How do you communicate with a website that requires HTTP basic authentication when building AIR with Flex 3 or Flash CS3? Take 饭否http://fanfou.com/home — the username contains an @ sign, and if you go straight to http://“+loginName+”:”+loginPass+”@api.fanfou.com/statuses/update.xml, you get an ioErr. I asked about this on Blueidea once and I’m still waiting for a reply. I searched online too, but most of what I found talks about how to configure server-side authentication, not how a client logs in… Someone asked about the login approach in C# and Java, but no answer there either. The only usable information was for VB and JS — with Ajax it’s easy, since the XML open method takes user and password parameters. Last year I scanned through the Flex code line by line and found that URLRequest has a setLoginCredentials method. Add the line urlR.setLoginCredentials(loginName,loginPass); and it will send the user credentials. Now that the new version of AIR has been released, that method is deprecated again. Since I never had the time to update the Fanfou AIR client I wrote last year, I didn’t pay much attention to it. Today I went to the official site and dug into it. The replacement: