The Essence of REST Architectural Style

Abstract

There is an increasing interest in understanding and using REST architectural style. Many books and tools have been created but there is still a general lack of understanding its fundamentals as an architecture style. The reason perhaps could be found in the fact that REST was presented in a doctoral dissertation, with relatively high entry barriers for its understanding, or because the description used models that were more oriented towards documentation than to working practitioners. In this chapter we examine, in a systematic manner, some of the issues about Fieldings doctoral dissertation that have caused so much confusion. We start examining REST as an architecture style as a sequence of architectural decisions. We use then influence diagrams to build a model that allows us to see how the architectural decisions take us from classic architectural styles like client-server and layered-system to REST. The graphical model not only facilitates the understanding of this important new architectural style, but also serves as a framework to assess the impact of relaxing or adding more constraints to it. As a final example we analyze the resource-oriented architecture (ROA) to find out one important constraint that is present in REST is missing in ROA and this has an impact on both scalability and modifiability.