Network Working Group P. Saint-Andre Internet-Draft J. Miller Expires: August 24, 2003 Jabber Software Foundation February 23, 2003 XMPP Instant Messaging draft-ietf-xmpp-im-03 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 24, 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 24, 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 . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 5 1.5 Intellectual Property Notice . . . . . . . . . . . . . . . . 5 2. Authentication and Authorization . . . . . . . . . . . . . . 6 3. Exchanging Messages . . . . . . . . . . . . . . . . . . . . 7 3.1 Specifying an Intended Recipient . . . . . . . . . . . . . . 7 3.2 Specifying a Message Type . . . . . . . . . . . . . . . . . 7 3.3 Specifying a Message Subject . . . . . . . . . . . . . . . . 8 3.4 Specifying a Conversation Thread . . . . . . . . . . . . . . 8 3.5 Specifying a Message Body . . . . . . . . . . . . . . . . . 9 3.6 Specifying Additional Information . . . . . . . . . . . . . 9 3.7 Message-Related Errors . . . . . . . . . . . . . . . . . . . 10 4. Exchanging Presence Information . . . . . . . . . . . . . . 11 4.1 Client and Server Responsibilities . . . . . . . . . . . . . 11 4.2 Sending Initial Presence . . . . . . . . . . . . . . . . . . 11 4.3 Specifying Availability Status . . . . . . . . . . . . . . . 12 4.4 Specifying Detailed Status Information . . . . . . . . . . . 12 4.5 Probing for Presence . . . . . . . . . . . . . . . . . . . . 12 4.6 Sending Final Presence . . . . . . . . . . . . . . . . . . . 12 4.7 Determining When a Contact Went Offline . . . . . . . . . . 13 5. Managing Subscriptions . . . . . . . . . . . . . . . . . . . 14 5.1 Requesting a Subscription . . . . . . . . . . . . . . . . . 14 5.2 Handling a Subscription Request . . . . . . . . . . . . . . 14 5.3 Cancelling a Subscription from Another Entity . . . . . . . 14 5.4 Unsubscribing from Another Entity's Presence . . . . . . . . 15 6. Managing One's Roster . . . . . . . . . . . . . . . . . . . 16 6.1 Retrieving One's Roster on Login . . . . . . . . . . . . . . 16 6.2 Adding a Roster Item . . . . . . . . . . . . . . . . . . . . 17 6.3 Deleting a Roster Item . . . . . . . . . . . . . . . . . . . 18 7. Integration of Roster Items and Presence Subscriptions . . . 20 7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7.2 User Subscribes to Contact . . . . . . . . . . . . . . . . . 20 7.3 Creating a Mutual Subscription . . . . . . . . . . . . . . . 24 7.4 Unsubscribing . . . . . . . . . . . . . . . . . . . . . . . 26 7.4.1 Case #1: Subscription Type 'to' . . . . . . . . . . . . . . 26 7.4.2 Case #2: Subscription Type 'both' . . . . . . . . . . . . . 28 7.5 Cancelling a Subscription . . . . . . . . . . . . . . . . . 29 7.5.1 Case #1: Subscription Type 'from' . . . . . . . . . . . . . 29 7.5.2 Case #2: Subscription Type 'both' . . . . . . . . . . . . . 30 7.6 Removing a Roster Item and Cancelling All Subscriptions . . 31 8. Blocking Communication . . . . . . . . . . . . . . . . . . . 33 8.1 Retrieving One's Privacy Lists . . . . . . . . . . . . . . . 33 8.2 Managing Active Lists . . . . . . . . . . . . . . . . . . . 35 Saint-Andre & Miller Expires August 24, 2003 [Page 2] Internet-Draft XMPP Instant Messaging February 2003 8.3 Managing the Default List . . . . . . . . . . . . . . . . . 35 8.4 Editing a Privacy List . . . . . . . . . . . . . . . . . . . 36 8.5 Removing a Privacy List . . . . . . . . . . . . . . . . . . 37 8.6 Blocking Messages . . . . . . . . . . . . . . . . . . . . . 37 8.7 Blocking Inbound Presence . . . . . . . . . . . . . . . . . 39 8.8 Blocking Outbound Presence . . . . . . . . . . . . . . . . . 40 8.9 Blocking IQs . . . . . . . . . . . . . . . . . . . . . . . . 42 8.10 Blocking All Communication . . . . . . . . . . . . . . . . . 43 8.11 Blocked Entity Attempts to Send Message to User . . . . . . 45 8.12 Higher-Level Heuristics . . . . . . . . . . . . . . . . . . 45 8.13 Processing Order . . . . . . . . . . . . . . . . . . . . . . 46 9. Security Considerations . . . . . . . . . . . . . . . . . . 48 References . . . . . . . . . . . . . . . . . . . . . . . . . 49 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 49 A. vCards . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 A.1 Retrieving One's vCard . . . . . . . . . . . . . . . . . . . 50 A.2 Updating One's vCard . . . . . . . . . . . . . . . . . . . . 51 A.3 Viewing Another User's vCard . . . . . . . . . . . . . . . . 52 B. Formal Definitions . . . . . . . . . . . . . . . . . . . . . 53 B.1 Schema for jabber:iq:last . . . . . . . . . . . . . . . . . 53 B.2 Schema for jabber:iq:privacy . . . . . . . . . . . . . . . . 53 B.3 Schema for jabber:iq:roster . . . . . . . . . . . . . . . . 54 B.4 DTD for vcard-temp . . . . . . . . . . . . . . . . . . . . . 55 C. Revision History . . . . . . . . . . . . . . . . . . . . . . 63 C.1 Changes from draft-ietf-xmpp-im-02 . . . . . . . . . . . . . 63 C.2 Changes from draft-ietf-xmpp-im-01 . . . . . . . . . . . . . 63 C.3 Changes from draft-ietf-xmpp-im-00 . . . . . . . . . . . . . 63 C.4 Changes from draft-miller-xmpp-im-02 . . . . . . . . . . . . 63 Intellectual Property and Copyright Statements . . . . . . . 