500 MB Nyheder Direkte fra Internet 2/500 MB nyheder direkte fra internet CD 2.iso/start/data/text/faq-1611.txt

Text File | 1995-05-01 | 45KB | 937 lines

Archive-name: www/faq/part2
Last-modified: 1995/26/1


                5.1: 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.

   To learn more about World Wide Web servers, you can consult a www
   server primer by Nathan Torkington, available at the URL
   http://www.vuw.ac.nz/who/Nathan.Torkington/ideas/www-servers.html .

   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.

5.2: Obtaining Servers

   Servers are available for Unix, Macintosh, MS Windows, Windows NT,
   OS/2, and VMS systems. If you know of a server for another operating
   system, please contact me.

   See http://info.cern.ch/hypertext/WWW/Daemon/Overview.html for more
   information on writing servers and gateways in general.

  5.2.1: UNIX SERVERS

   NCSA httpd
          NCSA has released a server, known as the NCSA httpd; it is
          available at the URL ftp://ftp.ncsa.uiuc.edu/Web/ncsa_httpd .

   EIT httpd
          EIT has created the Webmaster's Starter Kit, which installs
          their WWW server on your system via the web through a painless
          forms interface. Recommended for those unfamiliar with server
          installation. You can learn more about the starter kit and the
          EIT httpd at the starter kit site (URL is
          http://wsk.eit.com/wsk/doc/ ).

   CERN httpd
          CERN's server is available for anonymous FTP from info.cern.ch
          (URL is http://info.cern.ch/hypertext/WWW/Daemon/Status.html )
          and many other places. Use your local copy of archie to search
          for "www" in order to find a nearby site.

   GN Gopher/HTTP server
          The GN server is unique in that it can serve both WWW and
          Gopher clients (in their native modes). This is a good server
          for those migrating from Gopher to WWW, although it does not
          have the server-side-script capabilities of the NCSA and CERN
          servers. See the URL http://hopf.math.nwu.edu/ .

   Perl server
          There is also a server written in the Perl scripting language,
          called Plexus, for which documentation is available at the URL
          http://bsdi.com/server/doc/plexus.html .

   WN Server
          The WN Server, available at the URL
          http://hopf.math.nwu.edu/docs/manual.html , is designed with an
          emphasis on security and flexibility, and takes a different
          approach from the NCSA and CERN servers. It provides text
          searching facilities as a standard feature.

  5.2.2: MACINTOSH SERVERS

   There is a server for the Macintosh, MacHTTP, available at the URL
   http://www.uth.tmc.edu/mac_info/machttp_info.html .

  5.2.3: MS WINDOWS, IBM OS/2 AND MS WINDOWS NT SERVERS

   HTTPS (Windows NT)
          HTTPS is a server for Windows NT systems, both Intel and Alpha
          -- based. It is available via anonymous FTP from emwac.ed.ac.uk
          in the directory pub/https (URL is
          ftp://emwac.ed.ac.uk/pub/https). (Be sure to download the
          version appropriate to your processor.) You can read a detailed
          announcement at the FTP site, or by using the URL
          ftp://emwac.ed.ac.uk/pub/https/https.txt.

          A professional version is also available (URL is
          http://emwac.ed.ac.uk/html/internet_toolchest/https/prof.htm ).

   NCSA httpd for Windows
          The NCSA httpd for Windows has most of the features of the Unix
          version, including scripts (which generate pages on the fly
          based on user input). It is available by anonymous FTP from the
          ftp site ftp.alisa.com in the directory pub/win-httpd, and
          documentation can be found at the URL
          http://www.alisa.com/win-httpd/index.html .

   SerWeb
          A simple, effective server for Windows writtten by Gustavo
          Estrella. Available by anonymous ftp from
          winftp.cica.indiana.edu (or one of its mirror sites, such as
          nic.switch.ch), as the file serweb03.zip, in the directory
          /pub/pc/win3/winsock.

          There is also a Windows NT version of SerWeb, available by
          anonymous FTP from emwac.ed.ac.uk as /pub/serweb/serweb_i.zip.

   WEB4HAM
          Another Windows-based server, available by anonymous FTP from
          ftp.informatik.uni-hamburg.de as /pub/net/winsock/web4ham.zip.

   OS2HTTPD
          An OS/2 server, written by Frankie Fan. See the home page (URL
          is ftp://ftp.netcom.com/pub/kf/kfan/overview.html ) for
          details, or fetch the package by anonymous FTP from
          ftp.netcom.com in the directory pub/kf/kfan.

