Monday, April 1, 2013


After saying I'd do it for quite a while, I finally made some progress in my promise to write some E-related RSS stuff for Boris Faure, aka 'billiob': eRSSd is in git now, and it's moderately tested and (should be) fully functional.

Originally, Boris was working on a standalone app called ERSS on github. I chipped in a tiny bit to improve his Azy usage, since it's the easiest way to get and parse RSS feeds, but then, as E developers tend to do, I drifted away from the project and absolutely did not forget about it.
Over the time that I wasn't working on it, I wrote a ton of other projects and contributed to even more. Along the way, I realized that what would be great for RSS was if we had an underlying daemon which could then be accessed by all the apps and widgets, and which could run in a distributed fashion by synchronizing with other daemons over a network.

The hardest part of any project, aside from naming it, is starting the work. Aside from working out a number of kinks in Azy related to HTTP/1.1 chunked encoding, the whole thing was written in a weekend. During this process, I spent some time learning the ins and outs of the new dbus integration library, edbus2. It's certainly an improvement over the original, which was basically just libdbus, but it still feels pretty rough around the edges; iterators in particular are not great to work with.

Anyway, the basics of eRSSd:

Adding feeds
* Add a feed from cmdline of daemon or over dbus (or remote api once I iron it out)
* Feed is fetched and cached using eet
* Feed and items become available for use over dbus (and remote API)

Using feeds
* Feed is fetched on interval based on various http/rss attributes which indicate optimal cache length
* dbus signals sent to indicate freshness and new items
* Clients use eet to directly read cache file using local client API wrapper to avoid sending tons of data over socket
* Clients send signals back to daemon to mark items/feeds as read

Deleting feeds
* Client calls dbus delete method on daemon with URL for feed
* Daemon deletes feed, removes cache
* Signals sent over dbus (and remote) to indicate deletion of feed so UIs can be updated

A utility library for clients is provided, allowing developers to avoid having to write any eet/edbus2 code themselves and focus entirely on presentation/usage. At present, only a dummy configuration UI exists, but plans are in motion to create some cool stuff in the near future. RSS is a useful and common enough tool that we should spend some effort integrating it more!


  1. PS. despite the post date, this is not a joke.

  2. As a student, I learn many basic things about eRSSd from this post. I need to understand these basics of eRSSd and finally i got it from here. event app android