Subscription-based notification using event channels that each
correspond to a particular scope. Each channel manages notifications through the
use of a schema definition. The event subscriptions identify the position and attributes
that any desired event notification would take in 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.