  5.2.4: MSDOS AND NOVELL NETWARE SERVERS

   KA9Q   KA9Q NOS (nos11c.exe) is a internet server package for DOS that
          includes HTTP and Gopher servers. It can be obtained via
          anonymous FTP from one of the following sites:


inorganic5.chem.ufl.edu
biochemistry.cwru.edu

   GLACI-HTTPD
          GLACI-HTTPD is a Netware Loadable Module which allows a Novell
          NetWare server to become a World Wide Web server (URL is
          http://www.glaci.com/info/glaci-httpd.html ).



  5.2.5: VMS SERVERS

   CERN HTTP for VMS
          A port of the CERN server to VMS. Available at the URL
          http://delonline.cern.ch/disk$user/duns/doc/vms/distribution.html .

   Region 6 Threaded HTTP Server
          A native VMS server which uses DECthreads(tm). This is a
          potentially major performance advantage because VMS has a high
          overhead for each process, which is a problem for the
          frequently-forking NCSA and CERN servers that began life under
          Unix. A multithreaded server avoids this overhead. Available at
          the URL http://kcgl1.eng.ohio-state.edu/www/doc/serverinfo.html .



  5.2.6: AMIGA SERVERS

   NCSA's Unix server has been ported to the Amiga, and is bundled with
   the AMosaic browser. See the URL
   http://insti.physics.sunysb.edu/AMosaic/home.html for details.

  5.2.7: VM/CMS SERVERS

   A VM/CMS web server is available; see the URL
   http://ua1vm.ua.edu/~troth/rickvmsw/rickvmsw.html for more
   information. If you don't yet have a web browser to try this URL with,
   check out the VM/CMS Browsers section.

  5.2.8: YEAH, BUT WHICH IS BEST?



   To find out which server is best for your needs, you will want to
   consult Paul Hoffman's Server Comparison Chart (URL is
   http://sunsite.unc.edu/boutell/faq/chart.html ). That document is also
   available by anonymous FTP from ftp.netcom.com in the directory
   pub/bo/boutell/faq.

5.3: Producing HTML documents

   HTML is the simple markup system used to create hypertext documents.
   There are three ways to produce HTML documents: writing them yourself,
   which is not a very difficult skill to acquire, using an HTML editor,
   which assists in doing the above, and converting documents in other
   formats to HTML. The following three sections cover these
   possibilities in sequence.

  5.3.1: WRITING HTML DOCUMENTS YOURSELF

   You can write an HTML document with any text editor. Try the "source"
   button of your browser (or "save as" HTML) to look at the HTML for a
   page you find particularly interesting. The odds are that it will 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 . You
   can also find a plain text version (at the URL
   ftp://ftp.ncsa.uiuc.edu/ncsapubs/WWW/HTMLPrimer.txt) and a compressed
   Postscript version (at the URL
   ftp://ftp.ncsa.uiuc.edu/ncsapubs/WWW/HTMLPrimer.ps.Z). (Since the
   latter two are FTP URLs, you can fetch them by hand using FTP if you
   do not yet have a web browser.)

   There is also an HTML primer by Nathan Torkington at the URL
   http://www.vuw.ac.nz/who/Nathan.Torkington/ideas/www-html.html .

  5.3.2: HTML EDITORS

   Of course, most folks would still prefer to use a friendlier,
   graphical editor. Some editors are WYSIWYG (What You See Is What You
   Get), or close to it; others simply assist you in writing HTML by
   plugging in the desired markup tags for you from a menu.

   Fans of the EMACS editor can use EMACS and html-helper-mode , an EMACS
   "mode" for HTML editing (URL is http://www.reed.edu/~nelson/tools/ ).

   There is also another Emacs HTML mode, html-mode.el (URL is
   ftp://ftp.ncsa.uiuc.edu/Web/html/elisp/html-mode.el ).

   For Microsoft Windows users, there is an editor called HTML Assistant
   with features to assist in the creation of HTML documents. It can be
   had by anonymous FTP from ftp.cs.dal.ca in the directory /htmlasst/.
   Read the README.1ST file in this directory for information on which
   files to download.

   ANT_HTML.DOT is a Word for Windows 6.0 template designed to convert
   Word documents into HTML documents in a WYSIWYG environment. It
   includes a demo version of the ANT_PLUS utility, which converts HTML
   files to WYSIWYG. ANT_PLUS also converts HTML files to ASCII, RTF, or
   any other format possible in Word 6.0. Contact [e-mail]
   if you need more information.

