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Applying design patterns to Web services architectures: a few well-known patterns can simplify your development efforts. (Enterprise Solutions).

Article Excerpt
From the beginnings of the well-known "Gang of Four" design patterns book to more recent publications on J2EE design patterns, the software industry has always tried to find ways to design frameworks, ideas, and concepts that could be used repeatedly. With the introduction of Web services technologies, the need for design patterns remains the same.

The good news is that software architects today can apply many of the existing design patterns to Web services. Use of these patterns can greatly help the architect in building scalable, reliable, and robust Web services architectures. This article takes a look at four of the more well-known design patterns and discusses how they can be applied to Web services architectures. The following design patterns are examined here:

* Adapter: The Adapter pattern is often used to provide a different interface to an existing software component to make it more compatible to a client. This pattern can be used to wrap existing technologies, such as an HTML interface, to make it more compatible with SOAP.

* Facade: The Facade pattern has been used frequently in J2EE to reduce the coupling between client and server. This same design approach can be used to create the right level of granularity in the Web services that are exposed to a client.

* Proxy: The Proxy pattern is used to provide a placeholder for another object. Here, I show how the proxy pattern can be applied to a number of areas in Web services design, including client proxy generation, mobile processing, and Web services testing.

* Controller: The Controller pattern has been used as a way to separate presentation from data. It is often used in a Model-View-Controller (MVC) architecture. This article shows how an architect can introduce Web services to an existing MVC-based design.

While this is only a sampling of the many design patterns available today, it will hopefully give you a better sense of the value patterns can bring to Web services design and development. So, let's begin by taking a look at how the Adapter pattern can be used to incorporate incompatible technologies into a Web services architecture ...

Managing incompatible Interfaces

An organization will often look to existing software assets to exploit Web services technologies. In some cases, these existing applications utilize languages, protocols, or platforms that are not compatible with the target Web services platform. Managing these incompatible interfaces can be solved through the use of the Adapter pattern. The intent of this pattern is to "convert the interface of a class into another interface clients expect" (Design Patterns: Elements of Reusable Object-Oriented Software). It would typically be used to provide compatibility between multiple platforms or systems.

In the...

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