When designing applications for an X/Open environment, you need to create applications that include a client program, a server program, and an interface that binds the server and the client.

Client programs take user input and send it to the server program in the form of service requests. It is unlikely that you will use the DB XA Module in client programs.

Server programs provide one or more services. A server receives requests from the client and executes the appropriate services. The DB XA Module will usually be used in a server that is built as a middle layer in a multi-tier architecture.