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. It was described in his 1975 book Principles of Program Design. 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 originally developed JSP in the 1970s. He documented the system in his 1975 book Principles of Program Design. 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—sequence, iteration, and selection ("if/then/else").

Jackson Structured Programming was similar to Warnier/Orr structured programming although JSP considered both input and output data structures while the Warnier/Orr method focused almost exclusively on the structure of the output stream.

Motivation for the method

At the time that JSP was developed, most programs were batch COBOL programs that processed sequential files stored on tape. A typical program read through its input file as a sequence of records, so that all programs had the same structure— a single main loop that processed all of the records in the file, one at a time. Jackson asserted that this program structure was almost always wrong, and encouraged programmers to look for more complex data structures. In Chapter 3 of Principles of Program Design

See also

  • Jackson system development
  • Warnier/Orr diagram

References

  • A free graphical JSP Editor written in Java
  • A JSP editor
  • A brief history of the Jackson methods
  • Jackson Workbench site