Interactive Content Delivery— Instant Messaging

Instant messaging (IM) is a real-time, interactive content-delivery tool. Users alternate roles, taking turns as content consumers and content creators. The resulting communication is a bidirectional and symmetrical dialog. Research on spoken conversations highlights the importance of simultaneous feedback on signaling when to listen, the effective timing of taking turns, and maintaining a continuous interaction. Although text-only interactive systems provide users less feedback than face-to-face meetings, well-designed interactive systems can achieve interactional coherence and also allow types of language play that are not common in face-to-face interactions. Interactive systems engage users in ways that are impossible with communications requiring a significant time lag, such as letter writing or even e-mail. Interactive systems often rely on the rapid exchange of short messages. This chapter defines IM, explores various types of collaboration, introduces a reference model for IM and presence, and describes some basic requirements for such systems. Standard Internet Engineering Task Force (IETF) models for presence and instant messaging are described in the chapter along with various Internet-based IM and presence systems. These include the Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIMPLE), based on the Session Initiation Protocol (SIP), and the Extensible Messaging and Presence Protocol (XMPP), based on Jabber. The chapter describes the presence, pager mode, and message mode approaches of the SIMPLE standard; introduces popular IM systems, including AOL Instant Messenger, MSN Messenger, and Yahoo! Messenger; and discusses the wireless Short Messaging System (SMS), and the Multimedia Messaging Service (MMS).