The SOA service's job is to provide pluggable functionality as reusable building blocks by abstracting existing applications and data stores. Still, most of the time, these SOA services are too abstract or generic to be placed into concrete use cases as they are. Approaching the last mile, they leave you on your own at places where something concrete happens and where a user interacts with a system to solve a concrete business problem, such as booking a rental.

Composite applications form a set of best practices and technologies that support the positioning of our SOA services into the context of concrete use cases. These best practices ensure the pluggability of reusable services into concrete frontends. This kind of functionality, which is local to a concrete use case, a channel, or a scenario, is depicted in the preceding architectural figure as Application-centric Functionality and Services.

Composite applications can be seen as the latest step in the evolution...