Managing Transactions in Flexible Distributed Real-Time Systems

This paper describes the design and implementation of the Distributed Transaction Manager (DTM), a service that provides remote negotiation of contracts representing resource reservations in real-time distributed applications. We assume that there is an underlying middleware which can be used by the application to negotiate contracts locally: processor contracts have to be negotiated in the same processor where they will run, and network contracts have to be negotiated in a processing node connected to the specific network that will be used. In addition, the paper proposes the integration of the DTM in a distribution middleware based on CORBA and Ada’s Distributed Systems Annex (DSA) which supports advanced scheduling mechanisms based on contracts. The use of the distribution middleware enhances some implementation aspects of the DTM and provides new capabilities as, for example, routing messages through different networks.