65 Saint-Andre & Miller Expires August 24, 2003 [Page 3] Internet-Draft XMPP Instant Messaging February 2003 1. Introduction 1.1 Overview The core features of the Extensible Messaging and Presence Protocol are defined in XMPP Core [1]. These features -- specifically XML streams, stream authentication and encryption, and the , , and children of the stream root -- provide the building blocks for many types of near-real-time applications, which may be layered on top of the core by sending application-specific data scoped by particular XML namespaces. This document describes the 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, data gathering and forms submission, feature negotiation, message composing events, message expiration, delayed delivery, file transfer, publish-subscribe, and transports for XML-RPC and SOAP; 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 high-level 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 this is called a "roster") o Block communications to or from specific other users Detailed definitions of these functionality areas are contained in RFC 2779 [2]; although XMPP IM meets those requirements, it was not designed explicitly with RFC 2779 in mind, since the base protocol evolved through an open development process within the Jabber open-source community in 1999. Saint-Andre & Miller Expires August 24, 2003 [Page 4] Internet-Draft XMPP Instant Messaging February 2003 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]. 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 24, 2003 [Page 5] Internet-Draft XMPP Instant Messaging February 2003 2. Authentication and Authorization 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 user must first acquire an account on a server. Although account provisioning is outside the scope of XMPP, methods for doing so include account creation by a server administrator as well as in-band account registration using the 'jabber:iq:register' namespace; the latter method is defined by the Jabber Software Foundation [3] and appropriate documentation is available at the JSF's website. In order to gain access to the network, a user MUST authenticate with the server hosting his or her account. 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 in XMPP Core [1]. After authenticating, a user MUST also provide a resource name for the current session, for the purpose of addressing; the protocol for providing a resource is also defined in XMPP Core [1]. NOTE: Earlier iterations of the Jabber protocol contained a client-server authentication protocol that was enforced after the stream was negotiated; this protocol is not suppoted in XMPP but is documented by the Jabber Software Foundation [3] for historical purposes. Saint-Andre & Miller Expires August 24, 2003 [Page 6] Internet-Draft XMPP Instant Messaging February 2003 3. 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). As defined in the "Routing and Delivery Rules" section of XMPP Core [1], the sender's server is responsible for delivering the message to the intended recipient (if the recipient is on the same server) or for routing the message to the recipient's server (if the recipient is on a different server). 3.1 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. 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 the JID is invalid or cannot be contacted, the entity discovering that fact (usually the sender's or recipient's server) SHOULD return an error to the sender. 3.2 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]) Although the 'type' attribute is OPTIONAL, it is considered polite to mirror the type in any replies to a message; furthermore, some Saint-Andre & Miller Expires August 24, 2003 [Page 7] Internet-Draft XMPP Instant Messaging February 2003 specialized applications (e.g., a multi-user chat service) MAY at their discretion enforce the use of a particular message type (e.g., type='groupchat'). 3.3 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 distinct value. 3.4 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 24, 2003 [Page 8] 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 3.5 Specifying a Message Body A message stanza MAY (and often will) contain a child element specifying the main content of the message as CDATA. The body MUST NOT contain mixed content. If it is necessary to provide the main message content in an alternate form (e.g., encrypted using the public key infrastructure or formatted using XHTML), the alternate form MUST be contained in an appropriately-namespaced child of the message stanza, as defined for any such extended namespace. Multiple elements MAY be included, as long as each contains an 'xml:lang' attribute with a distinct value. 3.6 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 Saint-Andre & Miller Expires August 24, 2003 [Page 9] Internet-Draft XMPP Instant Messaging February 2003 within the child element. 3.7 Message-Related Errors If a message sent by a sender cannot be delivered, the entity discovering that fact (usually either the sender's or recipient's 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. We're sorry, Juliet just died 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 24, 2003 [Page 10] Internet-Draft XMPP Instant Messaging February 2003 4. 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 (with no 'to' address) 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.) 4.1 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 possess no 'to' address (signalling that it is meant to be handled by the server on behalf of the user) and SHOULD have no type. Upon receiving initial presence from a client, the server sends presence probes from the full JID (user@domain/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, 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 kept apprised of availability changes. Finally, the server MUST notify all of the subscribed and available entities when a connected resource becomes unavailable. 