Sun Java System Application Server Enterprise Edition 8.1 2005Q2 High Availability Administration Guide

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## JMS Hosts List

A JMS host represents an MQ broker. The Java Message Service contains a JMS Hosts list (also called `AddressList`) that contains all the JMS hosts that Application Server uses.

The JMS Hosts list is populated with the hosts and ports of the specified MQ brokers and is updated whenever a JMS host configuration changes. When you create JMS resources or deploy MDBs, they inherit the JMS Hosts list.

Note –

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

### Default JMS Host

One of the hosts in the JMS Hosts list is designated the default JMS host, named `Default_JMS_host`. The Application Server instance starts the default JMS host when the Java Message Service type is configured as LOCAL.

If you have created a multi-broker cluster in the Sun Java System Message Queue software, delete the default JMS host, then add the Message Queue cluster’s brokers as JMS hosts. In this case, the default JMS host becomes the first one in the JMS Hosts list.

When the Application Server uses a Message Queue cluster, it executes Message Queue specific commands on the default JMS host. For example, when a physical destination is created for a Message Queue cluster of three brokers, the command to create the physical destination is executed on the default JMS host, but the physical destination is used by all three brokers in the cluster.

### Creating JMS Hosts

You can create additional JMS hosts in the following ways:

- Use the Administration Console. Open the Java Message Service component under the relevant configuration, select the JMS Hosts component, and then click New. For more information, see To create a JMS host in Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

- Use the `asadmin create-jms-host` command. For details, see create-jms-host(1).

  The JMS Hosts list is updated whenever a JMS host configuration changes.

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