Multi-cloud serverless function composition

Function-as-a-service (FaaS) is an emerging model based on serverless cloud computing technology. It builds on the microservice architecture, where developers implement specific functionality, deploy it to a cloud provider to be executed independently in its own containerised environment. In this paper, we present a software composition approach that orchestrates FaaS from various cloud providers to fulfil the requirements of an application. Our solution integrates a hierarchical planner and a constraint satisfaction solver. Specifically, we discuss the planning method, constraint satisfaction solver, and the coordination of selected functions during the execution. We also present an experiment where our approach is tested using functions in the cloud.