TRANSACTION PROCESSING SYSTEM (TPS)

Transaction Processing Systems were the exclusive domain of mainframe computers. Typical examples of such systems would be Airline Reservation Systems, Banking Systems, or the Accounting System of almost any large company. Because of this, Transaction Processing Systems are mostly unknown to the world of personal computers.

But all of this is about to change drastically, and it's all because of the Internet. Today, many small companies, non-commercial organizations, and even private individuals are discovering applications that can benefit from a Transaction Processing System.

The main problems addressed by Transaction Processing Systems are:

• the need to handle hundreds, even thousands of simultaneous Users
• the need to allow many Users to work on the same set of data, with immediate updating
• the need to handle errors in a safe and consistent manner

Transaction processing systems provide three functional areas:

System runtime functions

Transaction processing systems provide an execution environment that ensures the integrity, availability, and security of data. It also ensures fast response time and high transaction throughput.

System administration functions

Transaction processing systems provide administrative support that lets users configure, monitor, and manage their transaction systems.

Application development functions

Transaction processing systems provide functions for use in custom business applications, including functions to access data, to perform intercomputer communications, and to design and manage the user interface.

The services of a transaction processing system runtime environment include the following:

• Scheduling and load balancing. Controlling the rate and order in which tasks are processed to give higher-priority tasks the best response times and to adapt to the availability of application servers and other system resources.
• Managing system resources. Maintaining a pool of operating system resources to be used for transaction processing, loading application programs, and acquiring and releasing storage.
• Monitoring. Monitoring the progress of tasks, suspending those waiting for input, adjusting task priorities, and resolving problems.
• Managing data. Obtaining required data needed by tasks, coordinating resource managers (such as file servers and database managers), locking data for update, and logging changes.
• Managing communications. Monitoring communications with users and between servers and other systems, starting communications sessions as needed, managing data handling and conversion, and routing data to the right destination.
• Time management. Managing transaction processing in relation to the passage of time, starting tasks at predefined times, logging the date and time of events onto disk, and regularly controlling part of the business system to provide degrees of automation.

Services for systems administration and application development are described in subsequent sections.