Taking a short break from the planned article list to rant about my new least favorite feature of BlackBerry OS.
If you have a BlackBerry that also happens to support WI-FI, you might be surprised to find out that your favorite networked application doesn't favor WI-FI over APN when you're in range.
In fact, these applications will never favor WI-FI over your regular data network link. This is because the BlackBerry operating system does not abstract this for the application programmer. In other words, unless the application programmer knows about this and explicitly codes support for WI-FI in his application, the application will never use WI-FI.
So how do you get WI-FI support in there? You have to append the magical string ";interface=wifi" to any URL that you want to open. So, assuming standard Java ME/CLDC network programming here, you would do something like:
String uri = "http://www.spectrumdt.com;interface=wifi";
HttpConnection c = (HttpConnection) Connector.open(uri);
Otherwise, your application will inform you that "Could not open tunnel - Max time out" or go over your regular data link.
And that's about it. Oh, and by the way, if you don't have WI-FI or you're out of range, the OS won't do you any favors and fall back to your regular data link, so you have to make sure to try out the regular data link in case of errors too.
Finally, I would like to say that this feature is mostly impossible to find in the BlackBerry documentation. I found it in a beta version of an upcoming manual. The only reason I noticed this is that my development BlackBerry doesn't have a sim card, the browser worked, but my application didn't. Also of interest, almost all non first party applications I tested couldn't use WI-FI either. I'm guessing quite a few people don't know about this.