Enhanced Presence System

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Built on the general-purpose category publication and subscription framework, the enhanced presence system takes the input of presence information from multiple presence sensors, aggregates the presence states from multiple sources, and then distributes it to presence receivers (Office Communications Server clients) that include Communicator, Outlook, or IP phones.

Aggregation is complex in cases such as state. In most other cases, however, there is no aggregation; the server sends out minimally filtered category instances to watchers.

The following figure provides an overview of the presence system and shows the major system components that sense, collect, and publish elements of a user's presence status to the presence system. In the figure, the components to the left of Office Communications Server are presence data sources, which provide presence data input. Office Communications Server performs aggregation of the presence statuses, as well as other static information such as contact card data and notes, and distributes the selected state and presence data to its clients. Office Communications Server applies access control list policies to determine the amount of a user's presence information to deliver to specified subscribers for display.