Methods and apparatus for accessing presence information

摘要

A presence server provides presence information to content subscribers via unicast transmission of the presence information. In the case where the presence server receives, from a subscriber, a subscription request for presence information having a relatively large number of subscribers, the presence server directs the content subscriber to a multicast transmission channel. The content subscriber, in turn, accesses the presence information via the multicast transmission channel. By directing content subscribers toward the multicast transmission channel, the presence server conserves connection resources associated with the presence system, thereby allowing the presence system to distribute presence information with a relatively high level of speed and efficiency. Furthermore, by directing content subscribers toward the multicast transmission channel, the presence server minimizes the costs associated with adding new subscribers to the presence system.