I see a web page containing the following band
www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
Does this mean this page use XHTML? Is there any difference between
HTML and XHTML?
Thanks
Scripsit gouqizi.lvcha@gmail.com:
> I see a web page containing the following band
>
>
> "http:// www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
>
>
> Does this mean this page use XHTML?
Assuming that there is no whitespace after http:// in the real markup (there
was a line break in your message and my newsreader did some reformatting),
it only means that the start of the document _claims_ that the document uses
XHTML 1.0 Transitional syntax. Quite often, that's pure technobabble and the
actual markup is a horrendous mess of classic HTML, XHTML, proprietary
extensions, and just errors.
> Is there any difference between
> HTML and XHTML?
Is that a tr...ick question? Try reading the group for a few days before
asking questions that have frequently been discussed ad nauseam. The short
answer is that since you had to ask, forget XHTML for the time being and use
HTML 4.01.
--
Jukka K. Korpela ("Yucca")
http://www.cs.tut.fi/~jkorpela/
On Apr 30, 2:04 pm, gouqizi.lv...@gmail.com wrote:
> I see a web page containing the following band
>
>
>
>
> Does this mean this page use XHTML? Is there any difference between
> HTML and XHTML?
Even if the code is completely valid html at the W3C validator, the
page on the web that someone views is not xhtml unless it is served as
application/xhtml+xml or application/xml, or very rarely another xhtml
mime type. On most servers, if you use the extension .html, the page
is served as the usual text/html mime type. If you then use .html for
a page written in xhtml code and use the .html extension, the page is
just served as ordinary html, and the xhtml code serves no useful
purpose over html 4.01 strict. If you want to serve the page as true
xhtml, on the server you must associate some extension other
than .html with a mime type for xhtml, since .html is already reserved
for ordinary html. For example you could associate .xhtml with the
mime type application/xhtml+xml. The W3C validator, in the extended
mode, will tell you if the page is being served as text/xhtml,
application/xhtml+xml, etc. If served properly, browsers that can
handle true xhtml become extremely strict and parse the page as xml. A
little error on a page served as html often does little harm, and the
page often can be viewed with perhaps some distortion. However, on a
page parsed as xml, the least little error often results in an error
message, and the page can not be viewed at all. For example,
absolutely everything must be closed in xhtml, because xml demands it.
On many xml devices, not closing is one of the most serious errors you
can make. Thus if you write
instead of
, the whole page may
be killed and you get only an xml error message when you try to view
the page. Use of xhtml may give you a nasty surprise if you use
javascript. A document.write will not be accepted. The reason is
document.write could generate some code that contains some xml error,
In this case the solution is often to use server side script such as
php to generate the code that a document.write would do. Then the
generated code is downloaded to the browser so it can be properly
parsed as xml and checked for xml errors. I would guess that over 90%
of pages written in xhtml code are mis-served as text/html. If you
serve as true xhtml, no IE browser, including IE7, can handle it. Thus
you must provide an html path for IE, using one of several tricks, or
complete separate html pages for IE.
In article
<1178039158.188868.107020@q75g2000hsh.googlegroups.com>,
cwdjrxyz
> I would guess that over 90%
> of pages written in xhtml code are mis-served as text/html.
I am thinking it is even higher.
--
dorayme
cwdjrxyz wrote:
> Even if the code is completely valid html at the W3C validator, the
> page on the web that someone views is not xhtml unless it is served as
> application/xhtml+xml or application/xml, or very rarely another xhtml
> mime type.
XHTML *should* be served as application/xhtml+xml but *may* be served as
application/xml, text/xml or text/html.
An oft-quoted W3C note says that XHTML 1.1 *should not* (note: not "must
not") be served as text/html, but the current draft of the XHTML 1.1
Second Edition recommendation does explicitly allow for XHTML 1.1 to be
served as text/html.
Of course, served as text/html, browsers will generally treat XHTML as
if it were HTML with a few extra slashes in some places, and won't process
it according to XML rules. Of course, they *could* process it as XHTML,
but browser makers tend to decide not to, as it may result in cryptic error
messages, which aren't generally very useful for the browser user.
