Link-able
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Stay
linkable
- it is the links that make the Web
Jahn Rentmeister
The World Wide Web is not a physical web of computers
connected by a network, but a logical web of documents
linked by hyperlinks. It is the hyperlinks that make
the WWW a Web, and it is the hyperlinks that allow
authors to enhance their documents in a way that has
never been available before: By refering to other
documents in a way that puts those documents only
a mouseclick (or a keyboard click, respectively) away.
In my humble opinion, this new possibility is the
reason that triggered the enormous success of the
WWW and HTML, because it facilitates a global network
of interconnected information. I am not alone with
that opinion:
"Anything that reduces the prevalence
and usefulness of cross-site linking is a direct attack
on the founding principle of the Web." -- Jakob
Nielsen in "Fighting
Linkrot"
In recent times, both frames and Java applets have
been used to accomplish a more pleasant presentation
of information on the WWW. While providing a pretty
surface, these techniques pose a severe drawback for
the information provider: They make information harder
or impossible to link from outside.
In this text, I will illustrate the problem and
discuss why information providers will want to avoid
it and how they can avoid it.
When frames were introduced, one argument against
them - among many others - was that a frameset can
not be bookmarked: If a site uses frames within all
of its pages, it is not possible for the visitor to
bookmark a page on that site. This is only a symptom
of a more general problem: A page on that site can
not be linked from outside. Thus, there is information
on that site that can link to other information, but
can not itself be linked from outside.
This may sound harmless, but a closer look reveals
that it is in fact a major drawback. First, it stands
against the vision of the WWW: The vision of a World
Wide Web of interconnected information, a single,
giant hypertext document, accessible to all for reading
as well as publishing. I will present less visionary
reasons for information providers to "Stay linkable"
later in this article.
(I would like to put a link here to an examples
page that can not be linked, but I simply can't. Sorry.
Simply look at any interesting page on a site that
uses frames.)
Java applets are a great enhancement of the possibilities
of the Web. But using applets to display information
can result in the same problem: Information that can
link other information, but can not itself be linked
from outside.
For an example, see the interactive
city map of Cologne, Germany: The map can be browsed
and contains links to the homepages of hotels and
museums. Thus, there are hyperlinks inside of the
map. But it is not possible to link to parts of the
map. If someone wrote a HTML document about a nice
place in Cologne, he could not provide a link to that
particular area of Cologne inside of the interactive
map. The area of interest is part of the map, but
one can not link to it directly. Of course, one could
link to the map and tell the reader how to get to
the specific area ("six squares up, three squares
right"). But that is just like linking to the
opening page of a framed site and telling the reader
how to get to the referenced page. The virtue of hyperlinks
is to make information directly accessible ("only
one click away"). If there has to be a description
how to get the information, we are somewhat back to
normal documents, where there are references, but
no hyperlinks.
The creators of the interactive city map have provided
a means to link to specific spots on the map by means
of a CGI script. For an example, see this link to
the position of the museum for east asian art in cologne.
Unfortunately, the CGI program does not seem to
allow to separate name-value pairs by ';' instead
of '&', therefore it is not possible to link from
HTML documents in a way that works reliably and
is valid. The above link will not work with older
browsers.
I do not mean to say that an interactive map should
be done in HTML, nor that it should not be done at
all. I mean to say that there should be a way to link
to areas inside of the map, because these areas are
information presented on the WWW, therefore they gain
by being linkable. In the future, there will be applets
for accessing different kinds of databases over the
Internet as part of WWW pages. These applets will
probably suffer from the same problem, i.e. a query
result can not be hyperlinked.
This subtopic is a rather theoretical one: I have
not seen any HTML document on the Web that could serve
as an example for it. It is listed here only for completeness,
because it too prevents information on the Web from
being hyperlinked.
