AbstractWeb services transactions have some unique characteristics. A Web transaction may be composed of a number of individual Web services, executed across multiple loosely coupled autonomous systems. Each Web service may be executed on an independent system belonging to an independent provider. There raises the question whether Web transactions can and should be maintained as a single business unit in a similar way to how transactions are maintained in classical database systems. In classical database systems, the transaction management protocol and mechanism are constrained by the primary properties of atomicity, consistency, isolation and durability (ACID). These ACID properties are the cornerstone of maintaining data integrity in transaction management. However, ACID properties were meant for centralised systems and are better suited for short transactions. Unlike short transactions, Web services transactions may be long-running; they can take hours or even days depending on the application. Composing certain actions from loosely coupled distributed business processes across multiple distributed applications is one of the essentials of Web services transactions. The classic ACID model, which is tightly coupled, is therefore seen as too rigid to support all the requirements of the new Web transactions model.
The research proposes a system that increases throughput while maintaining the consistency and correctness required by the particular applications that are using the model; the system is known as AuTrA (Adaptable user-defined Transaction relaxed Approach). AuTrA allows relaxation of each ACID property. The model is adaptable to meet different situations with different characteristics. For instance, in some cases it will be appropriate to relax atomicity, whereas in others it may be appropriate to relax isolation and atomicity while maintaining consistency. The research explores how transaction support for Web services can be customised to suit the needs of varying applications and result in improved service.
The AuTrA prototype has been implemented. The experimental results show that the AuTrA application is able to support the basic features of Web services transaction management, allowing users to specify their correctness requirements, and it can increase throughput of transactions in models in a flexible and reliable manner. Additional facilities allow users to specify application-specific, non-ACID criteria that can increase throughput. Safeguards have also been implemented to prevent execution of inappropriate user specifications, such as relaxation of properties that may damage data integrity. AuTrA can be used as a tool by software developers who need to compose applications from independent Web services and who wish to build applications which result in improved performance while maintaining application-required consistency.
|Date of Award||2012|
|Supervisor||Anne James (Supervisor)|
- web services transaction management