Physical Destinations

A physical destination on the broker is a memory location where messages are stored before being delivered to a message consumer. There are four kinds of physical destinations:

• Admin-created destinations are created by an administrator using Message Queue administration tools. Admin-created destinations correspond to destination administered objects created by an administrator and accessed by client applications by using a JNDI lookup. Admin-created destinations can also correspond to destination objects created programmatically by a client application. You use Message Queue administration tools to set or update properties for each admin-created destination.

• Auto-created destinations are automatically created by the broker whenever a message consumer or producer attempts to access a nonexistent destination. These are typically used during development. You can set a broker property to disallow the creation of such destinations. You set broker properties to configure all auto-create destinations on a particular broker.

  An auto-created destination is automatically destroyed by the broker when it is no longer being used: that is, when it has no consumer clients and no longer contains any messages. If a broker restarts, it only recreates this kind of destination if it contains persistent messages.

• Temporary destinations are explicitly created and destroyed programmatically by client applications that need a destination at which to receive replies to messages. As their name implies, these destinations are temporary. They are maintained by the broker only for the duration of the connection in which they are created.

  Temporary destinations are only stored persistently only if the consumer of the destination is set to automatically reconnect in the event of failure. Otherwise, they are not recreated when a broker is restarted. Nevertheless, temporary destinations are visible to administration tools.

• The dead message queue is a specialized destination, created automatically at broker startup and used to store dead messages for diagnostic purposes. You can set properties for the dead message queue using the imqcmd utility.

Managing Destinations

Managing a destination involves one or more of the following tasks:

• Creating, pausing, resuming, or destroying a destination

• Listing all destinations on a broker

• Displaying information about the state and properties of a destination

• Displaying metrics information for a destination

• Compacting disk space used to persist messages for a destination

• Updating a physical destination’s properties

Management tasks vary with the kind of destination being managed: admin-created, auto-created, temporary, or dead message queue. For example, temporary destinations do not need to be explicitly destroyed; auto created properties are configured using broker configuration properties which apply to all auto-created destinations on that broker.

Configuring Physical Destinations

For optimal performance, you can set properties when creating or updating physical destinations. Properties that can be set include the following:

• The type and name of the destination.

• Individual and aggregate limits for destinations (the maximum number of messages, the maximum number of total bytes, the maximum number of bytes per message, the maximum number of producers).

• What the broker should do when individual or aggregate limits are exceeded.

• The maximum number of messages to be delivered in a single batch.

• Whether deleted messages for a destination should be sent to the dead message queue.

• In the case of a broker cluster, whether a destination should be propagated to other brokers in the cluster.

For a queue destination you can also configure the maximum number of active and back up consumers and you can specify (for broker clusters) whether delivery to a local queue is preferred.

You can also configure the limits and behavior of the dead message queue. Note, however, that default properties for this queue differ from those of a standard queue.