gtpc3m0cConcepts and Structures

TPF Online System Elements

The user requests made of the TPF system are assumed to require very little computation, but considerable data manipulation. The online system is designed to prevent bottlenecks caused by queueing for system resources. The essence of the TPF system is to maximize performance for message driven applications on a given hardware configuration. Performance is viewed as a critical factor in the TPF system. This influences the techniques used to manage system resources. Generically, a control program or operating system defines application interfaces: control blocks, macros, supervisor calls, and so on. The TPF system has unique application interfaces that are influenced by techniques used to manage system resources.

The key elements of the TPF online system are:

The functions provided by these elements are outlined in the following sections.

Main Supervisor

The TPF main supervisor provides the resource management usually expected of a control program in direct control of physical facilities. The precise techniques used to accomplish this resource management are topics in TPF System Structural Characteristics. The principal functions performed by the main supervisor are:

Database Support

The structure of the online data is identified during system generation. Data is dynamically generated; however, the facilities for storing the data are identified prior to the online operation.

There are two organizations of file structures within the online data:

Figure 4. File Allocation Strategies


Communications Control

In the TPF system, communications control provides the interface to data communication networks and message formatting services for applications. Because of the historical evolution of the TPF system, the control and support of communications is divided into two distinct areas:

On input, a message is in a format that is specific to the device from which the message was entered. Because input messages can be entered from various types of devices, the TPF system converts an input message with device-specific data to a common system format so that an application is able to process it regardless of its origin.

On output, the reverse is true; an output message must be converted from its common system format to be device-specific.

Additional detail about communications support is the subject of Data Communications.