The most fundamental decision to make when designing and programming an AppServer application is what session model it will use, session-free or session-managed. This decision limits your choice of AppServer operating mode and the available features of ABL, some of which support particular operating modes. The decision of which session model to use depends on your particular application requirements, which cover all areas of the application, including network capabilities, available AppServer resources, and critical application functions.
Once you have determined the session model to use, you must design and build the AppServer procedures to support it. Typical applications (especially Open Client and Web service applications) start with development of an AppServer application that you then make available to the client application using the appropriate ABL, Open Client Toolkit, or Web service tools. You can also use parallel development techniques appropriate to the client type to develop both sides of the application at the same time. Whatever approach you use, the session model that you choose fundamentally determines the options for application development that are available to you. For more information on the differences between these two operating modes, see
AppServerand Client Interaction.
