IPO Model

The input–process–output (IPO) model, or input-process-output pattern, is a widely used approach in systems analysis and software engineering for describing the structure of an information processing program or other process. Many introductory programming and systems analysis texts introduce this as the most basic structure for describing a process.

A program or process using the input-process-output model receives inputs from a user or other source, does some computations on the inputs, and returns the results of the computations. In essence the system separates itself from the environment, thus defining both inputs and outputs, as one united mechanism. The system would divide the work into two categories:

In other words, such inputs may be materials, human resources, money or information, transformed into outputs, such as consumables, services, new information or money.

As a consequence, Input-Process-Output system becomes very vulnerable to misinterpretation. This is because, theoretically, it contains all the data, in regards to the environment outside the system, yet on practice, environment contains a significant variety of objects, that a system is unable to comprehend, as it exists outside systems control. As a result it is very important, to understand, where the boundary lies, between the system and the environment, which is beyond systems understanding. This is because, often various analysts, would set their own boundaries, favouring their point of view, thus creating much confusion.

The views differ, in regards to systems thinking. One of such definitions would outline the Input-process-output system, as a structure, would be:

"Systems thinking is the art and science of making reliable inferences about behaviour by developing an increasingly deep understanding of the understanding of the underlying structure"

Alternatively , it was also suggested that systems are not 'holistic' in the sense of bonding with remote objects (for example: trying to connect a crab, ozone layer and capital life cycle together).

There are five major categories that are the most cited in information systems literature:

A system which has not been created as a result of human interference. Examples of such would be the solar system as well as the human body, evolving into its current form

A system which has been created as a result of human interference, and is physically identifiable. Examples of such would be various computing machines, created by human mind for some specific purpose.

A system which has been created as a result of human interference, and is not physically identifiable. Examples of such would be mathematical and philosophical systems, which have been created by human minds, for some specific purpose.

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