Towards a dynamic and adaptable application server

Internetware is proposed as a new software paradigm to cope with the open, dynamic and ever-changing Internet environment for applications. The incarnated characteristics of Internetware promote the operating platform to be more dynamic and adaptable. As an operating platform, PKUAS (Peking University Application Server) has been successfully applied in various fields. However, its inexplicit module boundary, insufficient lifecycle management and absent dependency management, make it hardly meet challenges. In this paper we refactor PKUAS into PKUAS II by introducing OSGi (Open Services Gateway Initiative) to achieve a better dynamic capability. First, PKUAS II adopts service component oriented model as its structure so that the boundary among modules can be explicitly explained, and the continuous lifecycle management and dynamic dependency management can get supported. PKUAS II is able to upgrade without interruption of service and extend on the fly with new services. Second, PKUAS II supports application--aware customization, which can dynamically generate a just enough application server for the application at runtime, to satisfy different applications' requirements and reduce resource costs. Last but not least, some evaluations have been done, which show that PKUAS II is more flexible and dynamic without significant performance overhead, and might support Internetware better.