초록
Cloud computing emerges as a new computing paradigm which targets reliable and customizable services. The term builds on decades of research in virtual machine, distributed and parallel computing, utility computing, and more recently networking, web service, and software as a service. In this paper, we provide a seamless connection migration of web services. This is useful for cloud computing environment in which many client terminals have mobility. With the wireless internet facility, those mobile users can move place to place during internet communication. Therefore, we provide solutions to the two major problems in current virtualization based migration: communication failure problems and connection re-establishment. Communication channel flushing by zero window notification helps to resolve the communication failure problems and TCP port inheritance prevents connection re-establishment errors during socket reconstruction. Thus, our web service migration facility is now able to preserve open network connections, and even for server sockets. This is a highly transparent approach, in that we did not Introduce additional messages for channel flushing and did not make any modification to the TCP protocol stack. Experimental results show that the overhead due to connection migration of web services is almost negligible when compared with time to take the conventional web service migration.