It is the process which starts after the completion of Analysis Phase. In this phase the
planning of activity starts whereas in the Analysis phase the important data are
gathered.
System Designing consists of various activities. The main activities that are being
conducted here:
* Modeling Data Flow Diagram of System
* Creating Entity Relationship Diagram of System
* Creation of Database Dictionary Designing
* Database Design
* Input Form Design
* Output Forms or Reports Design.
Finally, after the completion of this phase, the development phase is performed where
these designs are used to achieve the proper look and feel of the software.
Data Flow Diagram for System
It is one of the important tools of System Designing which enables software engineer
to develop models of the information domain and functional domain at the same time.
It serves two purposes:
1. Provides an indication of how data are transformed as they move through the system
2. Depicts the Functions (and sub-functions) that transform the data flow.
The DFD provides additional information that is used during the analysis of the
information domain and serves as a basis for the modelling of function. A description
of each function presented in the DFD is contained in a Process Specification. As the
DFD is refined into greater levels of details, the analyst performs an implicit
functional decomposition of the system.
One of the faults in our process while developing the system was that the system was
analysed, designed and implemented but the DFDs were developed as an afterthought.
Thus, you will find the following problems in the DFDs:
* The dataflow have not been labeled in many cases.
* The processes are shown as linear processes especially in the second level DFDs
* The verification activities are being performed in sequence, although they are not practically done that way in the actual situation.
Exercise Demonstration:
You must discuss the DFDs thoroughly in your sessions and come up with the most optimum DFDs.
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