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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