Subscription-based notification using event channels that each
correspond to a particular scope. Each channel manages notifications through the
use of a a schema definition. The event subscriptions identify the position and
attributes that any desired event notification would take in the the schema definition.
The channel then receives event notifications in the form of XML fragments. The
channel then determines the position that the XML fragment would take as defined
by the schema definition. The channel determines whether the position and attributes
of the event notification matches the position and attributes of the event subscription.
If a match is found, then the event notification is copied and forwarded to the
recipient designated in the corresponding subscription.