Data Flow Modeling
Data Flow Modeling and Data Flow Diagrams (DFD):
In Business Process, DFD is a top-down approach, that focuses on the flow of data between various Business Processes and helps to capture & document the movements within a business or organization. Business process DFDs were created for the purpose of developing application software and they describe about the data sources, destinations, flows, data storage and transformation.
DFD contains five basic constructs namely: Activities (processes), Data Flows (arrows), Data Stores, External References and Physical Resources.
1. Activities or Processes:
An Activity describes an action that transforms or manipulates the data flows within the system or resources. Simply processes are transformations, changing incoming data flows into outgoing data flows. These activity boxes are generally rectangular, rounded corner ones and often labelled with a noun like a name of a system or an object rather than a verb as with the case in Process Flow Modeling. These Process boxes are divided into three sections, identification number, optional location or the role responsible for the process and the process name.
2. Data Flows or Arrows:
In Business Process DFD, arrows represent the flow of data between activities, data stores and external references with the arrowhead showing the direction of flow of data from source to destination.
In DFD, arrows can be split into multiple branches, and each new branch can re-labeled in order to reflect the decomposition of the data being processed. In the same way, arrows can be merged to show the aggregation of data.
3. Data Store:
In Business Process DFD, a data store represents a database, file or any other data store physical or logical.
4. External References:
In Business Process DFD, external references refer to any location or entity that acts as a source or destination of the data which are external to the scope. Only those entities which acts as a source or destination of data are represented on a DFD.
5. Physical Resources:
In Business Process DFD, physical resources represent the flow of physical objects like material movements and are represented as broad arrows. These differ from the data flows (arrows) in a way that these describe the actual flow of resources related to the information carried by the data flow arrows.