Editing Two-phase commit protocol (section)

==Assumptions==
The protocol works in the following manner: one node is a designated coordinator, which is the master site, and the rest of the nodes in the network are designated the participants. The protocol assumes that:
# there is [[stable storage]] at each node with a [[Write ahead logging|write-ahead log]], 
# no node crashes forever, 
# the data in the write-ahead log is never lost or corrupted in a crash, and 
# any two nodes can communicate with each other. 

The last assumption is not too restrictive, as network communication can typically be rerouted. The first two assumptions are much stronger; if a node is totally destroyed then data can be lost.

The protocol is initiated by the coordinator after the last step of the transaction has been reached. The participants then respond with an agreement message or an abort message depending on whether the transaction has been processed successfully at the participant.