Bridging Services and Resources with Structural Services

The most used approaches for distributed application integration are based on the Service-Oriented Architecture (SOA) and Representational State Transfer (REST) architectural styles. Each is more adequate to a different class of applications and exhibits advantages and disadvantages. This paper not only shows that they are dual architectural styles, SOA oriented towards behavior (services) and REST towards state (structured resources), but also contends that it is possible to combine them to maximize the advantages and to minimize the disadvantages. A new architectural style, Structural Services, is proposed and described. Unlike REST, resources are not constrained to offer a fixed set of operations and, unlike SOA, services are allowed to have structure. To minimize resource coupling, this style uses structural interoperability based on the concepts of structural compliance and conformance, instead of schema sharing (as in SOA) or standardized and previously agreed upon media types (as in REST).