   A WYSIWYG editor for the Web, SoftQuad HoTMetaL, is available for
   downloading at NCSA and numerous other sites. Many mirror sites exist;
   if you can't get through to one, try another, don't give up! That's
   what mirror sites are for. (Also be sure to use the copy closest to
   you geographically if possible.) Hotmetal is available for both Sun
   Sparc systems and Windows systems; note that Windows users need at
   least 6 megabytes of free memory. (A 2-megabyte swap file should just
   barely do the trick on a 4MB machine.)

   Known mirrors:
     * ftp://ftp.ncsa.uiuc.edu/Web/html/hotmetal/
     * ftp://ftp.ifi.uio.no/pub/SGML/HoTMetaL
     * ftp://sgml1.ex.ac.uk/SoftQuad
     * ftp://src.doc.ic.ac.uk/packages/WWW/ncsa/html/hotmetal/
     *
       ftp://askhp.ask.uni-karlsruhe.de/pub/infosystems/mosaic/contrib/Sof
       tQuad
     * ftp://ftp.cs.concordia.ca/pub/www
     *

   You need a Sun SPARC or Microsoft Windows system and 6MB of disk (6MB
   of RAM minimum for MS Windows; swap files count). Other Unix systems
   may be supported by the time you read this; have a look on one of the
   sites above.

   Because it is context-sensitive, HoTMetaL guides users in creating new
   HTML documents and in cleaning up old ones. A Publish command changes
   appropriate SRC and HREF attributes from local paths to http
   locations. For more information, FTP the README file from the same
   directory, or send email to [e-mail]. A HoTMetaL Pro
   commercially supported version is available for purchase from SoftQuad
   and its resellers.

   Also see Gabriel White's reviews of MS Windows HTML editors (URL is
   http://werple.mira.net.au/%7Egabriel/web/html/editors/ ). Another
   option, if you have an SGML editor, is to use it with the HTML DTD
   (URL is http://info.cern.ch/hypertext/WWW/MarkUp/DTDHeading.html ).

   An editor for all X users: TkWWW (listed above under X browsers)
   supports WYSIWYG HTML editing; and since it's a browser, you can try
   out links immediately after creating them.

   Another editor for X users: Phoenix (URL is
   http://www.bsd.uchicago.edu/ftp/pub/phoenix/README.html ) is a fully
   WYSIWYG HTML editor which insulates the user from direct control of
   the HTML tags. Available by anonymous FTP from www.bsd.uchicago.edu in
   the pub/phoenix subdirectory.

   Also for X users, there is a package called htmltext which supports
   WYSIWYG HTML editing. More information is available at the URL
   http://web.cs.city.ac.uk/homes/njw/htmltext/htmltext.html .

   For Macintosh users, there is a near-WYSIWYG package called HTML
   Editor (URL is http://dragon.acadiau.ca:1667/~giles/HTML_Editor).

   ANT_HTML is a Word for the Macintosh template designed to convert Word
   documents into HTML documents in a WYSIWYG environment. It includes a
   demo version of the ANT_PLUS utility, which converts HTML files to
   WYSIWYG. ANT_PLUS also converts HTML files to ASCII, RTF, or any other
   format possible in Word. At the time of this writing it was scheduled
   to have been released on the Macintosh (it has long been available for
   Windows). Contact [e-mail] for more information. Also
   for Macintosh users, the BBEdit HTML extensions allow the BBEdit and
   BBEdit Lite text editors for the Macintosh to conveniently edit HTML
   documents. (URL is http://www.uji.es/bbedit-html-extensions.html .)
   You can also obtain the extensions package by anonymous ftp from
   sumex-aim.stanford.edu as info-mac/bbedit-html-ext-b3.hqx.

   There is an alternative BBEdit extension package available as well
   (URL is http://www.york.ac.uk/~ld11/BBEditTools.html ). it is
   available by FTP from ftp.york.ac.uk in the directory
   /pub/users/ld11/BBEdit_HTML_Tools.sea.hqx.

   NCSA's List of Filters and Editors, for which the URL is
   http://www.ncsa.uiuc.edu/SDG/Software/Mosaic/Docs/faq-software.html#ed
   itors, mentions several editors, including two for MS Windows. In some
   cases, the "editor" amounts to a set of macros for an existing word
   processor, which can provide a near-WYSIWYG environment.

   Note that this URL contains uppercase and lowercase letters; certain
   operating systems won't allow mixed case on the command line, or will
   only allow it if it is quoted (VMS), so if you are launching Lynx or
   another client and specifying a URL at the command line, try quoting
   the URL in double-quotes ("URL").

