Two-phase committed protocol

Consider the scenario where I am having single client which use single service for communication and interacting with single database. In which service starts and manage the transaction, now it will be easy for the service to manage the transaction.
Consider for example client calling multiple service or service itself calling another service, this type of system are called as Distributed Service-oriented application. Now the questions arise that which service will begin the transaction? Which service will take responsibility of committing the transaction? How would one service know what the rest of the service feels about the transaction? Service could also be deployed in different machine and site. Any network failure or machine crash also increases the complexity for managing the transaction.

In order to overcome these situations, WCF come up with distributed transaction using two way committed protocol and dedicated transaction manager.
Transaction Manager is the third party for the service that will manage the transaction using two phase committed protocol.
Let us see how Transaction manager will manage the transaction using two-phase committed protocols.