11. Data Flow Diagrams (cont)

Let's break the diagram on the previous page down into the common parts of a DFD:

• Data flow
• Process
• External entities
• Data store

Data flow

The path that data takes through the system is represented by an arrowed line. The arrowed line should have a description of the data. Just for the sake of clarity on this web page, the data description has been left out in the example. But in a normal DFD you should include a description of the data set.

So you can see that the 'Confirm Order details' process has data flowing into it from the customer along with a feed from a data store called 'Product Options'. The outcome of the process are three streams of data feeding other processes. Ideally each data flow would have a name.