How is a context diagram different from a level 0 diagram?

Question

What is the difference, if any, between a context diagram and a level 0 diagram?

Answer 1

There are some conflicts in the literature regarding these two terms.
For example, on page 54 of this book . It is highly regarded in Google books and is the standard text in many schools. It says the context diagram is the same as level 0 DFD. This one disagrees on page 210.

First, I will consider the concept of "levels."

As we know, initially the whole system is represented by one large block, and the interactions with the system are clearly visible. Initially, we see the system with the naked eye.

Now think that you are holding something like a microscope. You mount the lens over the system unit and zoom in. This "increase" will lead you to the next level in the hierarchy. So now you see that the system consists of several blocks.

You take any of the sub-blocks, and then zoom in again, moving to the next level and so on.

So, we see that there is a hierarchy of diagrams, each level brings us to the next level of detail. The only bone of contention that remains now is the name of the first level (view with the naked eye).

As you can see, the question is not very objective, hence the ambiguity.

We can have:

Context Diagram -> Level 0 DFD -> -> Level n DFD</pre> 

OR

 Context Diagram/Level 0 DFD ->Level 1 DFD ->Level n DFD 

It comes down to looking better. In my personal opinion, the first hierarchy is more inclined. This is because initially all that we see is the system and context in which it works. I feel that anyone who understands the explanation should not worry about the nomenclature.

See this for more details .

Answer 2

Very difficult discussion. My thoughts: A context diagram has only one process, and a DFD level of 0 can have more.

Answer 3

The context diagram has established the context in the system under development, which is the interaction in the system with various external objects. In cases where the data flow diagram is a simple graphic designation that can be used to represent the system in terms of input to the system, various processing performed on this data and the output generated by the system. It is easy to understand and use.