What are aliases?

Aliases are used to provide a quality of service for messages. The queue manager alias enables a system administrator to alter the name of a target queue manager without causing you to have to change the applications. It also enables the system administrator to alter the route to a destination queue manager, or to set up a route that involves passing through a number of other queue managers (multi-hopping). The reply-to queue alias provides a quality of service for replies.

Queue manager aliases and reply-to queue aliases are created using a remote-queue definition that has a blank RNAME. These definitions do not define real queues; they are used by the queue manager to resolve physical queue names, queue manager names, and transmission queues.

Alias definitions are characterized by having a blank RNAME.

Queue name resolution

Queue name resolution occurs at every queue manager each time a queue is opened. Its purpose is to identify the target queue, the target queue manager (which might be local), and the route to that queue manager (which might be null). The resolved name has three parts: the queue manager name, the queue name, and, if the queue manager is remote, the transmission queue.

When a remote queue definition exists, no alias definitions are referenced. The queue name supplied by the application is resolved to the name of the destination queue, the remote queue manager, and the transmission queue specified in the remote queue definition. For more detailed information about queue name resolution, see Queue name resolution.

If there is no remote queue definition and a queue manager name is specified, or resolved by the name service, the queue manager looks to see if there is a queue manager alias definition that matches the supplied queue manager name. If there is, the information in it is used to resolve the queue manager name to the name of the destination queue manager. The queue manager alias definition can also be used to determine the transmission queue to the destination queue manager.

If the resolved queue name is not a local queue, both the queue manager name and the queue name are included in the transmission header of each message put by the application to the transmission queue.

The transmission queue used typically has the same name as the resolved queue manager, unless changed by a remote queue definition or a queue manager alias definition. If we have not defined such a transmission queue but you have defined a default transmission queue, then this is used.

Names of queue managers running on z/OS are limited to four characters.