@montague.net"
       from="juliet@capulet.com"
       type="unsubscribed"/>


7.3 Cancelling a Subscription from Another Entity

   If a user would like to cancel a previously-granted subscription
   request, it sends a presence stanza of type "unsubscribed".

   Cancelling a previously granted subscription request:

   <presence
       to="romeo@montague.net"
       from="juliet@capulet.com"
       type="unsubscribed"/>


7.4 Unsubscribing from Another Entity's Presence

   If a user would like to unsubscribe from the presence of another
   entity, it sends a presence stanza of type "unsubscribe".

   Unsubscribing from an entity's presence:

   <presence
       to="juliet@capulet.com"
       from="romeo@montague.net"
       type="unsubscribe"/>



















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8. Blocking Communication

   Most instant messaging systems have found it necessary to implement
   some method for users to block communications from specific other
   users (this is also required by section 2.3.5 of RFC 2779 [2]).  In
   XMPP this is done using the 'jabber:iq:privacy' namespace by managing
   one's privacy lists (also called "zebra lists" since they are
   flexible combinations of blacklists and whitelists).

8.1 Retrieving One's Privacy Lists

   Client requests privacy lists from server:

   <iq type='get' id='zebra1'>
     <query xmlns='jabber:iq:privacy'/>
   </iq>

   Server sends privacy lists to client:

   <iq type='result' id='zebra1' to='romeo@montague.net/orchard'>
     <query xmlns='jabber:iq:privacy'>
       <active name='private'/>
       <list name='public'>
         <item jid='tybalt@capulet.com' type='deny'/>
         <item type='allow'/>
       </list>
       <list name='private'>
         <item subscription='both' type='allow'/>
         <item type='deny'/>
       </list>
       <list name='special'>
         <item jid='juliet@capulet.com' type='allow'/>
         <item jid='benvolio@shakespeare.lit' type='allow'/>
         <item jid='mercutio@shakespeare.lit' type='allow'/>
         <item type='deny'/>
       </list>
     </query>
   </iq>

   In this example, the user has three lists: (1) 'public', which allows
   communications from everyone except one specific entity; (2)
   'private', which allows communications only from contacts who have a
   bi-directional subscription with the user; and (3) 'special', which
   allows communications only from three specific entities.  The active
   list currently being applied by the server is the 'private' list.






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8.2 Changing the Active List

   In order to change the active list currently being applied by the
   server, the user MUST send an IQ stanza of type 'set' with a <query/>
   element scoped by the 'jabber:iq:privacy' namespace that contains an
   empty <active/> child element possessing a 'name' attribute whose
   value is set to the desired list name.

   Client requests change of active list:

   <iq type='set' id='zebra2'>
     <query xmlns='jabber:iq:privacy'>
       <active name='special'/>
     </query>
   </iq>

   Server acknowledges success of active list change:

   <iq type='result' id='zebra2' to='juliet@capulet.com/balcony'/>


8.3 Editing a Privacy List

   In order to edit a privacy list, the user MUST send an IQ stanza of
   type 'set' with a <query/> element scoped by the 'jabber:iq:privacy'
   namespace that contains one or more <list/> child elements possessing
   a 'name' attribute whose value is set to the list name the user would
   like to edit.  Each <list/> element MUST contain one or more <item/>
   elements, which specify the user's desired changes to the list by
   including all elements in the list (not the "delta"); the same
   protocol is used to create a new list.

   Client edits a privacy list:

   <iq type='set' id='zebra3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='public'>
         <item jid='tybalt@capulet.com' type='deny'/>
         <item jid='paris@shakespeare.lit' type='deny'/>
         <item type='allow'/>
       </list>
     </query>
   </iq>








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   Server acknowledges success of list edit:

   <iq type='result' id='zebra3' to='juliet@capulet.com/balcony'/>

   In this example, the user has added one additional entity to the
   "blacklist" portion of this privacy list.

8.4 Removing a Privacy List

   In order to remove a privacy list, the user MUST send an IQ stanza of
   type 'set' with a <query/> element scoped by the 'jabber:iq:privacy'
   namespace that contains one or more empty <list/> child elements
   possessing a 'name' attribute whose value is set to the list name the
   user would like to remove.

   Client removes a privacy list:

   <iq type='set' id='zebra3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='private'/>
     </query>
   </iq>

   Server acknowledges success of list removal:

   <iq type='result' id='zebra3' to='juliet@capulet.com/balcony'/>


8.5 Blacklisted Entity Attempts to Communicate with User

   If a blacklisted entity attempts to communicate with the user, the
   user's server MUST return an error of type 405 (Not Allowed) to the
   sending entity.

