Data flow diagram (DFD) is used to show how data flows through the system and the processes that transform the input data into output. Data flow diagrams are a way of expressing system requirements in a graphical manner. DFD represents one of the most ingenious tools used for structured analysis. It is also known as a bubble chart.
In the normal convention, logical DFD can be completed using only four notations.
The DFD at the simplest level is referred to as the ‘CONTEXT ANALYSIS DIAGRAM’. These are expanded by level, each explaining its process in detail. Processes are numbered for easy identification and are normally labeled in block letters. Each data flow is labeled for easy understanding.
Steps to Construct Data Flow Diagrams
Four steps are commonly used to construct a DFD
Salient feature of DFD
Q The DFD shows flow of data, not of control loops and decision are controlled considerations do not appear on a DFD.
Q The DFD does not indicate the time factor involved in any process whether the data flows take place daily, weekly, monthly or yearly.
Q The sequence of events is not brought out on the DFD.
People are inherently resistant to change, and computers have been known to facilitate change. An estimate should be made about the reaction of the user staff towards the development of a computerized system. Computer installations have something to do with turnover, transfers and changes in job status. The introduction of a candidate system requires special effort to educate, sell and train the staff for conducting the business.
The candidate system was found to be technically, economically, and behaviorally feasible. The system was developed user friendly, needless training and improves the working environment. Justification for any capital outlay is that it will increase profit, reduce expenditure or improve the quality of service or goods, which in turn may be expected to provide increased profits. Disregarding the initial expenses, the candidate system was assessed to be feasible in all ways.
