How and why we turned our old Java projects into first-class serverless components

These days rule and workflow engines are often overlooked, possibly because people think that they are only useful inside heavyweight enterprise software products. However, this is not necessarily true. Simply put, a rule engine is just a piece of software that allows you to separate domain and business-specific constraint from the main application flow. Similarly a workflow engine allows you to put higher level abstraction (not always in graphical representation) over your logic, yet keeping you focused on actual business goal. We are the project leads of Drools and jBPM, respectively the rule and workflow engine of Red Hat, and our target was to modernize our projects and make them ready to be used in serverless environments. In this talk we will explore and make sense of technologies like GraalVM and Quarkus. In particular we will show, with very practical use cases like ours, what is necessary to change in a code base making extensive use of reflection, dynamic class loading and other Java sorceries in order to make it compatible with those technologies and demonstrate how this is allowing us to make Drools and jBPM part of the cloud and serverless revolution.