Example 2–2 shows how to create a connection factory object by direct instantiation and configure its properties.
// Instantiate the connection factory object. com.sun.messaging.ConnectionFactory myFactory = new com.sun.messaging.ConnectionFactory(); // Set the connection factory’s configuration properties. myFactory.setProperty(ConnectionConfiguration.imqAddressList, "localhost:7676,broker2:5000,broker3:9999");
The following procedure explains each program satement in the previous code sample.
Instantiate the connection factory object.
The name ConnectionFactory is defined both as a JMS interface (in package javax.jms) and as a Message Queue class (in com.sun.messaging) that implements that interface. Since only a class can be instantiated, you must use the constructor defined in com.sun.messaging to create your connection factory object. Note, however, that you cannot import the name from both packages without causing a compilation error. Hence, if you have imported the entire package javax.jms.*, you must qualify the constructor with the full package name when instantiating the object:
com.sun.messaging.ConnectionFactory myFactory = new com.sun.messaging.ConnectionFactory();
Notice that the type declaration for the variable myFactory, to which the instantiated connection factory is assigned, is also qualified with the full package name. This is because the setProperty method, used in Instantiating a Connection Factory, belongs to the ConnectionFactory class defined in the package com.sun.messaging, rather than to the ConnectionFactory interface defined in javax.jms . Thus in order for the compiler to recognize this method, myFactory must be typed explicitly as com.sun.messaging.ConnectionFactory rather than simply ConnectionFactory (which would resolve to javax.jms.ConnectionFactory after importing javax.jms.* ).
The most important configuration property is imqAddressList, which specifies the host names and port numbers of the message brokers to which the factory creates connections. By default, the factory returned by the ConnectionFactory constructor in Instantiating a Connection Factory is configured to create connections to a broker on host localhost at port number 7676. If necessary, you can use the setProperty method, described in the preceding section, to change that setting:
Of course, you can also set any other configuration properties your application may require. See Connection Factory Attributes in Sun Java System Message Queue 4.2 Administration Guide for a list of the available connection factory attributes.
You can now proceed to use the connection factory to create connections to the message service, as described in the next section.