(mongodb >=1.4.0)
The MongoDB\Driver\Session class represents a client session and is returned by MongoDB\Driver\Manager::startSession(). Commands, queries, and write operations may then be associated the session.
MongoDB\Driver\Session::TRANSACTION_NONEMongoDB\Driver\Session::TRANSACTION_STARTINGMongoDB\Driver\Session::TRANSACTION_IN_PROGRESSMongoDB\Driver\Session::TRANSACTION_COMMITTEDMongoDB\Driver\Session::TRANSACTION_ABORTED