Application can talk to other applications in real-time or in batch mode.
Many application systems have batch interfaces with other application systems.
An application interface allow one system to pass information or messages to
a second application. The
application system that is invoked responds to the request with message
indicating that the communication was successful or not. Often, some sort of middleware is used to connect two applications. The interaction occurs over a network using some type of
communication protocol (e.g. FTP - File Transfer Protocol).
Historically, it has been difficult to integrate application systems
online. The reason for this is that systems are built on different
platforms using different technologies which are not designed for
integration. In recent years, many software vendors are
beginning to support vendor-neutral technologies such as XML/SOA. This
is discussed in a later section.