  5.3.3: CONVERTING OTHER FORMATS TO HTML

   There is a collection of filters for converting your existing
   documents (in TeX and other non-HTML formats) into HTML automatically,
   including filters that can allow more or less WYSIWYG editing using
   various word processors:

   Rich Brandwein and Mike Sendall's List at CERN (URL is
   http://info.cern.ch/hypertext/WWW/Tools/Filters.html ).

   (Note that this URL contains uppercase and lowercase letters; certain
   operating systems such as VMS require you to quote mixed-case URLs
   when launching a borwser from the command line. This is NOT a bug in
   the browser.)

   There is also a Word for Windows template for writing HTML documents,
   available at the URL http://www.gatech.edu/word_html/release.htm .

  5.3.4: CHECKING YOUR HTML FOR ERRORS

   Tools to validate your HTML documents (check them for errors) are
   available. There is a form at the URL
   http://www.hal.com/%7Econnolly/html-test/service/validation-form.html
   which will check HTML documents for errors according to the latest
   specification; note that you are encouraged to set up the program on
   your own system if you make heavy use of the form. There is also a
   tool which will check the links in your documents for links to
   nonexistent resources, such as pages that have moved (URL is
   http://wsk.eit.com/wsk/dist/doc/admin/webtest/verify_links.html ).

   Also try weblint (URL is
   http://www.khoros.unm.edu/staff/neilb/weblint.html ), a Perl script
   that checks your HTML for errors; you can even try it out over the web
   through an HTML form. The script is available by anonymous FTP from
   ftp.khoros.unm.edu in the directory pub/perl/www.

   Another such tool is htmlchek (URL is:
   http://uts.cc.utexas.edu/~churchh/htmlchek.html ), which checks HTML
   documents for errors, creates a cross-reference, automatically expands
   entities (such as European characters) to their proper HTML form, and
   performs other useful services. htmlchek is available by anonymous FTP
   from ftp.cs.buffalo.edu in the directory pub/htmlchek.

5.4: How do I publicize my work?

   There are several things you can do to publicize your new HTML server
   or other offering:
     * Post to comp.infosystems.www.announce. PLEASE READ THE CHARTER
       POSTING FIRST. In general, always read a newsgroup first to
       familiarize yourself before posting to it.
     * Submit it to the NCSA What's New Page at the URL
       http://www.ncsa.uiuc.edu/SDG/Software/Mosaic/Docs/whats-new.html
       (see the page for details on how to submit your listing!).
     * Post it to the newsgroup comp.infosystems.announce. Please read
       the group first to get a feel for the contents. You should not
       post to comp.infosystems.www.users,.misc,.providers, etc., but if
       you feel compelled to do so, please choose .misc as announcements
       are of interest to both providers and users (and those who wear
       both hats).
     * Submit it to the maintainers of various catalogs, such as the WWW
       Virtual Library (at the URL
       http://info.cern.ch/hypertext/DataSources/bySubject/Overview.html
       ) and the ALIWEB index (at the URL
       http://web.nexor.co.uk/aliweb/doc/aliweb.html ).
     * Read Gareth Rees' guide to publishing on the World Wide Web. (URL
       is http://www.cl.cam.ac.uk/users/gdr11/publish.html ).

5.5: Can I buy space on an existing server?

   Yes, you can. A list of sites offering WWW space for lease is
   available (at the URL http://union.ncsa.uiuc.edu/www/leasing.shtml ).

5.6: How fast does my net connection need to be?

   The following response to this very-frequently-asked-question was
   provided by Mike Meyer ([e-mail]).

     The answer is "It depends." What it depends on is what kind of
     things you want to provide on your server. Here are some rules of
     thumb to use when deciding what kind of connection you need for your
     server.

     The first rule of thumb is:

     Don't worry about simultaneous access.

     Unless you have a very large site, simultaneous access is not a
     problem. If you have a very large site, you need as much bandwidth
     as you can afford. There is a bit more about this below.

     The second rule of thumb is:

     It should take at most 5 seconds to send a page.

     The five second rule dates from command line days, when that was
     about how long people would wait before getting impatient with the
     system. It seems like a reasonable number to use now.

     Since external images/audio/etc. are somewhat exceptional, allow
     more time for them. If you think they should have the same
     restrictions as above, buy the bandwidth your site will need to do
     so. However, the rule of thumb for external images/audio/etc is:

     It should take at most 30 seconds to send an external file.

