A message point is associated with a messaging engine and holds
messages for a bus destination.
A message point is the general term for the location on a messaging engine
where messages are held for a bus destination. A message point can be:
- A queue point
- A publication point
- A mediation point (this is a specialized message point)
For point-to-point messaging, the administrator selects one bus member,
which can be an application server
or server cluster,
to hold the messages of the queue destination. This action automatically defines
a
queue point for
each messaging engine in the
assigned bus member.
- For a queue destination assigned to an application server, all messages
sent to that destination are handled by the messaging engine of that server,
and message order is preserved.

- For a queue destination assigned to a server cluster,
there is a separate message point for each messaging engine in the cluster.
The message points partition the destination in the same way that a WebSphere
MQ cluster partitions a clustered queue. Multiple messages addressed to a
such a partitioned destination are handled by any messaging engine in the
cluster, but an individual message is handled by only one engine.

The messages of the
destination are split between the separate message stores for the messaging
engines. This configuration has the disadvantage that message order cannot
be preserved, but has advantages:- Multiple producers or consumers can be deployed across the same server
cluster and messaging operations are handled locally by the messaging engine
of a cluster member.
- Cluster monitoring can be used to detect the failure of a messaging engine,
and the surviving engines within the cluster can take over the message stores
containing the permanent state for the failed engine.
If message ordering must be preserved, there are several rules that must
be adhered to, see Message ordering.
For publish/subscribe messaging, the administrator configures a topic space
destination, but does not need to assign a bus member for the topic space.
A topic space has a publication point defined automatically for each messaging engine in the bus.
Message points can be remote from the application which
is producing to or consuming from the bus destination. In other words, message
points can reside on a messaging engine other than the messaging engine to
which the application is connected. In this situation the message point is
represented at runtime by a remote message point on the remote messaging
engine.
![[Version 6.0.2]](../was602.gif)
By monitoring message points and remote message points,
you can fully analyze and resolve problems arising from distributed application
messaging. For example, you can:
- Determine the state of a specific message request.
- Determine the location of a specific message.
- Examine message queues to determine if messages have been sent or received.
- Free or delete message requests that have become locked.
- Delete or move messages from remote message points.