Whether or not browsers *treat* it as XML, doesn't effect its intrinsic
XML-ness.
--
Toby A Inkster BSc (Hons) ARCS
http://tobyinkster.co.uk/
Geek of ~ HTML/SQL/Perl/PHP/Python/Apache/Linux
On May 2, 3:54 am, Toby A Inkster
wrote:
> cwdjrxyz wrote:
> > Even if the code is completely valid html at the W3C validator, the
> > page on the web that someone views is not xhtml unless it is served as
> > application/xhtml+xml or application/xml, or very rarely another xhtml
> > mime type.
>
> XHTML *should* be served as application/xhtml+xml but *may* be served as
> application/xml, text/xml or text/html.
>
> An oft-quoted W3C note says that XHTML 1.1 *should not* (note: not "must
> not") be served as text/html, but the current draft of the XHTML 1.1
> Second Edition recommendation does explicitly allow for XHTML 1.1 to be
> served as text/html.
>
> Of course, served as text/html, browsers will generally treat XHTML as
> if it were HTML with a few extra slashes in some places, and won't process
> it according to XML rules. Of course, they *could* process it as XHTML,
> but browser makers tend to decide not to, as it may result in cryptic error
> messages, which aren't generally very useful for the browser user.
>
> Whether or not browsers *treat* it as XML, doesn't effect its intrinsic
> XML-ness.
What many forget is that the html/xhtml code is just part of what gets
downloaded to the browser, and that other important information is
exchanged in the initial exchange between the server and browser. The
W3C rules allow xhtml 1.1 to be downloaded under mime type text/html
although it is discouraged, and for very good reason. An xhtml page
can be all html, all xml, or any combination thereof. If the xhtml
page contains some xml content, the xml likely will not work properly
if it is treated as text/html. Since many web pages do not contain xml
content, people who translate html pages to xhtml pages may seldom run
into this problem. I do not know why the W3C did not completely ban
serving an xhtml page as text/html, as this will not work in some
cases when the page contains some xml content. The reason could be
that the widely used IE browsers including the IE7 can not handle true
xhtml served properly, and they are attempting to get people used to
writing xhtml code in hopes that Microsoft will update their very
outdated browsers. Also Microsoft likely contributes more money to the
W3C than anyone - it is a pity that they do not build their browsers
to support what they are partly paying for. Hopefully, now that their
long-delayed Vista OS has been introduced, hopefully they will have
some time to devote to updating their browsers to modern standards.
There are of course many aspects of xml that most browsers do not
support, including many xml languages. A good example is the multi-
media language SMIL. In such cases, a special player is installed on
the computer to handle the xml language program. For example, the Real
player has nearly full W3C SMIL 2 support built into it. Thus SMIL
will work on just about any OS/browser combination that can handle a
Real player, and you can even view SMIL on the old Netscape 4 series
browsers, since you can install a recent Real player on them. I
believe the QT player has very limited support of SMIL. The IE6, and
likely the IE7 browsers do directly support a very limited mutant
version of SMIL, but it will work only on IE. I believe it makes use
of some Microsoftese filters etc, but I have absolutely no interest in
the details of it because it only works on IE.
cwdjrxyz wrote:
> An xhtml page can be all html, all xml, or any combination thereof.
An XHTML page is always all HTML *and* all XML by definition!
> If the xhtml page contains some xml content, the xml likely will not
> work properly if it is treated as text/html.
Assuming that you mean pages which extend XHTML by using elements from
other namespaces, yes you need to use an XML MIME type for these if you
expect them to work, but they're not valid XHTML anyway.
--
Toby A Inkster BSc (Hons) ARCS
http://tobyinkster.co.uk/
Geek of ~ HTML/SQL/Perl/PHP/Python/Apache/Linux
On May 2, 11:29 am, Toby A Inkster
wrote:
> cwdjrxyz wrote:
> > An xhtml page can be all html, all xml, or any combination thereof.
>
> An XHTML page is always all HTML *and* all XML by definition!
