Exercise 11 : TP monitors and transaction protocols

1. Give a description in your own words of the ACID properties of a transaction.

Atomicity:

All or nothing. The transaction is only committed if every part of it was successful otherwise it is completely rolled back.

Consistency:

Only data that satisfies database consistency rules, such as the logical relationships between data and transactions, and referential integrity, may be committed.

Isolation:

Changes being made to data by a transaction, prior to being committed, are isolated from other transactions.

Durability:

Any committed updates made by a transaction cannot be lost or rolled back.



2. Describe a TP monitor environment. How can a TP monitor stop an operating system being overwhelmed?

A Transaction Processing (TP) monitor is a control program that manages transactions to ensure that the ACID properties (above) are met and that data is processed reliably.

TP monitors provide load balancing to ensure that transactions are evenly spread across the available server resources.

References:

http://linuxfinances.info/info/tpmonitor.html