Barry, On Mar 14, 2012, at 11:02 AM, Barry Leiba wrote: Relevant? Yes. Gating? No. In fact, I would put it the other way around. The architecture documentis very useful, almost necessary, for deciding whether the solution is a good one. The cache management evaluations are another component of such an evaluation. Even understanding the cache management question is made significantly easier by having a clean architecture description. Indeed. At the risk of straining things with an analogy, I'll liken this to architecture of a building. At the architecture level, we do have to consider, say, bathrooms, and it's reasonable at that level to talk about having bathrooms on each floor, and perhaps the extent to which accessible bathrooms are needed. Deciding whether to have two pairs or three per floor is something that can be left to the detailed post-architecture specifications, and things like what sorts of fixtures to put in them *absolutely* come later. No one is saying that some discussion of caching issues (etc) won't be needed in defining and specifying the architecture. We're just saying that it's not necessary to do the caching document before, as long as the related discussion that happens at the architecture stage is preserved for when it's time to work on the caching doc. Analogies are always risky, but I'll continue. I don't think the proper analogy is a bathroom. Everyone knows you can build bathrooms that work, having seen successful examples in the past. You might instead think of a building which includes a perpetual motion machine [*] as a key element. --John [*] Forgive me, press of time prevents me from finding an example which is both less inflammatory, and still has the property "something whose practicability is debatable." Feel free to fill in your favorite.