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The Java EE 6 Tutorial

Securing Application Clients

The Java EE authentication requirements for application clients are the same as for other Java EE components, and the same authentication techniques can be used as for other Java EE application components. No authentication is necessary when accessing unprotected web resources.

When accessing protected web resources, the usual varieties of authentication can be used: HTTP basic authentication, SSL client authentication, or HTTP login-form authentication. These authentication methods are discussed in Specifying an Authentication Mechanism in the Deployment Descriptor.

Authentication is required when accessing protected enterprise beans. The authentication mechanisms for enterprise beans are discussed in Securing Enterprise Beans.

An application client makes use of an authentication service provided by the application client container for authenticating its users. The container’s service can be integrated with the native platform’s authentication system, so that a single sign-on capability is used. The container can authenticate the user either when the application is started or when a protected resource is accessed.

An application client can provide a class, called a login module, to gather authentication data. If so, the javax.security.auth.callback.CallbackHandler interface must be implemented, and the class name must be specified in its deployment descriptor. The application’s callback handler must fully support Callback objects specified in the javax.security.auth.callback package.

Using Login Modules

An application client can use the Java Authentication and Authorization Service (JAAS) to create login modules for authentication. A JAAS-based application implements the javax.security.auth.callback.CallbackHandler interface so that it can interact with users to enter specific authentication data, such as user names or passwords, or to display error and warning messages.

Applications implement the CallbackHandler interface and pass it to the login context, which forwards it directly to the underlying login modules. A login module uses the callback handler both to gather input, such as a password or smart card PIN, from users and to supply information, such as status information, to users. Because the application specifies the callback handler, an underlying login module can remain independent of the various ways that applications interact with users.

For example, the implementation of a callback handler for a GUI application might display a window to solicit user input. Or the implementation of a callback handler for a command-line tool might simply prompt the user for input directly from the command line.

The login module passes an array of appropriate callbacks to the callback handler’s handle method, such as a NameCallback for the user name and a PasswordCallback for the password; the callback handler performs the requested user interaction and sets appropriate values in the callbacks. For example, to process a NameCallback, the CallbackHandler might prompt for a name, retrieve the value from the user, and call the setName method of the NameCallback to store the name.

For more information on using JAAS for login modules for authentication, refer to the following sources (see Further Information about Security for the URLs):

Using Programmatic Login

Programmatic login enables the client code to supply user credentials. If you are using an EJB client, you can use the com.sun.appserv.security.ProgrammaticLogin class with its convenient login and logout methods. Programmatic login is specific to a server.