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What is meant by Data flow design? Explain the symbols used for showing different components of data flow diagram.

What is meant by Data flow design? Explain the symbols used for showing different components of data flow diagram.

Answer: A data flow diagram shows how data is processed within a system based on inputs and outputs. Visual symbols are used to represent the flow of information, data sources and destinations, and where data is stored. Data flow diagrams are often used as a first step toward redesigning a system. They provide a graphical representation of a system at any level of detail, creating an easy-to-understand picture of what the system does. A general overview of a system is represented with a context diagram, also known as a level 0 DFD, which shows a system as a single process. A level 1 diagram provides greater detail, focusing on a system’s main functions. Diagrams that are level 2 or higher illustrate a system’s functioning with increasing detail. It’s rare for a DFD to go beyond level 2 because of the increasing complexity, which makes it less effective as a communication tool. 
Entity produces and consumes data that flows between the entity and the system is diagrammed. These data flows are the inputs and outputs of the DFD. Since they are external to the system being analyzed, these entities are typically placed at the boundaries of the diagram. They can represent another system or indicate a subsystem.

                                        Entity symbol




Processes: An activity that changes or transforms data flows. Since they transform incoming data to outgoing data, all processes must have inputs and outputs on a DFD. This symbol is given a simple name based on its function, such as “Ship Order,” rather than being labeled “process” on a diagram. Processes are typically oriented from top to bottom and left to right on a data flow diagram.
 

                                                Processes symbol

Data Store – A data store does not generate any operations but simply holds data for later access. Data stores could consist of files held long-term or a batch of documents stored briefly while they wait to be processed. Input flows to a data store including information or operations that change the stored data. Output flows would be data retrieved from the store.
 

Data Store symbol
Data Flow – Movement of data between external entities, processes and data stores is represented with an arrow symbol, which indicates the direction of flow. This data could be electronic, written or verbal. Input and output data flows are labeled based on the type of data or its associated processor data store, and this name is written alongside the arrow
                                         Data flow Symbol
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