Jackson structured programming: Difference between revisions

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[[Image:JSP RLE output1.png|thumb|240px|Example of a JSP diagram.]]

'''Jackson structured programming''' ('''JSP''') is a method for [[structured programming]] developed by British software consultant [[Michael A. Jackson (computer scientist)|Michael A. Jackson]] and described in his 1975 book ''Principles of Program Design''.<ref name="PoPD">{{Citation | first = MA | last = Jackson | title = Principles of Program Design | publisher = Academic | year = 1975}}.</ref> The technique of JSP is to analyze the data structures of the files that a program must read as input and produce as output, and then produce a program design based on those data structures, so that the program control structure handles those data structures in a natural and intuitive way.

JSP describes structures (of both data and programs) using three basic structures – sequence, iteration, and selection (or alternatives). These structures are diagrammed as (in effect) a visual representation of a [[regular expression]].

== Introduction ==

[[Michael A. Jackson (computer scientist)|Michael A. Jackson]] originally developed JSP in the 1970s. He documented the system in his 1975 book ''Principles of Program Design''.<ref name="PoPD"/> In a 2001 conference talk,<ref name="perspective">{{Citation | first = MA | last = Jackson | title = JSP in Perspective | place = sd&m Pioneers’ Conference, Bonn, June 2001 | year=2001 | url = http://mcs.open.ac.uk/mj665/JSPPers1.pdf | access-date = 2017-01-26}}</ref> he provided a retrospective analysis of the original driving forces behind the method, and related it to subsequent software engineering developments. Jackson's aim was to make [[COBOL]] batch file processing programs easier to modify and maintain, but the method can be used to design programs for any [[programming language]] that has structured control constructs&mdash; sequence, iteration, and selection ("if/then/else").

Jackson Structured Programming was similar to [[Warnier/Orr Diagrams|Warnier/Orr structured programming]]<ref>{{Citation | first = JD | last = Warnier | year = 1974 | title = Logical Construction of Programs | publisher = Van Nostrand Reinhold | place = NY}}</ref><ref>{{Citation | first = KT | last = Orr | year = 1980 | contribution = Structured programming in the 1980s | title = Proceedings of the ACM 1980 Annual Conference | publisher = ACM Press | place = New York, NY | pages = 323–26 | doi = 10.1145/800176.809987 | isbn = 978-0897910286 | s2cid = 26834496 }}</ref> although JSP considered both input and output data structures while the Warnier/Orr method focused almost exclusively on the structure of the output stream.