Virtual Services in Cloud Computing

Cloud computing has aroused wide research interests and has been accepted by industry. Services are playing the essential role in cloud computing as cloud computing refers to “both the applications delivered as services over the Internet and the hardware and systems software in the datacenters that provide those services”. Therefore, service-oriented architecture should play an important role in cloud computing. In addition, one of the characteristics of cloud computing is to make services available on demand. Given a group of services, different demands may involve different set of services and in different order. This is related to services reuse and composition. However, existing methods only solve service composition in a binary manner: Either a solution exists or no solutions at all. In this paper, we propose the concept of virtual services, which physically do not exist, but are conceptually treated in the same way as physical services. Virtual services are useful when traditional service compositions fail. Virtual services can connect the existing physical services and enable the composition process to succeed. The specifications of virtual services will provide valuable information about how to develop real services to meet the requirements of the given demand. In this paper, we present algorithms that can help identify the virtual services in the case of composition failure and provide the specification of virtual services for further analysis and development.