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Archive-name: www/faq
Last-modified: 1994/03/15
COMP.INFOSYSTEMS.WWW FAQ
Contents
* 1: Recent changes to the FAQ
* 2: Information about this document
* 3: Elementary Questions
+ 3.1: What are WWW, hypertext and hypermedia?
+ 3.2: What is a URL?
+ 3.3: How can I access the web?
o 3.3.1: Browsers accessible by telnet
o 3.3.2: Obtaining browsers
+ 3.4: How can I provide information to the web?
o 3.4.1: Obtaining Servers
o 3.4.2: Producing HTML documents
+ 3.5: How does WWW compare to gopher and WAIS?
+ 3.6: What is on the web?
+ 3.7: I want to know more.
* 4: Advanced Questions
+ 4.1: How do I set up a clickable image map?
+ 4.2: How do I make a "link" that doesn't load a new page?
+ 4.3: Where can I learn how to create fill-out forms?
+ 4.4: How can I save an inline image to disk?
* 5: Credits
1: RECENT CHANGES TO THE FAQ
* 3/15/94: Information on saving inline images to disk added
2: INFORMATION ABOUT THIS DOCUMENT
This is an introduction to the World Wide Web project, describing the
concepts, software and access methods. It is aimed at people who know
a little about navigating the Internet, but want to know more about
WWW specifically. If you don't think you are up to this level, try an
introductory Internet book such as Ed Krol's "The Whole Internet" or
"Big Dummy's Guide to the Internet". The latter is available
electronically by anonymous FTP from ftp.eff.org in the directory
pub/Net_info/Big_Dummy.
This informational document is posted to news.answers,
comp.infosystems.www, comp.infosystems.gopher, comp.infosystems.wais
and alt.hypertext on the 1st and 15th of every month (please allow a
day or two for it to propagate to your site). The latest version is
always available on the web as
<http://siva.cshl.org/~boutell/www_faq.html>. (see the section titled
"What is a URL?" to understand what this means.)
The most recently posted version of this document is kept on the
news.answers archive on rtfm.mit.edu in
/pub/usenet/news.answers/www/faq
file://rtfm.mit.edu/pub/usenet/news.answers/www/faq>. For information
on FTP, send e-mail to mail-server@rtfm.mit.edu with "_send
usenet/news.answers/finding-sources_" in the body, instead of asking
me.
Thomas Boutell maintains this document. Feedback about it is to be
sent via e-mail to boutell@netcom.com.
In all cases, regard this document as out of date. Definitive
information should be on the web, and static versions such as this
should be considered unreliable at best. Please excuse any formatting
inconsistencies in the posted version of this document, as it is
automatically generated from the on-line version.
3: ELEMENTARY QUESTIONS
3.1: What are WWW, hypertext and hypermedia?
WWW stands for "World Wide Web". The WWW project, started by CERN (the
European Laboratory for Particle Physics), seeks to build a
distributed hypermedia system.
To access the web, you run a browser program. The browser reads
documents, and can fetch documents from other sources. Information
providers set up hypermedia servers which browsers can get documents
from.
The browsers can, in addition, access files by FTP, NNTP (the Internet
news protocol), gopher and an ever-increasing range of other methods.
On top of these, if the server has search capabilities, the browsers
will permit searches of documents and databases.
The documents that the browsers display are hypertext documents.
Hypertext is text with pointers to other text. The browsers let you
deal with the pointers in a transparent way -- select the pointer, and
you are presented with the text that is pointed to.
Hypermedia is a superset of hypertext -- it is any medium with
pointers to other media. This means that browsers might not display a
text file, but might display images or sound or animations.
3.2: What is a URL?
URL stands for "Uniform Resource Locator". It is a draft standard for
specifying an object on the Internet, such as a file or newsgroup.
URLs look like this:
* file://wuarchive.wustl.edu/mirrors/msdos/graphics/gifkit.zip
* file://wuarchive.wustl.edu/mirrors
* http://info.cern.ch:80/default.html
* news:alt.hypertext
* telnet://dra.com
The first part of the URL, before the colon, specifies the access
method. The part of the URL after the colon is interpreted specific to
the access method. In general, two slashes after the colon indicate a
machine name (machine:port is also valid).
