Chapter 11 What is DFD and Types Explain in Details

 CHAPTER 11

DFD 

 (DATA FLOW DIAGRAM ) 

DFD :- Data flow diagram and also known as “Bubble Chart”

DFD show the flow of data between various elements of a system in graphical form, It also express the requirements of the system and show how the content current system is implemented.

It is gives an overview of what data a system process, what transformations are being performed, what data are stored, what results are produced and where they flow.

It is graphical is natural makes, it’s a good communications tool between user and system design(System Analyst)

DFD is easy to understand and quite effectives tool for communications (between user and system analyst) when required design it’s not clear.

It requires a large number of iterations for obtaining the most accurate and complete solution.

Basic elements of DFD/ Components of DFD:- It  means used symbols in designing the DFD are:- 

Types of DFD:-

1.      Logical DFD :- It Show how data flow in a system, It describes what data is moved from one entity to another. It focus on what happen in the data flow. It show how system works not, how the system can be implement. It is implemented independent.

2.      Physical DFD :- It  show how data flow is actually implemented in the system. It describes how data is moved from one entity to another. It is implementation dependent.

Levels of DFD :-

There are mainly three levels.

1.      0 Level DFD

2.      1 Level DFD

3.      2 Level DFD                                                                                                                                  

Explain all level :-

1.      )  0 Level DFD :- It show the system  as a single process with it’s relationship to external entities, it’s represented the entire system a single process input data and output indicated by incoming / outcoming arrows, It is also known as fundamental system model and it show only abstract video.  

2.      ) 1 Level DFD :- In 1 level DFD, we decompose the context level DFD (0-level DFD) into multiple component and define each components in details.

3.      ) 2- level DFD :- In 2-level DFD we decompose the 1-level DFD into more details and define each necessary details about system functioning properly.

Some Extra example pending :-