The Java EE 6 Tutorial, Volume I

Specifying a Secure Connection in Your Application Deployment Descriptor

To specify a requirement that protected resources be received over a protected transport layer connection (SSL), specify a user data constraint in the application deployment descriptor. The following is an example of a web.xml application deployment descriptor that specifies that SSL be used:

        <web-resource-name>view dept data</web-resource-name>

A user data constraint (<user-data-constraint> in the deployment descriptor) requires that all constrained URL patterns and HTTP methods specified in the security constraint are received over a protected transport layer connection such as HTTPS (HTTP over SSL). A user data constraint specifies a transport guarantee (<transport-guarantee> in the deployment descriptor). The choices for transport guarantee include CONFIDENTIAL, INTEGRAL, or NONE. If you specify CONFIDENTIAL or INTEGRAL as a security constraint, that type of security constraint applies to all requests that match the URL patterns in the web resource collection and not just to the login dialog box.

The strength of the required protection is defined by the value of the transport guarantee.

The user data constraint is handy to use with basic and form-based user authentication. When the login authentication method is set to BASIC or FORM, passwords are not protected, meaning that passwords sent between a client and a server on an unprotected session can be viewed and intercepted by third parties. Using a user data constraint with the user authentication mechanism can alleviate this concern.