Create topics at runtime

 

There are four ways to create Topic objects at runtime:

  1. Construct a topic using the one-argument MQTopic constructor

  2. Construct a topic using the default MQTopic constructor, and then call the setBaseTopicName(..) method

  3. Use the session's createTopic(..) method

  4. Use the session's createTemporaryTopic() method

Example 1: Using MQTopic(..)

This technique requires a reference to the WebSphere MQ implementation of the JMS Topic interface, and therefore renders the code non-portable.

The constructor takes one argument, which must be a uniform resource identifier (URI). For WebSphere MQ classes for Java Message Service Topics, this must be of the form: 

topic://TopicName[?property=value[&property=value]*]

For further details on URIs and the permitted name-value pairs, see Sending a message.

The following code creates a topic for nonpersistent, priority 5 messages: 

// Create a Topic using the one-argument MQTopic constructor
String tSpec = "Sport/Football/Spurs/Results?persistence=1&priority=5";
Topic rtTopic = new MQTopic( "topic://" + tSpec );

Example 2: Using MQTopic(), then setBaseTopicName(..)

This technique uses the default MQTopic constructor, and therefore renders the code non-portable.

After the object is created, set the baseTopicName property using the setBaseTopicName(..) method, passing in the required topic name.

The topic name used here is the non-URI form, and cannot include name-value pairs. Set these by using the set methods, as described in Set properties with the set method.

The following code uses this technique to create a topic: 

// Create a Topic using the default MQTopic constructor
Topic rtTopic = new MQTopic();

// Set the object properties using the setter methods
((MQTopic)rtTopic).setBaseTopicName( "Sport/Football/Spurs/Results" );
((MQTopic)rtTopic).setPersistence(1);
((MQTopic)rtTopic).setPriority(5);

Example 3: Using session.createTopic(..)

We can also create a Topic object using the createTopic method of TopicSession, which takes a topic URI as follows: 
// Create a Topic using the session factory method
Topic rtTopic = session.createTopic( "topic://Sport/Football/Spurs/Results" );

Although the createTopic method is in the JMS specification, the format of the string argument is vendor-specific. Therefore, using this technique might make your code non-portable.

Example 4: Using session.createTemporaryTopic()

A TemporaryTopic is a Topic that can be consumed only by subscribers that are created by the same TopicConnection. A TemporaryTopic is created as follows: 
// Create a TemporaryTopic using the session factory method
Topic rtTopic = session.createTemporaryTopic();


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