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An Internet of Things (IoT) system is often an integration of a large number of hardware and software modules, which are expected to be easily replaced or reconfigured in order to cater for quickly-changing environments and requirements. With the popularity of microservices, people have attempted to introduce the microservice architecture to IoT systems, while paid little attention to the connectivity between the decomposed microservices, resulting in poor reconfigurability of the resulting system. In this paper, we propose a reconfigurable microservice-based migration technique for IoT systems, which first decomposes an IoT system as a set of microservices and then introduces variation contexts to make the decomposed microservices reconfigurable. We have conducted a case study on an open-source real-life unmanned aerial vehicle (UAV) system. The results demonstrate that the migrated UAV system can be dynamically reconfigured to handle various run-time changes.

In the current Web Service Description Language (WSDL), only the interface information of a web service is provided without any indication on its behavior logic. Naturally, it is difficult for the service user and developer to achieve a shared understanding of the service behavior through such a description. A particular challenge is how to make explicit the various behavior assumptions and restrictions of a service (for the user), and make sure that the service implementation conforms to them (for the developer). In order to improve the behavior conformance of services, in this paper we propose a constraint-based model-driven testing approach for web services. In our approach, constraints are introduced in an extended WSDL, called CxWSDL, to formally and explicitly express the implicit restrictions and assumptions on the behavior of web services, and then the predefined constraints are used to derive test cases in a model-driven manner to test the service implementation’s conformance to these behavior constraints from the user’s perspective. We have conducted an empirical study with three real-life web services as subject programs, and the experimental results have shown that our approach can effectively validate the service’s conformance to the behavior constraints.

Service compositions have become a powerful development paradigm to create distributed applications out of autonomous Web services. Since such applications are often deployed and executed in open and dynamic environments, variability management is a crucial enabling technique. To address the adaptation issue of service compositions, we proposed VxBPEL, an extension of BPEL for supporting variability, and a variability-based adaptive service composition approach which employs VxBPEL for variability implementation. In this paper, we present a VxBPEL engine for supporting the execution of VxBPEL service compositions. The engine is called VxBPEL_ODE and is implemented by extending a widely recognized open source BPEL engine, Apache ODE. We discuss key issues of developing VxBPEL_ODE, and three real-life service compositions are employed to evaluate and compare its performance with another VxBPEL engine we developed in our previous work. VxBPEL_ODE, together with analysis, design, and run-time management tools for VxBPEL, constitutes a comprehensive supporting platform for variability-based adaptive service compositions.