I hate to be a curmudgeon about this, but this fellow needs a beat-down:
I offer this as exhibit A (as in AJAX) about why application security may well be intractable, in part because we’ve got mainstream technical outlets teaching techniques to evade well-founded security principles.
(quick cut to Andy spitting up his coffee in disbelief at what he thinks he’s about to read)
On Microsoft’s IE 5 and 6, such requests are possible provided your browser security settings are low enough (though most users will still see a security warning that they have to accept before the request will proceed). On Firefox, Netscape, Safari, and the latest versions of Opera, the requests are denied…
(sounds like good security engineering to me… what’s the problem?)
There is hope, or rather, there are gruesome hacks, that can bring the splendor of seamless cross-browser XMLHttpRequests to your developer palette. The three methods currently in vogue are:
(Danger, Will Robinson! Glad I didn’t refill the coffee cup…)
Application proxies. Write an application in your favorite programming language that sits on your server, responds to XMLHttpRequests from users, makes the web service call, and sends the data back to users.
Apache proxy. Adjust your Apache web server configuration so that XMLHttpRequests can be invisibly re-routed from your server to the target web service domain.
The basic idea of all three hacks is the same: fool your user’s web browser into thinking that the data is coming from the same domain as the web page.
(Excellent. A good summation of potential threat vectors. But I can’t believe we’re about to read a serious discussion, signed-off by a serious publisher, about how to evade security protections.)
A word of caution here: there is a good reason why XMLHttpRequests are restricted. Allowing them to freely access any domain from within a web page opens up users to potential security exploitation. Not surprisingly, these three hacks, which offload the request to your web server, potentially threaten to disparage your web server’s identity, if not its contents. Caution is advised before deploying them.
(The obligatory “Kids, don’t try this at home” message…. followed by the Snake River motorcycle jump.)