Enhanced Presence Architecture
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The enhanced presence system is based on a flexible and general-purpose data publication and subscription framework supported by Office Communications Server 2007 R2. In this system, a piece of presence data, such as the presence state, contact information, or calendar data, is represented by a Presence Category instance. A category is a data type that was introduced in Office Communications Server 2007 R2. It is a flexible data type and can be used to represent, in addition to presence data, other types of data that can be serialized as XML blobs.
In this enhanced presence system, the presence information is taken from a presence sensor or data source, packaged as a category instance, and published to the server. The publication involves a presence sensing client sending specified presence category instances to specified Presence Container created and maintained by the server. The server then sends the published presence data to the subscribers included in the container's membership scope. The receiver of a specified subscriber gets notified of the publication, receives the presence data, and displays the information to the user (that is, the subscriber). User information obtained from Active Directory can also be published to special containers known as self-containers. The information is typically intended for use by its publisher. As such, it can be subscribed to only by the presence information publisher.
The following illustration offers an architectural illustration of the enhanced presence system, supported by Office Communications Server 2007 R2 and Office Communicator 2007 R2.
Publication need not always go through the aggregation script. In such cases, publication can go directly into containers.