gtpc3m08 | Concepts and Structures |
The TPF system provides an extremely responsive solution to very high volume online processing that is required in many business enterprises. The TPF system has wide acceptance within the airline industry but is also used in non-airline applications for processing relatively simple inquiry and response messages associated with a large population of terminals and workstations. The TPF system is most commonly used for the purpose of accessing a large centralized database that is an inventory of business information.
The TPF system is a high availability operating system designed to provide quick response times to high volumes of messages from large networks of terminals and workstations. A typical TPF system handles several hundred messages per second. A typical network varies from several hundred terminals and workstations to tens of thousands. The response time of the TPF system within a network is typically less than three seconds from the time the user sends a message to the time the user receives a response to that message. High availability is enhanced by the ability to quickly restart the system; restarting after a system failure takes between 30 seconds and two minutes.
These factors result in the unique design of the TPF system that can be summarized as:
An ESA1 configuration (see Figure 2), used by the TPF system, incorporates multiple central processing units (CPUs) that are packaged together to share main storage. An ESA configuration is, therefore, defined as a channel subsystem and a set of CPUs that share main storage.
The TPF system also supports interconnected ESA configurations through the use of the ESA channel subsystem. In particular, multiple ESA configurations can be interconnected through ESA channel-to-channel (CTC) communication. In a fiber optic channel environment, an Enterprise Systems Connection (ESCON) channel, operating in CTC mode, supports the CTC communication.
The term central processing complex (CPC) is used within the TPF system documentation to denote an ESA configuration that is attached through locally attached channel subsystems to a set of devices or other ESA configurations. ESA configuration and central processing complex (CPC) are described in TPF System Processing Milieu. The computing facilities housed at a single location, which can include interconnected ESA configurations, is viewed as a processing center, as shown in Figure 2.
Terminals and workstations are attached to a central processing complex (CPC) through wide area communication facilities. The phrase wide area communication facility means the use of transmission services provided by common communication carriers, which take two forms:
Processing centers can be linked together into networks through wide area communication facilities.