Frances,
I agree with what you say, 'that you have to understand the finished
picture before you put the pieces together'.
But putting the pieces together I like to consider to be the 'Design'.
Finding out what the picture is, is what I want to call 'Analysis'.
Discovering Use Cases comes before both 'Design' and 'Analysis'. It's a way
of finding out what is in your picture without going into the details.
So in the Use Case/Inception phase I'm trying to discoves what is in the
picture - in the Analysis phase I'm combining the parts I discovered in the
Inception phase and putting the details into the picture - in the design
and implementation phase I'm actually working with the pieces. (I don't
have a jigsaw analogy for the testing phase.)
I don't think this contradicts what I said yesterday. Basically in the use
case phase in order to discover whats in the picture, I'm observing the
pieces to see what they contain.
So I can see there's a horse, a house, sky, trees, etc. Note I haven't put
any pieces together, just grouped them into 'Packages'.
Now in the analysis phase, I'm going to try and put the pictures of the
horse, house, trees together to form an overall pictuse of the puzzle, and
at the same time I'm going to try and fill in the details of the grass,
walls, clouds, etc, until I'm satisfied that I have an accurate enough
picture to work from.
Now I go into my design and implementation phase and actually try to put
the pieces together.
In summary, during the use case phase we don't have a picture, it's the use
cases that help give the picture to us.
I actually have a whole paper on analysis and design which uses jigsaws as
an analogy for developing software. As I said, one phase that doesn't seem
to fit into the analogy is the testing phase. (Any ideas?)
Leslie.
"Butler,
Frances H. To: "'[EMAIL PROTECTED]'"
<[EMAIL PROTECTED]>
(FHB) " cc: [EMAIL PROTECTED],
[EMAIL PROTECTED]
<[EMAIL PROTECTED] Subject: RE: (ROSE) Use Cases and UC
Diagram
gov>
11/30/00
12:28 PM
Hi Leslie,
I love your analogy, but I don't agree with your conclusion. As a fan of
jigsaw puzzles, I think you have to understand the finished picture before
you can understand how to put the pieces together, especially the
1000-piece
variety. Most systems come under that category. Why work the puzzle if
you
don't know what the finished picture should be? I'm not convinced that the
finished picture is inaccurate.
Jeff was correct, and I'll bet he's a good jigsaw puzzle solver!
:-)
Frances
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| Frances H. Butler
| Computing Specialist
| BWXT Y-12 L.L.C.
| Oak Ridge, TN
| Phone: (865) 574-3694
| Internet: [EMAIL PROTECTED]
|
| Results! Why, man, I have gotten a lot of results.
| I know several thousand things that won't work.
| Thomas Edison
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 29, 2000 10:13 PM
Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]
Subject: RE: (ROSE) Use Cases and UC Diagram
Still sounds like functional decomposition to me also.
As for what's wrong with it?
1) More likely to be misinterpreted as a design for your system,
2) It's a mentality thing - for me I try to forget that such a beast exists
in case it interferes with my OO thought patterns.
3) It is unnecessary.
My take is to discover your use cases and then, once you have enough start
packaging them, which is the reverse of what is being suggested below (find
chunks and break them down).
Let me try an analogy.
We're trying to do a jigsaw puzzle. There are two different processes being
followed in order to complete the picture.
1) The puzzler (for want of a better word) is looking at the pieces and
grouping them into chunks and gradually building these chunks into bigger
chunks until the complete picture is formed.
2) The puzzler is working from the picture of the puzzle, breaking the
picture into manageable chunks and then looking for the pieces that go to
make up those chunks.
Or to summarise, one is working from the BIG picture the other is working
from the pieces.
After reading this, is it obvious that my preference is to work from the
pieces(1)? The reason for this is that the BIG picture is often flawed and
inaccurate. The pieces are not so.
Leslie.
P.S. Having been out of touch with Project Technology for a while, I'd be
interested to know when they added Use Cases to the S/M method.
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