- Definition of DFD
Data Flow Diagrams (DFD) provide a visual display of the flow of data and information from a system. The visual of this DFD depicts who is involved in the system from start to finish. DFD is often used to describe an existing system or a new system to be developed. For those of you who do not know DFD is a diagram made using notations to describe the flow of data from the system.
- Symbol DFD
So that you don’t use the DFD symbol incorrectly, you need to know the following DFD symbols along with their explanations:
- Entity/Entity/Terminator
Symbols that have functions as people, organizations and the like that are outside the system but interact with the system. This symbol needs to be named according to the original usually using nouns such as: workers, lecturers, students, sales systems and others depending on the system to be made.
- Process
Process is an activity or work that processes input data from entities to output. Usually for the process given verbs such as: work, teach, learn, sell and so on depending on the initial entity.
- Data flow
Data flow serves to explain the flow of data or information from one symbol to another. Usually naming the data stream also uses a noun.
- Data Store
Data Store or data source is a symbol that has to do with storage such as files or databases. The database symbol usually comes after the process symbol to store the processing output. In naming the data store, it is filled in according to what data is stored such as salary, class, employees and others.
Type DFD
- Level 0 Diagram (Context diagram)
Level 0 diagram or it could be context diagram is the lowest level diagram that describes how the system interacts with external entities. The context diagram will be given a number for each running process, generally starting from 0 for the initial start. All entities in the context diagram including the data flow will be directly directed to the system. In this context diagram there is also no information about the stored data and the diagram display is quite simple.
- Data Flow Diagram Level 1
DFD level 1 is a further step on DFD level 0, where all processes that exist in DFD level 0 will be detailed in full so that it is more complete and detailed. The existing main processes will be split into sub-processes.
- Difference DFD Level 0 and DFD Level 1
There are differences between the 2 DFD levels that you need to know, here are the differences:
- DFD level 0 only describes the basic system only.
- DFD level 0 only describes the flow of data from input to output.
- DFD level 1 describes a more complex data flow in each process which then forms a data store and data flow.
- DFD level 1 describes the system partially or completely in detail.
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