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ejb-multi-server: EJB Communication Across Servers

The ejb-multi-server quickstart shows how to communicate between multiple applications deployed to different servers using an EJB to log the invocation.

What is it?

The ejb-multi-server quickstart demonstrates communication between applications deployed to different {productNameFull} servers. Each application is deployed as an EAR and contains a simple EJB bean. The only function of each bean is to log the invocation.

This example consists of the following Maven projects, each with a shared parent:

Project Description

app-main

An application that can be called by the client. It can also call the different sub-applications.

app-one

app-two

These simple applications contain an EJB subproject that builds the ejb.jar file and an EAR subproject that builds the app.ear file. Each application contains only one EJB that logs a statement on a method call and returns the jboss.node.name and credentials.

app-web

A simple WAR application. It consists of one servlet that demonstrates how to invoke EJBs on a different server.

client

This project builds the standalone client and executes it.

The root pom.xml builds each of the subprojects in an appropriate order.

The server configuration is done using CLI batch scripts located in the root of the quickstart folder.

Start with a Clean Server Install

It is important to start with a clean version of {productName} before testing this quickstart. Make sure you unzip or install a fresh {productName} instance.

Add the Application Users

The following users must be added to the ApplicationRealm to run this quickstart. Make sure you use the names and passwords specified in the table as they are required to run this example.

UserName Realm Password Roles

quickuser

ApplicationRealm

quick-123

quickuser1

ApplicationRealm

quick123+

quickuser2

ApplicationRealm

quick+123

To add the users, open a terminal and type the following commands.

$ {jbossHomeName}/bin/add-user.sh -a -u quickuser -p quick-123
$ {jbossHomeName}/bin/add-user.sh -a -u quickuser1 -p quick123+
$ {jbossHomeName}/bin/add-user.sh -a -u quickuser2 -p quick+123
Note
 For Windows, use the {jbossHomeName}\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.

Configure the Server

You configure the domain server by running JBoss CLI commands. For your convenience, this quickstart batches the commands into a install-domain.cli script provided in the root directory of this quickstart.

  1. Before you begin, make sure you do the following:

  2. Review the install-domain.cli file in the root of this quickstart directory. This script configures and starts multiple servers needed to run this quickstart.

  3. Open a new terminal, navigate to the root directory of this quickstart, and run the following command, replacing {jbossHomeName} with the path to your server:

    $ {jbossHomeName}/bin/jboss-cli.sh -c --file=install-domain.cli
    Note
    		 For Windows, use the {jbossHomeName}\bin\jboss-cli.bat script.

    You should see a result of "outcome" ⇒ "success" for every step in the execution.

    Important
    		 Depending on your machine configuration, you might see "Exception in thread "main" java.lang.OutOfMemoryError: unable to create new native thread" exceptions in the server log when you run this script. If you do, you must increase the ulimit open files and max user processes settings. Instructions to do this are located here: http://ithubinfo.blogspot.com/2013/07/how-to-increase-ulimit-open-file-and.html. After you update the ulimit settings, you must reboot and start with a fresh instance of the server.

Review the Modified Server Configuration

There are too many additions to the configuration files to list here. Feel free to compare the domain.xml and host.xml to the backup copies to see the changes made to configure the server to run this quickstart.

Build and Deploy the Quickstart

  1. Make sure you have installed the quickstart parent artifact in your Maven repository.

  2. Make sure you have started and configured the {productName} server successfully as described above.

  3. Open a terminal and navigate to the root directory of this quickstart.

  4. Type this command to build the artifacts.

    $ mvn clean install

    You should see BUILD SUCCESS at the end of the build SUCCESS messages for each component.

  5. In the same terminal, deploy the applications using the provided CLI batch script by typing the following command.

    $ {jbossHomeName}/bin/jboss-cli.sh -c --file=deploy-domain.cli
    Note
    		 For Windows, use the {jbossHomeName}\bin\jboss-cli.bat script.

    This deploys the app-*.ear files to different server groups of the running domain. You should see the following result when you run the script.

