I’ve come to the belief lately that the web frameworks available in Python are increasingly fine-tuned to specific application requirements. Of course, anyone reading the ‘About’ sections for these frameworks should realize this as well. I wonder how many people actually read that section as I’ve seen people latch onto web frameworks without knowing the task it was originally made for.
Without knowing the reason the framework was created, its common for many people to leap to the conclusion that its another Rails wanna-be just because its a ‘full-stack’ web framework. I was playing around with a nice full-stack framework called WebObjects years ago which made it easy to setup database objects, generate CRUD, etc. Zope’s been doing the same stuff for what now seems like eons as well, yet I don’t see people declaring RoR a Zope clone (It obviously isn’t).
In light of that, I’m inclined to agree with Ian Bicking’s response about the lessons Python web people did learn from RoR.
The concept I want to focus on is that people create these new frameworks because they make their task easier than any of the other frameworks already out there. While they might pick up features from other frameworks, most of them aren’t aspiring to be “Python on Rails”. Sometimes this task is easier when other tools can be integrated to avoid code replication, as is the case in one framework I cover here.
Many people have declared the amount of Python web frameworks a “problem” that should be “solved” somehow, perhaps a Highlander fight with swords to the death (_There can be only one!_). I’d like to suggest the opposite, there’s a lot of Python programmers and I think there’s room for even more web frameworks. The variety is a strength because they make it easier to get specific web applications done.
The TurboGears site has a nice about page describing its purpose, though I feel it doesn’t completely explain the rationale for its creation. There’s some interesting and unique decisions made in TurboGears, like using Kid instead of Cheetah or Myghty for templating. Then there’s the inclusion of Mochikit and the TurboGears decorators for returning output as JSON for use with Mochikit.
So what kind of applications is this web framework geared for? (Please excuse the pun)
The best way to answer this is to look at the application this framework was created for, Zesty News, and the abilities of some of the tools being used. Zesty News is in a rather interesting category of web applications in that the end-users themselves will be installing it, quite likely on their home computer rather than a server. Being able to package it up and easily distribute/upgrade it becomes a key issue along with database portability and code thats database agnostic.
Two tools assist here, setuptools for distribution/packaging and SQLObject for portable database code. Zesty News deals extensively with RSS and XML, so it makes sense that the templating language chosen was actually created for dealing with web services.
These design decisions behind TurboGears should make it fairly obvious when to consider it for your next project. The cohesive toolset you get when you choose TurboGears is ideal for developing portable, easily deployable AJAX-enabled web applications that likely deal with XML frequently and need to stay database agnostic. Even if your web application doesn’t deal with XML frequently, the decisions TurboGears makes for AJAX integration will make it easy to add heavy dynamic interaction to a TG webapp.
Django was created to deal with the requirements of working in the web development department of a news publisher. As such, the framework was created specifically to deal with the requirements placed upon the author. What’s rather interesting is the lack of re-use in Django when it comes to doing things that have been done before in other projects (Database mapper, form validation, etc).
The tools and parts of Django were specifically built to work as one package, and using Django makes that very obvious. One of the things most common when in a newsroom or publishing environment is dealing with CRUD. That is, there is a lot of content and ways to get content into the system and administrate the content is a high priority. As a web framework built for dealing with Content, many of the design decisions reflect the common tasks present in CMS’s (Content Management System).
To start with, you get a slick administration interface for your conntent, that’s miles beyond any of the generated CRUD type stuff in other web frameworks. This differs from the philosophy of other web frameworks that give you basic CRUD (Scaffolding in Rails-speak) in that Django’s admin interface is aimed directly at being production-ready with no modification at all.
Django also makes it fairly easy to make a Django ‘application’ like a Forum or Blog, then slot it into other Django application environments. Again, this makes a lot of sense given the original requirements placed on the creator of Django. If a company has 4 websites, and wants them all to have the new Forum/Classified ability it makes a lot of sense for this task to be optimized.
So what web applications are you going to want to use Django for?
Quite a few, as it turns out dealing with Content is a very common task. If you’re writing a web application heavy on content, that needs a full featured web interface for managing the content it’d be really hard not to recommend Django. It’s easy to get started, and in almost no time you have very powerful functionality running that gives you a lot of usability.
Don’t be Everything for Everyone
Part of the reason I picked these two projects to talk about is that they’re both extracted from a working project (as Rails was). I also haven’t seen many people mention the fact that frameworks developed in such a manner are also inherently going to be optimized for the use-cases that brought them into existence.
Open-sourcing the project lets them grow to an extent, but their design is largely baked in and a useful limitation. Too much expansion past the initial design requirement will make them generic, and with that comes a lot of complexity (sometimes worth it though for the extra re-usability).
Note that the specific things Django gives you don’t help that much if you’re trying to write a Zesty News style application. The same goes in reverse as well, since building an Admin interface of your own isn’t fun and can be time consuming. While it’s possible to make web applications that do this in either framework, compensating for framework design will require extra time when you try to use one framework for everything.
If you’re using one framework for everything, maybe its time to take a look around.