I just committed my first draft of documentation for Manos’s middleware layer. Its a pretty quick and easy read and I’d appreciate any questions, comments, death threats or concerns that you may have. The doc is written in markdown so you can read is pretty easily on github here:

http://github.com/jacksonh/manos/blob/master/docs/middleware.md

Things still need to be fleshed out, especially with some examples of what methods can be called from inside the middleware hooks, but this gives you a basic idea.

The Gist

Middleware gives your application an easy way to “do something” for every request/response transaction that goes into an application.

You get these methods to register middleware:

RegisterMiddleware (IManosMiddleware mw);
RegisterMiddleware (string name, IManosMiddleware mw);

RegisterMiddlewareBefore (IManosMiddleware mw);
RegisterMiddlewareBefore (string name, IManosMiddleware mw);
RegisterMiddlewareAfter (IManosMiddleware mw);
RegisterMiddlewareAfter (string name, IManosMiddleware mw);

ReplaceMiddleware (string name, IManosMiddleware mw);

And your middleware can override any of these methods:

ProcessRequest (IManosContext)
PreProcessAction (IManosContext, IManosTarget)
PostProcessAction (IManosContext)
ProcessError (IManosContext)

From those methods you can easily re-write parts of the request, redirect to another URL, abort the transaction, manipulate the generated html or just log something to disk. Really the sky is the limit.

Most developers will never have to write their own middleware but a lot of really important plumbing pieces of a web framework can be written using middleware. Things such as the auth system, rate limiting, url rewriting, and red/black testing are important components of a web application and will make use of the middleware layer. So its important that I get this part right.