Described is a schema-based notification platform that provides regularized
notification handling including user control and normalization of the operation
of policies across different information types and contexts. Information-service
schemas and services are combined to build a content-sensitive and context-sensitive
information service to communicate information to recipient devices of users that
subscribe to those services. An information agent service collects the information,
and based on various criteria, determines if, when, and how to send and render
the information, and to which subscribing client device or devices. The set of
schemas include a notification schema that represents the subscription of a service
to an information source and details about that information, and a device schema
that represents information about user devices. The information agent service accesses
criteria including user preferences and user contextual information, including
presence information, location information, and schedule information along with
people and groups data and extended-context data. Preferences about subscriptions
and information handling policies may be stored and used at notification sources
or in more central preference encodings. Access to multiple preferences is maintained,
and a user interface is provided that allows users to inspect and control multiple
subscriptions in one conceptual place.