Network Working Group P. Saint-Andre Internet-Draft J. Miller Expires: August 4, 2003 Jabber Software Foundation February 03, 2003 XMPP Instant Messaging draft-ietf-xmpp-im-02 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 4, 2003. Copyright Notice Copyright (C) The Internet Society (2003). 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. Saint-Andre & Miller Expires August 4, 2003 [Page 1] Internet-Draft XMPP Instant Messaging February 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 5 1.5 Intellectual Property Notice . . . . . . . . . . . . . . . . 5 2. Authentication . . . . . . . . . . . . . . . . . . . . . . . 6 3. Authorizing a Resource . . . . . . . . . . . . . . . . . . . 7 4. Exchanging Messages . . . . . . . . . . . . . . . . . . . . 9 4.1 Specifying an Intended Recipient . . . . . . . . . . . . . . 9 4.2 Specifying a Message Type . . . . . . . . . . . . . . . . . 9 4.3 Specifying a Message Subject . . . . . . . . . . . . . . . . 10 4.4 Specifying a Conversation Thread . . . . . . . . . . . . . . 10 4.5 Specifying a Message Body . . . . . . . . . . . . . . . . . 11 4.6 Specifying Additional Information . . . . . . . . . . . . . 11 4.7 Message-Related Errors . . . . . . . . . . . . . . . . . . . 12 5. Exchanging Presence Information . . . . . . . . . . . . . . 13 5.1 Client and Server Responsibilities . . . . . . . . . . . . . 13 5.2 Sending Initial Presence . . . . . . . . . . . . . . . . . . 13 5.3 Specifying Availability Status . . . . . . . . . . . . . . . 14 5.4 Specifying Detailed Status Information . . . . . . . . . . . 14 5.5 Probing for Presence . . . . . . . . . . . . . . . . . . . . 14 5.6 Sending Final Presence . . . . . . . . . . . . . . . . . . . 14 5.7 Determining When a Contact Went Offline . . . . . . . . . . 15 6. Managing Subscriptions . . . . . . . . . . . . . . . . . . . 16 6.1 Requesting a Subscription . . . . . . . . . . . . . . . . . 16 6.2 Handling a Subscription Request . . . . . . . . . . . . . . 16 6.3 Cancelling a Subscription from Another Entity . . . . . . . 17 6.4 Unsubscribing from Another Entity's Presence . . . . . . . . 17 7. Blocking Communication . . . . . . . . . . . . . . . . . . . 18 7.1 Retrieving One's Privacy Lists . . . . . . . . . . . . . . . 18 7.2 Changing the Active List . . . . . . . . . . . . . . . . . . 19 7.3 Editing a Privacy List . . . . . . . . . . . . . . . . . . . 19 7.4 Removing a Privacy List . . . . . . . . . . . . . . . . . . 20 7.5 Blacklisted Entity Attempts to Communicate with User . . . . 20 8. Managing One's Roster . . . . . . . . . . . . . . . . . . . 22 8.1 Retrieving One's Roster on Login . . . . . . . . . . . . . . 22 8.2 Adding a Roster Item . . . . . . . . . . . . . . . . . . . . 23 8.3 Deleting a Roster Item . . . . . . . . . . . . . . . . . . . 24 9. Routing and Delivery Guidelines . . . . . . . . . . . . . . 26 10. Security Considerations . . . . . . . . . . . . . . . . . . 27 References . . . . . . . . . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 28 A. In-Band Registration . . . . . . . . . . . . . . . . . . . . 29 A.1 Registration Data Flow . . . . . . . . . . . . . . . . . . . 29 A.2 Cancellation Data Flow . . . . . . . . . . . . . . . . . . . 31 Saint-Andre & Miller Expires August 4, 2003 [Page 2] Internet-Draft XMPP Instant Messaging February 2003 B. Authentication Using jabber:iq:auth . . . . . . . . . . . . 32 C. vCards . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 C.1 Retrieving One's vCard . . . . . . . . . . . . . . . . . . . 34 C.2 Updating One's vCard . . . . . . . . . . . . . . . . . . . . 35 C.3 Viewing Another User's vCard . . . . . . . . . . . . . . . . 36 D. Formal Definitions . . . . . . . . . . . . . . . . . . . . . 37 D.1 jabber:iq:auth . . . . . . . . . . . . . . . . . . . . . . . 37 D.1.1 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 D.1.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 D.2 jabber:iq:last . . . . . . . . . . . . . . . . . . . . . . . 37 D.2.1 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 D.2.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 D.3 jabber:iq:privacy . . . . . . . . . . . . . . . . . . . . . 38 D.3.1 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 D.3.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 D.4 jabber:iq:register . . . . . . . . . . . . . . . . . . . . . 40 D.4.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 40 D.4.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 D.4.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 D.5 jabber:iq:roster . . . . . . . . . . . . . . . . . . . . . . 42 D.5.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 42 D.5.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 D.5.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 D.6 vcard-temp . . . . . . . . . . . . . . . . . . . . . . . . . 45 E. Revision History . . . . . . . . . . . . . . . . . . . . . . 52 E.1 Changes from draft-ietf-xmpp-im-01 . . . . . . . . . . . . . 52 E.2 Changes from draft-ietf-xmpp-im-00 . . . . . . . . . . . . . 52 E.3 Changes from draft-miller-xmpp-im-02 . . . . . . . . . . . . 