DFD vs Flow Chart

Data Flow Diagram
A data flow diagram is the graphic or visual representation of the data flow through business processes. These help in visualization of the flow of data and its transformation by different processes. These diagrams show the route that the data takes to flow within a system; they show the transformation of storage as well as the data by the processes.

The arrows represent the transfer of data between two elements which are within a system. They also show the transfer of data between different entities as well as different data storage media. These elements are within a system. The DFD does not show the elements which control the data.

Data flow diagrams deal with the logical part of the action. They represent the functional relationship and also include output values, input values, and data stored internally. They are used for design methods and structural analysis to represent the flow of data through a system. They are used by businesses to represent the relationship between organizations with external customers or other organizations or businesses. It is a view of the system at a very high level. At higher levels they are used for analysis. They are represented by five different symbols.

While building a data flow diagram, two things are necessary; entities to be allocated and the main process. The allocation of entities is important as entities are the points of entry for data in the main system. These entities could be organizations, personal places, etc. The next thing that is important is the main process which is the activity or process that transforms the data. A unique ID is allocated to each process.

Flow Chart

A flow chart is the graphic representation of the flow of data through information processing systems. It represents the processes within a system and the sequence or steps in which the processes take place.

These diagrams represent the logic for a business process, decisions, loops, computations, and interactions. They deal with the flow of control between different elements; these elements are decisions or instructions.

A flow chart deals with the physical aspect of an activity. It is a simpler representation as it includes steps which are being followed to start and finish an activity or process. It is the view of the system at a lower level. When used at a higher level, it becomes a designing tool. It is represented by three different symbols.

While building a flow chart, three things are necessary. First, one should allot a starting point; secondly, actions are added to show the steps required to finish the task; thirdly, dependent actions are added.

Summary:

1.A DFD is a graphic representation of the flow of data through business processes; a flow chart is the graphic representation of the flow of data through an information processing system.
2.DFDs are represented by five symbols; flow charts are represented by three.
3.A DFD deals with the logical aspect of the action; a flow chart deals with the physical aspect of the action.
4.A DFD is the view of the system at a high level; a flow chart is the view of the system at a lower level.
5.DFDs show the flow of data; flow charts show the flow of control.

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