XMPP Instant Messaging
From: http://www.ietf.org/internet-drafts/draft-miller-xmpp-im-01.txt
Reference: draft-miller-xmpp-im-01
------------------------------------------------------------------------
Network Working Group J. Miller
Internet-Draft P. Saint-Andre
Expires: April 23, 2003 Jabber Software Foundation
October 23, 2002
XMPP Instant Messaging
draft-miller-xmpp-im-01
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 April 23, 2003.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document describes the specific extensions to and applications
of the eXtensible Messaging and Presence Protocol (XMPP) that are
necessary to create a basic instant messaging and presence
application (specificlaly, an application that is compatible with the
open-source Jabber instant messaging system).
Miller & Saint-Andre Expires April 23, 2003 [Page 1]
Internet-Draft XMPP Instant Messaging October 2002
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Conventions Used in this Document . . . . . . . . . . . . . 4
1.5 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 5
1.6 Intellectual Property Notice . . . . . . . . . . . . . . . . 5
2. Registration . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Registration Data Flow . . . . . . . . . . . . . . . . . . . 6
2.2 Cancellation Data Flow . . . . . . . . . . . . . . . . . . . 7
2.3 Definition of the jabber:iq:register Namespace . . . . . . . 8
2.3.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. Authentication . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 Authentication Using SASL . . . . . . . . . . . . . . . . . 11
3.2 Authentication Using jabber:iq:auth . . . . . . . . . . . . 12
3.3 Definition of the jabber:iq:auth Namespace . . . . . . . . . 13
3.3.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Exchanging Messages . . . . . . . . . . . . . . . . . . . . 15
4.1 Specifying an Intended Recipient . . . . . . . . . . . . . . 15
4.2 Specifying the Sender . . . . . . . . . . . . . . . . . . . 15
4.3 Specifying a Message Type . . . . . . . . . . . . . . . . . 15
4.4 Specifying a Message Subject . . . . . . . . . . . . . . . . 16
4.5 Specifying a Message Thread . . . . . . . . . . . . . . . . 16
4.6 Specifying a Message Body . . . . . . . . . . . . . . . . . 17
4.7 Specifying Additional Information . . . . . . . . . . . . . 17
4.8 Message-Related Errors . . . . . . . . . . . . . . . . . . . 18
5. Exchanging Presence Information . . . . . . . . . . . . . . 19
5.1 Node and Host Responsibilities . . . . . . . . . . . . . . . 19
5.2 Sending Initial Presence . . . . . . . . . . . . . . . . . . 19
5.3 Specifying Availability Status . . . . . . . . . . . . . . . 20
5.4 Specifying Detailed Status Information . . . . . . . . . . . 20
5.5 Probing for Presence . . . . . . . . . . . . . . . . . . . . 20
5.6 Sending Final Presence . . . . . . . . . . . . . . . . . . . 20
6. Managing Subscriptions . . . . . . . . . . . . . . . . . . . 21
6.1 Requesting a Subscription . . . . . . . . . . . . . . . . . 21
6.2 Handling a Subscription Request . . . . . . . . . . . . . . 21
6.3 Cancelling a Subscription from Another Entity . . . . . . . 22
6.4 Unsubscribing from Another Entity's Presence . . . . . . . . 22
7. Managing One's Roster . . . . . . . . . . . . . . . . . . . 23
7.1 Receiving One's Roster on Login . . . . . . . . . . . . . . 23
7.2 Adding a Roster Item . . . . . . . . . . . . . . . . . . . . 23
7.3 Deleting a Roster Item . . . . . . . . . . . . . . . . . . . 24
Miller & Saint-Andre Expires April 23, 2003 [Page 2]
Internet-Draft XMPP Instant Messaging October 2002
7.4 Definition of the jabber:iq:roster Namespace . . . . . . . . 25
7.4.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.4.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.4.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8. Routing and Delivery Guidelines . . . . . . . . . . . . . . 28
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . 30
10.1 Secure Identity and Encryption . . . . . . . . . . . . . . . 30
10.2 Node Connections . . . . . . . . . . . . . . . . . . . . . . 30
References . . . . . . . . . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 31
Full Copyright Statement . . . . . . . . . . . . . . . . . . 33
Miller & Saint-Andre Expires April 23, 2003 [Page 3]
Internet-Draft XMPP Instant Messaging October 2002
1. Introduction
1.1 Scope
The core features of the XMPP protocol (XMPP Core [2]) provide the
building blocks for many types of near-real-time applications, which
may be layered on top of the core by sending XML chunks 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 2778 [8] and RFC 2779 [9].
Many other functionality areas are defined in the Jabber protocol,
including service discovery, multi-user chat, search, remote
procedure calls, data gathering and forms submission, encryption,
feature negotiation, message composing events, message expiration,
and file transfer; however, such functionality is not described
herein.