52 Full Copyright Statement . . . . . . . . . . . . . . . . . . 53 Saint-Andre & Miller Expires August 4, 2003 [Page 3] Internet-Draft XMPP Instant Messaging February 2003 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, 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 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 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 (in XMPP called a "roster") 1.3 Terminology This document inherits the terminology defined in XMPP Core [1]. The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [4]. Saint-Andre & Miller Expires August 4, 2003 [Page 4] Internet-Draft XMPP Instant Messaging February 2003 1.4 Discussion Venue The authors welcome discussion and comments related to the topics presented in this document. The preferred forum is the mailing list, for which archives and subscription information are available at . 1.5 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 the Jabber trademark in association with this specification and its successors, if any. Saint-Andre & Miller Expires August 4, 2003 [Page 5] Internet-Draft XMPP Instant Messaging February 2003 2. 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 first register an account with a server (or a server administrator must create such an account); for the sake of completeness, an in-band mechanism for registration is described non-normatively in In-Band Registration (Appendix A). Once a user has an account, the user must subsequently authenticate with the server in order to gain access to the network. If a user's client is capable of authenticating by means of SASL, it MUST include a 'version' attribute (set to a value of "1.0") within the opening 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; for the sake of completeness, this protocol, which uses the 'jabber:iq:auth' namespace, is described non-normatively in Authentication Using jabber:iq:auth (Appendix B). Saint-Andre & Miller Expires August 4, 2003 [Page 6] Internet-Draft XMPP Instant Messaging February 2003 3. 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 stanzas sent to or received from the server within the context of an active session 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: juliet Step 2: Server responds with the required fields (in this case, only the username and authorized resource): juliet Step 3: Client sends name of authorized resource: juliet balcony Step 4: Server informs client of successful session initiation: Saint-Andre & Miller Expires August 4, 2003 [Page 7] Internet-Draft XMPP Instant Messaging February 2003 Step 4 (alt): Server informs client of error encountered during session initiation: juliet Not Acceptable (empty resource) Saint-Andre & Miller Expires August 4, 2003 [Page 8] Internet-Draft XMPP Instant Messaging February 2003 4. Exchanging Messages Exchanging messages is a basic use of XMPP and is effected when a user sends a message stanza to another user (or, more generally, another entity). 4.1 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 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, another server, or a service). If no 'to' address is specified, it is implied that the message is addressed to the sending user itself (i.e., the user@host 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@host/ resource (which MAY be different from the connected resource that generated the message). 4.2 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 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]) Saint-Andre & Miller Expires August 4, 2003 [Page 9] Internet-Draft XMPP Instant Messaging February 2003 4.3 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: Imploring Wherefore art thou, Romeo? Multiple elements MAY be included, as long as each contains an 'xml:lang' attribute with a distince value. 4.4 Specifying a Conversation Thread A message stanza MAY contain a child element specifying the conversation thread in which the message is situated, for the purpose of tracking the conversation thread. The content of the element is a random string that is generated by the sender in accordance with the algorithm specified in XMPP Core [1]; this string MAY be copied back to the sender in subsequent replies. If included, the element MUST have no attributes and MUST NOT contain mixed content. Saint-Andre & Miller Expires August 4, 2003 [Page 10] Internet-Draft XMPP Instant Messaging February 2003 A threaded conversation: Art thou not Romeo, and a Montague? e0ffe42b28561960c6b12b944a092794b9683a38 Neither, fair saint, if either thee dislike. e0ffe42b28561960c6b12b944a092794b9683a38 How cam'st thou hither, tell me, and wherefore? e0ffe42b28561960c6b12b944a092794b9683a38 4.5 Specifying a Message Body A message stanza MAY (and often 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 element. 