Fundamentally, a session is the period of time between a user signing on and signing off.
This is a simple concept for a 5250 terminal application that runs exclusively from the server, and really is only slightly more complicated with traditional client server applications. At start up, a user id and password are entered and this results in a program being started on the server that would support the session. In both cases, and despite the differing User Interface, the result is something running on the server until the user signs off.
Visual LANSA's web applications process sessions differently. There are no server jobs running continuously, requests are sent to the server as and when they are needed, usually to read or write data to the database, so there is no job to start and end. This is known as stateless communication, where the dialog between the client and server consists of independent requests with responses.
There are two ways in which sessions can be practically handled: