daveb@geaclib.UUCP (David Collier-Brown) (03/31/89)
>>In article <46500057@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes: >> Resolved: Layered software functionality is sluggish, and therefore >> undesirable. From article <7977@boring.cwi.nl>, by jack@cwi.nl (Jack Jansen): > Actually, layered software doesn't *have* to be sluggish. However, it takes > quite a bit of work to build an efficient layered product. You have > to design an initial version, use it for a while, measure it, redesign > it (possibly moving features between levels), use it for a while, > measure it, etc etc etc. [discussion on intra-layer tuning elided] Actually, I'll claim that separation of function (AKA simplicity) usually makes things faster, because it makes a set of simple things out of a collection. This in turn makes reasoning about the parts at least **possible**, and allows one to come up with better algorithims. Layering is one technique that helps here, although it is by no means a panacea. Wulf commented years ago about the tendency to repeat the same feature at more than one level, and the difficulty of getting the layering right. And this has little if anything to do with architecture any more, so followup to comp.misc.... --dave c-b -- David Collier-Brown. | yunexus!lethe!dave Interleaf Canada Inc. | 1550 Enterprise Rd. | He's so smart he's dumb. Mississauga, Ontario | --Joyce C-B