>
> > If the xhtml page contains some xml content, the xml likely will not
> > work properly if it is treated as text/html.>
> Assuming that you mean pages which extend XHTML by using elements from
> other namespaces, yes you need to use an XML MIME type for these if you
> expect them to work, but they're not valid XHTML anyway.
One can serve only a html page such as html 4.01 that does not include
xml code. One can serve only an xml page that does not include any
html content. Often a "reader" or "viewer" program is required for
many xml languages on current browsers. The intent of xhtml is to
allow both what we use on an html and xml page to be served on the
same page according to some defined rules. With the present state of
browsers, we still may need a "viewer" or "reader" program to render
the content based on xml in a usable form. Thus I would say that an
xhtml page can contain what we could serve as html 4.01, for example,
or it can contain what we could serve as xml for example, or both. Of
course when an html page is converted to xhtml, xml rules take over
and everything must be closed, etc. This is because xml is much more
fussy about exact fromat than html. The structure of xhtml is much
closer to xml than html.
As an example, how do you serve a SMIL page as on a xhtml page? One
way is to use a recent Real player to handle the SMIL xml language.
One can for example use a .rpm playlist/redirector Real file to direct
to the SMIL external xml file so that Real player kicks in and handles
the SMIL file. The page validates properly as xhtml if correctly
coded. At some point hopefully most browsers will support W3C SMIL 2
directly so that you do not have to use a viewer program. In that case
the SMIL xml would be handled directly by the xhtml page.
On May 2, 2:02 pm, cwdjrxyz
> On May 2, 11:29 am, Toby A Inkster
> wrote:
>
> > cwdjrxyz wrote:
> > > An xhtml page can be all html, all xml, or any combination thereof.
>
> > An XHTML page is always all HTML *and* all XML by definition!
>
> > > If the xhtml page contains some xml content, the xml likely will not
> > > work properly if it is treated as text/html.>
> > Assuming that you mean pages which extend XHTML by using elements from
> > other namespaces, yes you need to use an XML MIME type for these if you
> > expect them to work, but they're not valid XHTML anyway.
>
> One can serve only a html page such as html 4.01 that does not include
> xml code. One can serve only an xml page that does not include any
> html content. Often a "reader" or "viewer" program is required for
> many xml languages on current browsers. The intent of xhtml is to
> allow both what we use on an html and xml page to be served on the
> same page according to some defined rules. With the present state of
> browsers, we still may need a "viewer" or "reader" program to render
> the content based on xml in a usable form. Thus I would say that an
> xhtml page can contain what we could serve as html 4.01, for example,
> or it can contain what we could serve as xml for example, or both. Of
> course when an html page is converted to xhtml, xml rules take over
> and everything must be closed, etc. This is because xml is much more
> fussy about exact fromat than html. The structure of xhtml is much
> closer to xml than html.
>
> As an example, how do you serve a SMIL page as on a xhtml page? One
> way is to use a recent Real player to handle the SMIL xml language.
> One can for example use a .rpm playlist/redirector Real file to direct
> to the SMIL external xml file so that Real player kicks in and handles
> the SMIL file. The page validates properly as xhtml if correctly
> coded. At some point hopefully most browsers will support W3C SMIL 2
> directly so that you do not have to use a viewer program. In that case
> the SMIL xml would be handled directly by the xhtml page.
To elaborate, a SMIL file is a special type of xml file with an
extension .smil and a Doctype and w3c dod. To see a complete SMIL
file, validate http://www.cwdjr.net/ram/realmix.smil at the w3c. The
validator there will validate SMIL and several other types of files
that are of sufficient importance to have their own special
specifications and extensions rather than a general .xml or .xhtml
one. If you link to this SMIL xml file directly, you may or may not
get a display, depending on if you have a "viewer" such as the Real
player and how your viewers or players are configured. In some cases,
you may get the QT player which has only limited SMIL support and will
not work for this SMIL 2 page. However you can, on your xhtml page,
link to a .rpm playlist/redirector file. This is understood by the
Real player and automatically starts playing the SMIL page in the Real
player. The Real player is the only one of the more common free
players that viewers are likely to have that will play this SMIL page,
although there are some expensive SMIL viewers one can buy that
sometimes are used for media on internal networks.