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1995-04-12
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MAP23: WWW
"Ah! the clock is always slow;
It is later than you think."
-- Robert W. Service, It is Later Than You Think
I wish I had six weeks just to talk about the World Wide Web (a.k.a.
WWW or "the Web."). If you think Gopher is neat, wait until you start
playing around on the Web :)
Unfortunately, I *don't* have six weeks to talk about the Web -- I only
have two days. Because of this, we are going to go through the Web like
Sherman went through Georgia (1).
That's the bad news. The good news is that there are a lot of REALLY good
Web guides available, and I am even seriously considering developing my own
Web workshop that I will offer *late* next year (2).
Until that time comes, however, let's talk about the BASICS of the Web.
Last week I showed you how most Gopher menus are linked together. We
started out in the gopher.squirrel.com root menu, and eventually ended
up at the SURAnet gopher menu. We were able to do this because the
menus that we travelled through had links to menus and files that were
located at other Gopher sites.
Because Gopher menus are linked together, a whole world of information
is available to us with just a few keystrokes!
Imagine if we were able to take these links one step further. Instead
of linking menus, we could link *DOCUMENTS* together. You could read
one document, find a keyword in that document that really interests
you, touch that keyword, and automatically be taken to a NEW document
somewhere else in the world -- and this new document could even have
links to OTHER documents around the world, and so on.
Sound too good to be true? It isn't, thanks to something called
"hypertext." If you have ever played with Apple's Hypercard program
or the "help" menus in the latest Microsoft packages, you have already
experienced hypertext. You "select" a highlighted word -- usually by
clicking on it with a mouse -- and you are taken into an entirely
new document or help screen.
The World Wide Web is based on hypertext. It is possible for you to
go roaming around the Web, bouncing from document to document, using
nothing but the links in those documents!
Just as you can access Gopherspace through a Gopher server or client,
you can access the Web through something called a "browser." A browser
can read documents, fetch documents, access files by FTP, read Usenet
newsgroups, telnet into remote sites, and even travel around Gopherspace.
In short, everything that we have talked about over the past three weeks
can be done using nothing but a Web browser!
The Web is able to accomplish all of this thanks to something called
URLs ("earls") -- Universal Resource Locators. URLs list the exact
location of *ANY* Internet resource.
If you think about it, giving every Internet resource a unique
address is the hard part. Once you have given something an address,
linking to it is pretty easy :)
What is really special about the Web is that the Web does all of this
"behind the scenes." It is possible for you to bounce from one link to
another without ever knowing the exact address of where you are, or
even how you got there.
If you ever want to jump *directly* to a particular Internet resource,
however, you are going to need to know a little bit more about URLs.
Here are a few basic URLs:
file://wuarchive.wustl.edu/mirrors/msdos/graphics/gifkit.zip
ftp://wuarchive.wustl.edu/mirrors
http://info.cern.ch:80/default.html
news:alt.hypertext
telnet://dra.com
Gee ... those look a little like FTP addresses, don't they?
The first part of an URL -- the stuff before the colon -- tells the
browser how to access that particular file. For example, to access
ftp://wuarchive.wustl.edu/mirrors
your browser would use FTP.
Most of the access methods are pretty straight-forward. Here is a list
of some of the more common access methods that you are going to see
listed in the first part of URLs:
method what it stands for
------ ---------------------------------------
ftp File Transfer Protocol
file File Transfer Protocol (same as ftp)
news Internet News Protocol (Usenet)
gopher Gopher
telnet Telnet
http Hypertext Transport Protocol
We've used all of these before, except for http. If you ever see a
URL with http at the beginning of it, that means that the file is
a hypertext document (with hypertext links to other documents).
The rest of a URL -- the stuff after the colon -- is the address of
that particular file. In general, two slashes (//) after the colon
indicates a machine name or address.
For example,
file://wuarchive.wustl.edu/mirrors/msdos/graphics/gifkit.zip
is the URL for an FTP file at wuarchive.wustl.edu, and
http://info.cern.ch:80/default.html
is the URL for a hypertext document at info.cern.ch, port 80.
TOMORROW: - How to access the Web by telnet
- Where you can obtain a Web browser (for those of you
with Level 3 connectivity and a SLIP or PPP connection)
- Doing some simple searches using the Web
- The difference between the Web and Mosaic (Mosaic is
just a browser that lets you access the Web).
HOMEWORK:
If you are planning on becoming a SERIOUS Web guru, I have
placed the WWW FAQ on the file server at the University of
Alabama. It is broken into two parts:
filename filetype
-------- --------
WWW FAQ1
WWW FAQ2
You can use the GET command to get it (remember, do not
reply to this letter -- you MUST write a new letter to the
LISTSERV with your GET commands).
SOURCES:
WWW FAQ, 8 August 1994.
NOTES:
(1) General William Tecumseh Sherman was the Union Army General
who burned a path 100 miles wide from Atlanta to the sea during
the U.S. Civil War.
(2) Kristen Burke, a friend of mine at the University, recently heard
me promise that after this workshop I would *NEVER* do anything like
this again. She bet me that I would change my mind. She won :)
PATRICK DOUGLAS CRISPEN THE VIEWS EXPRESSED IN THIS LETTER DO NOT
PCRISPE1@UA1VM.UA.EDU NECESSARILY REPRESENT THE VIEWS OF THE
THE UNIVERSITY OF ALABAMA UNIVERSITY OF ALABAMA - TUSCALOOSA
ROADMAP: COPYRIGHT PATRICK CRISPEN 1994. ALL RIGHTS RESERVED.