Why MVC is so confusing

I read vikas's blog: http://vikasnetdev.blogspot.com/2006/08/is-3-layered-architecture-mvc.html , which links to http://forums.asp.net/thread/1379168.aspx

This prompts me to think about why MVC is so confusing:

1. First of all, the difference between “design pattern” and “architecture pattern” is well-known; however, the difference between “architecture pattern” and “application pattern” is not well-known/well-established. Actually I feel the latter difference is a misleading concept: if I have a web application, then, should its architecture consult “application patterns” or “architecture patterns”?

I know the source where it comes from -- the SOA. A lot of people believe that SOA is an “architecture pattern” or “system pattern”, and because a “service” is not an “application”, so, a “service architecture” is different from an “application architecture”.

I do not believe so. Service is just a more flexible façade – usually is more coarse-grained and sometimes is async -- in the well-known three-layer application/system architecture. Web is different from Winform, however, we have the same three-layer (or n-layer) application/system architecture. Web service is just a glorified cgi (web). Sometimes, I feel that if those web service people had some hand on experiences with C/Perl (i.e. low level) CGI, then, they will really “feel” and “see” that a web service is just, well, a “web” -- why another architecture? Just marketing strategy?

2. Further, MVC is by itself a little confusing. It is in the introduction of the “design pattern” book, but it is not a low level, pure “OO-only”, “design pattern”; it is an “architecture-oriented” pattern. It has strong implication that it is about the UI – which means, if it is a layered architecture (almost always the case nowadays), then, it is within the UI layer. So, in a sense, it “depends” on the architecture, hence, it is “architecture-oriented”.

3. Another reason that MVC is confusing, my experience, is the usage of the word “model” in MVC. A lot of times, “model” means both the “entity” objects and the “façade objects” in layered architecture (why? because “façade” returns “entity”, together they are the “model”); however, “model” also specifically means the “entity” objects. This is confusing, because “controllers” always call “façade” objects and therefore people feel that “controllers” are “façades”, while sometimes “models” also means “façades”.

4. MVC is especially confusing in asp context, is that for asp, it is not easy to do MVC -- even the “worsened” variation (java/j2EE servlet “model 2” – it is “worsened”, not because the fault of java; it is because of http protocol), unless you do your own handler. ASP uses postback, and therefore, is page-bound (i.e., view-bound; i.e., “V” is inherently inseparable with “C”!). If you use code-behind (by the way, 2.0 has somewhat recovered code-inside!), then, the “code-behind” is something page-bound-controller -- but since it is page-bound, i.e., view-bound, so, it is by definition not a “controller” – I know, my previous sentences look like non-sense – that is exactly my point: as an ASP developer, thanks to M$, we are doomed that we cannot use MVC; as a result of that, in the context that we cannot really use it, and if we do not realize that we cannot use it, then, it creates a lot confusion.

5. The last reason that MVC is confusing is that the general idea of MVC can be, well, “generalized”. For example, “model” is like “entity” objects; “controller” is like a “façade” objects. Also, the way we treat “View” means that we should isolate technology from business logic. However, this is only our, well, “generalization”. MVC itself does not mean those things.