• A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system,

• DFDs can also be used for the visualization of data processing (structured design).

• They consist of two parts: a set of Data Flow Data Flow DiagramsDiagrams (DFDs) and a set of associated textual descriptions.

• Data Flow Diagram (DFD) is an important technique for modeling a system’s high-level detail by showing how input data is transformed to output results through a sequence of functional transformations.

Manager

e

Supplier

d

Purchase OrderCabinetM1

StockFile

M2

*

ReceiveStock

2 Stock Clerk

Manager

e

*

SellStock

3 Cashier

Customer

a

Purchase Order

Stock ListP.O.

Matched Orders

Orders

Purchase Order

Delivery

Bought Goods

Stock List

Sold Goods

Delivered Goods

OrderStock

1 Stock Clerk

M2 StockFile

Processes Data Stores

External Entities

• The DFD is a diagram that consists principally of four symbols, namely the external entityexternal entity, the data flowdata flow, the processprocess and the data storedata store

• External entities (source/destination of data) are represented by squares; Processes (input-processing-output) are represented by rectangles with rounded corners; Data Flows (physical or electronic data) are represented by arrows; and finally, Data Stores (physical or electronic files) are represented by open-ended rectangles.

d

Supplier

Cosmetics

Goods

Customer DetailsData Flow (usual)

Bi-directional Flow (rare)

Flow Between External Entities (for convenience)

Resource Flow (for convenience)

SellStock

Cashier3

D3 Suppliers

StockFileM1

T1 Unpaid Invoices

D1 Orders D1 Orders

A sequence diagram is a kind of interaction diagram that shows how processes operate with one another and in what order.

Sequence diagrams are sometimes called event diagrams, event scenarios, and timing diagrams.

Activity diagrams are graphical representations of workflows of stepwise activities and actions with support for choice, iteration and concurrency.

Activity diagrams can be used to describe the business and operational step-by-step workflows of components in a system. An activity diagram shows the overall flow of control.

SalesFulfillment