Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer's Guide

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# JMS Connection Features

The Sun Java System Message Queue software supports the following JMS connection features:

- Connection Pooling

- Connection Failover

Both these features use the `AddressList` configuration, which is populated with the hosts and ports of the JMS hosts defined in the Application Server. The `AddressList` is updated whenever a JMS host configuration changes. The `AddressList` is inherited by any JMS resource when it is created and by any MDB when it is deployed.

Note –

In the Sun Java System Message Queue software, the `AddressList` property is called `imqAddressList`.

## Connection Pooling

The Application Server pools JMS connections automatically.

To dynamically modify connection pool properties using the Administration Console, go to either the Connection Factories page (see Creating JMS Resources: Destinations and Connection Factories) or the Connector Connection Pools page (see Deploying and Configuring a Stand-Alone Connector Module).

To use the command line, use the `asadmin create-connector-connection-pool` command to manage the pool (see Deploying and Configuring a Stand-Alone Connector Module.

The `addresslist-behavior` JMS service attribute is set to `random` by default. This means that each `ManagedConnection` (physical connection) created from the `ManagedConnectionFactory` selects its primary broker in a random way from the `AddressList`.

When a JMS connection pool is created, there is one `ManagedConnectionFactory` instance associated with it. If you configure the `AddressList` as a `ManagedConnectionFactory` property, the `AddressList` configuration in the `ManagedConnectionFactory` takes precedence over the one defined in the Application Server.

## Connection Failover

To specify whether the Application Server tries to reconnect to the primary broker if the connection is lost, set the `reconnect-enabled` attribute in the JMS service. To specify the number of retries and the time between retries, set the `reconnect-attempts` and `reconnect-interval-in-seconds` attributes, respectively.

If reconnection is enabled and the primary broker goes down, the Application Server tries to reconnect to another broker in the `AddressList`. The `AddressList` is updated whenever a JMS host configuration changes. The logic for scanning is decided by two JMS service attributes, `addresslist-behavior` and `addresslist-iterations`.

You can override these settings using JMS connection factory settings. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

The Sun Java System Message Queue software transparently transfers the load to another broker when the failover occurs. JMS semantics are maintained during failover.

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