A Pattern Language for RESTful Conversations

As a good user interface design is important for the success of an app, so is a good API for the success of a Web service. Within the RESTful Web services community there is a need for a systematic approach in knowledge sharing, for which patterns are particularly suitable. Using a RESTful service to achieve a certain goal often requires multiple client-server interactions, i.e., to have a conversation. While patterns of such RESTful conversations can be uncovered from existing APIs' usage scenarios, or the service engineering literature, they have never been gathered in a pattern language, nor properly visualized with a Domain Specific Modeling Language (DSML). These patterns provide valuable input for API designers, as well as API consumers, by establishing a common vocabulary to describe recurring conversations. To do so, this paper uses RESTalk, a DSML, to model the basic RESTful conversation patterns structured around the life cycle of a resource (create, discover, read, edit, delete, protect) by showing the corresponding sequences of HTTP request-response interactions. We show how the resulting pattern language can be applied to individual resources, or also collections of resources