4.2 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 'to' address and SHOULD have no type. Saint-Andre & Miller Expires August 24, 2003 [Page 11] Internet-Draft XMPP Instant Messaging February 2003 Initial presence sent from client to server: 4.3 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 4.4 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 4.5 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'. 4.6 Sending Final Presence Upon ending its session with a server, a client SHOULD gracefully become unavailable by sending a final presence stanza that is explicitly of type unavailable. Sending final presence to express unavailable state: Saint-Andre & Miller Expires August 24, 2003 [Page 12] Internet-Draft XMPP Instant Messaging February 2003 Optionally, final presence MAY contain one or more elements specifying the reason why the user is no longer available. The server MUST NOT depend on receiving final presence from a connected resource, since the resource may become unavailable unexpectedly. If a server detects that a resource has become unavailable for any reason (either gracefully or ungracefully), it MUST send to all online entities that are subscribed to the associated user's presence. 4.7 Determining When a Contact Went Offline The server MUST maintain a record of the time at which a user became unavailable (whether gracefully or ungracefully). An authorized subscriber to that user's presence MAY determine the time of last activity by sending an IQ stanza to the user's bare JID (user@domain) containing an empty element scoped by the 'jabber:iq:last' namespace: Requesting the last active time of a user: If the entity requesting the time of last activity is an authorized subscriber to the user's presence, 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 24, 2003 [Page 13] Internet-Draft XMPP Instant Messaging February 2003 5. 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. 5.1 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: 5.2 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: Denying a presence subscription request: A user's server MUST NOT automatically accept subscription requests on the user's behalf. All subscription requests MUST be directed to the user's client. If there is no connected resource associated with the user when the subscription request is received, the user's server MUST store the subscription request offline for delivery when the user next becomes available. 5.3 Cancelling a Subscription from Another Entity If a user would like to cancel a previously-granted subscription Saint-Andre & Miller Expires August 24, 2003 [Page 14] Internet-Draft XMPP Instant Messaging February 2003 request, it sends a presence stanza of type "unsubscribed". Cancelling a previously granted subscription request: 5.4 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 24, 2003 [Page 15] Internet-Draft XMPP Instant Messaging February 2003 6. Managing One's Roster In XMPP, one's contact list is called a roster. A roster is stored by the server on the user's behalf so that a user may access roster information from any connected resource. 6.1 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 24, 2003 [Page 16] Internet-Draft XMPP Instant Messaging February 2003 6.2 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 associated with the user using an IQ stanza of type "set" (this is referred to as a "roster push"). This "roster push" enables all connected resources to remain in sync with the server-based roster information. Saint-Andre & Miller Expires August 24, 2003 [Page 17] 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. 6.3 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 24, 2003 [Page 18] Internet-Draft XMPP Instant Messaging February 2003 Client removes an 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 initiating a "roster push" to all connected resources associated with the user. For further information about the implications of this command, see Section 7.6. Saint-Andre & Miller Expires August 24, 2003 [Page 19] Internet-Draft XMPP Instant Messaging February 2003 7. Integration of Roster Items and Presence Subscriptions 7.1 Overview Some level of integration between roster items and presence subscriptions is normally expected by instant messaging users. This section describes the level of integration that must be supported within XMPP IM. There are four primary subscription states: o None -- Neither the user nor the contact is subscribed to the other's presence o To -- The user is subscribed to the contact's presence but there is no subscription from the contact to the user o From -- There is a subscription from the contact to the user, but the user has not subscribed to the contact's presence o Both -- Both the user and the contact are subscribed to each other's presence Each of these states is reflected in the roster of both the user and the contact, thus resulting in durable subscription states. The details regarding how these subscription states interact with roster items is explained in the following sub-sections. 7.2 User Subscribes to Contact The process by which a user subscribes to a contact, including the interaction between roster items and subscription states, is defined below. 