The Java EE 7 Tutorial

49.3 Examples: Securing Enterprise Beans

The following examples show how to secure enterprise beans using declarative and programmatic security.

49.3.1 The cart-secure Example: Securing an Enterprise Bean with Declarative Security

This section discusses how to configure an enterprise bean for basic user name/password authentication. When a bean that is constrained in this way is requested, the server requests a user name and password from the client and verifies that the user name and password are valid by comparing them against a database of authorized users in GlassFish Server.

If the topic of authentication is new to you, see Specifying Authentication Mechanisms.

This example demonstrates security by starting with the unsecured enterprise bean application, cart, which is found in the tut-install/examples/ejb/cart/ directory and is discussed in The cart Example.

In general, the following steps are necessary to add user name/password authentication to an existing application that contains an enterprise bean. In the example application included with this tutorial, these steps have been completed for you and are listed here simply to show what needs to be done should you wish to create a similar application.

Create an application like the one in The cart Example. The example in this tutorial starts with this example and demonstrates adding basic authentication of the client to this application. The example application discussed in this section can be found at tut-install/examples/security/cart-secure/.
If you have not already done so, complete the steps in To Set Up Your System for Running the Security Examples to configure your system for running the tutorial applications.
Modify the source code for the enterprise bean, CartBean.java, to specify which roles are authorized to access which protected methods. This step is discussed in Annotating the Bean.
Build, package, and deploy the enterprise bean; then build and run the client application by following the steps in To Run the cart-secure Example Using NetBeans IDE or To Run the cart-secure Example Using Maven.

49.3.1.1 Annotating the Bean

The source code for the original cart application was modified as shown in the following code snippet (modifications in bold). The resulting file can be found in the file tut-install/examples/security/cart-secure/cart-secure-ejb/src/main/java/javaeetutorial/cart/ejb/CartBean.java.

The code snippet is as follows:

package javaeetutorial.cartsecure.ejb;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javaeetutorial.cart.util.BookException;
import javaeetutorial.cart.util.IdVerifier;
import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.annotation.security.DeclareRoles;
import javax.annotation.security.RolesAllowed;

@Stateful
@DeclareRoles("TutorialUser")
public class CartBean implements Cart, Serializable {
    List<String> contents;
    String customerId;
    String customerName;

    @Override
    public void initialize(String person) throws BookException {
        if (person == null) {
            throw new BookException("Null person not allowed.");
        } else {
            customerName = person;
        }

        customerId = "0";
        contents = new ArrayList<>();
    }

    @Override
    public void initialize(String person, String id) throws BookException {
        if (person == null) {
            throw new BookException("Null person not allowed.");
        } else {
            customerName = person;
        }

        IdVerifier idChecker = new IdVerifier();

        if (idChecker.validate(id)) {
            customerId = id;
        } else {
            throw new BookException("Invalid id: " + id);
        }

        contents = new ArrayList<>();
    }

    @Override
    @RolesAllowed("TutorialUser")
    public void addBook(String title) {
        contents.add(title);
    }

    @Override
    @RolesAllowed("TutorialUser")
    public void removeBook(String title) throws BookException {
        boolean result = contents.remove(title);

        if (result == false) {
            throw new BookException("\"" + title + "\" not in cart.");
        }
    }

    @Override
    @RolesAllowed("TutorialUser")
    public List<String> getContents() {
        return contents;
    }

    @Override
    @Remove()
    @RolesAllowed("TutorialUser")
    public void remove() {
        contents = null;
    }
}

The @RolesAllowed annotation is specified on methods for which you want to restrict access. In this example, only users in the role of TutorialUser will be allowed to add and remove books from the cart and to list the contents of the cart. A @RolesAllowed annotation implicitly declares a role that will be referenced in the application; therefore, no @DeclareRoles annotation is required. The presence of the @RolesAllowed annotation also implicitly declares that authentication will be required for a user to access these methods. If no authentication method is specified in the deployment descriptor, the type of authentication will be user name/password authentication.

49.3.1.2 To Run the cart-secure Example Using NetBeans IDE

Follow the steps in To Set Up Your System for Running the Security Examples.
From the File menu, choose Open Project.
In the Open Project dialog box, navigate to:
```
tut-install/examples/security
```
Select the cart-secure folder.
Select the Open Required Projects check box.
Click Open Project.
In the Projects tab, right-click the cart-secure project and select Build.

