Hatley-Pirbhai modeling

"What follows is a fairly accurate description of Hatley-Pirbhai modeling when applied to software only. The Hatley/Pirbhai methods are, however, much broader than described here. They are system-level methods that apply to multi-disciplinary systems of all kinds, where software is just one technology of many. Examples of such systems are: a complete automobile or aircraft; the Intelligent Highway System (ITS); the International Space Station; and many more. The methods deal with the physical structure of the system as well as the functionality that it performs. The flows within the models represent material, energy, or information."cite book|last=Hatley et al|first=Derek|authorlink=Derek Hatley, Peter Hruschka & Imtiaz Pirbhai|title=Process for System Architecture and Requirements Engineering|origdate=2000|publisher=Dorset House Publishing|location=New York, NY|year=2000|isbn=0-932633-41-2|pages=434]

Hatley-Pirbhai modeling is an extension of the concept that every computer system can be modeled through the usage of an input-processing-output model by including the two additional features of user interface process and maintenance/self testing.cite book|last=Pressman|first=Roger S.|authorlink=Roger S. Pressman|title=Software Engineering - A Practitioner's Approach|origdate=1982|edition=6th|publisher=McGraw-Hill|location=Newyork, NY|year=2005|isbn=0-07-285318-2|pages=133] These 5 components are added to a system model template to allow allow for modeling of the system which allows for proper assignment to the processing regions. The templates components are User Interface, Input, System Function and Control, Output and Maintenance/Self Test. This modeling technique allows for creation of a hierarchy of detail of which the top level of this hierarchy should consist of a System Context Diagram. The developed system context diagram serves the purpose of, "establish [ing] the information boundary between the system being implemented and the environment in which the system is to operate." Further refinement of the system context diagram requires analysis of the system designated by the shaded rectangle through the development of a system flow diagram.

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