A user data constraint (user-data-constraint in the deployment descriptor) contains the transport-guarantee subelement. A user data constraint can be used to require that a protected transport-layer connection, such as HTTPS, be used for all constrained URL patterns and HTTP methods specified in the security constraint. The choices for transport guarantee are CONFIDENTIAL, INTEGRAL, or NONE. If you specify CONFIDENTIAL or INTEGRAL as a security constraint, it generally means that the use of SSL is required and applies to all requests that match the URL patterns in the web resource collection, not just to the login dialog box.
The strength of the required protection is defined by the value of the transport guarantee.
Specify CONFIDENTIAL when the application requires that data be transmitted so as to prevent other entities from observing the contents of the transmission.
Specify INTEGRAL when the application requires that the data be sent between client and server in such a way that it cannot be changed in transit.
Specify NONE to indicate that the container must accept the constrained requests on any connection, including an unprotected one.
In practice, Java EE servers treat the CONFIDENTIAL and INTEGRAL transport guarantee values identically.
The user data constraint is handy to use in conjunction 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. Configuring a user authentication mechanism is described in Specifying an Authentication Mechanism in the Deployment Descriptor.
To guarantee that data is transported over a secure connection, ensure that SSL support is configured for your server. SSL support is already configured for the GlassFish Server.
After you switch to SSL for a session, you should never accept any non-SSL requests for the rest of that session. For example, a shopping site might not use SSL until the checkout page, and then it might switch to using SSL to accept your card number. After switching to SSL, you should stop listening to non-SSL requests for this session. The reason for this practice is that the session ID itself was not encrypted on the earlier communications. This is not so bad when you’re only doing your shopping, but after the credit card information is stored in the session, you don’t want anyone to use that information to fake the purchase transaction against your credit card. This practice could be easily implemented by using a filter.