In this document, you will often see URLs surrounded by angle
brackets. This is done because some newsreaders (I am told) can
recognize them and treat them as "buttons". Do not enter the angle
brackets when entering a URL by hand to your web browser.
3.3: How can I access the web?
You have two options -- either use a browser that can be telnetted to,
or use a browser on your machine.
3.3.1: BROWSERS ACCESSIBLE BY TELNET
An up-to-date list of these is available on the Web as
http://info.cern.ch/hypertext/WWW/FAQ/Bootstrap.html and should be
regarded as an authoritative list.
info.cern.ch
No password is required. This is in Switzerland, so continental
US users might be better off using a closer browser.
ukanaix.cc.ukans.edu
A full screen browser "Lynx" which requires a vt100 terminal.
Log in as www.
www.njit.edu
(or telnet 128.235.163.2) Log in as www. A full-screen browser
in New Jersey Institute of Technology. USA.
vms.huji.ac.il
(IP address 128.139.4.3). A dual-language Hebrew/English
database, with links to the rest of the world. The line mode
browser, plus extra features. Log in as www. Hebrew University
of Jerusalem, Israel.
sun.uakom.cs
Slovakia. Has a slow link, only use from nearby.
info.funet.fi
(or telnet 128.214.6.102). Log in as info. Not working.
fserv.kfki.hu
Hungary. Has slow link, use from nearby. Login is as www.
3.3.2: OBTAINING BROWSERS
The preferred method of access of the Web is to run a browser
yourself. Browsers are available for many platforms, both in source
and executable forms. Here is a list generated from the authoritative
list, http://info.cern.ch/hypertext/WWW/Clients.html.
Terminal based browsers
Line Mode Browser
This program gives W3 readership to anyone with a dumb
terminal. A general purpose information retrieval tool.
Available by anonymous ftp from info.cern.ch in the directory
/pub/www/src.
"Lynx" full screen browser
This is a hypertext browser for vt100s using full screen, arrow
keys, highlighting, etc. Available by anonymous FTP from
ftp2.cc.ukans.edu.
Tom Fine's perlWWW
A tty-based browser written in perl. Available by anonymous FTP
from archive.cis.ohio-state.edu in the directory pub/w3browser
as the file w3browser-0.1.shar.
For VMS
Dudu Rashty's full screen client based on VMS's SMG screen
management routines. Available by anonymous FTP from
vms.huji.ac.il in the directory www/www_client.
NCSA Mosaic for VMS
Browser using X11/DecWindows/Motif. Multimedia magic. Full http
1.0 support including PUT-method forms, image maps, etc.
Recommended if you can run it. Available by anonymous FTP from
ftp.ncsa.uiuc.edu in the directory Mosaic.
Emacs w3-mode
W3 browse mode for emacs. Uses multiple fonts when used with
Lemacs or Epoch. See doc . Available by anonymous FTP from
Cello
Browser from Cornell LII. Available by anonymous FTP from
fatty.law.cornell.edu in the directory /pub/LII/cello.
Mosaic for Windows
From NCSA. Available by anonymous FTP from ftp.ncsa.uiuc.edu in
the directory PC/Mosaic.
Macintosh
NOTE: all of these browsers require that you have SLIP, PPP or other
TCP/IP networking on your PC. SLIP and PPP can be accomplished
over phone lines, but only with the active cooperation of your
network provider or educational institution. If you only have
normal dialup shell access, your best option at this time is to
run Lynx on the system you call.
Mosaic for Macintosh
From NCSA. Full featured. Available by anonymous FTP from
ftp.ncsa.uiuc.edu in the directory Mac/Mosaic.
Samba From CERN. Basic. Available by anonymous FTP from info.cern.ch
in the directory /ftp/pub/www/bin as the file mac.
XWindows
NCSA Mosaic for X
Browser using X11/Motif. Multimedia magic. Full http 1.0
support including PUT-method forms, image maps, etc.
