6.5. Invoking Session Beans

6.5.1. Invoke a Session Bean Remotely using JNDI

This task describes how to add support to a remote client for the invocation of session beans using JNDI. The task assumes that the project is being built using Maven.
The remote-ejb quick start contains working Maven projects that demonstrate this functionality. The quick start contains projects for both the session beans to deploy and the remote client. The code samples below are taken from the remote client project.
This task assumes that the session beans do not require authentication.

Prerequisites

The following prerequisites must be satisfied before beginning:
  • You must already have a Maven project created ready to use.
  • Configuration for the JBoss Enterprise Application Platform 6 Maven repository has already been added.
  • The session beans that you want to invoke are already deployed.
  • The deployed session beans implement remote business interfaces.
  • The remote business interfaces of the session beans are available as a Maven dependency. If the remote business interfaces are only available as a JAR file then it is recommended to add the JAR to your Maven repository as an artifact. Refer to the Maven documentation for the install:install-file goal for directions, http://maven.apache.org/plugins/maven-install-plugin/usage.html
  • You need to know the hostname and JNDI port of the server hosting the session beans.
To invoke a session bean from a remote client you must first configure the project correctly.

Procedure 6.7. Add Maven Project Configuration for Remote Invocation of Session Beans

  1. Add the required project dependencies

    The pom.xml for the project must be updated to include the necessary dependencies.

  2. Add the jboss-ejb-client.properties file

    The JBoss EJB client API expects to find a file in the root of the project named jboss-ejb-client.properties that contains the connection information for the JNDI service. Add this file to the src/resources/ directory of your project with the following content. 
    # Set this to true for SSL
remote.connectionprovider.create.options.org.xnio.Options.SSL_ENABLED=false
remote.connections=default
# Uncomment this for SSL
# remote.connection.default.connect.options.org.xnio.Options.SSL_STARTTLS=true
remote.connection.default.host=localhost
remote.connection.default.port = 4447
remote.connection.default.connect.options.org.xnio.Options.SASL_POLICY_NOANONYMOUS=false
# Add other SASL options if required
# remote.connection.default.connect.options.org.xnio.Options.SASL_POLICY_NOANONYMOUS=false
# remote.connection.default.connect.options.org.xnio.Options.SASL_POLICY_NOPLAINTEXT=false
# remote.connection.default.connect.options.org.xnio.Options.SASL_DISALLOWED_MECHANISMS=JBOSS-LOCAL-USER
    Change the host name and port to match your server. 4447 is the default port number. For a secure connection, set the SSL_ENABLED line to true and uncomment the SSL_STARTTLS lines. The Remoting interface in the container supports secured and unsecured connections using the same port.

  3. Add dependencies for the remote business interfaces

    Add the Maven dependencies to the pom.xml for the remote business interfaces of the session beans. 
    <dependency>
   <groupId>org.jboss.as.quickstarts</groupId>
   <artifactId>jboss-as-ejb-remote-server-side</artifactId>
   <type>ejb-client</type>
   <version>7.1.0.CR1-SNAPSHOT</version>
</dependency>
Now that the project has been configured correctly, you can add the code to access and invoke the session beans.

Procedure 6.8. Obtain a Bean Proxy using JNDI and Invoke Methods of the Bean

  1. Handle checked exceptions

    Two of the methods used in the following code (InitialContext() and lookup()) have a checked exception of type javax.naming.NamingException. These method calls must either be enclosed in a try/catch block that catches NamingException or in a method that is declared to throw NamingException. The remote-ejb quickstart uses the second technique.

  2. Create a JNDI Context

    A JNDI Context object provides the mechanism for requesting resources from the server. Create a JNDI context using the following code: 
    final Hashtable jndiProperties = new Hashtable();
jndiProperties.put(Context.URL_PKG_PREFIXES, "org.jboss.ejb.client.naming");
final Context context = new InitialContext(jndiProperties);
    The connection properties for the JNDI service are read from the jboss-ejb-client.properties file.

  3. Use the JNDI Context's lookup() method to obtain a bean proxy

    Invoke the lookup() method of the bean proxy and pass it the JNDI name of the session bean you require. This will return an object that must be cast to the type of the remote business interface that contains the methods you want to invoke. 
    final RemoteCalculator statelessRemoteCalculator = (RemoteCalculator) context.lookup(
   "ejb:/jboss-as-ejb-remote-app/CalculatorBean!" + RemoteCalculator.class.getName()
);
    Session bean JNDI names are defined using a special syntax.

  4. Invoke methods

    Now that you have a proxy bean object you can invoke any of the methods contained in the remote business interface. 
    int a = 204;
int b = 340;
System.out.println("Adding " + a + " and " + b + " via the remote stateless calculator deployed on the server");
int sum = statelessRemoteCalculator.add(a, b);
System.out.println("Remote calculator returned sum = " + sum);
    The proxy bean passes the method invocation request to the session bean on the server, where it is executed. The result is returned to the proxy bean which then returns it to the caller. The communication between the proxy bean and the remote session bean is transparent to the caller.
You should now be able to configure a Maven project to support invoking session beans on a remote server and write the code invoke the session beans methods using a proxy bean retrieved from the server using JNDI.