A Higher-Order Distributed Pi Calculus and Web Services Description Language Representation for Cloud Service

Cloud service is considered to be an attempt to change the traditional calculation model and the revolutionary technology of the system architecture, whose idea is similar to the grid computing. For this infrastructure, programmer must take into consideration of many complex aspects: the distribution of data and computing, parallel computing on different domains, processors, computers and load balance issues. In this article, we first define an extended Pi calculus to solve the distribution of cloud service by extension of domain, migration application of abstraction process, and the high-order trait by extension of high-order functionality. Based on the proposed calculus, the high-order cloud service components and their compositions are defined by the terms of the calculus. Hence, the proposed Higher-Order Cloud Service Component (HOCSC) is a novel SOA programming scheme, which can be widely used in a variety of cloud service environments. As a generic component, it can be parameterized and customized well. Unlike to the ordinary component, not only the data but also the running code can be customized. Compared to the First-Order Cloud services and their compositions, the essential characteristics of Higher-Order ones lie in the abstraction, application and migration application of abstraction process. In view of the special construction of cloud service composition, necessary extensions to WSDL have been carried on to represent the real services.