   Blacklisted entity attempts communication:

   <message to='romeo@montague.net' from='tybalt@capulet.com/pda'>
     <body>Have at thee, coward!</body>
   </message>












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   Server returns error to blacklisted entity:

   <message
       type='error'
       from='romeo@montague.net'
       to='tybalt@capulet.com/pda'>
     <body>Have at thee, coward!</body>
     <error code='405'>Not Allowed</error>
   </message>










































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9. Managing One's Roster

   One's list of contacts is called a roster.  A roster is stored by the
   server so that a user may access roster information from any
   connected resource.

9.1 Receiving One's Roster on Login

   Upon connecting to the server, a client SHOULD request the roster
   (however, because receiving the roster may not be desirable for all
   resources, e.g., a connection with limited bandwidth, the client's
   request for the roster is OPTIONAL).

   Client requests current roster from server:

   <iq id="roster_1" type="get">
     <query xmlns="jabber:iq:roster"/>
   </iq>

   Client receives roster from the server:

   <iq
       from="capulet.com"
       to="juliet@capulet.com/balcony"
       id="roster_1"
       type="result">
     <query xmlns="jabber:iq:roster>
       <item
           jid="romeo@montague.net"
           name="Romeo"
           subscription="both"/>
       <item
           jid="mercutio@montague.net"
           name="Mercutio"
           subscription="both">
         <group>Friends</group>
       </item>
       <item
           jid="benvolio@montague.net"
           name="Benvolio"
           subscription="both">
         <group>Friends</group>
       </item>
     </query>
   </iq>






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9.2 Adding a Roster Item

   At any time, a user MAY add an item to his or her roster.

   Client adds a new item:

   <iq type="set" id="roster_2">
     <query xmlns="jabber:iq:roster">
       <item
           name="Nurse"
           jid="nurse@capulet.com">
         <group>Servants</group>
       </item>
     </query>
   </iq>

   The server is responsible for updating the roster information in
   persistent storage, and also for pushing that change out to all
   connected resources for the user using an IQ stanza of type "set".
   This enables all connected resources to remain in sync with the
   server-based roster information.






























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   Server replies with an IQ result to the sending resource and pushes
   the updated roster information to all connected resources:

   <iq
       from="capulet.com"
       to="juliet@capulet.com/balcony"
       type="result"
       id="roster_2"/>
   <iq
       from="capulet.com"
       to="juliet@capulet.com/balcony"
       type="set"
       id="roster_3"/>
     <query xmlns="jabber:iq:roster">
       <item
           name="Nurse"
           jid="nurse@capulet.com">
         <group>Servants</group>
       </item>
     </query>
   </iq>
   <iq
       from="capulet.com"
       to="juliet@capulet.com/chamber"
       type="set"
       id="roster_3"/>
     <query xmlns="jabber:iq:roster">
       <item
           name="Nurse"
           jid="nurse@capulet.com"
           subscription="none">
         <group>Servants</group>
       </item>
     </query>
   </iq>


9.3 Deleting a Roster Item

   At any time, a user MAY delete an item from its roster by doing an IQ
   set and making sure that the value of the 'subscription' attribute is
   "remove".









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   Client removes a item:

   <iq type="set" id="roster_2">
     <query xmlns="jabber:iq:roster">
       <item
           name="Nurse"
           jid="nurse@capulet.com"
           subscription="remove">
         <group>Servants</group>
       </item>
     </query>
   </iq>

   Note: as with adding a roster item, when deleting a roster item the
   server is responsible for updating the roster information in
   persistent storage, and also for pushing that change out to all
   connected resources for the user using an IQ stanza of type "set".


































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10. Routing and Delivery Guidelines

   XML stanzas that are not handled directly by a server (e.g., for the
   purpose of data storage or rebroadcasting) are routed or delivered to
   the intended recipient of the stanza as represented by a JID in the
   'to' attribute.  The following rules apply:

   o  If the JID contains a resource identifier (to="user@domain/
      resource"), the stanza is delivered first to the resource that
      exactly matches the resource identifier, or secondarily to a
      resource that matches partially (e.g., resource "foo" partially
      matches resource identifier "foobar").

   o  If the JID contains a resource identifier and there are no
      matching resources, but there are other connected resources
      associated with the user, then message stanzas are further
      processed as if no resource is specified (see next item).  For all
      other stanzas, the server should return them to the sender with a
      type of "error" and an appropriate error code (503) and message.

   o  If the JID contains only a user@domain and there is at least one
      connected resource available for the user, the server should
      deliver the stanza to an appropriate resource based on the
      availability state, priority, and connect time of the connected
      resource(s).  (Existing XMPP implementations contain some
      hardcoded rules, based on <priority/> and most recent connection
      time, for the routing of such stanzas.  A more flexible approach
      to routing would be desirable.)

   o  If the JID contains only a user@domain and there are no connected
      resources available for the user (e.g., an IM user is offline),
      the server MAY choose to store the stanza (usually only message
      and presence subscription stanzas) on behalf of the user and
      deliver the stanza when a resource becomes available for that
      user.
















