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Python is the top choice for any first-time programmer. Since its release in 1991, Python has evolved and powered by several frameworks for web application development, scientific and mathematical computing, and graphical user interfaces to the latest REST API frameworks.
REST API Must Accept and Respond with JSON It is a common practice that APIs should accept JSON requests as the payload and also send responses back. JSON is a open and standardized format for data transfer. It is derived from JavaScript in a way to encode and decode JSON via the Fetch API or another HTTP client.
Something to be careful about when designing a RESTful API is the conflation of GET and POST, as if they were the same thing. It's easy to make this mistake with Django's function-based views and CherryPy's default dispatcher, although both frameworks now provide a way around this problem (class-based views and MethodDispatcher, respectively).
HTTP-verbs are very important in REST, and unless you're very careful about this, you'll end up falling into a REST anti-pattern.
Some frameworks that get it right are web.py, Flask and Bottle. When combined with the mimerender library (full disclosure: I wrote it), they allow you to write nice RESTful webservices:
import web
import json
from mimerender import mimerender
render_xml = lambda message: '<message>%s</message>'%message
render_json = lambda **args: json.dumps(args)
render_html = lambda message: '<html><body>%s</body></html>'%message
render_txt = lambda message: message
urls = (
'/(.*)', 'greet'
)
app = web.application(urls, globals())
class greet:
@mimerender(
default = 'html',
html = render_html,
xml = render_xml,
json = render_json,
txt = render_txt
)
def GET(self, name):
if not name:
name = 'world'
return {'message': 'Hello, ' + name + '!'}
if __name__ == "__main__":
app.run()
The service's logic is implemented only once, and the correct representation selection (Accept header) + dispatch to the proper render function (or template) is done in a tidy, transparent way.
$ curl localhost:8080/x
<html><body>Hello, x!</body></html>
$ curl -H "Accept: application/html" localhost:8080/x
<html><body>Hello, x!</body></html>
$ curl -H "Accept: application/xml" localhost:8080/x
<message>Hello, x!</message>
$ curl -H "Accept: application/json" localhost:8080/x
{'message':'Hello, x!'}
$ curl -H "Accept: text/plain" localhost:8080/x
Hello, x!
Update (April 2012): added information about Django's class-based views, CherryPy's MethodDispatcher and Flask and Bottle frameworks. Neither existed back when the question was asked.
Surprised no one mentioned flask.
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
return "Hello World!"
if __name__ == "__main__":
app.run()
We're using Django for RESTful web services.
Note that -- out of the box -- Django did not have fine-grained enough authentication for our needs. We used the Django-REST interface, which helped a lot. [We've since rolled our own because we'd made so many extensions that it had become a maintenance nightmare.]
We have two kinds of URL's: "html" URL's which implement the human-oriented HTML pages, and "json" URL's which implement the web-services oriented processing. Our view functions often look like this.
def someUsefulThing( request, object_id ):
# do some processing
return { a dictionary with results }
def htmlView( request, object_id ):
d = someUsefulThing( request, object_id )
render_to_response( 'template.html', d, ... )
def jsonView( request, object_id ):
d = someUsefulThing( request, object_id )
data = serializers.serialize( 'json', d['object'], fields=EXPOSED_FIELDS )
response = HttpResponse( data, status=200, content_type='application/json' )
response['Location']= reverse( 'some.path.to.this.view', kwargs={...} )
return response
The point being that the useful functionality is factored out of the two presentations. The JSON presentation is usually just one object that was requested. The HTML presentation often includes all kinds of navigation aids and other contextual clues that help people be productive.
The jsonView functions are all very similar, which can be a bit annoying. But it's Python, so make them part of a callable class or write decorators if it helps.
See Python Web Frameworks wiki.
You probably do not need the full stack frameworks, but the remaining list is still quite long.
I really like CherryPy. Here's an example of a restful web service:
import cherrypy
from cherrypy import expose
class Converter:
@expose
def index(self):
return "Hello World!"
@expose
def fahr_to_celc(self, degrees):
temp = (float(degrees) - 32) * 5 / 9
return "%.01f" % temp
@expose
def celc_to_fahr(self, degrees):
temp = float(degrees) * 9 / 5 + 32
return "%.01f" % temp
cherrypy.quickstart(Converter())
This emphasizes what I really like about CherryPy; this is a completely working example that's very understandable even to someone who doesn't know the framework. If you run this code, then you can immediately see the results in your web browser; e.g. visiting http://localhost:8080/celc_to_fahr?degrees=50 will display 122.0 in your web browser.
Take a look at
I don't see any reason to use Django just to expose a REST api, there are lighter and more flexible solutions. Django carries a lot of other things to the table, that are not always needed. For sure not needed if you only want to expose some code as a REST service.
My personal experience, fwiw, is that once you have a one-size-fits-all framework, you'll start to use its ORM, its plugins, etc. just because it's easy, and in no time you end up having a dependency that is very hard to get rid of.
Choosing a web framework is a tough decision, and I would avoid picking a full stack solution just to expose a REST api.
Now, if you really need/want to use Django, then Piston is a nice REST framework for django apps.
That being said, CherryPy looks really nice too, but seems more RPC than REST.
Looking at the samples (I never used it), probably web.py is the best and cleanest if you only need REST.
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