A Comprehensive Guide to IBM WebSphere Host Publisher Version 3.5

Chapter 17. EJB application support 537

Figure 17-32 ClientAsync ending

17.4.5 Scenario 5: Accessing Host Publisher EJB from user EJBs

In this scenario, we describe how to access the Host Publisher EJB Access Bean

from other user EJBs. To do this, a very simple EJB included in the Websphere

Application Server samples is used, called the HelloBean sample program.

The sample HelloBean application includes the following files:

򐂰 Hello.java

򐂰 HelloBean.java

򐂰 HelloHome.java

򐂰 HelloBeanResourceBundle.java

In this scenario, the Hello.java and HelloBean.java programs will be used. The

Hello.java file is the Hello interface and represents the EJB object instance that a

client can use to invoke remote methods. This interface is implemented by the

HelloBean. You can use the HelloHome interface to create a Hello session bean.

Step 1: Add method to access EJB Access Bean

In this sample scenario, the first step is to add a method in the sample EJB

(Hello.java) that will interface with the EJB Access Bean (see Figure 17-33 on

page 538).

Note: Source files of the sample HelloEJB java program can be found in the

WebSphere\AppServer\ sub-directory:

\hosts\default_host\WSsample_app\servlets\WebSphereSamples\HelloEJB\

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Figure 17-33 Hello.java interface

Step 2: Sample getClientData method (inquiries)

The sample method (getClientData) is written to instantiate and execute the EJB

Access Bean generated by the Host Access (Studio) for your Integration Object.

The method in the HelloBean.java is shown in Figure 17-34.

Figure 17-34 Sample getClientData method

package com.ibm.ejb.cb.samples.hello.tier2;

import javax.ejb.EJBObject;

import java.lang.String;

import java.rmi.RemoteException;

import IntegrationObject.*;

public interface Hello extends EJBObject {

public String getMessage() throws RemoteException;

// Invokes EJB Access Bean to access HPubEJB and obtain client data

public String[] getClientData(String Account) throws RemoteException;

}

public String[] getClientData(String Account) throws RemoteException

{

Hobj01Access0 client = new Hobj01Access0();

client.setHPubStartPoolName("hpool01");

client.setAccountVar(Account);

try

{

client.processRequest(); // execute request

}

catch(Exception e) { // add catch code here

}

String[] answer = new String[4];

if (client.getHPubErrorOccurred()==0)

{

answer[0] =client.getAccountOut();

answer[1]=client.getFirstnameOut();

answer[2]=client.getSurnameOut();

answer[3]=client.getAddressOut();

}

else

{

answer[0]=client.getHPubErrorMessage();

}

return answer;

}

Chapter 17. EJB application support 539

Step 3: Invoke the sample method getClientData

In this step, we show how the sample getClientData (Account) method can be

used to execute the Integration Object.

The sample code to do this is part of the HelloEJBServlet.java, which invokes

HelloEJB to instantiate the EJB Access Bean. In turn, the EJB Access Bean

communicates with the Host Publisher EJB via RMI/IIOP. The sample code is

shown in Figure 17-35.

Figure 17-35 HelloEJBServlet extract of doGet method

Note: To properly compile this Java servlet, you will also need to include the

statement import IntegrationObject.* at the beginning of the file.

try {

// create ejb

System.out.println( msgs.handleGetObject( "creating" ) );

Hello hello = getHome().create();

System.out.println("****creating hello");

// call methods

System.out.println( msgs.handleGetObject( "retrieving"));

out.println( hello.getMessage() );

out.println("<br>");

out.println("<br>");

//Calling HostPublisher EJB via HelloEJB

String[] ans =new String[4];

String Account=req.getParameter("accountVar");

ans=hello.getClientData(Account);

System.out.println("getClientData");

out.println("<b>Account: </b>");

out.println(ans[0]);

out.println("<br>");

out.println("<b>Firstname: </b>");

out.println(ans[1]);

out.println("<br>");

out.println("<b>Surname: </b>");

out.println(ans[2]);

out.println("<br>");

out.println("<b>Address: </b>");

out.println(ans[3]);

// destroy ejb

System.out.println( msgs.handleGetObject( "removing" ) );

hello.remove();

System.out.println( msgs.handleGetObject( "done") );

}

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Step 4: Class path files

In this scenario, the following files are required when you compile and run this

scenario:

򐂰 _wlm_DeployedHPubEJB.jar

򐂰 Hobj01Access0.jar

򐂰 HPubCommon.jar

In addition, they also need to be the classpath environment variable. In the

scenario, files are in the D:\EJBClasses directory, as shown in Figure 17-36.

Figure 17-36 Classpath files

Step 5: Update the classpath

In this step, you will add the required .jar files to the Application Server classpath

by using the -classpath directive in the command line arguments entry, as

shown Figure 17-37 on page 541.

For example, in this scenario the following statement can be used:

-classpath

d:\EJBClasses\_wlm_DeployedHPubEJB.jar;d:\EJBClasses\Hobj01Access0.jar;

d:\EJBClasses\HPubCommon.jar.

Chapter 17. EJB application support 541

Figure 17-37 Setting the classpath in WAS

Step 6: Update the EJB Access Bean properties file

Always remember to update the <IONameAccess.properties> file; the

PROVIDER_URL parameter must point to the server. For example, as shown in

Figure 17-38 on page 542, in this scenario the statement looks like this:

PROVIDER_URL=iiop://hostname

where hostname is the server name.