Composability

Service composition means the creation of new services from combining existing services. Following the design principles from the previous chapter improves the ability of services to be composed into larger blocks, thereby enabling rapid (re)use of functionality. Services need to be composable so that smaller services can be combined into larger services that provide a specific value. Think of it as building blocks that can be assembled into larger structures. A bank's MortgageService that provides loans to its customers for buying real estate is not comparable to the bank's ZipCodeService that validates zip codes in respect to the type of value they offer. Note however, that the ZipCodeService can contribute to the realization of the MortgageService.

Aggregation versus orchestration

Sometimes the terms service composition, service aggregation, and service orchestration are used interchangeably. While service composition denotes the fact that services are combined, it does not...