A Happy Medium? From WSGI to CherryPy

There have a been a couple of posts recently, the first an excellent one by Eric Florenzano about creating a pure wsgi application as a high throughput way of persisting the number of plays various songs have had. The second was by Christian (Doswki?) a comparitive version using CherrPy indicating how more readable a framework level solution was (albeit over 100% slower).

I was interested how our rest oriented toolkit would look and also how it would perform doing the same thing. My first step was to use paster to create a template project

paster create --template=restish

I named the project ‘songs’ and then edited the songs/resource/root.py as follows

from restish import http, resource

from collections import defaultdict

global counts
counts = defaultdict(int)

class Root(resource.Resource):

    @resource.GET(accept='text')
    def text(self, request):
        res = ','.join(['%s=%s' % (k, v) for k, v in counts.iteritems()])
        return http.ok([], res)

    @resource.DELETE(accept='text')
    def delete(self, request):
        return http.ok([], 'OK')

    @resource.child('song/{id}')
    def song(self, request, segments, id):
        return Song(id)

class Song(resource.Resource):

    def __init__(self, id):
        self.id = id

    @resource.GET(accept='text')
    def text(self, request):
        return http.ok([], str(counts[id]))

    @resource.POST(accept='text')
    def post(self, request):
        counts[id] += 1
        return http.ok([], str(counts[id]))

Restish tries not to perform much ‘magic’ and so you can construct your resources any way you like, in this case I’ve added decorators to mark up the methods that will process the http methods. I’ve made them all text/plain (using ‘text’ for shot).

The Root method is registered at the top of the application and I have a single child decorated method that passes control over to the Song resource.

The source code isn’t as readable as the CherryPy version nor is at as fast as the WSGI only version (On my Thinkpad T61 I got 750 req/sec for restish, 520 req/sec for CherryPy and 1100 req/sec for WSGI) . I’d like to think that it provides a well balanced middle ground, close to ‘meta’ but still readable and with a lot of restish (sic) flexibility.

I ran the test with spawning using the following

spawn --factory=spawning.paste_factory.config_factory development.ini -t 0

As a response to the original post, I really like the use of HTTP as a coupling protocol. I should add as an aside that I had to switch off a lot of instinctive reflexes in order to write that global line. (Sorry about the blog post title)