Here is a small snippet of code that I use on applications deployed on Google AppEngine to inform users that the application is in maintenance mode. It usually happen when the AppEngine team put the datastore in read-only mode for maintenance purpose but other capabilities can be tested as well.
def requires_datastore_write(view): def newview(request, *args, **kwargs): from google.appengine.api import capabilities datastore_write_enabled = capabilities.CapabilitySet('datastore_v3', capabilities=['write']).is_enabled() if datastore_write_enabled: return view(request, *args, **kwargs) else: from django.shortcuts import render_to_response from django.template import RequestContext return render_to_response('maintenance.html', context_instance=RequestContext(request)) return newview
This is a python decorator and you can use it to decorate views that require write access to the datastore. For example:
@requires_datastore_write def update(request): ...
You will need to create a Django template named maintenance.html to display a warning to your users. Mine looks like this:
<h2>Application Maintenance</h2> <p>The LibraryThing for Facebook application is currently in maintenance mode and some operations are temporarily unavailable.</p> <p>Thanks for trying back later. Sorry for the inconvenience.</p>



Facebook Pages Notifications
This is a problem for most page administrators and there is a 32 pages long (and growing) thread with people complaining about this missing feature. This is a problem because without such a feature you have to periodically crawl your own pages to check if anyone posted anything (status or comment) and get the opportunity to eventually respond to it, or spam it. I guess that since they won’t get notified about this thread the Facebook people will never notice the problem…
One proposed solution to this issue is to “like” each and every status update you post on your pages wall, however, beside the fact that liking everything you post may look a bit awkward, this does not gets you notified when someone posts a new status.
I have some pages I need to watch, so missing this feature was really a problem to me. And when it itches, I scratch… Besides, I wanted to experiment with the new Facebook Graph API.
So I created this application, it’s called “Watch My Pages!” and provides users with receiving daily e-mail notifications when someone posts a status or writes a comment to their pages wall. If you like it, have a problem with it or think about a feature, just drop a message on it’s wall, I’ll get notified ;)