Components of Data Flow Diagram

Following are the components of the data flow diagram that are used to represent source, destination, storage and flow of data.

• External Entity: External entity also known as Terminator, Actor, is the component of Data flow Diagram (DFD) that stands outside of the system and communicates with the system. It can be, for example, organizations like banks, groups of people like customers or different departments of the same organization, which is not a part of the model system and is an external entity. Modeled systems also communicate with terminator.
• Process: Input to output transformation in a system takes place because of process function. The symbols of a process are rectangular with rounded corners, oval, rectangle or a circle. The process is named a short sentence, in one word or a phrase to express its essence
• Data Flow: Data flow describes the information transferring between different parts of the systems. The arrow symbol is the symbol of data flow. A relatable name should be given to the flow to determine the information which is being moved. Data flow also represents material along with information that is being moved. Material shifts are modeled in systems that are not merely informative. A given flow should only transfer a single type of information. The direction of flow is represented by the arrow which can also be bi-directional.
• Warehouse (Data Store) : The data is stored in the warehouse for later use. Two horizontal lines represent the symbol of the store. The warehouse is simply not restricted to being a data file rather it can be anything like a folder with documents, an optical disc, a filing cabinet. The data warehouse can be viewed independent of its implementation. When the data flow from the warehouse it is considered as data reading and when data flows to the warehouse it is called data entry or data updating.

What symbols and notations are used to represent Components of DFD?

In Data-Flow Diagrams (DFDs), symbols and notations vary depending on the methodology being used. Here’s a summary of symbols and notations commonly associated with each methodology:

The different methodologies or approaches used for creating Data-Flow Diagrams (DFDs) are:

• Gane and Sarson
• Yourdon and De Marco
• SSADM
• UML

Each methodology provides its own set of guidelines, symbols, and notations for representing system components and their interactions.

Data Flow Diagrams (DFDs) are powerful visual tools representing information flow within systems. Understanding their types and components is important as each type has a different purpose, and components help in creating an accurate Data Flow Diagram (DFD).