Release 10.1A: OpenEdge Development:
Progress Dynamics Basic Development

Minimizing AppServer calls from the client

Regardless of what programming technique you use, you are well advised to minimize direct extra calls to the AppServer wherever possible. If the code you write forces a lot of calls from client to server beyond those that are already done for you to retrieve data and return updates, it affects the performance of your application in a distributed environment. When you attempt to write such a procedure, consider whether it is really necessary to have the database access occur immediately, or whether it is satisfactory (or necessary for performance reasons) to allow the code to be executed when values go back to the server anyway. Many calls from client to server are a likely sign of poor application design, and one that will not handle a distributed application or one with a non-Progress client as effectively as you wish.

The whole discussion of client-side and server-side logic in this chapter is based on the optimization of AppServer access. What can be done on the client without reference to the database should be done on the client, if this allows the application to provide feedback to the user without an AppServer call. What requires a database connection, or what does not specifically benefit from being executed on the client in terms of immediate feedback to the user, should be left in server-side procedures. This will not only reduce the number of calls to the server, but also reduce the amount of compiled code that must be deployed to client machines. The following section on the SDO and its logic procedure, as well as the section on business logic procedures, amplifies this basic principle.