Events in business process implementation: Early subscription and event buffering

Abstract

Event handling is a fundamental concept for the implementation of business processes. It enables the specification of how a process communicates with its environment and how this environment influences the execution of a process. However, even feature-rich languages for process specification such as BPMN are severely limited in their event handling semantics. They largely neglect the design choices to be made when deciding on when to subscribe to event sources and how to retrieve events for a particular process instance. In this paper, we therefore propose a model for event handling in business processes that is grounded in explicit subscriptions and event buffering. This model is integrated in BPMN using its extension mechanism and comes with formal execution semantics. Based on the latter, we further show how existing techniques for verification and adapter synthesis can be leveraged to analyse the interactions of a business process. Finally, we demonstrate the feasibility of our event handling model by means of an implementation in Camunda, an open-source process engine.