What is a TP Monitor? What advantages does a TP Monitor bring to an OLTP environment?

What will be an ideal response?

A TP Monitor forms the middle tier of a three-tier architecture. TP Monitors provide significant
advantages, including:
? Transaction routing: The TP Monitor can increase scalability by directing transactions to
specific DBMSs.
? Managing distributed transactions: The TP Monitor can manage transactions that require
access to data held in multiple, possibly heterogeneous, DBMSs. For example, a transaction
may require to update data items held in an Oracle DBMS at site 1, an Informix DBMS at
site 2, and an IMS DBMS as site 3. TP Monitors normally control transactions using the
X/Open Distributed Transaction Processing (DTP) standard. A DBMS that supports this
standard can function as a resource manager under the control of a TP Monitor acting as a
transaction manager.
? Load balancing: The TP Monitor can balance client requests across multiple DBMSs on one
or more computers by directing client service calls to the least loaded server. In addition, it
can dynamically bring in additional DBMSs as required to provide the necessary
performance.
? Funneling: In environments with a large number of users, it may sometimes be difficult for
all users to be logged on simultaneously to the DBMS. In many cases, we would find that
users generally do not need continuous access to the DBMS. Instead of each user connecting
to the DBMS, the TP Monitor can establish connections with the DBMSs as and when required, and can funnel user requests through these connections. This allows a larger
number of users to access the available DBMSs with a potentially much smaller number of
connections, which in turn would mean less resource usage.
? Increased reliability: The TP Monitor acts as a transaction manager, performing the necessary actions to maintain the consistency of the database, with the DBMS acting as a resource manager. If the DBMS fails, the TP Monitor may be able to resubmit the transaction to another DBMS or can hold the transaction until the DBMS becomes available again.