1. In preparation for being able to render the contact in the user's client interface and for the server to keep track of the subscription, the user's client MUST send an IQ stanza of type='set' in the jabber:iq:roster namespace; the element MUST possess a 'jid' attribute, MAY possess a 'name' attribute, may contain a child, and MUST NOT posses a 'subscription' attribute: Saint-Andre & Miller Expires August 24, 2003 [Page 20] Internet-Draft XMPP Instant Messaging February 2003 2. The server then MUST (1) reply with an IQ stanza of type='result' and (2) initiate a "roster push" for the new roster item to all connected resources associated with this user, setting the subscription state set to 'none': 3. In order to initiate the subscription, the user's client MUST then send a presence stanza of type='subscribe' to the contact: 4. The server MUST then initiate a second "roster push" to all connected resources associated with the user, setting the contact to the pending sub-state of the 'none' subscription state; this pending sub-state is denoted by the inclusion of the ask='subscribe' attribute in the roster item: 5. The server MUST also deliver the presence stanza to the contact or route it to the contact's server for delivery to the contact, first stamping the stanza with the user's bare JID as the 'from' address: Saint-Andre & Miller Expires August 24, 2003 [Page 21] Internet-Draft XMPP Instant Messaging February 2003 6. If the contact is online (i.e., there is a connected resource associated with the contact's account), the contact must now decide whether or not to accept the subscription request. (If the contact is offline, the contact's server MUST store the subscription request offline for delivery when the contact next becomes available.) Here we will assume the "happy path" that the contact accepts the subscription, in which case the contact's client MAY send a roster set to the server specifying the desired nickname and group for the user, and MUST send a presence stanza of type='subscribed' to the user. 7. The contact's server MUST now initiate a "roster push" to all connected resources associated with the contact, containing a roster item for the user with the subscription state set to 'from': 8. As a result of the fact that the contact has accepted the subscription request, the user's server MUST (1) deliver the presence stanza of type='subscribed' from the contact to the user, and (2) initiate a "roster push" to all connected resources associated with the user, containing an updated roster item for the contact with the subscription type set to a value of "to": Saint-Andre & Miller Expires August 24, 2003 [Page 22] Internet-Draft XMPP Instant Messaging February 2003 9. From the perspective of the user, there is now a subscription to the contact; from the perspective of the contact, there is now a subscription from the user. (Note: If at this point the user sends another subscription request to the contact, the user's server will "swallow" that request and not send it on the contact.) The above activity flow represents the "happy path" related to the user's subscription request to the contact. The main alternate flow occurs if the contact denies the user's subscription request; in order to deny the request, the contact's client MUST send a presence stanza of type "unsubscribed" to the user: The user's server MUST then (1) deliver that presence stanza to the user and (2) initiate a "roster push" to all connected resources associated with the user, with the subscription attribute set to a value of "none": Saint-Andre & Miller Expires August 24, 2003 [Page 23] Internet-Draft XMPP Instant Messaging February 2003 As a result of this activity, the contact is now in the user's roster with a subscription state of "none", whereas the user is not in the contact's roster at all. 7.3 Creating a Mutual Subscription The user and contaact can build on the foregoing to create a mutual subscription (i.e., a subscription of type "both"). The process is defined below. 1. The contact MUST send a subscription request to the user (subject to user preferences, the contact's client MAY send this automatically): 2. The contact's server MUST then initiate a "roster push" to all connected resources associated with the contact, with the user still in the 'from' subscription state but with a pending 'to' subscription denoted by the inclusion of the ask='subscribe' attribute in the roster item: 3. If the user is online (i.e., there is a connected resource associated with the user's account), the user must now decide whether or not to accept the subscription request. (If the user is offline, the user's server MUST store the subscription request offline for delivery when the user next becomes available.) Here we will assume the "happy path" that the user accepts the subscription, in which case the user's client MUST send a presence stanza of type='subscribed' to the contact. 4. The user's server MUST then initiate a "roster push" to all connected resources associated with the user, containing a roster item for the contact with the subscription attribute set to a value of "both": Saint-Andre & Miller Expires August 24, 2003 [Page 24] Internet-Draft XMPP Instant Messaging February 2003 5. As a result of the fact that the user has accepted the subscription request, the contact's server MUST (1) deliver the presence stanza of type='subscribed' from the user to the contact, and (2) initiate a "roster push" to all connected resources associated with the contact, containing an updated roster item for the user with the subscription type set to a value of "both": The user and the contact now have a mutual subscription to each other's presence -- i.e., the subscription is of type 'both'. (Note: If at this point the user sends a subscription request to the contact or the contact sends a subscription request to the user, the sending user's server will "swallow" that request and not send it on the intended recipient.) The above activity flow represents the "happy path" related to the contact's subscription request to the user. The main alternate flow occurs if the user denies the contacts's subscription request; in order to deny the request, the user's client MUST send a presence stanza of type "unsubscribed" to the contact: The contact's server MUST then (1) deliver that presence stanza to the contact and (2) initiate a "roster push" to all connected Saint-Andre & Miller Expires August 24, 2003 [Page 25] Internet-Draft XMPP Instant Messaging February 2003 resources associated with the contact, with the subscription attribute set to a value of "from" and with no 'ask' attribute: As a result of this activity, there has been no change in the subscription state; i.e., the contact is in the user's roster with a subscription state of "to" and the user is in the contact's roster with a subscription state of "from". 