REST

For a while now I've been flying the flag for using a post-redirect-get design pattern when writing web applications. In my opinion the current crop of web frameworks still make it very easy to do the "bad" thing since to do PRG properly you need to think what kind of an interaction you want with users and not cop out saying its technically very difficult in . If you resort to ActiveX controls, popups without navigation bars and/or weird javascript hacks to stop users from clicking refresh or back buttons then perhaps you should have written a better web application....

The Jersey JAX-RS project provides bindings for springframework and google-guice. However I wanted to see what it would take to use PicoContainer as an IoC container within Jersey. Verdict: not much at all. Nicely extensible. To see what I mean please take a look at my jersey-pico project on GitHub. I can now create JAX-RS services in Java or Groovy with a very simple IoC container....

Last year I blogged about a neat trick in Django to have multiple views per HTTP verb. Since then I’ve been playing with RESTful applications and decided to see if there was a nicer way to expose “resources” in Django. The following is what I’ve come up with so far. Listing: router.py from django.http import Http404, HttpResponseNotAllowed def get_handler_method(request_handler, http_method): try: handler_method = getattr(request_handler, http_method.lower()) if callable(handler_method): return handler_method except AttributeError: pass class Resource: http_methods = ['GET', 'POST', 'HEAD', 'PUT', 'DELETE', 'OPTIONS', 'TRACE'] @classmethod def dispatch(cls, request, *args, **kwargs): request_handler = cls() if request....

The following is just a reminder to stop me from getting confused ;-) GET Used to fetch a resource. The server sends back a representation of the resource in the response body. Safe operation (see below). DELETE Used to delete a resource. The response from a server may contain a status message or nothing at all. It is usually nice to send back at least a 204 (No Content). Idempotent operation (see below)....

I've uploaded to GitHub (http://github.com/tomcz/pico-webapp/tree/master) the web application that I use to teach people about dependency injection (using PicoContainer), post-redirect-get browser interaction, RESTful URIs and strict template rendering (using StringTemplate). This application does not use Spring Framework by deliberate design - as soon as I introduce it to any teaching session I spend more time talking about Spring then talking about what I am usually there to accomplish. As usual, any comments, bugs or enhancement requests are very welcome....