The Instant Messaging API is used by the applications located on the same host or in the remote host to access Instant Messaging services, such as Presence, Conference, Notification, Polls and News channels.
The Instant Messaging Service API can be used for:
A Java-based or web-based client, such as a portal channel.
A Bridge or a Gateway to enable another class of clients.
Integration of Instant Messenger and Presence into existing applications.
Displaying news feeds as Instant Messenger news.