    The batch executed successfully
process-state: reload-required

  6. You might see the following warnings in the server log. You can ignore these warnings.

    [Server:app-oneB] 13:00:13,346 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 13) JGRP000015: the send buffer of socket MulticastSocket was set to 1MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max send buffer in the OS correctly (e.g. net.core.wmem_max on Linux)
[Server:app-oneB] 13:00:13,346 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 13) JGRP000015: the receive buffer of socket MulticastSocket was set to 20MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max receive buffer in the OS correctly (e.g. net.core.rmem_max on Linux)
[Server:app-oneB] 13:00:13,347 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 13) JGRP000015: the send buffer of socket MulticastSocket was set to 1MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max send buffer in the OS correctly (e.g. net.core.wmem_max on Linux)
[Server:app-oneB] 13:00:13,347 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 13) JGRP000015: the receive buffer of socket MulticastSocket was set to 25MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max receive buffer in the OS correctly (e.g. net.core.rmem_max on Linux)
[Server:app-oneA] 13:00:13,407 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 11) JGRP000015: the send buffer of socket MulticastSocket was set to 1MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max send buffer in the OS correctly (e.g. net.core.wmem_max on Linux)
[Server:app-oneA] 13:00:13,408 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 11) JGRP000015: the receive buffer of socket MulticastSocket was set to 20MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max receive buffer in the OS correctly (e.g. net.core.rmem_max on Linux)
[Server:app-oneA] 13:00:13,408 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 11) JGRP000015: the send buffer of socket MulticastSocket was set to 1MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max send buffer in the OS correctly (e.g. net.core.wmem_max on Linux)
[Server:app-oneA] 13:00:13,408 WARN  [org.jboss.as.clustering.jgroups.protocol.UDP] (ServerService Thread Pool -- 11) JGRP000015: the receive buffer of socket MulticastSocket was set to 25MB, but the OS only allocated 212.99KB. This might lead to performance problems. Please set your max receive buffer in the OS correctly (e.g. net.core.rmem_max on Linux)
Important
 If errors appear in the server.log when installing or deploying the quickstart, stop the domain and restart it. This should ensure further steps run correctly.

Access the Remote Client Application

This example shows how to invoke an EJB from a remote standalone application.

  1. Make sure that the deployments are successful as described above.

  2. Navigate to the quickstart client/ subdirectory.

  3. Type this command to run the application:

    $ mvn exec:java

    The client will output the following information provided by the applications:

    InvokeAll succeed: MainApp[anonymous]@master:app-main  >  [ app1[quickuser1]@master:app-oneB > app2[quickuser2]@master:app-twoA ; app2[quickuser2]@master:app-twoA ]

    This output shows that the MainApp is called with the user anonymous at node master:app-main and the sub-call is proceeded by the master:app-oneA node and master:app-twoA node as quickuser2.

  4. Review the server log files to see the bean invocations on the servers.

  5. If it is necessary to invoke the client with a different {productName} version the main class can be invoked by using the following command from the root directory of this quickstart. Replace {jbossHomeName} with your current installation path. The output should be similar to the previous mvn executions.

    java -cp $ {jbossHomeName}/bin/client/jboss-client.jar:app-main/ejb/target/ejb-multi-server-app-main-ejb-client.jar:app-two/ejb/target/ejb-multi-server-app-two-ejb-client.jar:client/target/ejb-multi-server-client.jar org.jboss.as.quickstarts.ejb.multi.server.Client
Important

  • If exec is called multiple times, the invocation for app1 might use app-oneA and app-oneB node due to cluster loadbalancing.

  • A {productName} will deny the invocation of unsecured methods of appOne/appTwo since security is enabled but the method does not include @Roles. You need to set default-missing-method-permissions-deny-access = false for the ejb3 subsystem within the domain profile ha and default to allow the method invocation. See the install-domain.cli script.

Access the JSF Application Inside the Main Application

The JSF example shows different annotations to inject the EJB. Also how to handle the annotation if different beans implement the same interface and therefore the container is not able to decide which bean needs to be injected without additional informations.

  1. Make sure that the deployments are successful as described above.

  2. Use a browser to access the JSF application at the following URL: http://localhost:8080/ejb-multi-server-app-main-web/

  3. Insert a message in the Text input and invoke the different methods. The result is shown in the browser.

  4. See server logfiles and find your given message logged as INFO.

Access the Servlet Application Deployed as a WAR Inside a Minimal Server

An example how to access EJBs from a separate instance which only contains a web application.

  1. Make sure that the deployments are successful as described above.

  2. Use a browser to access the Servlet at the following URL: http://localhost:8380/ejb-multi-server-app-web/

  3. The Servlet will invoke the remote EJBs directly and show the results, compare that the invocation is successful

Undeploy the Quickstart

  1. Start the {productName} managed domain as described above.

  2. Open a terminal and navigate to the root directory of this quickstart.

  3. When you are finished testing, type this command to undeploy the archive:

    $ {jbossHomeName}/bin/jboss-cli.sh --connect --file=undeploy-domain.cli
    Note
    		 For Windows, use the {jbossHomeName}\bin\jboss-cli.bat.

EJB Client (ejb-client) currently has limited support in the Eclipse Web Tools Platform (WTP).