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SOA-Service-Oriented Architecture-is an approach to building IT systems out of common parts. SOA represents a breakthrough in the way we build IT systems. webMethods customers report overwhelmingly that SOA is providing real value to them.
According to many IT professionals, a primary reason inhibiting more rapid adoption of SOA principles and technology is the general lack of knowledge about SOA within enterprises. To understand why many IT professionals are so positive about SOA, it is necessary to know something about how SOA changes system development. This white paper explains in lay terms the nature and advantages of SOA and why webMethods, which was instrumental in pioneering SOA for integration, believes it is here to stay.
A Bit of Programming History
Thirty years ago, programmers were writing computer programs in assembly language, which was only one step removed from the 1s and 0s that computers understand. Only a small number of people had the skill to build a large system in that primitive kind of language. But then along came a breakthrough in the form of a procedural programming language called FORTRAN. Suddenly, many other people were able to create systems. For example, with FORTRAN physicists were able to program simulation systems. This pattern of dramatic revolution has been repeated every so often, with developments such as interpreted programming environments, object orientation, and so on. So every now and again, we have a breakthrough in the way we build systems. One of the things about a true breakthrough is that it makes developers more productive. Another is that it allows a broader group of people to actually participate in the building of systems, because it reduces the need for deep, low-level technical expertise.
An Analogy from the Automobile Industry
Twenty years ago, when manufacturers such as Ford and Chrysler built a new car, they would essentially design the automobile from scratch. The engineers loved that because engineering everything from scratch is fun, but engineering everything from scratch is very inefficient. Every time they designed and built a new car, they needed a new chassis, new suspension components, new instrument panels, etc. In some ways, it's also an easy way to build something, because you start from scratch every time, you don't have to figure out which parts can be shared between cars That changed when Japanese manufacturers figured out how to share a lot of common parts among various different automobile models. Three or four cars that look quite different from each other could have a common chassis and a lot of other common components. American manufacturers realized they had to change the way that they built cars in order to become competitive.
Building Systems Out of Common Parts in IT
Now, interestingly, the same thing is happening in IT. Essentially, SOA is causing companies to think seriously about how to assemble their business systems out of common parts. This takes a bit more thought and investment in the beginning, but it enables the companies that use it to build systems faster and faster as the inventory of reusable parts grows.
In a Service-Oriented Architecture, systems are composed of reusable components, called "services." A service is a software building block that performs a distinct function-such as retrieving customer information from a database-through a well-defined interface (an electronic description of how to call the service from other services).
SOA is an evolution of client/server architecture. In client/server systems, the functions of user interface, application logic, and data management are separated so that each can be implemented using the platforms and technologies best suited to the task. With SOA, these functions-most typically, the application logic-are decomposed still further. For example, instead of implementing business logic in a monolithic application server, an SOA-based system can transparently incorporate services running on different software platforms, even services hosted externally by a third-party service provider.
So, while it might seem like an obvious way to do things, only recently has building systems out of common parts become possible.
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