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11. Security Considerations

   For security considerations, refer to the relevant section of XMPP
   Core [1].















































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References

   [1]  Miller, J. and P. Saint-Andre, "XMPP Core (draft-ietf-xmpp-core-
        00, work in progress)", December 2002.

   [2]  Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for
        Presence and Instant Messaging", RFC 2779, February 2000,
        <http://www.ietf.org/rfc/rfc2779.txt>.

   [3]  Jabber Software Foundation, "Jabber Software Foundation", August
        2001, <http://www.jabber.org/>.

   [4]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [5]  Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
        Instant Messaging", RFC 2778, February 2000, <http://
        www.ietf.org/rfc/rfc2778.txt>.

   [6]  Dawson, F. and T. Howes, "vCard MIME Directory Profile", RFC
        2426, September 1998.


Authors' Addresses

   Jeremie Miller
   Jabber Software Foundation
   1899 Wynkoop Street, Suite 600
   Denver, CO  80202
   US

   EMail: jeremie@jabber.org
   URI:   http://www.jabber.org/people/jer.php


   Peter Saint-Andre
   Jabber Software Foundation
   1899 Wynkoop Street, Suite 600
   Denver, CO  80202
   US

   EMail: stpeter@jabber.org
   URI:   http://www.jabber.org/people/stpeter.php








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Appendix A. vCards

   Sections 3.1.3 and 4.1.4 of RFC 2779 [2] require that it be possible
   to retrieve non-IM contact information for other users (e.g.,
   telephone number or email address).  An XML representation of the
   vCard specification defined in RFC 2426 [6] is in common use within
   the Jabber community to provide such information.  For the sake of
   completeness, this section describes that protocol.  This section is
   non-normative.

   The basic functionality is for a user to store and retrieve an XML
   representation of his or her vCard using the data storage
   capabilities native to all existing Jabber server implementations.
   This is done by sending an <iq/> of type "set" (storage) or "get"
   (retrieval) to one's Jabber server containing a <vCard/> child scoped
   by the 'vcard-temp' namespace, with the <vCard/> element containing
   the actual vCard-XML elements as defined by the vCard-XML DTD.  Other
   users may then view one's vCard information.  (There is currently no
   access control over who may view vCard information.)

A.1 Retrieving One's vCard

   A user may retrieve his or her own vCard by sending XML of the
   following form to his or her own JID:

   <iq to='stpeter@jabber.org' type='get' id='vcard1'>
     <vCard xmlns='vcard-temp'/>
   </iq>

   The server must then return the vCard to the user:

   <iq
       from='stpeter@jabber.org'
       to='stpeter@jabber.org/Gabber'
       type='result'
       id='v1'>
     <vCard xmlns='vcard-temp'>
       <FN>Peter Saint-Andre</FN>
       <N>
         <FAMILY>Saint-Andre<FAMILY>
         <GIVEN>Peter</GIVEN>
         <MIDDLE/>
       </N>
       <NICKNAME>stpeter</NICKNAME>
       <URL>http://www.jabber.org/people/stpeter.php</URL>
       <BDAY>1966-08-06</BDAY>
       <ORG>
         <ORGNAME>Jabber Software Foundation</ORGNAME>



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         <ORGUNIT/>
       </ORG>
       <TITLE>Executive Director</TITLE>
       <ROLE>Patron Saint</ROLE>
       <TEL><VOICE/><WORK/><NUMBER>303-308-3282</NUMBER></TEL>
       <TEL><FAX/><WORK/><NUMBER/></TEL>
       <TEL><MSG/><WORK/><NUMBER/></TEL>
       <ADR>
         <WORK/>
         <EXTADD>Suite 600</EXTADD>
         <STREET>1899 Wynkoop Street</STREET>
         <LOCALITY>Denver</LOCALITY>
         <REGION>CO</REGION>
         <PCODE>80202</PCODE>
         <CTRY>USA</CTRY>
       </ADR>
       <TEL><VOICE/><HOME/><NUMBER>303-555-1212</NUMBER></TEL>
       <TEL><FAX/><HOME/><NUMBER/></TEL>
       <TEL><MSG/><HOME/><NUMBER/></TEL>
       <ADR>
         <HOME/>
         <EXTADD/>
         <STREET/>
         <LOCALITY>Denver</LOCALITY>
         <REGION>CO</REGION>
         <PCODE>80209</PCODE>
         <CTRY>USA</CTRY>
       </ADR>
       <EMAIL><INTERNET/><PREF/><USERID>stpeter@jabber.org</USERID></EMAIL>
       <JABBERID>stpeter@jabber.org</JABBERID>
       <DESC>
         More information about me is located on my
         personal website: http://www.saint-andre.com/
       </DESC>
     </vCard>
   </iq>


A.2 Updating One's vCard

   A user may update his or her vCard by sending an IQ of type "set" to
   the server, following the format in the previous use case.

