> 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. Fair enough, and now I understand where you fall on the issue. I agree that my analogy wasn't fully to the point. But here's the question: Do you really think the entire discussion has to finish in order to do a meaningful architecture? Is it not possible for the architecture document to have a section about <strike>perpetual-motion machines</strike> caching that talks about the needs, the benefits, the drawbacks, and the tradeoffs, and leaves the final design and decisions for later? Such a section might well explain why the required caching is difficult, bordering on impossible to get right, or whatever. At this level, do we need to *resolve* the questions and all the design points? Or is it possible to have a useful document that helps everyone understand the issues, while leaving many of those issues unresolved until later? Barry