Bridging the Interoperability Gap: Overcoming Combined Application and Middleware Heterogeneity

Interoperability remains a significant challenge in today’s distributed systems; it is necessary to quickly compose and connect (often at runtime) previously developed and deployed systems in order to build more complex systems of systems. However, such systems are characterized by heterogeneity at both the application and middleware-level, where application differences are seen in terms of incompatible interface signatures and data content, and at the middleware level in terms of heterogeneous communication protocols. Consider a Flickr client implemented upon the XML-RPC protocol being composed with Picasa’s Service; here, the Flickr and Picasa APIs differ significantly, and the underlying communication protocols are different. A number of ad-hoc solutions exist to resolve differences at either distinct level, e.g., data translation technologies, service choreography tools, or protocol bridges; however, we argue that middleware solutions to interoperability should support developers in addressing these challenges using a unified framework. For this purpose we present the Starlink framework, which allows an interoperability solution to be specified using domain specific languages that are then used to generate the necessary executable software to enable runtime interoperability. We demonstrate the effectiveness of Starlink using an application case-study and show that it successfully resolves combined application and middleware heterogeneity.