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More on Layers

I was told yesterday that entity-relationship diagrams can be OK as high level descriptions of database schemata, but are not appropriate for designing a database. Enough information is missing that they are not able to model the problem.

Could the same be true of layer diagrams? Perhaps they’re OK as stratospheric guides to your software, but not useful for designing that software as too much information is missing.

I don’t think that’s the case, though. Layer diagrams tend to be pretty much interchangeable between systems, so that I can’t really tell which system I’m looking at from the layer cake. Add the difficulty that I probably can’t tell how the layers communicate, and certainly can’t tell how the subsystems within the layers are composed. All I can tell is that you like drawing boxes, but not too many boxes.