Data Flow Model

Data Flow Model

• Captures the flow of data in a system.
• It helps in developing an understanding of system’s functionality.
• What are the different sources of data, what different transformations take place on data and what are  final outputs generated by these transformations.
• It describes data origination, transformations and consumption in a system.
• Information is organized and disseminated at different levels of abstraction. Thus this technique  becomes a conduit for top down system analysis and requirements modeling.

The Notation
There are several notations of the data flow diagrams. In the following, four different shapes are explained.

Process

• What are different processes or work to be done in the system.
• Transforms of data. 

Process

External AgentExternal systems which are outside the boundary of this system. These are represented using the squares

External Agent

 Data Store

• Where data is being stored for later retrieval.
• Provides input to the process
• Outputs of the processes may be going into these data stores.

Data Store

 Data Flow

• Where the data is flowing.
• Represents the movement of the data in a data flow diagram.

Data Flow