Beyond @CloudFunction: Powerful Code Annotations to Capture Serverless Runtime Patterns

Simplicity in elastically scalable application development is a key concern addressed by the serverless computing paradigm, in particular the code-level Function-as-a-Service (FaaS). Various FaaSification frameworks demonstrated that marking code methods to streamline their offloading as cloud functions offers a simple bridge to software engineering habits. As application complexity increases, more complex runtime patterns with background activities, such as keeping containerised cloud functions warm to ensure the absence of cold starts, usually require giving up on simplicity and instead investing efforts into orchestrating infrastructure. By bringing infrastructure-as-code concepts into the function source via powerful code annotations, typical orchestration patterns can be simplified again. We evaluate this idea and demonstrate its practical feasibility with FaaS Fusion, an annotations library and transpiler framework for JavaScript.