The two-phase commit protocol ensures that all the resource managers either commit a transaction or abort it. In the first phase, the JTS asks each resource manager if it is prepared to commit. If all the participants affirm, then in the second phase the JTS(Java Transaction Service) broadcasts a commit message to all of them. If any part of the transaction fails - for instance, if a resource manager fails to respond to the prepare request, or if a resource manager responds negatively, then the JTS notifies all of the resource managers that the transaction is aborted. This is the essence of the two-phase commit protocol.