Enterprise SOA

What are composite applications?

Composite applications, illustrated in Figure 4-3, are applications built using services as building blocks. The word composite has two shades of meaning that make it easier to understand. As a noun, composite means something that is composed of many different things. For an application to be a composite, it means that it is assembled from many existing parts. This is in sharp contrast to applications that are built through so-called greenfield development in which the entire application is created from scratch. The idea of composite applications is that development is accelerated because existing services are used as a starting point and development of new functionality is kept to a minimum. Composite applications are about reuse. Another shade of meaning enters when we think of the verb composing. Composite applications are composed rather than developed. Composing means assembling all the required services and orchestrating them so that they work together to perform a new task. Composing frequently takes place through use of modeling rather than coding in traditional languages. Development of composite applications is accelerated in another way. Modeling and the use of services mean that the logic connecting the services is not nearly as complex as traditional applications and is clearly separated into layers. This makes adapting a composite to meet new purposes much easier and faster. So, what are composite applications about? Reuse, speed of ...