7.4 Unsubscribing At any time after subscribing to a contact's presence, a user MAY unsubscribe. While the XML that the user sends to make this happen is the same in all instances, the subsequent subscription state is different depending on the subscription state obtaining when the unsubscribe command is sent. Both possible scenarios are defined below. 7.4.1 Case #1: Subscription Type 'to' In the first case, the user has a subscription to the contact but the contact does not have a subscription to the user (i.e., the subscription is not yet mutual). 1. In order to unsubscribe from the contact's presence, the user MUST a presence stanza of type "unsubscribe" to the contact: 2. As a result, the user's server MUST send a "roster push" to each connected resource associated with the user, containing a roster item for the contact with the 'ask' attribute set to unsubscribe to indicate that the unsubscribe is pending: Saint-Andre & Miller Expires August 24, 2003 [Page 26] Internet-Draft XMPP Instant Messaging February 2003 3. Since the unsubscribe command does not need to be approved by the contact, the contact's server then SHOULD auto-reply on behalf of the contact by sending a presence stanza of type "unsubscribed" to the user: 4. The contact's server also MUST initiate a "roster push" to all connected resources associated with the contact, containing a roster item for the user with the 'subscription' attribute set to a value of "none" (if the contact is offline, the contact's server MUST modify the roster item and send that modified item the next time the contact requests the roster): 5. As a result of the fact that the contact has acknowledged the unsubscribe command, the user's server MUST (1) deliver the presence stanza of type='unsubscribed' from the contact to the user, and (2) initiate a "roster push" to all connected resources associated with the user, containing an updated roster item for the contact with the subscription type set to a value of "none" and with no 'ask' attribute: Saint-Andre & Miller Expires August 24, 2003 [Page 27] Internet-Draft XMPP Instant Messaging February 2003 7.4.2 Case #2: Subscription Type 'both' In the second case, the user has a subscription to the contact and the contact also has a subscription to the user. 1. In order to unsubscribe from the contact's presence, the user MUST a presence stanza of type "unsubscribe" to the contact: 2. As a result, the user's server MUST send a "roster push" to each connected resource associated with the user, containing a roster item for the contact with the 'ask' attribute set to unsubscribe to indicate that the unsubscribe is pending: 3. Since the unsubscribe command does not need to be approved by the contact, the contact's server then SHOULD auto-reply on behalf of the contact by sending a presence stanza of type "unsubscribed" to the user: 4. The contact's server also MUST initiate a "roster push" to all connected resources associated with the contact, containing a roster item for the user with the 'subscription' attribute set to Saint-Andre & Miller Expires August 24, 2003 [Page 28] Internet-Draft XMPP Instant Messaging February 2003 a value of "to" (if the contact is offline, the contact's server MUST modify the roster item and send that modified item the next time the contact requests the roster): 5. As a result of the fact that the contact has acknowledged the unsubscribe command, the user's server MUST (1) deliver the presence stanza of type='unsubscribed' from the contact to the user, and (2) initiate a "roster push" to all connected resources associated with the user, containing an updated roster item for the contact with the subscription type set to a value of "from" and with no 'ask' attribute: NOTE: Obviously this does not result in removal of the roster item from the user's roster, and the contact still has a subscription to the user's presence. In order to more completely cancel a mutual subscription and fully remove the roster item from the user's roster, the user should update the roster item with subscription='remove' as defined in Section 7.6. 7.5 Cancelling a Subscription At any time after approving a subscription request from a user, a contact MAY cancel that subscription. While the XML that the contact sends to make this happen is the same in all instances, the subsequent subscription state is different depending on the subscription state obtaining when the cancellation is sent. Both possible scenarios are defined below. 7.5.1 Case #1: Subscription Type 'from' Saint-Andre & Miller Expires August 24, 2003 [Page 29] Internet-Draft XMPP Instant Messaging February 2003 In the first case, the user has a subscription to the contact but the contact does not have a subscription to the user (i.e., the subscription is not yet mutual). 