Compatibility Checking of REST API Based on Coloured Petri Net

Abstract

One of the underutilized advantages of REST API is extensibility. Extensibility allows a REST API to make certain changes to its resource representation, identification, interaction, and connection without breaking its clients. A client can cope with these changes in the REST API through hypertext-driven interactions - an iterative process in which the client can determine the resource identification based on its representation, utilize its identification to determine the interactions, and follow the interactions to determine its connections. However, our analysis reveals that there are limitations to the flexibility of the hypertext-driven navigation due to the dependency between these interaction layers in the REST API, and there is a critical need to determine if two REST APIs are compatible for the client. To address this issue, we describe a structured approach to REST client modelling that decomposes a REST client into two functional components: client oracle and client agent. From this client model, we derive a formal definition of compatibility based on the REST Chart representation of the REST API, and an efficient algorithm is developed to verify the compatibility between two REST Charts. A prototype system has been implemented, and the preliminary experimental results show that the approach is feasible and promising.