Yes, that's precisely the violation of
Postel's Law I was
Steve, someone is sending us this User-Agent, is that you?:))
User-Agent: Mozilla 5.0 (Compatible; with Safari, with Opera, Chrome, Netscape, MSIE etc.
You get the idea. It's compatible with everything!) Let me tell you a story. Once upon
a time, there was a browser named SeaMonkey. It was of noble inheritance, as it was a
direct descendant of the famous Netscape of old. Oh, it could have been so proud, this
browser, it could have stood up, radiant and tall and strong. But no, that was not to be.
Many websites closed their doors for this browser, saying, We don't know who you are,
go away! And poor SeaMonkey would have no other choice than to go in disguise, to make the
websites believe it was some other browser. And you who read this, you are one of those
websites that are putting SeaMonkey to shame. Listen. All browsers support HTML. If you
just send the same HTML, all browsers will accept it. Only in some borderline cases will
the page you send to the client need to be tailored to a specific client. In the majority
of cases, the standard HTML you send to, say, Opera, can be sent to every other browser as
well; K-Meleon, Galeon, etc. There is no need to scan the user agent string for keywords
like Firefox, Konqueror, Midori or whatever. Just send the standard HTML, OK? But even if
you do scan the user agent string, even if you do insist on sending different stuff to
different browsers, you should look for distinguishing signs of the rendering engines:
Gecko, Webkit, KHTML, Trident, Presto, and so on, not for different browser names.
SeaMonkey works the same way as Firefox, Netscape and Flock; they all have Gecko/yyyymmdd
in the user agent string. Similarly, Google Chrome works the same way as Safari, Midori
and SRWare Iron; they can be identified by the word AppleWebKit in the string. And so on.
Distinguishing browsers by name is not only overkill, but it even can backfire in cases
such as this, when a misrepresentation is made. Anyway, even more important than that,
above all, what you never ever should to is send fatal errors! The real error,
incidentally, is not in the content part of the page you send, but in the header: putting
info in the header that identifies the page as XHTML, while sending the content of the
page as HTML, which will trigger the fatal error message. Errors like that will make you
look silly, or worse, they make you look like you're doing it on purpose; sending bad
stuff to some browsers, while sending perfectly OK looking pages to others. You're not
REALLY doing it on purpose, are you? Trying to make people think that their browsers
aren't good enough, that for instance MS Internet Explorer is a better browser than
the ones they're using now, because MSIE can display the site while their own browsers
can't? No, let's just give you the benefit of the doubt; you're not doing it
on purpose. Blame your content management system if you want. Still, it's nothing I
can help from here; you will have to make the change to your site to make sure to not
saddle some browsers like SeaMonkey or Kazehakaze with your errors. So please, would you
consider having a look? Thanks in advance!