Flowchart

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A flowchart that a member of the Wikipedia community could use for guidance when dealing with a difficult editor.
A flowchart that a member of the Wikipedia community could use for guidance when dealing with a difficult editor.

A flowchart (also spelled flow-chart and flow chart) is a schematic representation of an algorithm or a process.

A flowchart is one of the seven basic tools of quality control, which also includes the histogram, Pareto chart, check sheet, control chart, cause-and-effect diagram, and scatter diagram. They are commonly used in business/economic presentations to help the audience visualize the content better, or to find flaws in the process. Alternatively, one can use Nassi-Shneiderman diagrams.

A flowchart is described as "cross-functional" when the page is divided into different "lanes" describing the control of different organizational units. A symbol appearing in a particular "lane" is within the control of that organizational unit. This technique allows the analyst to locate the responsibility for performing an action or making a decision correctly, allowing the relationship between different organizational units with responsibility over a single process.

Contents

[edit] History

The first structured method for documenting process flow, the flow process chart, was introduced by Frank Gilbreth to members of ASME in 1921 as the presentation “Process Charts—First Steps in Finding the One Best Way”. Gilbreth's tools quickly found their way into industrial engineering curricula. In the early 1930s, an industrial engineer, Allan H. Mogensen began training business people in the use of some of the tools of industrial engineering at his Work Simplification Conferences in Lake Placid, New York.

A 1944 graduate of Mogensen's class, Art Spinanger, took the tools back to Procter and Gamble where he developed their Deliberate Methods Change Program. Another 1944 graduate, Ben S. Graham, Director of Formcraft Engineering at Standard Register Corporation, adapted the flow process chart to information processing with his development of the multi-flow process chart to displays multiple documents and their relationships. In 1947, ASME adopted a symbol set derived from Gilbreth's original work as the ASME Standard for Process Charts.

According to Herman Goldstine, he developed flowcharts with John von Neumann at Princeton University in late 1946 and early 1947.[1]

[edit] Software

[edit] Manual

Any vector-based drawing program can be used to create flowchart diagrams, but these will have no underlying data model and accordingly cannot be used to represent a process to other programs.

Some tools offer special support for flowchart drawing, e.g., OpenOffice.org Draw, ConceptDraw, SmartDraw, EDraw, Visio, OmniGraffle, Dia, SFC [1], FreeDFD (GPL free software downloadable here) and RFFlow (samples from which demonstrate the range of typical presentations). Most such products, including the above, are designed as stand-alone desktop applications and have little or no capability to share data with databases or other programs such as project management systems or spreadsheets.

Some web services directly support flowchart creation and sharing. This latter class includes the Flash-based DrawAnywhere and Gliffy or flowchart.com which does not rely on any plugins.

There are also flowchart editor components designed to be included in more specialized software such as in corporate intranets: yEd graph editor for Java or flowchart studio for Eclipse (sourceforge) or CFlowchartEditor ([2]). These are commonly used in software that allows for both manual editing and automatic tagging or annotation of flowcharts.

[edit] Automatic

Many software packages exist that can create flowcharts automatically, either directly from source code, or from a flowchart description language:

For example, Graph::Easy, a Perl package, takes a textual description of the graph, and uses the description to generate various output formats including HTML, ASCII or SVG. The example graph listed below was generated from the text shown below. The automatically generated SVG output is shown on the right:

A simple flowchart, created automatically.
A simple flowchart, created automatically.
graph         { flow: south; }
node.start    { shape: rounded; fill: #ffbfc9; }
node.question { shape: diamond; fill: #ffff8a; }
node.action   { shape: rounded; fill: #8bef91; }

[ Lamp doesn't work ] { class: start }
  --> [ Lamp\n plugged in? ] { class: question; }
   -- No --> [ Plug in lamp ] { class: action; }

[ Lamp\n plugged in? ]
  --> [ Bulb\n burned out? ] { class: question; }
   -- Yes --> [ Replace bulb ] { class: action; }

[ Bulb\n burned out? ]
  -- No --> [ Buy new lamp ] { class: action; }

There exist also various MediaWiki Extensions to incorporate flowchart descriptions directly into wiki articles.

[edit] Examples

A simple flowchart for computing factorial N (N!)
A simple flowchart for computing factorial N (N!)

A flowchart for computing factorial N (N!) Where N! = 1 * 2 * 3 *...* N. This flowchart represents a "loop and a half" — a situation discussed in introductory programming textbooks that requires either a duplication of a component (to be both inside and outside the loop) or the component to be put inside a branch in the loop.

Since computer programming languages do not contain all of the constructs that can be created by the drawing of flowcharts, they do not often help new programmers learn the concepts of logical flow and program structure.[citation needed] To try writing flowcharts for computer programs, an on-line applet for iconic programming is available that limits the flowchart components and connections to those that can be directly converted into any programming language. (Note: click on the yellow square to begin.)

[edit] Symbols

A typical flowchart from older Computer Science textbooks may have the following kinds of symbols:

  • Start and end symbols, represented as lozenges, ovals or rounded rectangles, usually containing the word "Start" or "End", or another phrase signaling the start or end of a process, such as "submit enquiry" or "receive product".
  • Arrows, showing what's called "flow of control" in computer science. An arrow coming from one symbol and ending at another symbol represents that control passes to the symbol the arrow points to.
  • Processing steps, represented as rectangles. Examples: "Add 1 to X"; "replace identified part"; "save changes" or similar.
  • Input/Output, represented as a parallelogram. Examples: Get X from the user; display X.
  • Conditional (or decision), represented as a diamond (rhombus). These typically contain a Yes/No question or True/False test. This symbol is unique in that it has two arrows coming out of it, usually from the bottom point and right point, one corresponding to Yes or True, and one corresponding to No or False. The arrows should always be labeled. More than two arrows can be used, but this is normally a clear indicator that a complex decision is being taken, in which case it may need to be broken-down further, or replaced with the "pre-defined process" symbol.
  • A number of other symbols that have less universal currency, such as:
    • A Document represented as a rectangle with a wavy base;
    • A Manual input represented by parallelogram, with the top irregularly sloping up from left to right. An example would be to signify data-entry from a form;
    • A Manual operation represented by a trapezoid with the longest parallel side at the top, to represent an operation or adjustment to process that can only be made manually.
    • A Data File represented by a cylinder
  • Note: All process symbols within a flowchart should be numbered. Normally a number is inserted inside the top of the shape to indicate which step the process is within the flowchart.[citation needed]

Flowcharts may contain other symbols, such as connectors, usually represented as circles, to represent converging paths in the flow chart. Circles will have more than one arrow coming into them but only one going out. Some flow charts may just have an arrow point to another arrow instead. These are useful to represent an iterative process (what in Computer Science is called a loop). A loop may, for example, consist of a connector where control first enters, processing steps, a conditional with one arrow exiting the loop, and one going back to the connector. Off-page connectors are often used to signify a connection to a (part of another) process held on another sheet or screen. It is important to remember to keep these connections logical in order. All processes should flow from top to bottom and left to right.

[edit] References

  1. ^ Goldstine, Herman (1972). The Computer from Pascal to Von Neumann. Princeton University Press, 266-267. ISBN 0-691-08104-2. 

[edit] See also

[edit] External links

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