When presented with a data flow diagram of a proposed new system project what ac

Question

When presented with a data flow diagram of a proposed new system project what actions would you take and what feedback would you provide the analyst if you have difficulty reviewing the diagram?

What are the four elements of a Data Flow Diagram (DFD), what is the purpose of these elements, and how does the system development team use these elements? What is a process model and how is it related to a data flow diagram?

Explain the concept of decomposition and why process models are created as a hierarchy of DFDs. Describe several common syntax and semantic errors found when reviewing DFDs for quality, describe the process for correcting these errors.

Explanation / Answer

It’s very crucial to carefully examine and evaluate the Data flow diagramming (DFD) process proposed for the new system project as DFD is regarded as an effective technique which facilitates to explain the flow of information through a system. Furthermore it helps to carefully understand the present system and then facilitates to represent the required system.

The basic elements required to create data-flow diagrams are processes, data-flows, data stores and external entities. A process is represented in the model if an activity from the input information is influenced or changed in some way where the out flow data when compared to flowed in data is changed.

Data-flow elucidates a package of information flowing between two objects in the data-flow diagram. It is utilized to represent the flow of information in – elements between - out of the system. Data store facilitates storage and retrieval of data within the system for instance it may be a file, consumer contracts file etc.

External entities are referred as entities outside the system which can interrelate with the system for instance can send or receive information into the system. It may be external to the whole business or just external to the application area where user activities are not directly supported by the system under investigation.

Process models are referred as processes of identical nature which indeed can be categorized together into a model. Thus it is regarded as a description of a process at the type level where the same process model is used repeatedly for the development of numerous applications.

Process model regarded as a core diagram in structured analysis and design is used to recommend how things can or should be done thus it is roughly an anticipation of what the process would look like whereas what the process should be would really be ascertained during the actual system development. A high-level process in an entire DFD can actually be decomposed into other processes with data flows and stores. Furthermore each component of decomposition is regarded as a DFD in itself and one can continue to break down processes until one reach a point where no further decomposition would be possible or it would seem meaningless.

Syntax errors in DFD can be errors due to the matter of fact that the syntax of the language is not respected whereas semantic errors can be due to an improper use of program statements. One of the basic patterns of data flow analysis is that all data flow must initiate with or end at a processing step.

Furthermore this makes sense because presumably data cannot simply metastasize on its own without being processed thus this simple rule means that the subsequent mistakes can easily be identified and accordingly rectified in a DFD.

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