Recommended if you can run it. Available by anonymous FTP from
ftp.ncsa.uiuc.edu in the directory Mosaic.
tkWWW Browser/Editor for X11
Browser/Editor for X11. (Beta test version.) Available for
anonymous ftp from export.lcs.mit.edu in the directory contrib
as tkWWW-0.10.tar.Z. (Note: this document may be up to date, so
you may prefer to ftp to this site by hand and look for an even
newer version rather than using the link above.)
MidasWWW Browser
From Tony Johnson. (Beta, works well.)
Chimera
Browser using Athena (doesn't require Motif). Supports forms,
inline images, etc.; closest to Mosaic in feel of the non-Motif
X11 browsers. Available for anonymous FTP from ftp.cs.unlv.edu
in the directory /pub/chimera.
NeXTStep
Browser-Editor on the NeXT
A browser/editor for NeXTStep. Allows wysiwyg hypertext
editing. Requires NeXTStep 3.0. Available for anonymous FTP
from info.cern.ch in the directory /pub/www/src.
Batch Mode
Batch mode browser
A batch-mode "browser", url_get, which is available through the
URL <http://wwwhost.cc.utexas.edu/test/zippy/url_get.html>. (I
am not aware of an anonymous FTP site for the same package at
present.) This package is intended for use in cron jobs and
other settings in which fetching a page in a command-line
fashion is useful.
Unreleased or Unsupported
Browser on CERNVM
A full-screen browser for VM. Nonexistent. Use the line mode
www. Might arrive suddenly one day.
Dave Ragget's Browser
Unreleased. For X11, (later PC?)
Erwise
X-windows early browser. Unsupported, now of historical
interest only.
NJIT's Browser
Assumes a character-grid terminal with cursor addressing, and provides
a full-screen interface to the web.
3.4: How can I provide information to the web?
Information providers run programs that the browsers can obtain
hypertext from. These programs can either be WWW servers that
understand the HyperText Transfer Protocol HTTP (best if you are
creating your information database from scratch), "gateway" programs
that convert an existing information format to hypertext, or a
non-HTTP server that WWW browsers can access -- anonymous FTP or
gopher, for example.
If you only want to provide information to local users, placing your
information in local files is also an option. This means, however,
that there can be no off-machine access.
3.4.1: OBTAINING SERVERS
CERN's server is available for anonymous FTP from info.cern.ch and
many other places. Use archie to search for "www" or "WWW" to find
copies close to you. NCSA has also released a server, available for
FTP from ftp.ncsa.uiuc.edu.
See http://info.cern.ch/hypertext/WWW/Daemon/Overview.html for more
information on writing servers and gateways in general.
3.4.2: PRODUCING HTML DOCUMENTS
There are several ways to produce HTML. One is to simply write it by
hand; try the "source" button of of your browser to look at the HTML
for an interesting page. The odds are that it'll be a great deal
simpler than you would expect. If you're used to marking up text in
any way (even red-pencilling it), HTML should be rather intuitive. A
beginner's guide to HTML is available at the URL
<http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html>.
Of course, most folks would still prefer to use a friendlier,
graphical editor. One option is to use an SGML editor with the HTML
DTD . Another, for EMACS fans, is to use EMACS and html-mode.el .
In addition, there are two collections of filters for converting your
existing documents (in TeX and other non-HTML formats) into HTML
automatically:
Rich Brandwein and Mike Sendall's List at CERN .
NCSA's List of Filters and Editors , which also mentions two editors
for MS Windows.
Finally, TkWWW (listed above under XWindows browsers) supports HTML
editing.
3.5: How does WWW compare to gopher and WAIS?
While all three of these information presentation systems are
client-server based, they differ in terms of their model of data. In
gopher, data is either a menu, a document, an index or a telnet
connection. In WAIS, everything is an index and everything that is
returned from the index is a document. In WWW, everything is a
(possibly) hypertext document which may be searchable.
In practice, this means that WWW can represent the gopher (a menu is a
list of links, a gopher document is a hypertext document without
links, searches are the same, telnet sessions are the same) and WAIS
(a WAIS index is a searchable page, returning a document with no
links) data models as well as providing extra functionality.
