Step 4: Identify any Application Interfaces

In addition to seeking common methods and data to integrate, it is important to take note of the available application interfaces in support of application interface-level application integration, or integration with application interfaces and other application integration levels.

Interfaces are quirky. They differ greatly from application to application. What's more, many interfaces, despite what the application vendors or developers may claim, are not really interfaces at all. It is important to devote time to validating assumptions about interfaces.

The best place to begin with interfaces is with the creation of an application interface directory. As with other directories, this is a repository for gathered information about available interfaces, along with the documentation for each interface. This directory is used, along with the common business model and the enterprise metadata model, to understand the points of integration within all systems of the application integration problem domain.

Application Interface Directory

The application interface directory can be thought of as a list of business processes that are available from an application packaged or custom made. It must, however, be a true application (database, business processes, or user interface) and not a database or simple middleware service. The application interface directory expands on the enterprise metadata model, tracking both data and methods that act upon the data.

Application Semantics

The first portion of the application interface directory is a list of application semantics. These establish the way and form in which the particular application refers to properties of the business process. For example, the very same customer number for one application may have a completely different value and meaning in another application. Understanding the semantics of an application guarantees that there will be no contradictory information when the application is integrated with other applications. Achieving consistent application semantics requires an application integration "Rosetta Stone" and, as such, represents one of the major challenges to the application integration solution.

The first step in creating this Rosetta Stone is to understand which terms mean what in which applications. Once that is accomplished, you have taken the first very difficult step toward success.

Business Processes

Business processes are listings of functions or methods provided by the application. In some applications, such a listing is easy to determine because the business processes are well documented and easily found by invoking the user interface. However, in other applications, determining these processes requires a search through the source code to discover and understand the various methods and functions available.

As with application semantics, it is critical to understand all business processes that are available within a particular application. Once understood and documented in the application interface directory, it is possible to determine the particular combination of processes to invoke in order to carry out a specific integration requirement. For example, in an application that contains as many as 30 business processes for updating customer information, it is vital to know which process wants to invoke what, and why.