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# Create uniform distributed topics in a system module

When configuring uniform distributed topics, WebLogic Server uniformly creates the necessary members on the JMS servers to which a JMS module is targeted. This ensures the consistent configuration of all distributed destination parameters, particularly in regards to weighting, security, persistence, paging, and quotas.

The legacy weighted distributed topic feature is still available for users who prefer to manually fine-tune distributed topic members. However, BEA strongly recommends configuring uniform distributed topics to ensure the consistent configuration and deployment of topic members across a cluster. For more information on creating a weighted distributed topic, see Create weighted distributed topics in a system module.

To create a uniform distributed topic:

1. If you have not already done so, in the Change Center of the Administration Console, click Lock & Edit (see Use the Change Center).
2. In the Administration Console, expand Services > Messaging and select JMS Modules.
3. In the JMS Modules table, click the name of JMS module in which to configure the topic resource.
4. On the module's Settings page, click the New button in the Summary of Resources table.
5. On the Create a New JMS System Module Resource page, select Distributed Topic from the list of JMS resources, and then click Next.
6. On the Distributed Topic Properties page, define the uniform distributed topic's basic properties:
   1. In Name, enter a name for the uniform distributed topic.

      Once you create a uniform distributed topic, you cannot rename it. Instead, you must delete it and create another one that uses the new name.

   2. In JNDI Name, enter the JNDI name used to look up the uniform distributed topic within the JNDI namespace. Applications use the JNDI Name to look up the distributed topic.

      If you do not specify a JNDI name for the distributed topic, it will not be available for JNDI lookup even after it has been targeted to a server resource. Therefore, you will only be able to access the distributed topic using the `javax.jms.topicSession.createtopic()` API or in an application-scoped context.

   3. In Load Balancing Policy, specify a policy (Round Robin or Random) for how messages are distributed to the members of this uniform distributed topic.
   4. Leave the Allocate Members Uniformly check box enabled in order for WebLogic Server to uniformly create and allocate the members of this uniform distributed topic.
7. Click Next to proceed to the targeting page or click Finish to create the uniform distributed topic.

   Caution: If you click Finish at this point, the uniform distributed topic will be created without any targeting information. As a result, the uniform distributed topic will not be deployed and thus will not be available to applications until you manually select a subdeployment target, as described in Uniform distributed topics - specify subdeployments.

   On the targeting page, you can either target the uniform distributed topic to system-selected JMS server(s), server instance(s), or cluster, or optionally proceed to an advanced targeting page where you can either select an existing subdeployment or create a new subdeployment. A subdeployment is a mechanism by which JMS module resources (such as standalone destinations, uniform distributed destinations, and connection factories) are grouped and targeted to server resources (such as JMS servers, server instance(s), or cluster).

8. For basic system-selected targeting, in the Targets box simply select a JMS server(s), server instance(s), or cluster, and then click Finish. A system-owned subdeployment is automatically generated for the uniform distributed topic and the selected target(s), using the BEA_JMS_SUBDEPLOYMENT_XXXX name space, where XXXX is the name of the parent module.

   Note: JMS administrators cannot create any subdeployment beginning with BEA_JMS_SUBDEPLOYMENT. This naming restriction is validated during the subdeployment creation process.

   Upon clicking Finish, the configured uniform distributed topic is added to the module's Summary of Resources table, which displays its system-generated subdeployment name and its targets. You can also reconfigure subdeployment targets later if you wish. For more information about managing subdeployments, refer to Configure subdeployments in JMS system modules.

9. For advanced targeting, click Advanced Targeting, which allows you to select an existing subdeployment or to create a new one.
   - To select an existing subdeployment for the uniform distributed topic, select one from the Subdeployments drop-down. When a valid subdeployment is selected, its targeted JMS server(s), server(s), or cluster appear as selected in the Targets box. (A subdeployment with standalone destinations can only be targeted to a single JMS server.) Click Finish to add the uniform distributed topic to the selected subdeployment.
   - To create a new subdeployment for the uniform distributed topic, click the Create a new Subdeployment button. On the Subdeployment Properties page, enter a name for the subdeployment, and then click OK. On the ensuing subdeployment targeting page, select a JMS server(s), server instance(s), or cluster in the Targets box. (A subdeployment with standalone destinations can only be targeted to a single JMS server.) Click Finish to add the uniform distributed topic to the new subdeployment.

   Upon clicking Finish, the configured uniform distributed topic is added to the module's Summary of Resources table, which displays the user-defined subdeployment name and its targets. You can also reconfigure subdeployment targets later if you wish. For more information about managing subdeployments, refer to Configure subdeployments in JMS system modules.

10. To activate these changes, in the Change Center of the Administration Console, click Activate Changes.
    Not all changes take effect immediately—some require a restart (see Use the Change Center).

After you finish

If you want to configure additional parameters for a new uniform distributed topic, including general properties, thresholds and quotas, producer overrides, logging, message delivery failure, and multicast properties, see Configure uniform distributed topics.