The principal difference between the three systems, it turns out, is
deployment. WWW does not have as large a user base as gopher, mainly
because of the small number of WWW browsers that are out. This is
changing as WWW reaches critical mass (usage of the server at CERN
doubles every 4 months -- twice the rate of Internet expansion).
3.6: What is on the web?
Currently accessible through the web:
* anything served through gopher
* anything served through WAIS
* anything on an FTP site
* anything on Usenet
* anything accessible through telnet
* anything in hytelnet
* anything in hyper-g
* anything in techinfo
* anything in texinfo
* anything in the form of man pages
* sundry hypertext documents
One of the few limitations of the current networked information
systems is that there is no simple way to find out what has changed,
what is new, or even what is out there. As a result, a definitive list
of the web's contents is impossible at this moment. There are,
however, several resources which provide a great deal of information
on new and established servers by topic. These are just two:
* The WWW Virtual Library at the URL
<http://info.cern.ch/hypertext/DataSources/bySubject/Overview.html
>, a good place to find resources on a particular subject
* What's New With NCSA Mosaic at the URL
<http://www.ncsa.uiuc.edu/SDG/Software/Mosaic/Docs/whats-new.html>
, which carries announcements of new servers on the web
3.7: I want to know more
To find out more, use the web. This FAQ hopefully provides enough
information for you to locate and install a browser on your system. If
you have system specific questions regarding FTP, networking and the
like, please consult newsgroups relevant to your particular hardware
and operating system!
Later you may return to this FAQ for answers to some of the advanced
questions covered in the second section. The advanced section contains
the most-asked technical questions in the group.
4: ADVANCED QUESTIONS
4.1: How do I set up a clickable image map?
There are really two issues here: how to indicate in HTML that you
want an image to be clickable, and how to configure your server to do
something with the clicks returned by Mosaic, Chimera, and other
clients capable of delivering them.
You can read about image maps and the NCSA server at the URL
<http://hoohoo.ncsa.uiuc.edu/docs/setup/admin/Imagemap.html>.
4.2: How do I make a "link" that doesn't load a new page?
Such links are useful when a form is intended to perform some action
on the server machine without sending new information to the client,
or when a user has clicked in an undefined area in an image map; these
are just two possibilities.
Rob McCool of NCSA provided the following wisdom on the subject:
Yechezkal-Shimon Gutfreund (sg04@gte.com) wrote:
: Ok, here is another bizzare request from me:
: I am currently running scripts which I "DO NOT" want to return
: any visible result. That is, not text/plain, not text/HTML, not
: image/gif. The entire results are the side effects of the
: script and nothing should be returned to the viewer.
: It would be nice to have an internally supported null viewer
: so that I could do this, more "cleanly" (ok, ok, I hear your groans).
HTTP now supports a response code of 204, which is no operation. Some
browsers such as Mosaic/X 2.* support it. To use it, make your script a nph
script and output an HTTP/1.0 204 header. Something like:
HTTP/1.0 204 No response
Server: Myscript/NCSA httpd 1.1
(You can learn more about nph scripts from the NCSA server
documentation at the URL <http://hoohoo.ncsa.uiuc.edu/docs>.)
Essentially they are scripts that handle their own HTTP response
codes.
4.3: Where can I learn how to create fill-out forms?
You can read about the Common Gateway Interface at the URL
<http://hoohoo.ncsa.uiuc.edu:80/cgi/>. In addition to documenting the
standard interface for which scripts can now be written for both NCSA
and CERN-derived servers, these pages also cover HTML forms and how to
handle the results on the server side.
4.4: How can I save an inline image to disk?
Here are two ways:
1. Turn on "load to local disk" in your browser, if it has such an
option; then reload images. You'll be prompted for filenames instead
of seeing them on the screen. Be sure to shut it off when you're done
with it.
2. Choose "view source" and browse through the HTML source; find the
URL for the inline image of interest to you; copy and paste it into
the "Open URL" window. This should load it into your image viewer
instead, where you can save it and otherwise muck about with it.
5: CREDITS
* Thomas Boutell _boutell@netcom.com_
* Nathan Torkington _Nathan.Torkington@vuw.ac.nz_
* Marc Andreessen _marca@ncsa.uiuc.edu_
* Tony Johnson
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