Data Flow Diagram

The data flow diagram or DFD is the most data centric of the entire process diagram. Instead of showing a control flow through a series of process steps, it focuses on the data that flows through the process steps. By combining diagrams hierarchically, the data flow diagram combines the best of the flowchart and the function diagram. Data flow diagram s became immensely popular in the late 1970s and early 1980s, largely due to the work of Chris Gane and Trish Sarson Fach process on a data flow diagram can be broken down using another complete page until the desired level of detail is reached.

The components of a DFD are simple:

Processes are represented with rounded rectangles. Processes are typically numbered hierarchically. The first page of a data flow diagram might have processes numbered 1. 2, 3, and 4. The next page might break down process number I and would have processes numbered 1.1, 1.2, and so forth. If process 1.2 were broken down on yet another page, the processes on that page would be numbered 1.2.1, 1.2.2, and so forth.

Data stores are represented with an open-ended rectangle. A data store is a generic representation of data that is made persistent through being stored somewhere, such as a file, database, or even a written document. The term was chosen so that no particular type of storage is implied. Because here already have an ERD as an example, we should closely align the data stores with the entities that have already identified. But you will find lots of information on the internet about this data flow diagram. There are several books are also provide more information about the data flow diagram.

Questionnaire:

• What is data flow diagram?
• Explain more about the data flow diagram?