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Byron Ellacott
bje at apnic.net
Mon Jan 10 18:12:32 EST 2005
pit.grinja at gmx.de wrote: > Many thanks for your hints. In fact, the problem had nothing to do with an > incorrect path, and the content type 'text/html' is in principle ok. The > problem seems to be the combination of the content type AND the xml > declaration. It turned out that the directly opening the file in mozilla did > not give the expected results (<b>sometext</b>,<i>someother</i>,<br />... > parts were ignored if not defined in the css). After lots of > experimentation, I found that all what is needed is the following tag as a > child of the head-tag: > <meta content="application/xhtml+xml"/>. There are a couple of caveats to beware of here. First, as you have probably surmised, <?xml-stylesheet ...?> is only valid in an XML document, which text/html is not. Even if you send an XHTML document, complete with a <?xml ...?> opener, browsers will /not/ treat it as an XHTML document. This is trivial to demonstrate with the following page: --------------------- <?xml version="1.0"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>Test page</title> </head> <body> <p> <script type="text/javascript"> document.write('Hello, World!'); </script> </p> </body> </html> -------------------- If you serve this file up as text/html, you will get a blank page with 'Hello, World!' on it. If you serve this file up as application/xhtml+xml, you will get a blank page. This is because an XHTML document is parsed differently; a DOM tree is built before anything is interpreted, to ensure the document is valid, and so the document.write does not happen until after the parse, when it's too late to add anything new to the parse. Also, Internet Explorer will ask if you wish to save the file to disk, since it does not recognise XHTML. Since you have direct control over the MIME type you're sending, I would recommend that you send the correct MIME type directly, rather than relying on a <meta ...> element. Also note that in the example you gave, your DOCTYPE was not entirely correct -- the system should not be a relative URL, it should be the absolute URL pointing to the w3c's dtd for XHTML. I use XHTML Strict when I produce XHTML. > Now I have a file that is well-formed, valid and correctly rendered in the > browser with respect to the standard html tags. Beware well-formedness and validity with XHTML. If you do not send the correct content-type to the w3c's validator, your page will not be validated as XHTML! Also beware the subtle differences in how CSS applies to XHTML documents compared to HTML. Most notably, XHTML elements are case sensitive, so your CSS selectors must be all lower case. Also, CSS attributes you would normally apply to a body element must instead be applied to an html element. Finally, it bears repeating: Internet Explorer, all versions, does not recognise XHTML. As far as I know, it never will. If you need to support IE, you are far better off producing HTML4.01 Strict than XHTML1 Transitional, since HTML4.01 Strict is understood by all browsers with its correct MIME type. See http://www.hixie.ch/advocacy/xhtml for an explanation of XHTML and HTML differences, and why XHTML should never be sent as "text/html". -- bje
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