A new and improved IResource

[lvh]

There are a number of problems with IResource. A (possibly non-exhaustive) list:

1. #3711 (returning deferreds from render methods)
2. #3621 (returning deferreds from getChild and friends)
3. #288 (accessing uploaded data while in progress)

None of these problems can be fixed without breaking IResource, which is something we don't want to do. As a result, we need a new IResource interface.

The goal of this ticket is to produce that interface, and to introduce fixes for each individual ticket into an integration branch related to this interface. That way, once all the tickets have been addressed, we can just merge this into trunk.

[lvh]

exarkun has noted that we should probably have something like Nevow's locateChild rather than IResource's getChild.

[Itamar Turner-Trauring]

If we have a new resource implementation with locateChild, ala Nevow or web2, we can require that locateChild implementations not depend on the body of request. That means we can add support for streaming uploads (#288) in a separate branch, thus allowing more incremental development.

[Itamar Turner-Trauring]

Although I guess you wouldn't want to have it using the old API for looking at bodies, so maybe it does need to be one fell swoop.

[Itamar Turner-Trauring]

Here is a proposed series of steps, each of which can be reviewed separately:

1. New resource model with locateChild, and render ala web2. In particular, return a Response object from render that has response code, headers, and body producer. Actual design details may differ. The new resource would be default for twisted.web, and old resources would have backwards compatibility layer.

2. Add support for streaming request bodies, e.g. for POST.

3. Method dispatching in render (to render_GET, render_HEAD, etc.).

4. Add support for POSTed forms, including file uploads.

5. Update documentation.

[Itamar Turner-Trauring]

I need to write up this plan in much more detail on a wiki page.

[Itamar Turner-Trauring]

Beginning of plan: ​http://twistedmatrix.com/trac/wiki/WebResourceImprovements