Working with Security Roles

If you read Working with Realms, Users, Groups, and Roles (page 875), you will remember the following definitions:

The example code used in the following sections is taken from the sample application (available only if the samples server is installed) <AS_INSTALL>/samples/webapps/apps/simple/web.

Declaring Security Roles

You can declare security role names used in web applications using either the @DeclareRoles annotation (preferred) or the security-role-ref elements of the deployment descriptor. Declaring security role names in this way enables you link these security role names used in the code to the security roles defined for an assembled application. In the absence of this linking step, any security role name used in the code will be assumed to correspond to a security role of the same name in the assembled application.

A security role reference, including the name defined by the reference, is scoped to the component whose class contains the @DeclareRoles annotation or whose deployment descriptor element contains the security-role-ref deployment descriptor element.

You can also use the security-role-ref elements for those references that were declared in annotations and you want to have linked to a security-role whose name differs from the reference value. If a security role reference is not linked to a security role in this way, the container must map the reference name to the security role of the same name. See Declaring and Linking Role References for a description of how security role references are linked to security roles.

For an example using each of these methods, read the following sections:

Specifying Security Roles Using Annotations

Annotations are the best way to define security roles on a class or a method. The @DeclareRoles annotation is used to define the security roles that comprise the security model of the application. This annotation is specified on a class, and it typically would be used to define roles that could be tested (i.e., by calling isUserInRole) from within the methods of the annotated class.

Following is an example of how this annotation would be used. In this example, employee is the only security role specified, but the value of this parameter can include a list of security roles specified by the application. 

@DeclareRoles("employee")
public class CalculatorServlet {
  //...
}

Specifying @DeclareRoles("employee") is equivalent to defining the following in the web.xml: 

<security-role>
  <role-name>employee</role-name>
</security-role>

This annotation is not used to link application roles to other roles. When such linking is necessary, it is accomplished by defining an appropriate security-role-ref in the associated deployment descriptor, as described in Declaring and Linking Role References.

When a call is made to isUserInRole from the annotated class, the caller identity associated with the invocation of the class is tested for membership in the role with the same name as the argument to isUserInRole. If a security-role-ref has been defined for the argument role-name, the caller is tested for membership in the role mapped to the role-name.

Specifying Security Roles Using Deployment Descriptor Elements

The following snippet of a deployment descriptor is taken from the simple sample application. This snippet includes all of the elements needed to specify security roles using deployment descriptors: 

<servlet>
   ...
  <security-role-ref>
    <role-name>MGR</role-name>
    <!-- role name used in code -->
    <role-link>employee</role-link>
  </security-role-ref>
</servlet>

<security-constraint>
  <web-resource-collection>
    <web-resource-name>Protected Area</web-resource-name>
    <url-pattern>/jsp/security/protected/*</url-pattern>
    <http-method>PUT</http-method>
    <http-method>DELETE</http-method>
    <http-method>GET</http-method>
    <http-method>POST</http-method>
  </web-resource-collection>
  <auth-constraint>
    <role-name>role1</role-name>
    <role-name>employee</role-name>
  </auth-constraint>
</security-constraint> 

<!-- Security roles referenced by this web application -->
<security-role>
  <role-name>role1</role-name>
</security-role>
<security-role>
  <role-name>employee</role-name>
</security-role>

In this example, the security-role element lists all of the security roles used in the application: role1 and employee. This enables the deployer to map all of the roles defined in the application to users and groups defined on the Application Server.

The auth-constraint element specifies the roles (role1, employee) that can access HTTP methods (PUT, DELETE, GET, POST) located in the directory specified by the url-pattern element (/jsp/security/protected/*). You could also have used the @DeclareRoles annotation in the source code to accomplish this task.

The security-role-ref element is used when an application uses the HttpServletRequest.isUserInRole(String role) method. The value of the role-name element must be the String used as the parameter to the HttpServletRequest.isUserInRole(String role) method. The role-link must contain the name of one of the security roles defined in the security-role elements. The container uses the mapping of security-role-ref to security-role when determining the return value of the call.

Mapping Security Roles to Application Server Groups

To map security roles to application server principals and groups, use the security-role-mapping element in the runtime deployment descriptor (DD). The runtime deployment descriptor is an XML file that contains information such as the context root of the web application and the mapping of the portable names of an application's resources to the Application Server's resources. The Application Server web application runtime DD is located in /WEB-INF/ along with the web application DD. Runtime deployment descriptors are named sun-web.xml, sun-application.xml, or sun-ejb-jar.xml.

The following example demonstrates how to do this mapping: 

<sun-web-app>
  
  <security-role-mapping>
    <role-name>CEO</role-name>
    <principal-name>smcneely</principal-name>
  </security-role-mapping>

  <security-role-mapping>
    <role-name>Admin</role-name>
    <group-name>director</group-name>
  </security-role-mapping>

  ...

</sun-web-app>

A role can be mapped to specific principals, specific groups, or both. The principal or group names must be valid principals or groups in the current default realm. The role-name element must match the role-name in the security-role element of the corresponding application deployment descriptor (web.xml, ejb-jar.xml) or the role name defined in the @DeclareRoles.

Sometimes the role names used in the application are the same as the group names defined on the Application Server. Under these circumstances, you can use the Admin Console to define a default principal to role mapping that apply to the entire Application Server instance. From the Admin Console, select Configuration, then Security, then check the enable box beside Default Principal to Role Mapping. For more information, read the Application Server's Developer's Guide or Administration Guide (links to which are included in Further Information).