If someone creates a big HTML document and deals
with several topics within that document, it is not
possible to link to a portion of that HTML document
from outside, unless the portion of interest has been
given a name by the author (using the anchor tag of
HTML). Usually, HTML documents on the WWW are not
big enough to run into this problem, because big documents
need too much time to download. There are documents
on the WWW that are big enough to demonstrate this
problem, but they usually provide names for every
section of the document, so that portions can be linked
from outside. (These names are usually needed for
the documents own hyperlinked table of contents.)
It is desirable to make portions of the document linkable
if they deal with different topics: Someone might
want to link to one section, but not to the whole
document, just like someone might want to link to
one page on a site, but not to the opening page.
Information providers on the WWW want people to
visit their pages, therefore they are grateful for
every link to their site. There are many companies
on the Web who pay money for banner ads that link
to their sites.
If a page can not be linked, it will not be linked.
If a site provides useful information, maintainers
of other sites will want to link to that information,
like linking to "The Alert Box"
on the Sun Microsystems site or to the HTML
2.0 standard on the W3C site. There are a lot
of external links to both of these sites. How many
links would point there if it were only possible to
link to the Sun Microsystems main page or to the W3C
main page? Hardly any, I think. Thus, the big number
of links to these sites is due to their content and
due to the fact that their pages can be easily hyperlinked.
In short, if your information can not be directly
referenced by a hyperlink, you loose a lot of potential
visitors because they are not refered to your site
or are refered to the wrong page on your site (the
opening page). If you support the vision of the WWW
as a huge, constantly changing, world-spanning hypertext
document, you will dislike any information that can
not be hyperlinked. You should support this vision,
because it is what makes the WWW attractive. (In case
you ever wondered: It is not the advertising that
makes the WWW attractive, just like advertising is
not the reason why people read newspapers.) In any
way, if you present pages on the WWW, you will want
them to be linkable, because you want people to visit
them.
For the users of the WWW, information is only valuable
if they find it. The easiest way to find information
is to be refered to it by a hyperlink. Thus, information
that can not be linked is harder to find. But the
provider of that information wants it to be found
- else, he/she would not have put it on the WWW. It
is not only users and site maintainers who link to
pages from outside of a site, it is also search engines.
If a company puts interesting information on the
WWW to promote their site or to sell advertising space,
search engines and framed pages can make their nightmare
come true: Visitors are refered to the information
by a search engine, but they are not refered to the
framed version, but to the plain HTML version without
a navigation bar and without advertising banners.
Such, they can neither explore the site further nor
do they see any advertising. To avoid this, one could
prohibit the pages from being indexed by search engines,
but then they are not found at all, which is even
worse.
For frames, there are two possible solutions. The
best solution would be a different frame definition
for future HTML versions. I don't think there is much
hope for this, because the "big players"
in the browser market both support the same frame
tags. Maybe the W3C will fix some of the problems
in their future HTML versions. The second solution
is for site maintainers to provide a separate mechanism
for linking to a specific page. For example, one could
provide a CGI script that builds the needed frameset,
and put a comment in every HTML document that gets
displayed inside the main frame where the visitor
can read the URL he/she should use to link to that
page. This will not solve the bookmarking problem,
but if there is a prominent notice about how to link
to pages, other site's maintainers will probably use
this to link directly to the page they want to refer
to, rather than to link to the opening page or to
not refer to the information at all. Site maintainers
who want to link to framed pages can also use their
own CGI script for this.
For Java applets, a similar solution is possible:
A CGI script that calls the applet with appropriate
parameters. Of course, the applet needs to support
these parameters. By this method, the interactive
map of Cologne supports links to specific spots inside
Cologne. Of course, if this were documented (so people
knew how to link to a spot on the map), and if there
were a way to specify the zoom status and the "point
activation" over the CGI script, it would be
even better, but it is worth mentioning that it is
at least possible to link to specific spots on the
map.
Every Java applet that implements a viewer for large
information sets should support appropriate parameters
for external links, and every page that uses such
an applet should provide a description on how to link
to parts of the Java-presented information. An appropriate
CGI script should be provided. It is in the interest
of everyone involved that information on the Web is
linkable.
rentmei@uni-muenster.de
© Jahn Rentmeister
