Engineering Flexible Service-Oriented Transactions

The traditional ACID properties for transactions are not always appropriate in service-oriented environments. Instead, it is often preferable to "relax" the transactional guarantees, reducing isolation or atomicity to ensure acceptable performance at a reasonable cost. Existing standards require providers to constantly offer a fixed level of transaction support to each client that requests a particular service. We present a mechanism that allows providers to dynamically alter the level of transaction support offered on a per-service-call basis. Further, we engineer a cost-based model, based on πt−calculus, that allows clients to automatically reason about workflows consisting of service requests with various levels of transaction support. The viability of this scheme is tested with a Web Services transactions simulator, with results indicating potential benefits for both clients and service providers.