   If a user attempts to perform an IQ set on another user's vCard, the
   server must return a 403 "Forbidden" error.






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A.3 Viewing Another User's vCard

   A user may view another user's vCard by sending an IQ of type "get"
   to the other user's bare JID.  A compliant server must return the
   vCard to the requestor and not forward the IQ to the requestee's
   connected resource.

   <iq
       to='jer@jabber.org'
       type='get'
       id='v3'>
     <vCard xmlns='vcard-temp'/>
   </iq>

   The server should then return the other user's vCard to the
   requestor:

   <iq
       from='jer@jabber.org'
       to='stpeter@jabber.org/home'
       type='result'
       id='v3'>
     <vCard xmlns='vcard-temp'>
       <FN>JeremieMiller</FN>
       <N>
         <GIVEN>Jeremie</GIVEN>
         <FAMILY>Miller</FAMILY>
         <MIDDLE/>
       </N>
       <NICKNAME>jer</NICKNAME>
       <EMAIL><INTERNET/><PREF/><USERID>jeremie@jabber.org</USERID></EMAIL>
       <JABBERID>jer@jabber.org</JABBERID>
     </vCard>
   </iq>

















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Appendix B. Authentication Using jabber:iq:auth

   This section is provided for informational purposes only and is not
   normative.

   The 'jabber:iq:auth' namespace provides two things: (1) a simple way
   for a client to authenticate with a server and (2) a way to define an
   authorized resource representing a specific connection or session.

   The following is the data flow for a complete example of
   authentication and authorization with a server using the
   'jabber:iq:auth' namespace.

   Step 1: Client queries server regarding information that is required
   in order to authenticate:

   <iq type="get" id="auth_1">
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
     </query>
   </iq>

   Step 2: Server responds with the required authentication fields:

   <iq type="result" id="auth_1">
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
       <digest/>
       <resource/>
     </query>
   </iq>

   Step 3: Client sends authentication information (encrypted password):

   <iq type="set" id="auth_2">
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
       <digest>64d60e40febe09264c52bc9cbddd5dd1147fae97</digest>
       <resource>balcony</resource>
     </query>
   </iq>

   Step 4: Server informs client of successful authentication:

   <iq type="result" id="auth_2"/>






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   Step 4 (alt): Server informs client of failed authentication:

   <iq
       type="error"
       from="capulet.com"
       id="auth_2"/>
     <query xmlns="jabber:iq:auth">
       <username>juliet</username>
       <digest>64d60e40febe09264c5wrongpassword2bc9cbddd5dd1147fae97</digest>
       <resource>balcony</resource>
     </query>
     <error code="401">Unauthorized</error>
   </iq>






































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Appendix C. Formal Definitions

C.1 jabber:iq:last

C.1.1 DTD

   <!ELEMENT query EMPTY>
   <!ATTLIST query seconds #IMPLIED>


C.1.2 Schema

   <?xml version='1.0' encoding='UTF-8'?>
   <xsd:schema
       xmlns:xsd='http://www.w3.org/2001/XMLSchema'
       targetNamespace='http://www.jabber.org/protocol'
       xmlns='http://www.jabber.org/protocol'
       elementFormDefault='qualified'>

     <xsd:element name='query'>
       <xsd:complexType>
         <xsd:attribute name='seconds' type='xsd:unsignedLong' use='optional'/>
       </xsd:complexType>
     </xsd:element>

   </xsd:schema>


C.2 jabber:iq:privacy






















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C.2.1 DTD

   <!ELEMENT query (active? | list*)>
   <!ELEMENT active EMPTY>
   <!ATTLIST active name CDATA #REQUIRED>
   <!ELEMENT list (item*)>
   <!ATTLIST list name CDATA #REQUIRED>
   <!ELEMENT item ((iq? | message? | presence?)*)>
   <!ATTLIST item
       jid CDATA #IMPLIED
       type (allow | deny) #REQUIRED
       subscription (from | to) #IMPLIED>
   <!ELEMENT iq EMPTY>
   <!ELEMENT message EMPTY>
   <!ELEMENT presence EMPTY>


C.2.2 Schema

   <?xml version='1.0' encoding='UTF-8'?>
   <xsd:schema
       xmlns:xsd='http://www.w3.org/2001/XMLSchema'
       targetNamespace='http://www.jabber.org/protocol'
       xmlns='http://www.jabber.org/protocol'
       elementFormDefault='qualified'>

     <xsd:element name='query'>
       <xsd:complexType>
         <xsd:choice minOccurs='0' maxOccurs='unbounded'>
           <xsd:element ref='active' minOccurs='0' maxOccurs='1'/>
           <xsd:element ref='list' minOccurs='0' maxOccurs='unbounded'/>
         </xsd:choice>
       </xsd:complexType>
     </xsd:element>