     Given these rules, it's pretty straightforward to work out how large
     an HTML page and external files can be. At least, it's easy after
     you simplify things by ignoring IP overhead on the line, compression
     on modem lines, and anything that's less than 10% of the total (or
     even a little bit more than 10%).

     The one simplification not to ignore is the multiple packet
     round-trips it takes to get data flowing through an HTTP channel.
     For modem lines, this is nearly a second for each HTTP connection,
     which is significant. For leased lines, it's more like .1 or .2
     seconds, which is not significant.

     On a 14.4 line assumed to be sending 1.4K bytes of data/second, with
     a 1 second startup, you get 4 * 1.4 or 5.6K of HTML. If you want to
     include a single inline image, that's 2 seconds of startup, so
     you're down to 3 * 1.4 or 4.2K of HTML + image. This means smallish
     HTML pages, and simple inline images. For external files, you get 29
     * 1.4 or 40K, which is still a small image. If you have a 28.8 line,
     you get to double those figures; for a 9600 line, figure 2/3rds of
     that size.

     On a 56K leased line assumed to be sending 5K/second, you get 25K of
     HTML, or mixed HTML/data. For external images, it's 150K. That
     should cover any reasonable HTML document, and small to medium
     external files. An MPEG movie might be a bit much.

     With a T1 line assumed to be sending 150K/second, you get 750K of
     HTML, or 4.5 megabytes in an external file. Barring very large
     animations, this should be sufficient for anything you want to
     serve. More would be faster, but it also gets drastically more
     expensive.

     Given the above guidelines, let's look at simultaneous access again.
     Under the worst case conditions, you're using all of your line for
     HTML pages, each of which takes 5 seconds to send, so your server is
     sending 12 pages a minute, or 720 pages an hour, or 17,000 pages a
     day (pages, not accesses; each inline image in a page generates an
     access, unless the client cached it). This makes you one of the
     busier sites on the web. While you'll have contention problems
     before you get to this point, anything but a modem connection will
     be sending most pages in a small fraction of five seconds, which
     should leave plenty of bandwidth with no contention. If you have
     this kind of access rates on a modem line, you should seriously
     consider upgrading your connection.

     The bottom line on simultaneous access is that the WWW server is
     more likely to have contention with other uses of the line than with
     itself. Since I don't know what else you use your line for, I can't
     factor it in. You'll have to consider that issue yourself.



  5.7.1: 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 .

   Using imagemaps requires that you create a map file; you can do this
   by hand or with a WYSIWYG tool.

   VERY IMPORTANT: Creating imagemaps requires a real web server (not
   an FTP server) and a cooperative web server administrator. It is not
   usually as simple as wrapping a link around an IMG SRC tag and adding
   the ISMAP directive; the server must also be told about the map file,
   and the way to accomplish this varies from server to server. So read
   your server documentation, and don't waste time making maps before
   making sure you have the necessary tools to deliver them.

   Mapedit
          Mapedit (URL is:
          http://sunsite.unc.edu/boutell/mapedit/mapedit.html ) is a
          WYSIWYG imagemap editing tool for Microsoft Windows and the X
          Window System.

   MapMaker
          For users of John Bradley's xv image display software for the
          X Window System, Mapmaker can turn the miniature images created
          by xv's Visual Schnauzer into an imagemap. This is useful if
          you would like to make an entire directory of images available
          (but note that you should also make textual links to allow
          those with text- based browsers to download the images for
          external viewing). (URL is:
          http://icg.stwing.upenn.edu:80/~mengwong/mapmaker.html )

   WebMap
          On the Macintosh, you may want to use WebMap (URL is
          ftp://ftp.uwtc.washington.edu/pub/Mac/Network/WWW ). . It
          produces both NCSA and CERN-compatible maps, which can also be
          used with MacImagemap and a Macintosh-based server (MacImagemap
          is found in the same directory). Alternatively, you may want to
          use MacMapMaker, also available from
          ftp://ftp.uwtc.washington.edu/pub/Mac/Network/WWW (the same
          directory).

   Tkmapedit
          For Unix systems and other systems on which the Tk/Tcl language
          toolkit has been installed, Tkmapedit provides a WYSIWYG
          imagemap editor which is capable of directly testing links if
          the tkWWW web browser is available. Available by anonymous FTP
          from the TCL archive on ftp.aud.alcatel.com.



  5.7.2: 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 ([e-mail]) 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.

  5.7.3: WHERE CAN I LEARN HOW TO CREATE FILL-OUT FORMS?

