5.5. Adding Service Look-ups Through JNDI

Until now, you have used the Microcontainer to look up references to bean instances which represent services. This is not ideal, because it requires a reference to the Microcontainer kernel before the controller can be accessed. This is shown in Example 5.7, “Looking Up References To Beans”.

Example 5.7. Looking Up References To Beans

private HRManager manager;
private EmbeddedBootstrap bootstrap;
private Kernel kernel;
private KernelController controller;
private final static String HRSERVICE = "HRService";

...

// Start JBoss Microcontainer
bootstrap = new EmbeddedBootstrap();
bootstrap.run();

kernel = bootstrap.getKernel();
controller = kernel.getController();

...

 ControllerContext context = controller.getInstalledContext(HRSERVICE);
if (context != null) { manager = (HRManager) context.getTarget(); }

private HRManager manager;
private EmbeddedBootstrap bootstrap;
private Kernel kernel;
private KernelController controller;
private final static String HRSERVICE = "HRService";

...

// Start JBoss Microcontainer
bootstrap = new EmbeddedBootstrap();
bootstrap.run();

kernel = bootstrap.getKernel();
controller = kernel.getController();

...

 ControllerContext context = controller.getInstalledContext(HRSERVICE);
if (context != null) { manager = (HRManager) context.getTarget(); }

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Handing out kernel references to every client that looks up a service is a security risk, because it provides wide-spread access to the Microcontainer configuration. For better security, apply the ServiceLocator pattern and use a class to performs look-ups on behalf of the clients. Even better, pass the bean references, along with their names, to the ServiceLocator at deployment time, using a life-cycle callback. In that scenario, the ServiceLocator can look them up without knowing about the Microcontainer at all. Undeployment would subsequently remove the bean references from the ServiceLocator to prevent further look-ups.

It would not be difficult to write your own ServiceLocator implementation. Integrating an existing one such as JBoss Naming Service (JBoss NS) is even quicker, and has the additional benefit of complying to the Java Naming and Directory Interface (JNDI) specification. JNDI enables clients to access different, possibly multiple, naming services using a common API.

Procedure 5.3. Writing Your Own ServiceLocator Implementation

First, create an instance of JBoss NS using the Microcontainer.
Next, add a life-cycle callback to perform the binding and unbinding of the bean references during deployment and undeployment.
Mark the bean classes you wish to bind references for, using annotations.
Now, you can locate the beans at run-time using the shorthand pointcut expression as shown earlier.

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5.5. Adding Service Look-ups Through JNDI

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