1. In order to cancel the user's subscription, the contact MUST a presence stanza of type "unsubscribed" to the user: 2. As a result, the contact's server MUST send a "roster push" to each connected resource associated with the contact, containing a roster item for the user with the 'subscription' attribute set to a value of "none": 3. The user's server MUST then initiate a "roster push" to all connected resources associated with the user, containing a roster item for the contact with the 'subscription' attribute set to a value of "none" (if the user is offline, the user's server MUST modify the roster item and send that modified item the next time the user requests the roster): 7.5.2 Case #2: Subscription Type 'both' In the second case, the user has a subscription to the contact and the contact also has a subscription to the user. 1. In order to cancel the user's subscription, the user MUST a presence stanza of type "unsubscribed" to the user: Saint-Andre & Miller Expires August 24, 2003 [Page 30] Internet-Draft XMPP Instant Messaging February 2003 2. As a result, the contact's server MUST send a "roster push" to each connected resource associated with the contact, containing a roster item for the user with the 'subscription' attribute set to a value of "to": 3. The user's server MUST then initiate a "roster push" to all connected resources associated with the user, containing a roster item for the contact with the 'subscription' attribute set to a value of "from" (if the user is offline, the user's server MUST modify the roster item and send that modified item the next time the user requests the roster): NOTE: Obviously this does not result in removal of the roster item from the contact's roster, and the contact still has a subscription to the user's presence. In order to more completely cancel a mutual subscription and fully remove the roster item from the contact's roster, the contact should update the roster item with subscription='remove' as defined in Section 7.6. 7.6 Removing a Roster Item and Cancelling All Subscriptions Because there may be many steps involved in completely removing a roster item and reverting the subscription state to "none", XMPP IM includes a "shortcut" method for doing so. The process may be initiated by either a contact or a user no matter what the current subscription state is, by means of sending a roster set with the subscription attribute set to a value of "remove". Saint-Andre & Miller Expires August 24, 2003 [Page 31] Internet-Draft XMPP Instant Messaging February 2003 For example, a user may send the following XML: When the user removes a contact from his or her roster by setting the 'subscription' attribute to a value of "remove", the user's server MUST automatically cancel any existing presence subscription between the user and the contact by sending presence stanzas of type "unsubscribe" and "unsubscribed" from the user to the contact. A contact may also send such a command, resulting in the same type of system behavior. Saint-Andre & Miller Expires August 24, 2003 [Page 32] Internet-Draft XMPP Instant Messaging February 2003 8. Blocking Communication Most instant messaging systems have found it necessary to implement some method for users to block communications from particular other users (this is also required by sections 5.1.5, 5.1.15, 5.3.2, and 5.4.10 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). Server-side privacy lists enable successful completion of the following use cases: o Retreiving one's privacy lists. o Adding, removing, and editing one's privacy lists. o Setting, changing, or declining active lists. o Setting, changing, or declining the default list. o Allowing or denying messages based on JID, group, or subscription type (or globally). o Allowing or denying inbound presence information based on JID, group, or subscription type (or globally). o Allowing or denying outbound presence information based on JID, group, or subscription type (or globally). o Allowing or denying IQs based on JID, group, or subscription type (or globally). o Allowing or denying all communications based on JID, group, or subscription type (or globally). 8.1 Retrieving One's Privacy Lists Client requests names of privacy lists from server: Saint-Andre & Miller Expires August 24, 2003 [Page 33] Internet-Draft XMPP Instant Messaging February 2003 Server sends names of privacy lists to client, including default list and active list: Client requests complete privacy lists from server: Server sends complete 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 Saint-Andre & Miller Expires August 24, 2003 [Page 34] Internet-Draft XMPP Instant Messaging February 2003 allows communications only from three specific entities. The active list currently being applied by the server is the 'private' list. 8.2 Managing Active Lists In order to set or 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: In order to decline the use of any active list (i.e., to use the domain's stanza routing rules), a user MUST send an empty element with no name. Client declines the use of active lists: 8.3 Managing the Default List In order to change the default list associated with an account, 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. Saint-Andre & Miller Expires August 24, 2003 [Page 35] Internet-Draft XMPP Instant Messaging February 2003 Client requests change of default list: Server acknowledges success of default list change: In order to decline the use of any default list (i.e., to use the domain's stanza routing rules), a user MUST send an empty element with no name. Client declines the use of active lists: 8.4 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 24, 2003 [Page 36] 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. 