Looking Ahead in Open Multithreaded Transactions

Abstract & Acknowledgements Complex distributed object-oriented systems often need complex concurrency features, which may go beyond the traditional concurrency control associated with separate method calls. A transaction groups together a sequence of operations, and can therefore encapsulate complex behavior and method calls. Transactions are able to hide the effects of concurrency and at the same time prevent the propagation of errors, making them appropriate building blocks for structuring reliable distributed systems. The open multithreaded transaction model, introduced by Prof. J. Kienzle, in his PhD thesis, 2001, provides features for controlling and structuring not only accesses to objects, as usual in transaction systems, but also threads taking part in transactions. The model allows several threads to enter the same transaction in order to perform a joint activity. It provides a flexible way of manipulating threads executing inside a transaction by allowing them to be forked and terminated, but it restricts their behavior in order to guarantee correctness of transaction nesting and isolation among transactions. The model also incorporates disciplined exceptio