WebSphere WebSphere Application Server Version 6.1.x Feature Pack for Web Services Operating Systems: AIX, HP-UX, i5/OS, Linux, Solaris, Windows, z/OS

Point-to-point messaging across multiple buses

A messaging application connected to a bus can send messages directly to another bus. There is a one-to-one mapping between the sender and receiver of messages because they must both specify the same destination when communicating with the messaging provider. In point-to-point messaging, the destination is usually referred to as a queue, in which the messages are stored.

When you create the message producer for a queue in a different bus, you identify the name of the bus that hosts the queue, that is, the foreign bus. You then establish a service integration bus link that connects the local bus and the foreign bus. A foreign bus is a representation of another service integration bus, or a WebSphere MQ queue manager, with which an existing service integration bus can exchange messages. The local bus knows of the destination’s bus through a foreign bus definition. If the bus directly connected to the local bus does not hold the specified destination, more service integration links are used to flow the message to the next bus on route to the destination’s bus. When the message enters the destination’s bus, that bus attempts to deliver the message to the intended destination.

A JMS application connected to Bus 1 creates a producer for Queue 2 in Bus 2. You can achieve this by specifying the JNDI object that identifies Queue 2 when establishing a connection factory.
Figure 1. Establishing point-to-point messaging between two busesA messaging application connected to Bus 1 can send a message to a queue in a foreign bus, Bus 2.
Important: When sending messages to destinations in a foreign bus, in this case Bus 2, it is not possible for the local bus, Bus 1, to verify the existence of the destination. You must make sure that the destination exists.
The actual existence of a particular destination is only known by the bus hosting the destination. If a message arrives via the service integration bus link for a destination that does not exist in the foreign bus the message is routed to the exception destination of the link’s messaging engine.

When sending to a destination, you get a number of messaging defaults and the defaults apply when sending to destinations in a foreign bus. These defaults are inherited from the Destination defaults associated with a foreign bus definition. It is possible to administratively override these defaults for individual destinations in foreign buses. You can do this by defining a Foreign Destination in the local bus that identifies the destination in the foreign bus, and explicitly sets the defaults associated with it. For more information, see Configuring destination defaults for a foreign bus.

Note: An application cannot consume messages from a destination that is located in a different bus to the one that the application is connected to. Any attempt to create a consumer to a destination on a foreign bus is rejected.

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Timestamp icon Last updated: 27 November 2008
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