HTTP resource watcher
I’ve got most of the features of my HTTP resource watching code I was working on for GWeather done. The main benefits over the existing gnome-vfs based code are:
- Simpler API. Just connect to the updated signal on the resource object, and you get notified when the resource changes.
- Supports gzip and deflate content encodings, to reduce bandwidth usage.
- Keeps track of Last-Modified date and Etag value for the resource so that it can do conditional GETs of the resource for simple client side caching.
- Supports the Expires header. If the update interval is set at 30 minutes but the web server says that the it won’t be updated for an hour, then use the longer timeout til the next check.
- If a permanent redirect is received, then the new URI is used for future checks.
- If a 410 Gone response is received, then future checks are not queued (they can be restarted with a refresh() call).
I’ve also got some code to watch the HTTP proxy settings in GConf, but that seems to trigger a hang in libsoup (bug 309867).
While I wrote the code for use in GWeather, it could be quite useful for other tasks that require watching an HTTP resource such as:
- HTTP calendar backend of evolution-data-server.
- A stock ticker applet like gtik.
- Possibly an RSS reader.
The code is available in my Bazaar archive:
baz get http://www.gnome.org/~jamesh/arch/james@jamesh.id.au/http-resource--devel--0