Contemporary SOA promotes architectural composability

Contemporary SOA promotes architectural composability


Composability is a deep-rooted characteristic of SOA that can be realized on different levels. For example, by fostering the development and evolution of composable services, SOA supports the automation of flexible and highly adaptive business processes. As previously mentioned, services exist as independent units of logic. A business process can therefore be broken down into a series of services, each responsible for executing a portion of the process.

A broader example of composability is represented by the second-generation Web services framework that is evolving out of the release of the numerous WS-* specifications. The modular nature of these specifications allows an SOA to be composed of only the functional building blocks it requires.

What provides this flexibility is the fact that second-generation Web services specifications are being designed specifically to leverage the SOAP messaging model. Individual specifications consist of modular extensions that provide one or more specific features. As the offering of WS-* extensions supported by a given vendor platform grows, the flexibility to compose allows you to continue building solutions that only implement the features you actually need (Figure 3.10). In other words, the WS-* platform allows for the creation of streamlined and optimized service-oriented architectures, applications, services, and even messages.
Figure 3.10. Different solutions can be composed of different extensions and can continue to interoperate as long as they support the common extensions required.






With respect to our definition, let's represent this characteristic by describing the architecture as a whole as being composable. This represents both composable services, as well as the extensions that comprise individual SOA implementations.