Scaling Java-based Dynamic Web Services: Second-Year Project

Managing distributed state is a di cult challenge for building scalable, distributed, wide-area applications. This project presents the design of an infrastructure, called Ivory, to simplify construction of distributed applications by automatically caching and replicating data structures and code. We illustrate the use of our infrastructure in service caches that replicate Web service code and data used to generate dynamic content. The service cache relies on Ivory to maintain consistency of cached data as a basis for scalable dynamic Web services. Ivory is designed to automate key aspects of state management in a exible, e cient, and scalable way. A key element to our approach is the use of bytecode transformers that automatically adapt Java applications to the Ivory infrastructure. Bytecode transformers insert new code into compiled applications to notify Ivory of data structure modi cations and to invoke operations for maintaining consistency; the transformation is powerful but requires only minimal application programmer involvement. Furthermore, to reduce the space and communication overhead necessary for maintaining data, we use conits|groups of application-de ned related objects|as the granularity for caching, consistency, and synchronization. Using bytecode transformers and the conit granularity in the infrastructure design allows authors to choose application-appropriate data management and consistency policies.