     <xsd:element name='active'>
       <xsd:complexType>
         <xsd:attribute name='name' type='xsd:string' use='required'/>
       </xsd:complexType>
     </xsd:element>

     <xsd:element name='list'>
       <xsd:complexType>
         <xsd:choice minOccurs='0' maxOccurs='unbounded'>
           <xsd:element ref='item' minOccurs='0' maxOccurs='unbounded'/>
         </xsd:choice>
         <xsd:attribute name='name' type='xsd:string' use='required'/>
       </xsd:complexType>



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     </xsd:element>

     <xsd:element name='item'>
       <xsd:complexType>
         <xsd:choice>
           <xsd:element ref='iq' minOccurs='0' maxOccurs='1'/>
           <xsd:element ref='message' minOccurs='0' maxOccurs='1'/>
           <xsd:element ref='presence' minOccurs='0' maxOccurs='1'/>
         </xsd:choice>
         <xsd:attribute name='jid' type='xsd:string' use='required'/>
         <xsd:attribute name='type' use='required'>
           <xsd:simpleType>
             <xsd:restriction base='xsd:NCName'>
               <xsd:enumeration value='allow'/>
               <xsd:enumeration value='deny'/>
             </xsd:restriction>
           </xsd:simpleType>
         </xsd:attribute>
         <xsd:attribute name='subscription' use='optional'>
           <xsd:simpleType>
             <xsd:restriction base='xsd:NCName'>
               <xsd:enumeration value='to'/>
               <xsd:enumeration value='from'/>
               <xsd:enumeration value='both'/>
             </xsd:restriction>
           </xsd:simpleType>
         </xsd:attribute>
       </xsd:complexType>
     </xsd:element>

     <xsd:element name='iq'/>
     <xsd:element name='message'/>
     <xsd:element name='presence'/>

   </xsd:schema>


C.3 jabber:iq:register

C.3.1 Children

   While numerous fields are available for use in the
   'jabber:iq:register' namespace, only those fields (other than
   <instructions/>) sent from the server in an IQ result are REQUIRED in
   order to register.  The following are the allowable children of a
   <query/> element scoped by the 'jabber:iq:register' namespace:

   o  instructions



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   o  username

   o  password

   o  name

   o  email

   o  address

   o  city

   o  state

   o  zip

   o  phone

   o  url

   o  date

   o  misc

   o  text

   o  remove - request to unregister (sent only in an IQ set)
























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C.3.2 DTD

   <!ELEMENT query ((instructions? | username? |
       password? | name? | email? | address? |
       city? | state? | zip? | phone? | url? |
       date? | misc? | text? | remove?)*)>

   <!ELEMENT instructions (#PCDATA)>
   <!ELEMENT username (#PCDATA)>
   <!ELEMENT password (#PCDATA)>
   <!ELEMENT name (#PCDATA)>
   <!ELEMENT email (#PCDATA)>
   <!ELEMENT address (#PCDATA)>
   <!ELEMENT city (#PCDATA)>
   <!ELEMENT state (#PCDATA)>
   <!ELEMENT zip (#PCDATA)>
   <!ELEMENT phone (#PCDATA)>
   <!ELEMENT url (#PCDATA)>
   <!ELEMENT date (#PCDATA)>
   <!ELEMENT misc (#PCDATA)>
   <!ELEMENT text (#PCDATA)>
   <!ELEMENT remove EMPTY>


C.3.3 Schema

   <?xml version='1.0' encoding='UTF-8'?>
   <xsd:schema
       xmlns:xsd='http://www.w3.org/2001/XMLSchema'
       targetNamespace='http://www.jabber.org/protocol'
       xmlns='http://www.jabber.org/protocol'
       elementFormDefault='qualified'>

     <xsd:element name='query'>
       <xsd:complexType>
         <xsd:choice minOccurs='0' maxOccurs='unbounded'>
           <xsd:element ref='instructions'/>
           <xsd:element ref='username'/>
           <xsd:element ref='password'/>
           <xsd:element ref='name'/>
           <xsd:element ref='email'/>
           <xsd:element ref='address'/>
           <xsd:element ref='city'/>
           <xsd:element ref='state'/>
           <xsd:element ref='zip'/>
           <xsd:element ref='phone'/>
           <xsd:element ref='url'/>
           <xsd:element ref='date'/>



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           <xsd:element ref='misc'/>
           <xsd:element ref='text'/>
           <xsd:element ref='remove'/>
         </xsd:choice>
       </xsd:complexType>
     </xsd:element>

