The Internet Engineering Steering Group (IESG) has announced a Last Call review of the Internet Draft Indication of Message Composition for Instant Messaging, prepared by the IETF's SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) Working Group.

The Internet Draft describes an XML-based status message that can be used to indicate the current composing status to participants in an IM conversation. "In instant messaging (IM) systems, it is useful to know during an IM conversation that the other party is composing a message, e.g., typing or recording an audio message. The document defines a new status message content type and XML namespace that conveys information about a message being composed. Status messages are carried as XML, as instances of the XML Schema defined in the draft and labeled as an application/im-iscomposing+xml content type."

The draft distinguishes two types of messages used in an IM conversation: one is the "content message" which "conveys actual content between two or more users engaged in an instant messaging conversation; the other is the "status message" which "indicates the current composing status to the other participants in a conversation. The status message can indicate the composition of a message of any type, including text, voice or video. The status messages are delivered to the instant messaging recipient in the same manner as the instant messages themselves.

The Internet Draft Indication of Message Composition for Instant Messaging is legally encumbered, according to an IETF Patent Disclosure and Licensing Declaration from Microsoft on the version -00 'is-composing ' draft of March 2004. Microsoft declined to make a royalty-free declaration provided in the IPR Template ("Royalty-Free, Reasonable and Non-Discriminatory License to All Implementers"), electing instead a RAND declaration for two issued patents and potentially for related unpublished pending patent application(s).

The IESG solicits public comment on this Internet Draft by 2004-06-28.

Bibliographic Information

Indication of Message Composition for Instant Messaging. By Henning Schulzrinne (Columbia University, Department of Computer Science); WWW. IETF Internet Draft. Reference: 'draft-ietf-simple-iscomposing-02'. Section 6 provides the XML Schema Definition. June 1, 2004, expires November 30, 2004. 13 pages.

Acknowledgements: "Ben Campbell, Miguel Garcia, Christian Jansson, Cullen Jennings, Hisham Khartabil, Aki Niemi, Jonathan Rosenberg and Xiaotao Wu provided helpful comments."

Previous versions:

• Indication of Message Composition for Instant Messaging. Reference: draft-ietf-simple-iscomposing-01.
• is-composing Indication for Instant Messaging Using the Session Initiation Protocol (SIP). Reference: 'draft-ietf-simple-iscomposing-00'.

Summary: Indication of Message Composition for Instant Messaging

An initial version of this Internet Draft was published in March 2004 under the title is-composing Indication for Instant Messaging Using the Session Initiation Protocol (SIP).

From the version -02 Introduction: "By definition, instant messaging (IM) is message-based, i.e., a user composes a message by typing, speaking or recording a video clip. This message is then sent to one or more recipients. Unlike email, instant messaging is often conversational, so that the other party is waiting for a response. If no response is forthcoming, a participant in an instant messaging conversation may erroneously assume that either the communication partner has left or that it is her turn to type again, leading to two messages 'crossing on the wire'.

To avoid this uncertainty, a number of commercial instant messaging systems feature an 'is-typing' indication that is sent as soon as one party starts typing a message. In this document, we describe a generalized version of this indication, called isComposing. As described in Section 3 in more detail, a status message is delivered to the instant message recipient in the same manner as the messages themselves. The isComposing messages can announce the composition of any media type, not just text. For example, it might be used if somebody is recording an audio or video clip. In addition, it can be extended to convey other instant messaging user states in the future.

The status messages are carried as XML, as instances of the XML schema defined in Section 6 and labeled as an application/im-iscomposing+xml content type.

These status messages can be considered somewhat analogous to the comfort noise packets that are transmitted in silence-suppressed interactive voice conversations.

Events and extensions to presence, such as PIDF, were also considered, but have a number of disadvantages. They add more overhead, since an explicit and periodic subscription is required. For page-mode delivery, subscribing to the right user agent and set of messages may not be easy. An in-band, message-based mechanism is also easier to translate across heterogeneous instant messaging systems.

The mechanism described here aims to satisfy the requirements in J. Rosenberg, Advanced Instant Messaging Requirements for the Session Initiation Protocol (SIP)..."

XML Schema Definition: "An isComposing document is an XML document that MUST be well-formed and SHOULD be valid. isComposing documents MUST be based on XML 1.0 and MUST be encoded using UTF-8. This specification makes use of XML namespaces for identifying isComposing documents. The namespace URI for elements defined for this purpose is a URN, using the namespace identifier 'ietf'. This URN is: urn:ietf:params:xml:ns:im-iscomposing..."