4.6 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 element but MAY be any element, as long as the 'xmlns' namespace declaration is something other than the streams namespace or the default namespace; this extended namespace defines all elements contained within the child element. Saint-Andre & Miller Expires August 4, 2003 [Page 11] Internet-Draft XMPP Instant Messaging February 2003 4.7 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: Sleep dwell upon thine eyes Sleep dwell upon thine eyes No Such JID An entity that receives a message stanza of type 'error' MUST NOT respond to the stanza by sending a further message stanza of type 'error'; this helps to prevent looping. Saint-Andre & Miller Expires August 4, 2003 [Page 12] Internet-Draft XMPP Instant Messaging February 2003 5. Exchanging Presence Information Exchanging presence information is made relatively straightforward 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.) 5.1 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 SHOULD have no type. Upon receiving initial presence from a client, the server sends presence probes from the full JID (user@host/resource) of the user to any remote entities that are subscribed to the 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.) 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. 5.2 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 SHOULD have no type. Initial presence sent from client to server: Saint-Andre & Miller Expires August 4, 2003 [Page 13] Internet-Draft XMPP Instant Messaging February 2003 5.3 Specifying Availability Status A client MAY provide further information about its availability status by using the element. As defined in XMPP Core [1], the recognized values for the show element are "away", "chat", "xa", and "dnd". Availability status: away 5.4 Specifying Detailed Status Information In conjunction with the element, a client MAY provide detailed status information by using the element. The content of this element is a natural-language description of the client's current availability status. Detailed status information: dnd Busy fighting the Romans 5.5 Probing for Presence A server MAY probe for the current presence of another entity. A user or client SHOULD NOT send presence stanzas of type 'probe'. 5.6 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: Optionally, final presence MAY contain one or more elements specifying the reason why the user is no longer available. Saint-Andre & Miller Expires August 4, 2003 [Page 14] Internet-Draft XMPP Instant Messaging February 2003 5.7 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 element scoped by the 'jabber:iq:last' namespace: Requesting the last active time of a user: 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: 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: Forbidden Saint-Andre & Miller Expires August 4, 2003 [Page 15] Internet-Draft XMPP Instant Messaging February 2003 6. 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. 6.1 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: 6.2 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: Saint-Andre & Miller Expires August 4, 2003 [Page 16] Internet-Draft XMPP Instant Messaging February 2003 Denying a presence subscription request: 6.3 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: 6.4 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: Saint-Andre & Miller Expires August 4, 2003 [Page 17] Internet-Draft XMPP Instant Messaging February 2003 7. 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). 7.1 Retrieving One's Privacy Lists Client requests privacy lists from server: Server sends privacy lists to client: 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. Saint-Andre & Miller Expires August 4, 2003 [Page 18] Internet-Draft XMPP Instant Messaging February 2003 7.2 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 element scoped by the 'jabber:iq:privacy' namespace that contains an empty child element possessing a 'name' attribute whose value is set to the desired list name. Client requests change of active list: Server acknowledges success of active list change: 7.3 Editing a Privacy List In order to edit a privacy list, the user MUST send an IQ stanza of type 'set' with a element scoped by the 'jabber:iq:privacy' namespace that contains one or more child elements possessing a 'name' attribute whose value is set to the list name the user would like to edit. Each element MUST contain one or more 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: Saint-Andre & Miller Expires August 4, 2003 [Page 19] Internet-Draft XMPP Instant Messaging February 2003 Server acknowledges success of list edit: In this example, the user has added one additional entity to the "blacklist" portion of this privacy list. 7.4 Removing a Privacy List In order to remove a privacy list, the user MUST send an IQ stanza of type 'set' with a element scoped by the 'jabber:iq:privacy' namespace that contains one or more empty 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: Server acknowledges success of list removal: 7.5 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: Have at thee, coward! Saint-Andre & Miller Expires August 4, 2003 [Page 20] Internet-Draft XMPP Instant Messaging February 2003 Server returns error to blacklisted entity: Have at thee, coward! Not Allowed Saint-Andre & Miller Expires August 4, 2003 [Page 21] Internet-Draft XMPP Instant Messaging February 2003 8. 