Foreign destinations

A foreign destination is a type of bus destination. A foreign destination represents a destination that is defined in another bus (a foreign bus). You use a foreign destination for point-to-point messaging when you need to override messaging defaults, security settings, or both for an individual destination on a foreign bus.

Usually, you do not need to configure a foreign destination:

To use a foreign destination, you define the foreign destination on the local bus. When an application that is connected to the local bus sends messages to the destination in the foreign bus, the attributes of the foreign destination override the destination default values. You can set properties and destination roles, but you cannot map to an alternative name for the destination.

The foreign bus can be another service integration bus or a WebSphere® MQ network (that is, one or more interconnected WebSphere MQ queue managers or queue-sharing groups).

To override messaging defaults of a destination on a foreign bus, you configure the properties (for example, the default priority) of the foreign destination. To override security settings and control which users and groups in the local bus have access to a destination in a foreign bus, you configure the destination roles of the foreign destination. These properties apply when an application that is connected to the local bus sends messages to the destination in the foreign bus.

When you define a foreign destination, use the actual names of the foreign bus and the destination on the foreign bus, so that the JMS destination object does not change.

When an application that is connected to the local bus sends messages to the destination in the foreign bus, service integration in the local bus uses the properties and destination roles of the foreign destination, rather than the default values from the definition of the foreign bus (on the local bus). Typically, you configure the properties of a foreign destination to match the properties that are configured for that destination in the foreign bus (where that destination is a local destination), but this is not essential.

You can also configure destination roles for the foreign destination. Service integration in the local bus uses these roles to control which users and groups in the local bus have access to the destination. It also complements any access controls that the foreign bus applies.

You do not use foreign destinations for publish-subscribe messaging. Instead, applications publish messages locally using a topic space destination in the local bus, and you configure a service integration bus link or a WebSphere MQ link. These links propagate the published messages into the foreign bus, or buses, where subscribers receive the messages. For a link to a service integration bus, configure topic space mappings, as described in Configuring topic space mappings between service integration buses. For a link to a WebSphere MQ network, configure a publish/subscribe bridge, as described in Publishing and subscribing with a WebSphere MQ network.

Service integration cannot use configuration information that is scoped to a foreign bus. Therefore, if an appropriate foreign destination is not defined on the local bus, service integration uses default values for the destination attributes.

Figure 1 shows a JMS application that sends messages from the local bus, Bus 1, to a destination in a foreign bus, Bus 2. Bus 1 has a foreign bus connection defined, which it uses to forward the message to the foreign bus. The foreign destination is not defined in the local bus. Bus 1 gets the destination defaults from the foreign bus connection.

Figure 1. Point-to-point messaging between two buses with no foreign destination configured
Graphic is described in the surrounding text.

Figure 2 shows a JMS application that sends messages from the local bus, Bus 1, to a destination in a foreign bus, Bus 2. Bus 1 has a foreign bus connection defined, which it uses to forward the message to the foreign bus. Bus 1 includes a foreign destination definition. Bus 1 gets the destination defaults from the foreign destination.

Figure 2. Point-to-point messaging between two buses with a foreign destination configured on the local bus
Graphic is described in the surrounding text.




Related concepts
Planning issues for multiple-bus topologies
Bus destinations
Learning about bus destinations
Related tasks
Creating a foreign destination on a bus
Concept topic    

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Last updated: Sep 20, 2010 11:08:29 PM CDT
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