What do you mean by balancing of DFD? Explain with a suitable example.
Balancing of DFD:
The concept of balancing states that all the incoming flows to a process and all the outgoing flows from a process in the parent diagram should be preserved at the next level of decomposition. The goal of the balancing feature is to check the system internal consistency, which is particularly useful as different levels of expertise are generally involved in a project. When we decompose a process, Power Designer helps you initialize, in the sub diagram, the objects from the upper-level to link to the sub-process. Power Designer automatically retrieves global objects, such as external entities or data stores and creates object shortcuts, if need be.
The following example shows a top level DFD, in which we are going to decompose the Collect Payment process:
The following example shows the default sub-process diagram of the Collect Payment decomposed process containing its related objects coming from the upper-level. Then, we have to link the objects. Each object we link afterwards to the parent process in the upper-level is automatically displayed in the sub-process diagram:
In addition, PowerDesigner ensures, using balancing checks, that each data on flows or in data stores in the upper-level exist in the sub-diagram.
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