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. 8.1 Retrieving One's Roster on Login Upon connecting to the server, a client MAY 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: Client receives roster from the server: Friends Friends Saint-Andre & Miller Expires August 4, 2003 [Page 22] Internet-Draft XMPP Instant Messaging February 2003 8.2 Adding a Roster Item At any time, a user MAY add an item to his or her roster. Client adds a new item: Servants 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. Saint-Andre & Miller Expires August 4, 2003 [Page 23] Internet-Draft XMPP Instant Messaging February 2003 Server replies with an IQ result to the sending resource and pushes the updated roster information to all connected resources: Servants Servants Updating an existing roster item (e.g., changing the Group) is done in the same way as adding a new roster item, i.e., by sending the roster item in an IQ set to the server. 8.3 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" (a compliant server SHOULD ignore any other values of the 'subscription' attribute when received from a client). Saint-Andre & Miller Expires August 4, 2003 [Page 24] Internet-Draft XMPP Instant Messaging February 2003 Client removes a item: Servants 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". A server implementation SHOULD cancel any existing presence subscriptions when a roster item is removed. Saint-Andre & Miller Expires August 4, 2003 [Page 25] Internet-Draft XMPP Instant Messaging February 2003 9. 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@host/ resource"), the stanza is delivered first to the resource that exactly matches the resource identifier. 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@host 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 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@host 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. If offline storage is not enabled, the server MUST return a 404 ("Not Found") error to the sender. Saint-Andre & Miller Expires August 4, 2003 [Page 26] Internet-Draft XMPP Instant Messaging February 2003 10. Security Considerations For security considerations, refer to the relevant section of XMPP Core [1]. Saint-Andre & Miller Expires August 4, 2003 [Page 27] Internet-Draft XMPP Instant Messaging February 2003 References [1] Saint-Andre, P. and J. Miller, "XMPP Core (draft-ietf-xmpp-core- 02, work in progress)", February 2003. [2] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for Presence and Instant Messaging", RFC 2779, February 2000, . [3] Jabber Software Foundation, "Jabber Software Foundation", August 2001, . [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, . [6] Dawson, F. and T. Howes, "vCard MIME Directory Profile", RFC 2426, September 1998. Authors' Addresses Peter Saint-Andre Jabber Software Foundation EMail: stpeter@jabber.org URI: http://www.jabber.org/people/stpeter.php Jeremie Miller Jabber Software Foundation EMail: jeremie@jabber.org URI: http://www.jabber.org/people/jer.php Saint-Andre & Miller Expires August 4, 2003 [Page 28] Internet-Draft XMPP Instant Messaging February 2003 Appendix A. In-Band Registration This section is provided for informational purposes only and is not normative. 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 elements in the 'jabber:iq:register' namespace. Because in- band registration is not required by RFC 2779 or any XMPP-specific requirements, this section is non-normative. A.1 Registration Data Flow Step 1: Client queries server regarding information that is required in order to register: Step 2: Server responds with the required registration fields: Choose a username and password to register with this service. Note: the client is REQUIRED to provide information for all of the elements (other than ) 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.) Saint-Andre & Miller Expires August 4, 2003 [Page 29] Internet-Draft XMPP Instant Messaging February 2003 Step 3: Client provides required information: juliet@capulet.com R0m30 juliet Step 4: Server informs client of successful registration: Step 4 (alt 1): Server informs client of failed registration (required field not provided): juliet@capulet.com R0m30 Not Acceptable Saint-Andre & Miller Expires August 4, 2003 [Page 30] Internet-Draft XMPP Instant Messaging February 2003 Step 4 (alt 2): Client is already registered: juliet@capulet.com R0m30 juliet Bad Request A.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 element as shown below. Step 1: Client sends request to unregister: Step 2: Server informs client of successful unregistration: Saint-Andre & Miller Expires August 4, 2003 [Page 31] Internet-Draft XMPP Instant Messaging February 2003 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 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: juliet Step 2: Server responds with the required authentication fields: juliet Step 3: Client sends authentication information (encrypted password): juliet 64d60e40febe09264c52bc9cbddd5dd1147fae97 balcony Step 4: Server informs client of successful authentication: Saint-Andre & Miller Expires August 4, 2003 [Page 32] Internet-Draft XMPP Instant Messaging February 2003 Step 4 (alt): Server informs client of failed authentication: juliet 64d60e40febe09264c5wrongpassword2bc9cbddd5dd1147fae97 balcony Unauthorized The algorithm for generating digest passwords is as follows: 1. Concatenate the Stream ID received from the server with the password. 