didn’t seem to be any
objection to the assertion that HTML is the primary markup language for
visible Web, and that XML is not appropriate for the visible Web. This
very interesting, as some rather revealing assertions may be derived:
more a piece of knowledge becomes available, the more valuable it
becomes, because of the wider array of possible uses for it.”
is from: The Wisdom of Crowds
Surowiecki, p. 166-167.
on the hidden Web has limited availability.
on the visible Web has wide availability. (There are a billion
users. Potentially each of them could use information that is on the
information is most valuable when available on the visible Web.
services are part of the hidden Web, and thus obsessing over their
nature (e.g., SOAP
versus REST) is not valuable.
maximum impact, focus your main efforts on making information available
From: Costello, Roger
Sent: Sunday, July 16,
Subject: Why is there
of XML on the "visible Web"?
- VISIBLE WEB
By “visible Web” I
mean the portion of the Web that produces information intended for
consumption. In particular, in this message I will focus on the
of the Web that produces information to be consumed by humans via a
– HIDDEN WEB
The “hidden Web”,
on the other hand, is the portion of the Web that produces the
intended to be consumed by machines (i.e., machine-to-machine
XML ON THE VISIBLE WEB VERSUS NOT
USING XML ON THE VISIBLE WEB
two examples to demonstrate
what I mean by using XML on the visible Web versus not using XML on the
I realize that XHTML is XML, but for this discussion when I refer to “XML” I am not
referring to XHTML.
USING XML ON THE VISIBLE WEB
that you have a Web site where
you make available your grocery list to anyone with a browser. “Using XML on
the visible Web” means that you create an
that contains the raw grocery list, and a separate document (e.g., XSLT) which transforms
grocery list into a visually appealing form. Here is grocery.xml:
the URL to your grocery list
client that issues this URL
will receive grocery.xml, and then it will dynamically transform the
HTML using grocery.xsl
imagine that grocery.xsl
displays the grocery items as an unordered bulleted list, and so the
rendered by the browser like this:
site is employing XML on the
NOT USING XML ON THE
contrast the above
example with not using XML on the visible Web, instead, using HTML. A
browser client that issues the above URL will receive from your Web
browser immediately renders the
HTML. The same bulleted list shown above is displayed.
site is not employing
XML on the visible Web!
OF USING XML ON THE VISIBLE
tags <grocery-list>, <fruit>, <meat>, <vegetable> are more “semantically rich” than the tags <ul> and <li>. Thus, it seems plausible
search tool could recognize that the above XML document is not relevant
query for, say, orange cars. But the search tool would not be able to
recognize that the above HTML document is not relevant. So, using XML
the visible Web has the potential to facilitate more accurate searches.
2. The job
of styling the information is
offloaded to the clients. The Web server is relieved of the
burden and thus can potentially process more requests.
is little usage of XML on the visible Web.
several assertions which
attempt to explain why there is little usage of XML on the visible Web.
is not the necessary “critical mass” of browsers which support the
styling of XML using either CSS or XSLT.
1 listed above is a myth, i.e.,
is not more “semantically
In fact, the opposite is the case.
The tags <ul>
have clear semantics (i.e., an
unordered list of items) that are understood by
every browser on the planet. Conversely, <grocery-list>,
have vague semantics, are understood only by
English-speaking people, and probably zero applications on the visible
would be able to do anything useful with the tags or the data within
2 listed above is also an advantage of HTML, i.e.,
the data is contained in an HTML document and the presentation
contained in a separate CSS document.
is not appropriate for the visible Web. XML will continue to have
usage on the visible Web. As Len Bullard says, “XML
the visible Web, HTML will continue to be the primary markup language
assertions do you accept, and
which do you reject? For those assertions you reject, why?
that you are in charge of a Web
(you control the funding of all the Web sites). Would you issue this
mandate to all the Web site developers: “All
information on the
visible Web must be in XML”? If
you would issue this mandate,
think that XML should have a more
prominent role on the visible Web? If so, how would you stimulate
usage of XML on the visible Web?