WF-Interop: Adaptive and Reflective REST Interfaces for Interoperability between Workflow Engines

Abstract

Software service providers are evolving towards a business process outsourcing (BPO) model to benefit from specialised services and facilities of external partners. Activation of external processes as well as having long-term and coarse-grained interaction with the outsourced processes results in remote workflow interactions between heterogeneous and federated workflow systems. WF-Interop aims at addressing the interoperability issues by defining a set of REST interfaces that enable standardised communication between these workflow engines. The WF-Interop interface focuses on deployment, activation and progress monitoring of workflows. It intends to be an interface for new as well as the existing workflow engines in order to expose their functionalities in a RESTful architecture. Amongst all functionalities proposed by WF-Interop, some may not be supported by some engines. As such, our standard API should be adaptive to the capabilities of each workflow engine and be reflective to the consumers by describing supported capabilities on demand. As a validation of the principles and architecture of WF-interop, we created a proof-of-concept middleware and prototyped an accounting workflow with outsourced billing workflow on top of it using jBPM[13] and Ruote[9] workflow engines.