2. Hash the concatenated string according to the SHA1 algorithm. 3. Ensure that the hash output is in hexidecimal format, not binary or base64). 4. Convert the hash output to all lowercase characters. Saint-Andre & Miller Expires August 4, 2003 [Page 33] Internet-Draft XMPP Instant Messaging February 2003 Appendix C. vCards This section is provided for informational purposes only and is not normative. 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 of type "set" (storage) or "get" (retrieval) to one's Jabber server containing a child scoped by the 'vcard-temp' namespace, with the 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.) C.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: The server must then return the vCard to the user: Peter Saint-Andre Saint-Andre Peter stpeter http://www.jabber.org/people/stpeter.php Saint-Andre & Miller Expires August 4, 2003 [Page 34] Internet-Draft XMPP Instant Messaging February 2003 1966-08-06 Jabber Software Foundation Executive Director Patron Saint 303-308-3282 Suite 600 1899 Wynkoop Street Denver CO 80202 USA 303-555-1212 Denver CO 80209 USA stpeter@jabber.org stpeter@jabber.org More information about me is located on my personal website: http://www.saint-andre.com/ C.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. Saint-Andre & Miller Expires August 4, 2003 [Page 35] Internet-Draft XMPP Instant Messaging February 2003 C.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. The server should then return the other user's vCard to the requestor: JeremieMiller Jeremie Miller jer jeremie@jabber.org jer@jabber.org Saint-Andre & Miller Expires August 4, 2003 [Page 36] Internet-Draft XMPP Instant Messaging February 2003 Appendix D. Formal Definitions D.1 jabber:iq:auth D.1.1 DTD D.1.2 Schema D.2 jabber:iq:last Saint-Andre & Miller Expires August 4, 2003 [Page 37] Internet-Draft XMPP Instant Messaging February 2003 D.2.1 DTD D.2.2 Schema D.3 jabber:iq:privacy D.3.1 DTD D.3.2 Schema Saint-Andre & Miller Expires August 4, 2003 [Page 39] Internet-Draft XMPP Instant Messaging February 2003 D.4 jabber:iq:register D.4.1 Children While numerous fields are available for use in the 'jabber:iq:register' namespace, only those fields (other than ) sent from the server in an IQ result are REQUIRED in order to register. The following are the allowable children of a element scoped by the 'jabber:iq:register' namespace: o instructions o username o password o name o email o address o city o state o zip o phone o url o date Saint-Andre & Miller Expires August 4, 2003 [Page 40] Internet-Draft XMPP Instant Messaging February 2003 o misc o text o remove - request to unregister (sent only in an IQ set) D.4.2 DTD D.4.3 Schema Saint-Andre & Miller Expires August 4, 2003 [Page 41] Internet-Draft XMPP Instant Messaging February 2003 D.5 jabber:iq:roster D.5.1 Children A element scoped by the 'jabber:iq:roster' namespace MAY contain zero or more 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 - An OPTIONAL attribute that captures the current Saint-Andre & Miller Expires August 4, 2003 [Page 42] Internet-Draft XMPP Instant Messaging February 2003 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. * 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 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. D.5.2 DTD D.5.3 Schema Saint-Andre & Miller Expires August 4, 2003 [Page 44] Internet-Draft XMPP Instant Messaging February 2003 D.6 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. Saint-Andre & Miller Expires August 4, 2003 [Page 46] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 4, 2003 [Page 50] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 4, 2003 [Page 51] Internet-Draft XMPP Instant Messaging February 2003 Appendix E. Revision History Note to RFC editor: please remove this entire appendix, and the corresponding entries in the table of contents, prior to publication. E.1 Changes from draft-ietf-xmpp-im-01 o Made numerous small editorial changes. E.2 Changes from draft-ietf-xmpp-im-00 o Moved registration and authentication via jabber:iq:auth to non- normative appendices. o Changed initial presence stanza from MUST be empty to SHOULD be empty. o Specified that user or clients should not send presence stanzas of type 'probe'. o Specified the algorithm for digest passwords. E.3 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). Saint-Andre & Miller Expires August 4, 2003 [Page 52] Internet-Draft XMPP Instant Messaging February 2003 Full Copyright Statement Copyright (C) The Internet Society (2003). 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. 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