Structural Interoperability as a Basis for Service Adaptability

Web Services appeared essentially as an interoperability solution and REST as a closer match to the semantics of protocols such as HTTP. Clearly influenced by the original browsing goals of the Web, these technologies are not native solutions to the service-oriented paradigm, exhibit limitations to interoperability, and behavior has to be implemented in a separate language. Web Services offer a WSDL document to describe them, but assume that complex data use the same schema in both interacting services, which increases their coupling. This chapter discusses interoperability, from the perspective of both the consumer (compliance) and provider (conformance) services, and it argues that compliance is a weaker requirement for service interoperability than conformance and should be the cornerstone to decrease coupling and to favor adaptability. Structural interoperability is used, given that the lifecycles of distributed resources are decoupled. Metrics to quantify adaptability, based on similarity and decoupling, are proposed.