CST(55)-Transaction Process Monitors

TP monitors are like operating systems for transaction processing TP monitors performs the following tasks they are

1. Process Management : This includes the starting the server process , funneling work to them monitoring their execution and balancing their work loads.
2. Transaction management : This means that it guarantees the ACID properties to all programs that run under its protection.

TP monitors were originally introduced to handle the requests made by number of clients at a time and it is done by running number of classes . If all the clients make a request to the server at the same time then the server will become a bottle neck and it will fail. So the TP monitors provide an operating system on the top of the existing operating systems that connect the real time impatient humans with a pool of shared server processes.

Funneling :

The funneling act is part of what a TP monitor must do to manage the server side of a user written OLTP application. . In PC environments the server side of the OLTP application is typically packaged as a DLL and the DLL contains the related functions . The TP monitor assigns the work of execution of the DLL to server classes which are classes and pre started pools or threads waiting for the work.

When the clients sends a request , the TP monitor hands it to an available process in the server class pool . The server process dynamically links the DLL functions called by the client . After that completes , the server process can be reused by the client. TP monitor removes process per client by funneling. If the number of requests exceed the number of processes the TP monitor creates some new process to handle the task . This process is called as the Load balancing..

In addition to load balancing capacity TP monitor shares the work across various Multiprocessing servers and it acts as a traffic policemen