How to send a Facebook App Notification via the Graph API?

Question

I'd like my Facebook canvas app to send an App Notification to a user's friend when they interact with the app. Here is my server-side code (using App Engine and urllib). conf.FACEBOOK_APP_ACCESS_TOKEN is an App Access Token which I got by making a single call to the Graph API and then hardcoding the returned value, as explained in the link. The app access token looks something like:

426547656256546|4fhe34FJdeV3WvfF6SNfehs7GfW

This isn't my actual token: I've substituted numbers for other numbers, capital letters for other capital letters, etc, so you can see the format.

url = 'https://graph.facebook.com/'+friendID+'/notifications'
values = {'access_token' : conf.FACEBOOK_APP_ACCESS_TOKEN,
          'href' : 'http://localhost:8080/', 
          'template' : '@['+userID+'] says hi.'}
data = urllib.urlencode(values)
req = urllib2.Request(url, data)
urllib2.urlopen(req)

urlopen gives the errors:

WARNING  Stripped prohibited headers from URLFetch request: ['Content-Length', 'Host']
ERROR    HTTP Error 403: Forbidden

What do I need to correct in this code to successfully send an app notification?

Answer 1

App notifications can only be send from Canvas apps. My app was set to Website with Facebook Login in the Facebook settings, which doesn't allow notifications. To solve the problem, I just checked App on Facebook in addition to Website with Facebook Login (though I believe it works with only App on Facebook as well) and specified a canvas URL.