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[nycphp-talk] Top down or bottom up design (Was Automatically Generating Code from the Database)

Francisco Reyes lists at natserv.com
Tue Mar 22 22:39:51 EST 2005


On Tue, 22 Mar 2005, Brian Kaney wrote:

> That's because he is used to the older data-driven design methodology.
> PHP (especially v5) and other OO languages allow us to use domain-driven
> design.

While trying to not go too offtopic PHP...
  I don't think this is an "old approach". It has to do with how someone 
sees the problem and his/her background.. For example to ask a database 
designer to think of the problem as processes and not of data is like 
asking a fish to feel confortable outside of water. :-)

> Instead of starting from the database structure and working outward to
> try to solve the process, start with the business problem, build your
> workflows/objects and finish with the data storage.  I find there is
> much less iteration with this method.

I personally think there is more risk on the top down approach. In 
particular users, over time, tend to internalize the process. They don't 
see certain parts of the process anymore because they just "do it" when 
the screen/process comes up. If you just ask abou the processes one needs 
to be carefull to make sure those internalized steps are not skipped.

On the other hand I find users tend to know the data they work with fairly 
well.

Moreover, when doing a re-engineering project asking about processes tends 
to get you feedback of how things are.. but the whole purpose of the 
re-engineering is to re-do that.. Doing a bottom up approach allows the 
user to tell you what it is that needs to be captured.. as long as their 
current process.. and let's the designer come up with new ways to do the 
process.

I really think that either approach will work.. it's just how a person 
sees processes/design and how experienced they are.



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