In this vertical integration example we look at the steps that are followed with SCORE Adaptive Bridges and MDLI when building adaptive services that connect an existing legacy application to (in this case) a Web services platform. The same integration approach applies independently of the technology platforms selected.

The numbered steps below explain the numbered steps in the diagram. We suggest you have the expanded diagram open to refer to as you read:

• Discovery – In many cases there is no PIM for the existing application, all we have is the source code, which is of course platform specific by nature. The first step is therefore to obtain a PSM of the interfaces to the legacy application. In most cases discovering the PSM can be automated, as is the transformation from the PSM to a PIM.
• Composition – The service-based composition model is created from the various PIMs of the legacy applications and data stores. Composition involves describing the adaptive services to be created, as well as mapping between the services providers (the legacy systems) and that of the service consumers (the new application or client). Mapping includes both static and dynamic views – the structure (composition) and behavior (choreography).
• Production – The next step in MDLI is the transformation of the adaptive services as defined by the composition model into PSMs and then into code for the application adapter (on the server side) and the adaptive proxy (on the client side). The application adapter and adaptive proxy are created independently of each other. This allows additional proxies to be generated for new platforms, for example, without affecting your legacy applications.
• Runtime – The generated application adapter and adaptive proxy communicate with each other at runtime using the chosen middleware platform. The existing application and the new client application have no knowledge of each other, and so are not affected by changes in the chosen middleware platform.
• Target Platform PIM/PSM – When working with Web services it is often the case that a PSM (in the form of a WSDL document) is available for the service that is to be created. For other platforms this is not always the case. For these situations it is possible to automatically create the PIM and PSM for the target platform from the composition model.

Where to Go Next?

For more information about the discovery, composition and production processes in SCORE Adaptive Bridges please see the Process View. If you are interested in the architecture of the generated application adapters and adaptive proxies then please see the Runtime View, otherwise please continue to the next section where we take a look at an example of Horizontal Integration.