CouchDB in desktop applications

Following my last post I was considering writing a Venus filter which adds all feed items into a CouchDB database. This could then be queried by a modified wxVenus or a  webapp (using the CouchDB jQuery library) or whatever.

Thinking specifically about wxVenus, which is a desktop appliaction, CouchDB is like MySQL in that you must have the server up and running before your application tries to use it, and (afaik) there is no way to embed the server itself into your application, which places quite a bit of burden on the user.

My initial plans were to use SQLite which I can embed and use happily without another daemon running beforehand, but would mean I have to set up a schema and do all that tedious INSERTing, SELECTing and so on (I appreciate I could go all ORM on its ass, but again the development effort is much much higher than that with CouchDB).

So, what to do? I suspect that for the moment I’ll go about getting CouchDB all nice and integrated, but it doesn’t look like it’d leave me with an application people can download, install the dependencies, and just run, does it?


venus-ng is a fork of Venus which uses Newsgator to provide both the reading list and the feeds.

This means that venus-ng will, at a particular point in time, give you an accurate representation of your currently unread Newsgator feed entries. Here is the output from the web aggregator and venus-ng:

Screenshot of unread feeds Screenshot of venus-ng unread feeds

venus-ng does not mark feeds as read on the Newsgator server when in retrieves them, although that will likely get added when I have a test Newsgator account set up.

It is currently a fork because I’ve had to modify in a few ways which probably stop it working with other data sources:

  1. I’ve changed the way it deals with passed-in urllib2 handlers
  2. I’ve commented out the HTTP 401 response behaviour (since I’m passing it an HTTPBasicAuthHandler already)
  3. It always passes through an additional X-NGAPIToken HTTP header containing a Newsgator API key

As far as I can tell, the handler refactoring should be fine, but the 401-handling and extra HTTP header seem like a deal-breakers.

I have no idea how to stop the 401 handler in _FeedURLHandler() conflicting with that in urllib2.HTTPBasicAuthHandler.

I suspect there is a good solution in subclassing urllib2.HTTPBasicAuthHandler to provide the additional Newsgator HTTP header but I’ve not worked out some of the details yet.

You can get the latest source via bzr get – there is a sample newsgator.ini file in the /examples directory, but it relies on you already having a Newsgator account and some feeds set up.

Once I’d traced through the Venus code to semi-understand it, this was quite straightforward to do (deal-breaking fork-causers aside) so were Google Reader to introduce an official API it would not take long to integrate.