   Writing an HTML form is easy, but the form doesn't accomplish anything
   until you write a CGI program to interpret the results on the server
   side! For more information, see section 5.7.14.

   See the section on email forms for a simple solution to the most
   commonly desired form.

    5.7.3.1: How can I create hidden fields in forms (keeping state)?

   Use INPUT TYPE=hidden. An example:

<INPUT TYPE=hidden NAME=state VALUE="hidden info to be returned with form">

   By now, most browsers can handle the hidden type, but understand that
   some browsers will fail to hide the field (and probably confuse the
   user). Note that "hidden" doesn't mean "secret"; the user can always
   click on "view source".

    5.7.3.2: How can users send me email through their browsers?

   There are two ways:

   Using a mailto: URL
          You can simply create a link which looks like this:

          <A HREF="mailto:[e-mail]">Send Me Mail</A>

          This works great for browsers that support the mailto: URL.
          Perhaps 80% of web users will be able to use such a link. But
          not all browsers support it.

   Installing an email form
          If you have access to the server's configuration files, or if
          your server administrator permits users to create their own CGI
          scripts, you can create a form which sends mail to you from any
          browser that supports forms. I've written a simple email forms
          package (URL is: http://siva.cshl.org/email/index.html ), which
          does it in ANSI C. There is also a package written in Perl,
          known as the WWW Mailto Gateway (URL is
          http://www.mps.ohio-state.edu/mailto/mailto_info.html ).
          GetComments (URL is:
          http://everest.cs.ucdavis.edu/~hoagland/getcomments.html) is a
          more general package, also written in Perl, which can handle
          many different types of comment forms.

          If you want to learn how these forms actually work, see section
          5.7.14.



  5.7.4: HOW DO I COMMENT AN HTML DOCUMENT?



   Use the <!-- tag at the beginning of EACH line commented out; close
   this for EACH line with the --> tag. Note that comments do not nest,
   and the sequence "--" may not appear inside a comment except as part
   of the closing --> tag. (It's officially allowed, but some browsers
   won't handle it properly.)

   You should not try to use this to "comment out" HTML that would
   otherwise be shown to the user, since some browsers (notably Mosaic)
   will still pay attention to tags inside the comment and close it
   prematurely.

   Thanks to Joe English for clearing up this issue.

  5.7.5: HOW CAN I CREATE DECENT-LOOKING TABLES AND STOP USING <PRE>... </PRE>?

   Tables are a standard feature in HTML Level 3, a new version of HTML.
   Unfortunately, they are at present implemented only by the latest NCSA
   Mosaic versions and the Viola and Emacs-W3 browsers, to my knowledge.
   In addition, most implementations are incomplete. In some
   implementations, at the time of this writing, text in tables cannot be
   selected and/or cannot be a link.

   However, there is a way to use HTML Level 3 tables now and convert
   them automatically to HTML, allowing you to design proper tables and
   install those pages directly when table support arrives in the
   majority of clients. You can do this using the html+tables package, by
   Brooks Cutter ([e-mail]), which is available for anonymous
   ftp from sunsite.unc.edu in the directory
   pub/packages/infosystems/WWW/tools/html+tables.shar. This package
   requires the shell language Perl, which is primarily used on Unix
   systems but is also available for other systems (such as MSDOS
   machines). html+tables accepts HTML Level 3 and outputs html using the
   <PRE>...</PRE> construct to represent tables, allowing you to write
   HTML Level 3 now, knowing that it will look better when clients are
   ready for it.

  5.7.6: WHAT IS HTML LEVEL 3 AND WHERE CAN I LEARN MORE ABOUT IT?

   HTML Level 3, also known as HTML+, is an enhanced version of HTML
   designed to address some of the limitations of HTML. HTML Level 3
   supports true tables, right-justified text, centered text, line breaks
   that do not double space, and many other desired features.

   However, most clients support only a handful of HTML Level 3 features
   (such as the partial implementation of tables in Mosaic) at the time
   of this writing. If you have access to a Unix system with the X Window
   System installed, you can try out many features of HTML Level 3 using
   the experimental Arena browser.

   You can access information about new developments in HTML at the CERN
   server (at the URL
   http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html ).

   (HTML Level 1 is the original version. HTML Level 2 is essentially the
   same, but with the addition of forms.)

  5.7.7: HOW CAN I MAKE TRANSPARENT AND INTERLACED GIFS? AND WHAT ARE THEY?

