A mediation handler list is a collection of mediation handlers
that are invoked in sequence.
A
mediation handler list is a simple pipeline of mediation
handlers. The same parameters are passed from one mediation handler to the
next mediation handler in the list.
Figure 1. Mediation handler lists.
This figure shows how parameters are passed from one mediation handler
to the next, in a mediation handler list. The result of the operation of each
mediation handler in the list determines whether the next mediation handler
in the list is called, or if the message is routed to the next destination. 
A mediation handler list may contain one or more mediation handlers. Membership
of a mediation handler list is specified when a mediation is deployed.
When you configure the messaging provider in the administrative console,
you can associate a mediation handler list with one or more selected destinations.
This makes the mediation handler list eligible to mediate messages that arrive
at the destination.