1.2 Terminology
This document inherits the terminology defined in XMPP Core [2].
1.3 Requirements
For the purposes of this document, we stipulate that a basic instant
messaging and presence application needs to enable a node to perform
the following functionality:
o Register an account with a host
o Authenticate with a host
o Exchange messages with other nodes
o Exchange presence information with other nodes
o Manage subscriptions to and from other nodes
o Manage the items in the node's roster (a.k.a. contact list)
1.4 Conventions Used in this Document
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 [1].
Miller & Saint-Andre Expires April 23, 2003 [Page 4]
Internet-Draft XMPP Instant Messaging October 2002
1.5 Discussion Venue
The authors welcome discussion and comments related to the topics
presented in this document, preferably on the "xmppwg@jabber.org"
mailing list (archives and subscription information are available at
http://www.jabber.org/cgi-bin/mailman/listinfo/xmppwg/).
1.6 Intellectual Property Notice
This document is in full compliance with all provisions of Section 10
of RFC 2026. Parts of this specification use the term "jabber" for
identifying URI schemes, namespaces, and other protocol syntax.
Jabber[tm] is a registered trademark of Jabber, Inc. Jabber, Inc.
grants permission to the IETF for use of Jabber trademark in
association with this specification and its successors, if any.
Miller & Saint-Andre Expires April 23, 2003 [Page 5]
Internet-Draft XMPP Instant Messaging October 2002
2. Registration
Registering with a host is necessary in order for a node to engage in
any desired functionality. Certainly such registration MAY (and
frequently does) occur outside the context of an instant messaging
and presence application. However, XMPP also enables a node to
register with a host within the context of an IM system. This
functionality is enabled by sending and receiving IQ chunks in a
request-response pattern, where the IQ chunks contain
elements in the jabber:iq:register namespace.
2.1 Registration Data Flow
Step 1: Node queries host regarding information that is required in
order to register:
Step 2: Host responds with the required registration fields:
Choose a username and password to register with this service.
Note: the node is REQUIRED to provide information for all of the
elements (other than ) contained in the IQ result.
(Note also that the XML chunk shown above does not include a 'to'
attribute, since the connected socket does not yet have an account.)
Miller & Saint-Andre Expires April 23, 2003 [Page 6]
Internet-Draft XMPP Instant Messaging October 2002
Step 3: Node provides required information:
juliet@capulet.com
R0m30
juliet
Step 4: Host informs node of successful registration:
Step 4 (alt): Host informs node of failed registration:
Not Acceptable
2.2 Cancellation Data Flow
The jabber:iq:register namespace also makes it possible for a user to
cancel a registration with a host by sending a element as
shown below.
Step 1: Node sends request to unregister:
Miller & Saint-Andre Expires April 23, 2003 [Page 7]
Internet-Draft XMPP Instant Messaging October 2002
Step 2: Host informs node of successful unregistration:
2.3 Definition of the jabber:iq:register Namespace
2.3.1 Children
While numerous fields are available for use in the jabber:iq:register
namespace, only those fields (other than ) sent from
the host in an IQ result are REQUIRED in order to register. The
officially-recognized fields available for use are as follows:
o instructions
o username
o password
o name
o email
o address
o city
o state
o zip
o phone
o url
o date
o misc
o text
o remove - request to unregister (sent only in an IQ set)
Miller & Saint-Andre Expires April 23, 2003 [Page 8]
Internet-Draft XMPP Instant Messaging October 2002
2.3.2 DTD
2.3.3 Schema
Miller & Saint-Andre Expires April 23, 2003 [Page 9]
Internet-Draft XMPP Instant Messaging October 2002
Miller & Saint-Andre Expires April 23, 2003 [Page 10]
Internet-Draft XMPP Instant Messaging October 2002
3. Authentication
In order to gain access to the network of XMPP-compliant applications
and thus engage in standard IM functionality such as exchanging
messages and presence, a node must authenticate with a host. The
preferred authentication method is SASL. Authentication using the
older jabber:iq:auth method is OPTIONAL and MAY be used if a node
does not support SASL.
3.1 Authentication Using SASL
If a node is capable of authenticating with SASL, it MUST include the
agreed-upon SASL namespace within the opening
element with which it initiated communications with the host.
For the protocol describing how a node authenticates with a host,
refer to XMPP Core [2].
Once a node has authenticated its streams with a host, it MUST
provide a resource associated with the connection. This is
accomplished by means of the jabber:iq:auth namespace. The protocol
for doing so is described below.
