Wyatt Baldwin

I’m Working on a Python 3 (only) Web Framework

I’ve been working on a Python 3 (3.3+) only Web Framework for the past few weeks. My initial motivation was to try to build something “RESTful” that doesn’t use the concepts (or terms) “view” or “controller” at all.

That’s because I don’t even know what a “view” is (or is supposed to be be). I’ve tried to think of views as “representations” (i.e., in the sense of representing some data as a particular content type like HTML or JSON), but in the real world view functions are often used to implement business logic, and the term “view” seems misleading (“action” seems more appropriate in this case). The term view is also used by some frameworks to refer to templates (e.g., Rails), and this usage actually makes a bit more sense to me.

If you’re just throwing some code together, maybe this type of thing doesn’t matter too much, but when things get complex (as they tend to) and you’re looking for ways to keep things simple (in terms of concepts, code organization, etc), I think it can make a big difference. Your core abstractions inform (and possibly limit) your thinking; they can also limit, to an extent, what’s possible or at least easily doable.

A different way to say this is that “views” and “controllers” don’t really fit my brain, so I’m experimenting with something different. I actually tried to implement something like this on top of Pyramid at one point (pyramid_restler), but I got hung up trying to build on top of views (although it’s still useful, IMO).

So, I set out to create a new framework that uses resources and representations as its main abstractions. Resources are things that are mounted at a particular path, respond to HTTP methods, and return data that gets represented according to the requested content type (i.e., as specified by the Accept header (note to self: should look at Accept-* headers as well)).

I’ve also put some effort into making the framework “correct” in terms of HTTP status codes and other RESTful concepts. But I’m finding that it’s not so easy to create a general purpose framework that handles every scenario right out of the box. For example, it’s okay (according to the RFC) to return various status codes for a POST or a PUT depending on the circumstances, so you can’t just say, “Oh, it’s a POST, so we’ll automatically return a 201 Created.”

I’m not sure how to completely generalize HATEOAS either. For certain scenarios you can say things like, “This container resource has these items, so generate a set of links to the items and include that in the representation.” But I’m not sure how you could cover every link scenario in a generic manner. If certain constraints are enforced, maybe… (maybe I just haven’t thought hard enough about this…)

That said, I think it’s possible to create a framework that at least nudges people in the “right” direction (or at least a particular direction).

So that’s the gist of it. As it matures, I plan to post more about it (including links to the source, which will be MIT licensed). For now, I’m mostly avoiding the term RESTful and just calling it resource-oriented.

Python 3

This is the first project that I’ve really used Python 3 for, and it’s been fun playing with all the shiny new stuff (hello, built in namespace packages). I was planning to say more about the choice of Python 3 (3.3+ in particular) in this post, but I think it’s gotten a bit long already. I’ll be writing another post about that soon, including the issues I’ve run into (or lack thereof).