This step builds and packages the application into cart-secure.ear, located in the cart-secure-ear/target/ directory, and deploys this EAR file to your GlassFish Server instance, retrieves the client stubs, and runs the client.
In the Login for user: dialog box, enter the user name and password of a file realm user created in GlassFish Server and assigned to the group TutorialUser; then click OK.

If the user name and password you enter are authenticated, the output of the application client appears in the Output tab:
```
...
Retrieving book title from cart: Infinite Jest
Retrieving book title from cart: Bel Canto
Retrieving book title from cart: Kafka on the Shore
Removing "Gravity's Rainbow" from cart.
Caught a BookException: "Gravity's Rainbow" not in cart.
Java Result: 1
...
```
If the user name and password are not authenticated, the dialog box reappears until you enter correct values.

49.3.1.3 To Run the cart-secure Example Using Maven

Follow the steps in To Set Up Your System for Running the Security Examples.

In a terminal window, go to:

tut-install/examples/security/cart-secure/

To build the application, package it into an EAR file in the cart-secure-ear/target subdirectory, deploy it, and run it, enter the following command at the terminal window or command prompt:
```
mvn install
```
In the Login for user: dialog box, enter the user name and password of a file realm user created in GlassFish Server and assigned to the group TutorialUser; then click OK.

If the user name and password you enter are authenticated, the output of the application client appears in the Output tab:
```
...
Retrieving book title from cart: Infinite Jest
Retrieving book title from cart: Bel Canto
Retrieving book title from cart: Kafka on the Shore
Removing "Gravity's Rainbow" from cart.
Caught a BookException: "Gravity's Rainbow" not in cart.
Java Result: 1
...
```
If the user name and password are not authenticated, the dialog box reappears until you enter correct values.

49.3.2 The converter-secure Example: Securing an Enterprise Bean with Programmatic Security

This example demonstrates how to use the getCallerPrincipal and isCallerInRole 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 occur only when the requester is in the role of TutorialUser.

This example can be found in the tut-install/examples/security/converter-secure directory. This example is based on the unsecured enterprise bean application, converter, which is discussed in Chapter 33, "Getting Started with Enterprise Beans" and is found in the tut-install/examples/ejb/converter/ directory. This section builds on the example by adding the necessary elements to secure the application by using the getCallerPrincipal and isCallerInRole methods, which are discussed in more detail in Accessing an Enterprise Bean Caller's Security Context.

In general, the following steps are necessary when using the getCallerPrincipal and isCallerInRole methods with an enterprise bean. In the example application included with this tutorial, many of these steps have been completed for you and are listed here simply to show what needs to be done should you wish to create a similar application.

Create a simple enterprise bean application.
Set up a user on GlassFish Server in the file realm, in the group TutorialUser, and set up default principal to role mapping. To do this, follow the steps in To Set Up Your System for Running the Security Examples.
Modify the bean to add the getCallerPrincipal and isCallerInRole methods.
If the application contains a web client that is a servlet, specify security for the servlet, as described in Specifying Security for Basic Authentication Using Annotations.
Build, package, deploy, and run the application.

49.3.2.1 Modifying ConverterBean

The source code for the original ConverterBean class was modified to add the if..else clause that tests whether 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 example can be found in tut-install/examples/security/converter-secure/converter-secure-ejb/src/main/java/javaeetutorial/converter/ejb/ConverterBean.java.

The code snippet (with modifications shown in bold) is as follows:

package javaeetutorial.convertersecure.ejb;

import java.math.BigDecimal;
import java.security.Principal;
import javax.ejb.Stateless;
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 final BigDecimal yenRate = new BigDecimal("104.34");
    private final BigDecimal euroRate = new BigDecimal("0.007");

    @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); 
        }
    }
}

49.3.2.2 Modifying ConverterServlet

The following annotations specify security for the converter web client, ConverterServlet:

@WebServlet(urlPatterns = {"/"})
@ServletSecurity(
@HttpConstraint(transportGuarantee = TransportGuarantee.CONFIDENTIAL,
    rolesAllowed = {"TutorialUser"}))

49.3.2.3 To Run the converter-secure Example Using NetBeans IDE

Follow the steps in To Set Up Your System for Running the Security Examples.
From the File menu, choose Open Project.
In the Open Project dialog box, navigate to:
```
tut-install/examples/security
```
Select the converter-secure folder.
Click Open Project.
Right-click the converter-secure project and select Build.

This command builds and deploys the example application to your GlassFish Server instance.

49.3.2.4 To Run the converter-secure Example Using Maven

Follow the steps in To Set Up Your System for Running the Security Examples.