generic n-tier question re sql strings 5

[misterstick]

out of ignorance and hubris over the last month or so i've pulled an n-tier application out of my special magic pocket.

i thought i'd understood the general principles of it all, but a brisk reading of this microsoft article on mimicking ado in .net gives me pause for thought.

i fear that what i thought was the data access layer is, in fact, merely a wrapper for the various data access protocols.

my question, therefore, is how, and where, should sql strings be stored and handled in your bog-standard n-tier architecture?

i've got them in the "business" layer currently. should they be moved to the "data access" layer? should i create a new layer in between "business" and "data access" that actually handles the data access?

should it all be done with stored procedures, moving the actual data access into the database?

mr s. <

 

[chiph]

He uses UML diagrams, and learning them is a gradual process. You'll want another Martin Fowler book for a quick-start on them. Everyone where I'm working has a copy on their desk that they paid for out of their own pocket -- it's that good.

Martin Fowler's book:
UML Distilled, 3rd ed.
ISBN 0321193687

Good start on UML:

http://www.oracle.com/technology/pr...rs/10g/GettingStartedWithUMLClassModeling.pdf

The Oracle document is specific to Java and JBuilder, but given the similarities between it and C#, the concepts transfer easily.

Chip H.


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[NeilTrain]

this thread is golden, thanks for the book suggestions guys, I've found it hard to find good books that are more than just programming, but more into Enterprise Level architecture.

 

[misterstick]

thanks, chip, for the oracle model document. i see what they're saying, but i still don't get how mr fowler is applying the uml structure to design patterns.

perhaps they're as obvious as the oracle examples, it's just me that has to get my head round what is being said.

i'll read it again, slower, then read some more of the pattern book. but not today.

thanks again,

mr s. <

 

[chiph]

The UML diagram is just a graphical representation of what he's saying.

Here's a good walkthrough of a design process, using the MVC pattern.

http://www.codeproject.com/aspnet/ModelViewController.asp

There are several UML diagrams there that have accompanying text, which should be helpful. Some are class diagrams, some are sequence diagrams, and some are use-case diagrams. Each serves a different purpose.

Use-case diagrams show the very high level interaction between an actor and the system.

Class diagrams show classes and their dependencies on other classes.

Sequence diagrams take the classes defined earlier and show the method calls needed to accomplish a task.

Chip H.


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