Example: Using the isCallerInRole and getCallerPrincipal Methods

This example demonstrates how to use the getCallerPrincipal() and isCallerInRole(String role) methods with an enterprise bean. This example starts with a very simple EJB application, converter, and modifies the methods of the ConverterBean so that currency conversion will only occur when the requester is in the role of TutorialUser.

Modifying ConverterBean

The source code for the original converter application was modified as shown in the following code snippet (modifications in bold) to add the if..else clause that tests if the caller is in the role of TutorialUser. If the user is in the correct role, the currency conversion is computed and displayed. If the user is not in the correct role, the computation is not performed, and the application displays the result as 0.

The code snippet is as follows:

package converter.secure.ejb;

import java.math.BigDecimal;
import javax.ejb.*;
import java.security.Principal;
import javax.annotation.Resource;
import javax.ejb.SessionContext;
import javax.annotation.security.DeclareRoles;
import javax.annotation.security.RolesAllowed;
@Stateless()
@DeclareRoles("TutorialUser")
public class ConverterBean{
    @Resource SessionContext ctx;
    private BigDecimal yenRate = new BigDecimal("96.0650");
    private BigDecimal euroRate = new BigDecimal("0.0078");

    @RolesAllowed("TutorialUser")
     public BigDecimal dollarToYen(BigDecimal dollars) {
        BigDecimal result = new BigDecimal("0.0");
        Principal callerPrincipal = ctx.getCallerPrincipal();
        if (ctx.isCallerInRole("TutorialUser")) {
            result = dollars.multiply(yenRate);
            return result.setScale(2, BigDecimal.ROUND_UP);
        }else{
            return result.setScale(2, BigDecimal.ROUND_UP);
        }
        }
    @RolesAllowed("TutorialUser")
    public BigDecimal yenToEuro(BigDecimal yen) {
        BigDecimal result = new BigDecimal("0.0");
        Principal callerPrincipal = ctx.getCallerPrincipal();
         if (ctx.isCallerInRole("TutorialUser")) {
             result = yen.multiply(euroRate);
             return result.setScale(2, BigDecimal.ROUND_UP);
        }else{
            return result.setScale(2, BigDecimal.ROUND_UP);
        }
    }
}

Building, Deploying, and Running the Secure Converter Example Using NetBeans IDE

After you've made the changes to the enterprise bean, follow the instructions in Compiling, Packaging, and Running the converter Example.

Building, Deploying, and Running the Secure Converter Example Using Ant

After you've made the changes to the enterprise bean, follow the instructions in Compiling, Packaging, and Running the converter Example.

Troubleshooting the Secure Converter Application

Problem: The application displays zero values after authentication, as shown here:

appclient-command-common:
    [exec] $100.00 is 0.00 Yen.
    [exec] 0.00 Yen is 0.00 Euro.

Solution: Verify that the user name and password that you entered for authentication match a user name and password in the Enterprise Server, and that this user is assigned to the group named TutorialUser. User names and passwords are case-sensitive. Read Adding Users to the Enterprise Server for more information on adding users to the file realm of the Enterprise Server.