   Transparent GIFs are useful because they appear to blend in smoothly
   with the user's display, even if the user has set a background color
   that differs from that the developer expected. They do this by
   assigning one color to be transparent -- if the web browser supports
   transparency, that color will be replaced by the browser's background
   color, whatever it may be.

   Interlaced GIFs appear first with poor resolution and then improve in
   resolution until the entire image has arrived, as opposed to arriving
   linearly from the top row to the bottom row. This is great to get a
   quick idea of what the entire image will look like while waiting for
   the rest. This doesn't do much for you if your web browser doesn't
   support progressive display as the image is downloaded, but
   non-progressive-display web browsers will still display interlaced
   GIFs once they have arrived in their entirety.

   To create transparent and interlaced GIFs, check out David Koblas'
   giftool, a program which can manipulate those options and many more
   aspects of your GIF file.

   In addition, there is a document explaining transparent GIFs available
   at the URL http://melmac.corp.harris.com/transparent_images.html . You
   can fetch the program giftrans by anonymous ftp from
   ftp.rz.uni-karlsruhe.de at the path /pub/net/www/tools/giftrans.c.

   There is also a Perl Script (URL is:
   http://www.omron.co.jp:80/~jfriedl/perl/ ) which makes transparent
   GIFs.

   There is also a utility for the Macintosh, Transparency (URL is:
   http://www.med.cornell.edu/~giles/projects.html#transparency).

  5.7.8: HOW COME MAILTO: URLS DON'T WORK?

   The mailto: URL is a feature found in Lynx, Netscape, Spry Mosaic, the
   latest NCSA Mosaics, Emacs w3 mode and many other browsers. In
   general, about 80% of web browsers support mailto: at the time of this
   writing. However, it is not in numerous older browsers. In the
   meantime, you can set up forms which send mail to you; see Section
   5.7.3.2.

  5.7.9: HOW CAN I RESTRICT AND CONTROL ACCESS TO MY SERVER?

   All major servers have features that allow you to limit access to
   particular sites, and many clients have authentication features that
   allow you to identify specific users. There is a tutorial on security
   and user authentication with the NCSA server and Mosaic available,
   written by Marc Andreessen (URL is
   http://wintermute.ncsa.uiuc.edu:8080/auth-tutorial/tutorial.html ).
   See your server documentation for further information.

  5.7.10: WHICH FORMAT IS BETTER FOR WWW IMAGE PURPOSES, JPEG OR GIF?



   JPEG does a better job with realistic images such as scanned
   photographs. Most browsers cannot handle inline JPEGs, however, so you
   must link to them as external images (using a regular <A HREF...>
   instead of <IMG SRC...>).

   GIF does a better job with crisp, sharp images, such as those
   typically used to construct buttons, graphs and the like. All browsers
   that can display graphics at all can display GIFs inline.

  5.7.11: HOW CAN I MIRROR PART OF ANOTHER SERVER?

   Scripts are available to do this, but at this time they are not very
   friendly to the server you are attempting to mirror; their behavior
   resembles that of the more poorly written WWW robots. If you are
   trying to improve access times to a distant server, you will likely
   find the "proxy" capabilities of CERN's WWW server to be a more
   effective and general solution to your problem.

  5.7.12: HOW CAN I KEEP ROBOTS OFF MY SERVER?

   Programs that automatically traverse the web can be quite useful, but
   have the potential to make a serious mess of things. Every so often
   someone will write a "depth-first" searching robot that brings servers
   to their knees. See the section on writing robots (4.10) for details.

   Fortunately, most robots on the web follow a simple protocol by which
   you can keep them off your server if you wish, or keep them out of
   portions of your server which are robot traps (ie, they contain an
   infinite number of possible links). Read the document World Wide Web
   Robots, Wanderers and Spiders (URL is:
   http://web.nexor.co.uk/mak/doc/robots/robots.html ) and learn about
   the emerging standards for exclusion of robots from areas in which
   they are not wanted. You can also read about existing robots there,
   including useful cataloging robots you probably do not want to keep
   off your server.

  5.7.13: HOW CAN I KEEP STATISTICS ABOUT MY WEB SERVER?

   There are several tools which can generate statistics about your web
   server:

   getstats
          getstats is a versatile log analyzer, also written in C, which
          provides reports for various time periods with a high degree of
          flexibility. Add-on packages have been written to generate
          reports in HTML and also to generate graphs. You can access the
          getstats home page for more information (URL is
          http://www.eit.com/software/getstats/getstats.html ), or obtain
          the package by anonymous FTP from ftp.eit.com in the directory
          /pub/web.software/getstats.

