Towards Conformance Testing of REST-based Web Services

Abstract

Despite the lack of standardisation for building REST-ful HTTP applications, the deployment of REST-based Web Services has attracted an increased interest. This gap causes, however, an ambiguous interpretation of REST and induces the design and implementation of REST-based systems following proprietary approaches instead of clear and agreed upon definitions. Issues arising from these shortcomings have an influence on service properties such as the loose coupling of REST-based services via a unitary service contract and the automatic generation of code. To overcome such limitations, at least two prerequisites are required: the availability of specifications for implementing REST-based services and auxiliaries for auditing the compliance of those services with such specifications. This paper introduces an approach for conformance testing of REST-based Web Services. This appears conflicting at the first glance, since there are no specifications available for implementing REST by, e.g., t he prevalent technology set HTTP/URI to test against. Still, by providing a conformance test tool and leaning it on the current practice, the exploration of service properties is enabled. Moreover, the real demand for standardisation gets explorable by such an approach. First investigations conducted with the developed conformance test system targeting major Cloud-based storage services expose inconsistencies in many respects which emphasizes the necessity for further research and standardisation.