     <xsd:element name='instructions' type='xsd:string'/>
     <xsd:element name='username' type='xsd:string'/>
     <xsd:element name='password' type='xsd:string'/>
     <xsd:element name='name' type='xsd:string'/>
     <xsd:element name='email' type='xsd:string'/>
     <xsd:element name='address' type='xsd:string'/>
     <xsd:element name='city' type='xsd:string'/>
     <xsd:element name='state' type='xsd:string'/>
     <xsd:element name='zip' type='xsd:string'/>
     <xsd:element name='phone' type='xsd:string'/>
     <xsd:element name='url' type='xsd:string'/>
     <xsd:element name='date' type='xsd:string'/>
     <xsd:element name='misc' type='xsd:string'/>
     <xsd:element name='text' type='xsd:string'/>
     <xsd:element name='remove'/>

   </xsd:schema>


C.4 jabber:iq:roster

C.4.1 Children

   A <query/> element scoped by the 'jabber:iq:roster' namespace MAY
   contain zero or more <item/> elements.  An item element MAY contain
   the following attributes:

   o  jid - A REQUIRED attribute that contains the complete JID of the
      contact that this item represents

   o  name - An OPTIONAL attribute that contains a natural-language name
      for the contact

   o  subscription - The current status of the subscription related to
      this item.  Should be one of the following (all other values are
      ignored):

      *  none - no subscription.

      *  from - this entity has a subscription to the contact.




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      *  to - the contact has a subscription to this entity.

      *  both - subscription is both to and from.

      *  remove - item is to be removed.

   o  ask - An OPTIONAL attribute specifying the current status of a
      request to this contact.  Should be one of the following (all
      other values are ignored):

      *  subscribe - this entity is asking to subscribe to that
         contact's presence.

      *  unsubscribe - this entity is asking unsubscribe from that
         contact's presence.

   An <item/> element MAY contain zero or more instances of the
   following element:

   o  group - Natural-language name of a user-specified group for the
      purpose of categorizing contacts into groups.


C.4.2 DTD

   <!ELEMENT query ((item)*)>

   <!ELEMENT item ((group)*)>
   <!ATTLIST item
       jid CDATA #REQUIRED
       name CDATA #IMPLIED
       subscription ( to | from | both | none | remove ) #IMPLIED
       ask ( subscribe | unsubscribe ) #IMPLIED
       >
   <!ELEMENT group (#PCDATA)>


C.4.3 Schema

   <?xml version='1.0' encoding='UTF-8'?>
   <xsd:schema
       xmlns:xsd='http://www.w3.org/2001/XMLSchema'
       targetNamespace='http://www.jabber.org/protocol'
       xmlns='http://www.jabber.org/protocol'
       elementFormDefault='qualified'>

     <xsd:element name='query'>
       <xsd:complexType>



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         <xsd:sequence minOccurs='0' maxOccurs='unbounded'>
           <xsd:element ref='item'/>
         </xsd:sequence>
       </xsd:complexType>
     </xsd:element>

     <xsd:element name='item'>
       <xsd:complexType>
         <xsd:sequence minOccurs='0' maxOccurs='unbounded'>
           <xsd:element ref='group'/>
         </xsd:sequence>
         <xsd:attribute name='jid' type='xsd:string' use='required'/>
         <xsd:attribute name='name' type='xsd:string' use='optional'/>
         <xsd:attribute name='subscription' use='optional'>
           <xsd:simpleType>
             <xsd:restriction base='xsd:string'>
               <xsd:enumeration value='to'/>
               <xsd:enumeration value='from'/>
               <xsd:enumeration value='both'/>
               <xsd:enumeration value='none'/>
               <xsd:enumeration value='remove'/>
             </xsd:restriction>
           </xsd:simpleType>
         </xsd:attribute>
         <xsd:attribute name='ask' use='optional'>
           <xsd:simpleType>
             <xsd:restriction base='xsd:string'>
               <xsd:enumeration value='subscribe'/>
               <xsd:enumeration value='unsubscribe'/>
             </xsd:restriction>
           </xsd:simpleType>
         </xsd:attribute>
       </xsd:complexType>
     </xsd:element>

     <xsd:element name='group' type='xsd:string'/>

   </xsd:schema>


C.5 vcard-temp

   The following DTD is a slightly modified version of that contained in
   the second vCard-XML Internet-Draft authored by Frank Dawson.  The
   only modifications were to add the JABBERID and DESC elements.

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




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   <!--
   Copyright (C) The Internet Society (2000). All Rights Reserved.

   This document and translations of it may be copied and
   furnished to others, and derivative works that comment
   on or otherwise explain it or assist in its implmentation
   may be prepared, copied, published and distributed, in whole
   or in part, without restriction of any kind, provided that
   the above copyright notice and this paragraph are included
   on all such copies and derivative works.

   However, this document itself may not be modified in any
   way, such as by removing the copyright notice or references
   to the Internet Society or other Internet organizations,
   except as needed for the purpose of developing Internet
   standards in which case the procedures for copyrights
   defined in the Internet Standards process MUST be followed,
   or as required to translate it into languages other than English.

