The goal of this research project is to provide application recovery in a realistic setting. The server software, called an SOA, or Service-Oriented Application, is realized as a process and provides its service through an interface consisting of application methods. A client, either an end client application or another SOA, uses the SOA service via remote procedure call to application methods. Many mission-critical electronic business application servers fit this model.
The recovery model is tiered. The innermost tier consists of shared memory (application variables shared by the different threads of the server process). The middle tier, called a service domain, consists of tightly-coupled SOAS. Optimistic logging is used within the service domain. Optimistic logging does not write log records to disk before sending messages and is thus low-overhead. Communication outside the service domain uses pessimistic logging, where log records are written to disk before messages are sent. Special result logging is used to communicate with transactional systems such as DBMSs.
The results of this research will help provide availability for applications which use web services. Since many mission-critical electronic business application servers fit this model, the greatest impact of this research will be in increasing availability for those servers and hence for the applications which depend on them. In addition, the project will be used in training of Computer Science Ph.D. students, currently a national priority. The code and manuscripts for this project will be disseminated via the project web site www.ccs.neu.edu/home/salzberg/soa/
