I know this is a very common issue.
I keep finding way too many software that claim to interact with Web 2.0 sites or services, and connect here or there…. still forgetting one basic simple rule, that is: letting people use a proxy.
Most programmers for some reasons just assume that since they are directly connected to the internet, everybody is. Which isn't always the case. Most companies have proxies and will only let you out to port 80 – by using their proxy.
…which in turn is one of the reasons why most applications now "talk" and tunnel whatever application protocol on top of HTTP… still a lot of softwares simply "forget" or don't care proving a simple checkbox "use proxy", which will translate in two or three extra lines of code… three lines which I personally usually include in my projects, when I am not even a *developer*!! (but that might explain why I *think* of it… I come from a security and networking background )
I thought of writing this post after having read this post by Saqib Ullah.
Anyway. I keep finding this thing over and over again. Both in simple, hobbyist, sample and/or in complex, big, expensive enterprise software. Last time I got pissed off about a piece of code missing this feature was some days ago when testing http://www.codeplex.com/FacebookToolkit. The previous time was during Windows Vista beta-testing (I had found a similar issue in beta2, and had it fixed for RC1.)
Actually, I am being polite saying it is "missing a feature". To be honest I think missing this "feature" would have to be considered a bug: every piece of software using HTTP *should* include the possibility to pass thorugh proxy (also, don't forget about AUTHENTICATED proxies), or the purpose of using HTTP in the first place is defeated!!
Developers!!! You have to remember people ARE behind proxies !!!!!