8.5 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: 8.6 Blocking Messages Server-side privacy lists enable a user to block incoming messages from other users based on the other user's JID, roster group, or subscription status, or globally. The following examples illustrate the required protocol. User blocks based on JID: As a result of creating and applying the foregoing list, the user Saint-Andre & Miller Expires August 24, 2003 [Page 37] Internet-Draft XMPP Instant Messaging February 2003 will not receive messages from the user with the specified JID. User blocks based on roster group: As a result of creating and applying the foregoing list, the user will not receive messages from any users in the specified roster group. User blocks based on subscription type: As a result of creating and applying the foregoing list, the user will not receive messages from any users with the specified subscription type. User blocks globally: As a result of creating and applying the foregoing list, the user will not receive messages from any other users. Saint-Andre & Miller Expires August 24, 2003 [Page 38] Internet-Draft XMPP Instant Messaging February 2003 8.7 Blocking Inbound Presence Server-side privacy lists enable a user to block incoming presence information from other users based on the other user's JID, roster group, or subscription status, or globally. The following examples illustrate the required protocol. User blocks based on JID: As a result of creating and applying the foregoing list, the user will not receive presence information from the user with the specified JID. User blocks based on roster group: As a result of creating and applying the foregoing list, the user will not receive presence information from any users in the specified roster group. Saint-Andre & Miller Expires August 24, 2003 [Page 39] Internet-Draft XMPP Instant Messaging February 2003 User blocks based on subscription type: As a result of creating and applying the foregoing list, the user will not receive presence information from any users with the specified subscription type. User blocks globally: As a result of creating and applying the foregoing list, the user will not receive presence information from any other users. 8.8 Blocking Outbound Presence Server-side privacy lists enable a user to block outgoing presence information to other users based on the other user's JID, roster group, or subscription status, or globally. The following examples illustrate the required protocol. Saint-Andre & Miller Expires August 24, 2003 [Page 40] Internet-Draft XMPP Instant Messaging February 2003 User blocks based on JID: As a result of creating and applying the foregoing list, the user will not send presence information to the user with the specified JID. User blocks based on roster group: As a result of creating and applying the foregoing list, the user will not send presence information to any users in the specified roster group. User blocks based on subscription type: As a result of creating and applying the foregoing list, the user will not send presence information to any users with the specified subscription type. Saint-Andre & Miller Expires August 24, 2003 [Page 41] Internet-Draft XMPP Instant Messaging February 2003 User blocks globally: As a result of creating and applying the foregoing list, the user will not send presence information to any other users. 8.9 Blocking IQs Server-side privacy lists enable a user to block incoming IQ requests from other users based on the other user's JID, roster group, or subscription status, or globally. The following examples illustrate the required protocol. User blocks based on JID: As a result of creating and applying the foregoing list, the user will not receive IQ requests from the user with the specified JID. User blocks based on roster group: Saint-Andre & Miller Expires August 24, 2003 [Page 42] Internet-Draft XMPP Instant Messaging February 2003 As a result of creating and applying the foregoing list, the user will not receive IQ requests from any users in the specified roster group. User blocks based on subscription type: As a result of creating and applying the foregoing list, the user will not receive IQ requests from any users with the specified subscription type. User blocks globally: As a result of creating and applying the foregoing list, the user will not receive IQ requests from any other users. 8.10 Blocking All Communication Server-side privacy lists enable a user to block all communications from and presence to other users based on the other user's JID, roster group, or subscription status, or globally. The following examples illustrate the required protocol. Saint-Andre & Miller Expires August 24, 2003 [Page 43] Internet-Draft XMPP Instant Messaging February 2003 User blocks based on JID: As a result of creating and applying the foregoing list, the user will not receive any communications from, nor send presence to, the user with the specified JID. User blocks based on roster group: As a result of creating and applying the foregoing list, the user will not receive any communications from, nor send presence to, any users in the specified roster group. User blocks based on subscription type: As a result of creating and applying the foregoing list, the user will not receive any communications from, nor send presence to, any users with the specified subscription type. Saint-Andre & Miller Expires August 24, 2003 [Page 44] Internet-Draft XMPP Instant Messaging February 2003 User blocks globally: As a result of creating and applying the foregoing list, the user will not receive any communications from, nor send presence to, any other users. 8.11 Blocked Entity Attempts to Send Message to User If a blocked entity attempts to send a message to the user, the user's server SHOULD return an error of type 405 (Not Allowed) to the sending entity. Blocked entity attempts to send message: Have at thee, coward! Server returns error to blacklisted entity: Have at thee, coward! Not Allowed Such error messages SHOULD also be sent regarding IQ messages, not regarding presence. 