A Catalogue of Adaptation Rules to Support Local Changes in Microservice Compositions Implemented as Choreographies of BPMN Fragments

Abstract

Microservices need to be composed in order to provide their customers with valuable services. To do so, event-based choreographies are used many times since they help to maintain a lower coupling among microservices. In previous works, we presented an approach that proposed creating the big picture of the composition in a BPMN model, splitting it into BPMN fragments and distributing these fragments among microservices. In this way, we implemented a microservice composition as an event-based choreography of BPMN fragments. Based on this approach, this work focuses on supporting the evolution of a microservice composition. We pay special attention to how a microservice composition can be evolved from the local perspective of a microservice since changes performed locally can affect the communication among microservices and as a result the integrity of the whole composition. In particular, we present a catalogue of compensation rules that characterize all the local changes that can be done in an event-based communication element of a BPMN fragment. We also analyse the generated inconsistencies and propose the required actions to adapt the affected participants and guarantee a functional composition.