   The limited permissions granted above are perpetual and will
   not be revoked by the Internet Society or its successors or
   assigns.

   This document and the information contained herein is provided
   on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIMS 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.
   -->

   <!-- ==== -->

   <!-- Root element and container for one
     or more vCard objects -->
   <!ELEMENT xCard (vCard)+>

   <!-- Individual vCard container -->
   <!ELEMENT vCard (
     (VERSION, FN, N),
     (NICKNAME?,
     PHOTO?,
     BDAY?,
     ADR?,
     LABEL?,
     TEL?,
     EMAIL?,



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     JABBERID?,
     MAILER?,
     TZ?,
     GEO?,
     TITLE?,
     ROLE?,
     LOGO?,
     AGENT?,
     ORG?,
     CATEGORIES?,
     NOTE?,
     PRODID?,
     REV?,
     SORT-STRING?,
     SOUND?,
     UID?,
     URL?,
     CLASS?,
     KEY?,
     DESC?
   )*)>

     <!-- vCard specification version property.
       This MUST be 2.0, if the document conforms to RFC 2426. -->
     <!ELEMENT VERSION (#PCDATA)>

     <!-- Formatted or display name property. -->
     <!ELEMENT FN (#PCDATA)>

     <!-- Structured name property. Name components with multiple
       values must be specified as a comma separated
        list of values. -->
     <!ELEMENT N ( FAMILY?, GIVEN?, MIDDLE?, PREFIX?, SUFFIX?)>

       <!ELEMENT FAMILY (#PCDATA)>
       <!ELEMENT GIVEN (#PCDATA)>
       <!ELEMENT MIDDLE (#PCDATA)>
       <!ELEMENT PREFIX (#PCDATA)>
       <!ELEMENT SUFFIX (#PCDATA)>

     <!-- Nickname property. Multiple nicknames must be
       specified as a comma separated list value. -->
     <!ELEMENT NICKNAME (#PCDATA)>

     <!-- Photograph property. Value is either a BASE64 encoded
       binary value or a URI to the external content. -->
     <!ELEMENT PHOTO ((TYPE, BINVAL) | EXTVAL)>




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     <!-- Birthday property. Value must be an ISO 8601 formatted
       date or date/time value. -->
     <!ELEMENT BDAY (#PCDATA)>

     <!-- Structured address property. Address components with
       multiple values must be specified as a comma separated list
       of values. -->
     <!ELEMENT ADR (
       HOME?,
       WORK?,
       POSTAL?,
       PARCEL?,
       (DOM | INTL)?,
       PREF?,
       POBOX?,
       EXTADR?,
       STREET?,
       LOCALITY?,
       REGION?,
       PCODE?,
       CTRY?
     )>

       <!ELEMENT POBOX (#PCDATA)>
       <!ELEMENT EXTADR (#PCDATA)>
       <!ELEMENT STREET (#PCDATA)>
       <!ELEMENT LOCALITY (#PCDATA)>
       <!ELEMENT REGION (#PCDATA)>
       <!ELEMENT PCODE (#PCDATA)>
       <!ELEMENT CTRY (#PCDATA)>

     <!-- Address label property. -->
     <!ELEMENT LABEL (
       HOME?,
       WORK?,
       POSTAL?,
       PARCEL?,
       (DOM | INTL)?,
       PREF?,
       LINE+
     )>

       <!-- Individual label lines. -->
       <!ELEMENT LINE (#PCDATA)>

     <!-- Telephone number property. -->
     <!ELEMENT TEL (
       HOME?,



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       WORK?,
       VOICE?,
       FAX?,
       PAGER?,
       MSG?,
       CELL?,
       VIDEO?,
       BBS?,
       MODEM?,
       ISDN?,
       PCS?,
       PREF?,
       NUMBER
     )>

       <!-- Phone number value. -->
       <!ELEMENT NUMBER (#PCDATA)>

     <!-- Email address property. Default type is INTERNET. -->
     <!ELEMENT EMAIL (
       HOME?,
       WORK?,
       INTERNET?,
       X400?,
       USERID
     )>

       <!ELEMENT USERID (#PCDATA)>

     <!-- Jabber ID. Value must be in the form of user@host. -->
     <!ELEMENT JABBERID (#PCDATA)>

     <!-- Mailer (e.g., Mail User Agent Type) property. -->
     <!ELEMENT MAILER (#PCDATA)>

     <!-- Time zone's Standard Time UTC offset. Value must be an
       ISO 8601 formatted UTC offset. -->
     <!ELEMENT TZ (#PCDATA)>

     <!-- Geographical position. Values are the decimal degress of
       LATitude and LONgitude. The value should be specified to
       six decimal places.-->
     <!ELEMENT GEO (LAT, LON)>

