Transactions Concurrency Control in Web Service Environment

Business transactions in web service environments run with relaxed isolation and atomicity property. In such environments, transactions can commit and roll back independently on each other. Transaction management has to reflect this issue and address the problems which result for example from concurrent access to web service resources and data. In this paper we propose an extension to the WS-Transaction Protocol which ensures the consistency of the data when independent business transactions access the data concurrently under the relaxed transaction properties. Our extension is based on transaction dependency graphs maintained at the service provider side. We have implemented such a protocol on top of WS-Transaction. The extension on the web service provider side is simple to achieve as it can be an integral part of the service invocation mechanism. It has also an advantage from an engineering point of view as it does not change the way consumers or clients of web services have to be programmed. Furthermore, it avoids direct communication between transaction coordinators which preserves security by keeping the information about business transactions restricted to the coordinators which are responsible for them.