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ejb-remote: Remote EJB Client Example

The ejb-remote quickstart uses EJB and JNDI to demonstrate how to access an EJB, deployed to WildFly, from a remote Java client application.

What is it?

The ejb-remote quickstart shows how to access an EJB from a remote Java client application. It demonstrates the use of EJB and JNDI in WildFly Application Server.

There are two components to this example:

  1. A server side component:

    The server component is comprised of a stateful EJB and a stateless EJB. It provides both an EJB JAR that is deployed to the server and a JAR file containing the remote business interfaces required by the remote client application.

  2. A remote client application that accesses the server component.

    The remote client application depends on the remote business interfaces from the server component. This application looks up the stateless and stateful beans via JNDI and invokes a number of methods on them.

Each component is defined in its own standalone Maven module. The quickstart provides a top level Maven module to simplify the packaging of the artifacts.

Build and Run the Client Application

  1. Navigate to the client subdirectory.

    $ cd ../client

  2. Compile the client code.

    $ mvn clean compile

  3. Execute the client application within Maven.

    $ mvn exec:exec

Investigate the Console Output

When the client application runs, it performs the following steps:

  1. Obtains a stateless session bean instance.

  2. Sends method invocations to the stateless bean to add two numbers, and then displays the result.

  3. Sends a second invocation to the stateless bean subtract two numbers, and then displays the result.

  4. Obtains a stateful session bean instance.

  5. Sends several method invocations to the stateful bean to increment a field in the bean, displaying the result each time.

  6. Sends several method invocations to the stateful bean to decrement a field in the bean, displaying the result each time.

The output in the terminal window will look like the following:

  Obtained a remote stateless calculator for invocation
  Adding 204 and 340 via the remote stateless calculator deployed on the server
  Remote calculator returned sum = 544
  Subtracting 2332 from 3434 via the remote stateless calculator deployed on the server
  Remote calculator returned difference = 1102
  Obtained a remote stateful counter for invocation
  Counter will now be incremented 5 times
  Incrementing counter
  Count after increment is 1
  Incrementing counter
  Count after increment is 2
  Incrementing counter
  Count after increment is 3
  Incrementing counter
  Count after increment is 4
  Incrementing counter
  Count after increment is 5
  Counter will now be decremented 5 times
  Decrementing counter
  Count after decrement is 4
  Decrementing counter
  Count after decrement is 3
  Decrementing counter
  Count after decrement is 2
  Decrementing counter
  Count after decrement is 1
  Decrementing counter
  Count after decrement is 0

Logging statements have been removed from this output here to make it clearer.

Build and Run The Quickstart as an Executable JAR

The remote client application can also be built as a standalone executable JAR with all of its dependencies.

  1. Open a terminal and navigate to the ejb-remote/client quickstart directory

    $ cd client

  2. Type the following in the command line:

    $ mvn clean package assembly:single

  3. You can then run the executable JAR using the java -jar command. You will see the same console output as above.

    $ java -jar target/{artifactId}-client-jar-with-dependencies.jar

Undeploy the Archive

To undeploy the server-side component from the WildFly server:

  1. Navigate to the server-side subdirectory:

    $ cd ../server-side

  2. Type the following command:

    $ mvn wildfly:undeploy

Using EJB over HTTP

You can use HTTP as the transport for remote EJB invocations by specifying -Dhttp=true on both the Maven and command line based execution. This should not change the output, but it will use EJB over HTTP for the invocations. This means that each EJB request maps to a single HTTP request (actually HTTP/2 by default, if it is enabled on the server).

Before you can use it, you need to set up a user on the server as HTTP does not support transparent authentication.

To add the user, open a terminal and type the following command.

$ WILDFLY_HOME/bin/add-user.sh -a -u 'quickstartUser' -p 'quickstartPwd1!'
Note
 For Windows, use the WILDFLY_HOME\bin\add-user.bat script.

If you prefer, you can use the add-user utility interactively. For an example of how to use the add-user utility, see the instructions located here: Add an Application User.

This quickstart consists of multiple projects, so it deploys and runs differently in JBoss Developer Studio than the other quickstarts.

  1. Install the required Maven artifacts and deploy the server side of the quickstart project.

    • Right-click on the {artifactId}-server-side project and choose Run As → Maven Install.

    • Right-click on the {artifactId}-server-side project and choose Run As → Run on Server.

  2. Build and run the client side of the quickstart project.

    • Right-click on the {artifactId}-client project and choose Run As → Java Application.

    • In the Select Java Application window, choose RemoteEJBClient - org.jboss.as.quickstarts.ejb.remote.client and click OK.

    • The client output displays in the Console window.

  3. To undeploy the project, right-click on the {artifactId}-server-side project and choose Run As → Maven build. Enter wildfly:undeploy for the Goals and click Run.

Debug the Application

If you want to debug the source code of any library in the project, run the following command to pull the source into your local repository. The IDE should then detect it.

mvn dependency:sources