In general, an application client module running in a JEUS client container is used to call a Java EE application or be provided with Java EE service.

An application client is a stand-alone client that runs in a Java EE environment. It operates within the application client container, that is defined in Java EE Specification. An application client module, a type of JEUS clients, is useful for client/server systems, testing, or debugging.

JEUS application client can use JEUS services, including naming service, scheduler, and security, by using a client container. Without using a client container, parts of Java EE services, like JNDI and security, can be used through the JEUS client library. However, dependency injection and JEUS scheduler cannot be used.

This section describes JEUS client and server architectures, and describes some examples using sample codes.

1.2.1. Program Architecture

An application client is a client program that runs on a JVM that is different from the server.

An application client calls and executes the main() method and runs until the JVM terminates. Like other JavaEE application components, an application client also runs in a client container that provides system services, but the container uses less system resources than other JavaEE containers. It provides the environment in which Java EE services offered by JEUS can be provided for a general client application.

The services include scheduler, security, JNDI, and some services that allow users to use the application components (EJB) and system resources (JDBC data source, JMS connection factory, etc.) that are bound to JEUS via JNDI.

[Figure 1.1] Application/applet client architecture

package helloejb;

import java.io.*;
import javax.ejb.EJB;

public class HelloClient {
    @EJB(mappedName="helloejb.Hello")
    private static Hello hello;
    
    public static void main(String[] args) {
        System.out.println("EJB output : " + hello.sayHello());
    }
}

This section describes how to create a deployment descriptor.

<jeus-client-dd>
    <env>
        <name>year</name>
        <type>java.lang.Integer</type>
        <value>2002</value>
    </env>
    <ejb-ref>
        <jndi-info>
            <ref-name>count</ref-name>
            <export-name>count_bean</export-name>
        </jndi-info>
    </ejb-ref>
    <res-ref>
        <jndi-info>
            <ref-name>datasource</ref-name>
            <export-name>Oracle_DataSource</export-name>
        </jndi-info>
    </res-ref>
    <res-env-ref>
        <jndi-info>
            <ref-name>jms/SalaryInfo</ref-name>
            <export-name>jms/salary_info_queue1</export-name>
        </jndi-info>
    </res-env-ref>
</jeus-client-dd>

Client module packaging methods are done in two ways, manual packaging and packaging with IDE.

An application client module can be deployed "manually" or by using JEUS WebAdmin. In the module, depending on the need, there are the Java EE standard descriptor files, namely the application-client.xml file, and the jeus-client-dd.xml file, which is provided by JEUS. First, create a module file for the application client, and then move the file to a preferred location.

If there is a function that is controlled by the web service client, perform additional deployment via a console tool named jeusadmin or WebAdmin, or use appcompiler to create a web service stub.

This section introduces JEUS libraries which is additionally required by each service, and describes how to execute modules in the console.

To use a web service as an application client, additional libraries are needed and JEUS_HOME/lib/client/clientcontainer.jar needs to be executed. They are located under JEUS_HOME/lib/system(SYSTEM_LIB_DIR). Refer to the following table.

The following is the list of required JEUS libraries