As mentioned in a previous post, a data flow diagram is a two dimensional diagram that explains how data is transferred and processed in a system. The graphical depiction identifies each source of data and how it interacts with other data sources to create a common output. By numbering processes and keeping the process names simple, the systems analysit can easily and accurately reference the specific processes. Examples of a process: Calculating a monthly salary, calculating interest rates, printing reports.
There are many advantages to using a DFD:
Clarity of Flow
A data flow diagram shows a flow as a curved or straight arrow line. On a DFD the arrow line is labeled to describe data or information that is being moved or processed. The point of the arrow line shows the source and the arrow of the next process, store or terminator. With the aid of a data flow diagram, a systems analyst can determine if a system has all the required input and output data for a process.
Appropriate Data Flow
A data flow diagram shows a store as two parallel lines. A store is any type of storage for data or informatio and can refer to any automated database or filing system. A data flow diagram can help a systems analyst to determine if the data store has the required input data to be processed to generate the needed information. A data flow diagram can assist in determining if the data store is appropriate for the generated output information.
Levels of Data Flow Diagram
A DFD has many levels that helps a systems analyst review a system, process by process. The ranking of the levels in the DFD helps the systems analyst in breaking down the details easily and determining any problems that may occur in a system.
The above advantages are essential in the choosing of a data flow diagram!