Sessions and session tracking

In general, a session is a client-server connection that enables the exchange of information between the two computers. A session's state is a set of data that describes the session's attributes, its configuration, or its content. When you establish a client-server connection over the Web, the nature of HTTP limits the duration of each session to a single page of information; thus, your web browser retains the state of each session in memory only for as long as any single Web page is displayed. As soon as you move from one web page to another, the state of the first session is discarded and replaced with the state of the next session. Consequently, Web sites and Web applications must somehow store the state of one session if they need to reuse its information in another.

Crystal Enterprise uses two common methods to store session state: cookies and session variables. A cookie is a small text file that stores session state on the client side: the user's web browser caches the cookie for later use. The Crystal Enterprise logon token is an example of this method. A session variable is a portion of memory that stores session state on the server side. When Crystal Enterprise grants a user an active identity on the system, information such as the user's authentication type is stored in a session variable. So long as the session is maintained, the system neither has to prompt the user for the information a second time nor has to repeat any task that is necessary for the completion of the next request.

Ideally, the system should preserve the session variable while the user is active on the system. And, to ensure security and to minimize resource usage, the system should destroy the session variable as soon as the user has finished working on the system. However, because the interaction between a web browser and a web server can be stateless, it can be difficult to know when users leave the system, if they do not log off explicitly. To address this issue, Crystal Enterprise implements session tracking.

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• WCS session tracking
• APS session tracking