Building a connection in a JMS application

To create a Connection object, an application uses the createConnection() method of a ConnectionFactory object, as shown in the following example:

ConnectionFactory factory;
Connection connection;
.
.
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connection = factory.createConnection();

The QueueConnectionFactory interface and the TopicConnectionFactory interface each inherits the createConnection() method from the ConnectionFactory interface. You can therefore use the createConnection() method to create a domain specific object, as shown in the following example:

QueueConnectionFactory qcf;
Connection connection;
.
.
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connection = qcf.createConnection();

This fragment of code creates a QueueConnection object. An application can now perform a domain independent operation on this object, or an operation that is applicable only to the point-to-point domain. However, if the application attempts to perform an operation that is applicable only to the publish/subscribe domain, an IllegalStateException exception is thrown with the following message:

JMSMQ1112: Operation for a domain specific object was not valid.
           Operation createProducer() is not valid for type com.ibm.mq.jms.MQTopic

This is because the connection was created from a domain specific connection factory.

The JMS specification states that a connection is created in the stopped state. Until a connection starts, a message consumer that is associated with the connection cannot receive any messages. To start a connection, an application uses the start() method of a Connection object, as shown in the following example:

connection.start();