Data Filter
Data filters are used to transform data as it is sent to a Channel.
Messages are filtered as the message is published to a channel, invoking the
Channel.publish(Message)
method.
This method gets invoked in two different scenarios, the first being when a message is received from
a remote client, and the Bayeux implementation invokes the publish method directly.
The second scenario is when a local client invokes
Channel.publish(Message)
directly in the local JVM.