8.12 Higher-Level Heuristics When building a representation of a higher-level privacy heuristic, a client SHOULD use the simplest possible representation. For example, the heuristic "block all communications with any user not in my roster" could be constructed in any of the following ways: o accept communications from all JIDs in my roster (i.e., listing each JID as a separate list item), but deny communications with Saint-Andre & Miller Expires August 24, 2003 [Page 45] Internet-Draft XMPP Instant Messaging February 2003 everyone else o accept communications from any user who is in one of the groups that make up my roster (i.e., listing each group as a separate list item), but deny communications from everyone else o accept communications from any user with whom I have a subscription of 'both' or 'to' or 'from' (i.e., listing each subscription value separately), but deny communications from everyone else o deny communications from anyone whose subscription state is 'none' The final representation is the simplest and SHOULD be used; here is the XML that would be sent in this case: Client constructs simple representation of heuristic for accepting communications only with those in the user's roster: A more complete list of such heuristics and their simplest representations may be provided in a future revision of this document. 8.13 Processing Order The order in which privacy list items are processed by the server is important. List items MUST be processed in order of granularity, according to the following hierarchy of 'filter' attribute values (from most to least granular): 1. jid 2. group 3. subscription 4. No 'filter' attribute ("fall-through" case) As soon as a rule is matched, the server can appropriately route the stanza and cease processing. Saint-Andre & Miller Expires August 24, 2003 [Page 46] Internet-Draft XMPP Instant Messaging February 2003 If no fall-through item is provided in a list, the fall-through action is assumed to be "accept". Saint-Andre & Miller Expires August 24, 2003 [Page 47] Internet-Draft XMPP Instant Messaging February 2003 9. Security Considerations For security considerations, refer to the relevant section of XMPP Core [1]. Saint-Andre & Miller Expires August 24, 2003 [Page 48] Internet-Draft XMPP Instant Messaging February 2003 References [1] Saint-Andre, P. and J. Miller, "XMPP Core (draft-ietf-xmpp-core-03, 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 24, 2003 [Page 49] Internet-Draft XMPP Instant Messaging February 2003 Appendix A. 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.) 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: 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 24, 2003 [Page 50] 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/ 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. Saint-Andre & Miller Expires August 24, 2003 [Page 51] Internet-Draft XMPP Instant Messaging February 2003 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. 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 24, 2003 [Page 52] Internet-Draft XMPP Instant Messaging February 2003 Appendix B. Formal Definitions B.1 Schema for jabber:iq:last B.2 Schema for jabber:iq:privacy Saint-Andre & Miller Expires August 24, 2003 [Page 53] Internet-Draft XMPP Instant Messaging February 2003 B.3 Schema for jabber:iq:roster Saint-Andre & Miller Expires August 24, 2003 [Page 54] Internet-Draft XMPP Instant Messaging February 2003 B.4 DTD for 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 24, 2003 [Page 55] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 24, 2003 [Page 57] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 24, 2003 [Page 58] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 24, 2003 [Page 59] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 24, 2003 [Page 60] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 24, 2003 [Page 61] Internet-Draft XMPP Instant Messaging February 2003 Saint-Andre & Miller Expires August 24, 2003 [Page 62] Internet-Draft XMPP Instant Messaging February 2003 Appendix C. Revision History Note to RFC editor: please remove this entire appendix, and the corresponding entries in the table of contents, prior to publication. C.1 Changes from draft-ietf-xmpp-im-02 o Added a great deal more detail to the narrative regarding server-side privacy rules as well as the interaction between rosters and subscriptions. o Removed DTDs in favor of schemas (with the exception of vCard XML). o Removed non-normative documentation of authentication using jabber:iq:auth and of in-band registration using jabber:iq:register, since these are maintained by the Jabber Software Foundation and are not part of the XMPP specification. C.2 Changes from draft-ietf-xmpp-im-01 o Made numerous small editorial changes. C.3 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. C.4 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 Saint-Andre & Miller Expires August 24, 2003 [Page 63] Internet-Draft XMPP Instant Messaging February 2003 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 24, 2003 [Page 64] Internet-Draft XMPP Instant Messaging February 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. 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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 Saint-Andre & Miller Expires August 24, 2003 [Page 65] Internet-Draft XMPP Instant Messaging February 2003 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. Saint-Andre & Miller Expires August 24, 2003 [Page 66]