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Next: Internet Relay Chat Up: Lecture 19 Previous: Presence and Chat

Instant Messengers

Instant Messaging clients

• register their presence with service provider when starting up
• unregister their presence when terminating
• display presence status of entries on buddy list
• provide access point for spawning chat window

Messaging is done by

• clicking on buddy who is available online
• spawning linked chat windows at both ends
• communicating directly

Instant messaging servers

• are not party to communications between clients
• register and unregister authenticated clients
• notify clients when status of buddies change
• notify clients of host and port of contacts

Examples of Instant Messengers are

Standards for such services include RFCs 2778 , 2779 , 3920 , 3921