Question

I just checked my webspace and it’s signature says: Apache/2.2.9 (Debian) mod_python/3.3.1 Python/2.5.2 mod_ssl/2.2.9 OpenSSL/0.9.8g

This give me hope that Python is somehow supported. Why is python listed twice? mod_python/3.3.1 AND Python/2.5.2 ???

There is a cgi-bin folder on my webspace.

What I want to do: I need to do a cross-site call to get some text-data from a server. The text-data is not JSON but I guess I should convert it to JSON (or is there an option to do cross-site without JSON?)

The python script gets the request for some JSONP. Depending on the request (I guess I should somehow parse the URL) the python script is to load the a requested text-data file from the webserver and wrap it in some JSON and return it.

Can somebody tell me how I do these three steps with python on my webspace?

Answer 1

First off, the signature isn’t listing python twice. Its listing first the version of mod_python, which is an Apache web server plugin, then it is listing the version of the python interpreter on the system.

python cgi module – This is really an inefficient approach to writing python server code, but here it is. Ultimately you should consider one of the many amazing python web frameworks out there. But, using the cgi module, your response would always start with this:

print 'Content-Type: application/json\n\n'

Your python script would run on the server from an HTTP request. In that script you would check the request and determine the data you will want to serve from either the URL value or the query string.

At the very least you would just wrap your return value in a basic JSON data structure. The text data itself can just be a string:

import json
text_data = "FOO"
json_data = json.dumps({'text': text_data})
print json_data
# {"text": "FOO"}

For the JSONP aspect, you would usually check the query string to see if the request contains a specific name for the callback function the client wants, or just default to ‘callback’

print "callback(%s);" % json_data
# callback({"text": "FOO"});

Returning that would be a JSONP type response, because when the client receives it, the callback is executed for the client.

And to conclude, let me add that you should be aware that python cgi scripts will need to start a brand new python interpreter process for every single request (even repeat requests from the same client). This can easily overwhelm a server under increased load. For this reason, people usually go with the wsgi route (mod_wsgi in apache). wsgi allows a persistant application to keep running, and handles ongoing requests.