HP Reliable Transaction Router - Manual (Page 43)

Flexibility and Growth
RTR also allows parallel execution. This means that different
parts of a single transaction can be processed in parallel by
multiple servers.
RTR provides a comprehensive set of monitoring tools to help
you evaluate the volume of traffic passing through the system.
These tools can help you respond to unexpected load changes,
making you aware of system degradation that you can sometimes
alleviate by altering the system configuration dynamically.
Transaction Integrity
RTR greatly simplifies the design and coding of distributed
applications because, with RTR, database actions can be bundled
together into transactions.
To ensure that your application deals with transactions correctly,
its transactions must have the ACID properties, fundamental
properties of transaction processing systems. A transaction that
has the ACID properties is:
• Atomic
• Consistent
• Isolated
• Durable
An atomic transaction is all or nothing; that is, either the
entire transaction is totally committed or totally rolled back. A
consistent transaction either creates a new, valid state of data,
or, from any failure, returns all data to its state as it was before
the start of the transaction. An isolated transaction does not
cause changes to shared resources until commitment of the
transaction. A durable transaction survives system and media
failures after transaction commitment. A durable transaction is
thus both persistent and stable.
For more detail on these properties and their use in transaction
processing, refer to the HP Reliable Transaction Router
Application Design Guide.
Architectural Concepts 2–5