WebRing Controller
by Roedy Green ©1996-2008 Canadian Mind Products
This essay is about a suggested
student project in
Java programming. This essay gives a rough overview of how it might work. It
does not describe an actual complete program. I have
no source, object,
specifications, file layouts or anything else useful to implementing this
project. Everything I have to say to help you with this project is written below.
I am
not prepared to help you implement it; I have too many other
projects of my own.
I do contract work for a living, which could include writing a program such as
this. However, I don’t do people’s homework
for them. That just robs them of an education.
You have my full permission to implement this project any way you please.
WebRings are groups of like-minded websites. You can browse from site to site in
a circle by clicking a button. You can go forward or back. You can jump to a
random site. You can see a list of all the sites, and jump directly to any one
of them. Yahoo organises
such rings for free. For details on how they work, see WebRing
in the Java glossary.
There is a central controller CGI app running on a server that figures out where
to jump to next when a given button is pressed. When the user hits next
, prev , random or list
, (usually on a custom CGI graphic map or a snippet of JavaScript) the server
forwards the user to the appropriate site in the circle. There are three major
problems with WebRings as they currently exist:
- The HTML for linking at each site is not properly verified. The target URL
should be precisely the spot on the page where the link control to the
next site is, with #NAME tag. With the current unverified schemes, you may land
at somebody’s home page, and have to dig through his entire site to find
the next link. (There might not even be one, if the site’s owner made an
HTML error, or dropped out of the ring without informing the Ring Master.) You
may land on a page with links to 20 other WebRings on it. You have to find the
link for the WebRing you are interested in. We need to automatically
verify (and periodically reverify) that the HTML target URL and the link control
HTML buttons at that target are properly configured. You need a precise target
URL of the form:
http://www.MySite.com/ringpage.html#SuperRing$209078$7752$13413
where "SuperRing" is the ring software scheme, "20978" is
the server id, "7752" is the ring id, and "13413" is the
site id. IDs are small integers evenly divisible by 17 (which acts as a simple
checksum, yet allows ids (after division by 17) to directly index tables).
- Like the old serial Christmas tree lights, if any link in the chain goes down,
the entire ring is broken. The central site needs to keep tabs on all the sites
and remove ones (temporarily, and eventually permanently) that do not respond.
Some rings have a button to bypass the next site to help get around the problem.
However, that won’t help unless the user knows to try that. It also
requires there not be two dead sites in a row. Note that current schemes don’t
directly send the user to the next site in the ring. They always send him to the
ring hub for redirection. However, if there is no working link back to the ring
hub, the chain is broken.
- Users periodically reorganise their websites. This means that rings may move
from page to page without officially informing the central site of the new
location. These links can be made self-healing.
- Automatically. At night the central site chases rings looking for broken links.
When it finds one, it searches that website for the moved reference. If it can’t
find it, it takes the website off-line.
- Semi-Automatically. When you click the icon it could send its location to the
central site. If it has changed, and if the old page no longer contains the link,
the central information could be automatically updated. If the old page is still
valid, the central system could generate an email asking for clarification. It
might be quite reasonable to have several references to the same ring on a
website, though of course there has to be one master link where incoming
visitors are deposited.
On the other extreme, you could insert a perfectly standard piece of HTML
in a web page, not customised in any way. It looks up the web page URL to see
what rings are registered there. You could put that link on every web page, then
manage centrally at the ring hub which rings you want to appear on which pages.
You could have a ring appear more than once on your website. You could see
centrally which links are valid. What you want to avoid is the problem of
needing to install new gobbledegook nav bar codes every time a web page is
renamed or split.
Your job is to write a servlet that runs a collection of WebRings, sending
browsers onto the next link. You need to find low-cost, solutions to the above
three problems. You want the user interface extremely simple so that almost
anyone could set up a WebRing server and run it with little time investment.
There are four levels of organisation:
Individual Site Master
One for each site on a ring. A site may be on several rings. They may be on
rings using different software schemes.Ring Master
Decides the ring’s charter, and who should be allowed on the ring.
Monitors that members are conforming to the charter. Handles technical support
for the sites on the ring. Maintain the master list of sites on the ring, and a
home page for the ring. Composes a logo for the ring.Server Master
Runs a server than services many rings. Handles technical support from the Ring
Masters, but not from individuals or individual Site Masters. Maintains a master
list of rings handled by the server and a home page for the server’s ring
service.Global Directory Master
Much the way DNS works, the server sites automatically share their directories
of rings to form a master directory of rings. This way each site has a copy of
the global directory of all rings on the Internet (ideally even including ones
not using your software). Alternatively, server sites may not keep a local copy
of the complete list, but instead maintain a link to where a global copy can be
obtained. End users of the system are, for the most part, unaware of these
organisation levels. They can find a list of sites on a ring, a list of other
WebRings on the server or a master list of all the WebRings (categorised and
keyword searchable) just by clicking buttons.- You need to use a program like
HTML
Validator to verify any fragments asked to be included in other people’s
pages. It is highly annoying to be given bad html code to be inserted in your
web page, even if it works in IE. Even though not all browsers support
JavaScript, it is probably best to use it to generate complex displays from a
tiny piece of embedded HTML.
- To make rings more accessible, even the ringmaster should not need to know HTML.
She should be able to generate the necessary embedded HTML master template by
answering multiple choice questions.
- The ringmaster should have ways of generating individual or bulk Emails to
various subsets of the ring members. Members should have a way of sending emails
to the ringmaster. People visiting the sites should be able, using the ring, to
send mail to the owner of the site, or to the ringmaster.
- If the ringmaster does not log in for a month, the system automatically polls
the existing ring members to assign a new ringmaster.
- The ringmaster should have the option of requesting an automatic email any time
someone asks to join the ring or changes their description.
- The ringmaster should be given the power to edit the URLs or site descriptions.
- Since most people can’t edit HTML, think about how you could have a server
system that did not require any embedded HTML, just a link to a page or virtual
page on the ring server that contained all the rings that site owned. There
could be a link back to the site for each ring.
- Become a ringmaster on Yahoo
and learn what the practical problems are and the deficiencies with the Yahoo
system.
- Site owners are usually both unwilling and incapable of inserting nav bars or
ring icons into their HTML. Perhaps this process could be semi-automated.
Perhaps the ring master could do it and email the corrected page back for
uploading. You want tools so the ringmaster can do this quickly.
Please email your feedback for publication, errors, omissions, broken/redirected link reports