       <!-- Latitude value. -->
       <!ELEMENT LAT (#PCDATA)>

       <!-- Longitude value. -->



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       <!ELEMENT LON (#PCDATA)>

     <!-- Title property. -->
     <!ELEMENT TITLE (#PCDATA)>

     <!-- Role property. -->
     <!ELEMENT ROLE (#PCDATA)>

     <!-- Organization logo property. -->
     <!ELEMENT LOGO ((TYPE, BINVAL) | EXTVAL)>

     <!-- Administrative agent property. -->
     <!ELEMENT AGENT (vCard | EXTVAL)>

     <!-- Organizational name and units property. -->
     <!ELEMENT ORG (ORGNAME, ORGUNIT*)>

       <!ELEMENT ORGNAME (#PCDATA)>

       <!ELEMENT ORGUNIT (#PCDATA)>

     <!-- Application specific categories property. -->
     <!ELEMENT CATEGORIES (KEYWORD+)>

       <!ELEMENT KEYWORD (#PCDATA)>

     <!-- Commentary note property. -->
     <!ELEMENT NOTE (#PCDATA)>

     <!-- Identifier of product that generated the vCard property. -->
     <!ELEMENT PRODID (#PCDATA)>

     <!-- Last revised property. The value must be an
          ISO 8601 formatted UTC date/time. -->
     <!ELEMENT REV (#PCDATA)>

     <!-- Sort string property. -->
     <!ELEMENT SORT-STRING (#PCDATA)>

     <!-- Formatted name pronunciation property. The value is
          either a textual phonetic pronunciation, a BASE64
          encoded binary digital audio pronunciation or a URI to
          an external binary digital audio pronunciation.-->
     <!ELEMENT SOUND (PHONETIC | BINVAL | EXTVAL)>

       <!-- Textual phonetic pronunciation. -->
       <!ELEMENT PHONETIC (#PCDATA)>




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     <!-- Unique identifier property. -->
     <!ELEMENT UID (#PCDATA)>

     <!-- Directory URL property. -->
     <!ELEMENT URL (#PCDATA)>

     <!-- Description. -->
     <!ELEMENT DESC (#PCDATA)>

     <!-- Privacy classification property. -->
     <!ELEMENT CLASS (PUBLIC | PRIVATE | CONFIDENTIAL)>

       <!ELEMENT PUBLIC EMPTY>

       <!ELEMENT PRIVATE EMPTY>

       <!ELEMENT CONFIDENTIAL EMPTY>

     <!-- Authentication credential or encryption  key property. -->
     <!ELEMENT KEY (TYPE?, CRED)>

       <!ELEMENT CRED (#PCDATA)>

   <!-- ==== -->

   <!-- Common elements. -->

   <!-- Addressing type indicators. -->
   <!ELEMENT HOME EMPTY>
   <!ELEMENT WORK EMPTY>
   <!ELEMENT POSTAL EMPTY>
   <!ELEMENT PARCEL EMPTY>
   <!ELEMENT DOM EMPTY>
   <!ELEMENT INTL EMPTY>
   <!ELEMENT PREF EMPTY>
   <!ELEMENT VOICE EMPTY>
   <!ELEMENT FAX EMPTY>
   <!ELEMENT PAGER EMPTY>
   <!ELEMENT MSG EMPTY>
   <!ELEMENT CELL EMPTY>
   <!ELEMENT VIDEO EMPTY>
   <!ELEMENT BBS EMPTY>
   <!ELEMENT MODEM EMPTY>
   <!ELEMENT ISDN EMPTY>
   <!ELEMENT PCS EMPTY>
   <!ELEMENT INTERNET EMPTY>
   <!ELEMENT X400 EMPTY>




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   <!-- Format type parameter. -->
   <!ELEMENT TYPE (#PCDATA)>

   <!-- Base64 encoded binary value. -->
   <!ELEMENT BINVAL (#PCDATA)>

   <!-- URI to external binary value -->
   <!ELEMENT EXTVAL (#PCDATA)>

   <!-- ==== -->









































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Appendix D. Revision History

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

D.1 Changes from draft-miller-xmpp-im-02

   o  Added information about the 'jabber:iq:last' protocol to meet the
      requirement defined in section 3.2.4 of RFC 2779.

   o  Added information about the 'jabber:iq:privacy' protocol to meet
      the requirement defined in section 2.3.5 of RFC 2779.

   o  Added information about the vCard XML protocol to meet the
      requirement defined in sections 3.1.3 and 4.1.4 of RFC 2779.

   o  Changed the material describing authentication (but not resource
      authorization) with 'jabber:iq:auth' to non-normative.

   o  Noted that the only watchers are subscribers.

   o  Nomenclature changes: (1) from "chunks" to "stanzas"; (2) from
      "host" to "server"; (3) from "node" to "client" or "user" (as
      appropriate).



























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Full Copyright Statement

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS 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.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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