The previous patterns have aimed at dynamic content handling in the form of uploaded content. But it is obvious to most system administrators that this is not the only form of dynamic content in a system. Besides being able to upload and download files themselves, dynamic data can exist in the form of session data or state information. Imagine for a moment, a very simple server setup that consists of a web application in the form of a user management page and a database.

One system might compose the database while the other system handles the user management of the application. To do this, a user must log in with credentials to manipulate the data that comes in and out of the database server. If the system has no other components then when the user logs in, this information is retained in memory. This is not a good practice as memory itself is volatile and restricted in size. If a lot of users were to log in, or the system had to be rebooted, then the user would have...