Retrospection on the HERMES project: implementation of a heterogeneous transaction management system

The goal of the HERMES project was to conceive means to integrate existing heterogeneous database products in a transaction management system. The project produced the 2PC Agent method based on the 2PC protocol. The method is based on simulation of the prepared state at participating sites and it guarantees serializable executions in the presence of site and transaction failures. A restriction on the behaviour of local transactions is imposed: the (necessary) condition called DLRP has to be maintained, meaning no local transaction should update the data read by a subtransaction being in the prepared state