Step 1: Node queries host regarding information that is still
required to begin a session:
juliet
Step 2: Host responds with the required fields (in this case, only
the username and resource):
juliet
Miller & Saint-Andre Expires April 23, 2003 [Page 11]
Internet-Draft XMPP Instant Messaging October 2002
Step 3: Node sends resource information:
juliet
balcony
Step 4: Host informs node of successful session initiation:
3.2 Authentication Using jabber:iq:auth
Earlier iterations of XMPP contained a client-server authentication
protocol that was enforced after the stream was negotiated; this
protocol, which uses the jabber:iq:auth namespace, is described for
completeness in this section.
The jabber:iq:auth namespace provides two things: (1) a simple way
for a node to authenticate with a host and (2) a way to create a
resource representing a specific connection or session associated
with the node.
The following is the data flow for a complete example of a node
authenticating with a host.
Step 1: Node queries host regarding information that is required in
order to authenticate:
juliet
Miller & Saint-Andre Expires April 23, 2003 [Page 12]
Internet-Draft XMPP Instant Messaging October 2002
Step 2: Host responds with the required authentication fields:
juliet
Step 3: Node sends authentication information (encrypted password):
juliet
64d60e40febe09264c52bc9cbddd5dd1147fae97
balcony
Step 4: Host informs node of successful authentication:
Step 4 (alt): Host informs node of failed authentication:
Unauthorized
3.3 Definition of the jabber:iq:auth Namespace
3.3.1 Children
o username - the unique username for this node (usually an IM user).
o password - the secret key or passphrase for the node's access to
the host.
o digest - the concatenation of the stream id and the password,
encrypted according to the SHA1 Secure Hash Algorithm [3] and
represented as all lowercase hex.
o resource - unique value to represent current connection.
Miller & Saint-Andre Expires April 23, 2003 [Page 13]
Internet-Draft XMPP Instant Messaging October 2002
3.3.2 DTD
3.3.3 Schema
Miller & Saint-Andre Expires April 23, 2003 [Page 14]
Internet-Draft XMPP Instant Messaging October 2002
4. Exchanging Messages
Exchanging messages is simple within XMPP: using the data
element, a node can send a message to any other node (or, more
generally, any entity).
4.1 Specifying an Intended Recipient
A node MAY 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 node (for exceptions, see the next paragraph). The
intended recipient MAY be any valid JID (e.g., a node on the same
host, a node on a different host, the host itself, or another host).
If no 'to' address is specified, it is implied that the message is
addressed to the sending node itself (i.e., the node@host sending the
chunk); furthermore, a message explicitly or implicitly addressed to
the sending node itself is processed by the host on behalf of that
node. A message addressed to a specific connected resource
associated with the sending node is delivered to that node@host/
resource (which MAY be different from the connected resource that
generated the message).
4.2 Specifying the Sender
A node MAY specify the sender's address by including a 'from'
attribute in the message chunk, and MAY specify any resource or full
JID in that 'from' attribute. However, a host MUST verify that the
value of the 'from' attribute matches the node@host/resource of the
connected resource that generated the message chunk. If no 'from'
attribute is included, the host MUST add the valid and authenticated
from address of the connected resource sending the chunk (i.e., the
node@host/resource).
4.3 Specifying a Message Type
As mentioned in XMPP Core [2], 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 node 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 no type is set or if the
type is set to a value other than those specified here, the value
SHOULD be defaulted to "normal" by the host. If included, the 'type'
attribute SHOULD have one of the following values:
o normal - A single message
Miller & Saint-Andre Expires April 23, 2003 [Page 15]
Internet-Draft XMPP Instant Messaging October 2002
o chat - A message sent in the context of two-way chat between two
entities
o groupchat - A message sent in the context of multi-user chat among
multiple entities
o headline - A message that represents one of a list of items (e.g.,
in a news feed or information ticker)
o error - A message returned to a sender specifying an error
associated with a previous message sent by the sender to an
intended recipient (for a full list of error messages, see XMPP
Core [2])
4.4 Specifying a Message Subject
A message chunk MAY contain a child element specifying the subject of
the message. The subject MAY NOT contain mixed content.
A message with a subject:
Imploring
Wherefore art thou, Romeo?
4.5 Specifying a Message Thread
A message chunk MAY contain a child element specifying the thread of
the message for the purpose of tracking a conversation thread. The
content of the element is a random string that is generated
by the sender; this string MAY be copied back to the sender in
subsequent replies. If included, the element MUST have no
attributes and MAY NOT contain mixed content.
Miller & Saint-Andre Expires April 23, 2003 [Page 16]
Internet-Draft XMPP Instant Messaging October 2002
A simple threaded conversation:
Art thou not Romeo, and a Montague?
283461923759234
Neither, fair saint, if either thee dislike.
283461923759234
How cam'st thou hither, tell me, and wherefore?
283461923759234
4.6 Specifying a Message Body
A message chunk MAY (and usually will) contain a child element
specifying the body of the message. The body MAY 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 element other
than the