   WebStat
          WebStat is a package written in the language Python which
          supplies statistics on usage by domain, country, etc., with
          daily, weekly, monthly and annual reports available. You will
          need Python in order to use it. See the WebStat home page (URL
          is
          http://www.pegasus.esprit.ec.org/people/sijben/statistics/advertisment.html
          ) for details, or obtain Python from ftp.cwi.nl in
          the directory /pub/python and WebStat from
          ftp.pegasus.esprit.ec.org in the directory /pub/misc.

   Wusage
          Wusage, which I wrote, is a C program which generates simple
          weekly reports in HTML, with inline image graphs displaying
          server growth and the distribution of accesses by continent.
          You can also exclude irrelevant accesses (inline images, local
          machines, etc.) from the results. Read the Wusage home page
          (URL is http://siva.cshl.org/wusage.html ) for more
          information, or obtain Wusage by anonymous FTP from
          isis.cshl.org in the directory pub/wusage.

   wwwstat
          wwwstat is a full-featured log analyzer written in the language
          Perl. (See the newsgroup comp.lang.perl for more information
          about the language.) See the wwwstat home page (URL is
          http://www.ics.uci.edu/WebSoft/wwwstat/ ) for more information,
          or obtain the package by anonymous FTP from liege.ics.uci.edu
          in the directory /pub/arcadia/wwwstat. See also gwstat (URL is
          http://dis.cs.umass.edu/stats/gwstat.html ), a package which
          produces GIF graphs from the output of wwwstat.



  5.7.14: I WANT TO GENERATE WEB PAGES FROM A PROGRAM. DO I HAVE TO WRITE A
  CUSTOM SERVER?

   No, you will not need to write a custom server. Most web servers
   support one variation or another of a standard for adding your own
   programs to the web server. The standard is called CGI (Common Gateway
   Interface).

   Marc Hedlund has written a FAQ on CGI programming (URL is:
   http://www.halcyon.com/hedlund/cgi-faq/ ) which makes a good
   introduction to the subject. The standard itself can be found at NCSA
   (URL is: http://hoohoo.ncsa.uiuc.edu/ ).

    5.7.14.1: How can I generate GIFs on the fly from my CGI scripts?

   If you want to generate GIF images on the fly as part of your
   application, examine the gd library (URL is:
   http://siva.cshl.org/gd/gd.html ). Hint: your HTML page and your
   inline images are separate documents with separate URLs. Generate them
   in response to separate requests! (Yes, there are tricks to speed this
   up, but be careful not to break inline images on HTML pages you didn't
   write that refer to your gd-generated image.)

   It's also possible to use gnuplot and the pbmplus utilities. This is
   slower, but can require less programming if gnuplot is sufficient for
   your purposes. (See archie for both tools.)

                  6: WHERE CAN I DISCUSS THE WORLD WIDE WEB?

6.1: What newsgroups discuss the Web?

   You can find discussion of World Wide Web topics in three newsgroups,
   and one newsgroup which will soon be removed:

   comp.infosystems.www.users
          A forum for the discussion of WWW client software and its use
          in contacting various Internet information sources. New user
          questions, client setup questions, client bug reports,
          resource-discovery questions on how to locate information on
          the web that can't be found by the means detailed in the FAQ
          and comparison between various client packages are among the
          acceptable topics for this group. Please specify what browser
          and what system type (Windows, Mac, Unix, etc.) your post is
          about if you are asking questions about a specific program.

   comp.infosystems.www.providers
          A forum for the discussion of WWW server software and the use
          of said software to present information to users. General
          server design, setup questions, server bug reports, security
          issues, HTML page design and other concerns of information
          providers are among the likely topics for this group.

   comp.infosystems.www.misc
          A forum for general discussion of WWW (World Wide Web)- related
          topics that are NOT covered by the other newsgroups in the
          hierarchy. This will likely include discussions of the Web's
          future, politicking regarding changes in the structure and
          protocols of the web that affect both clients and servers, et
          cetera.

   comp.infosystems.www.announce
          A moderated forum for the announcement of new and updated World
          Wide Web resources and software.

   comp.infosystems.www (DEFUNCT)
          The old catch-all newsgroup, which may still exist on your
          system but was officially removed on September 7th, 1994,
          according to David Lawrence, moderator of
          news.announce.newgroups. If your system still carries this
          group, ask your administrator to remove it.



6.2: What mailing lists discuss the Web?

   [e-mail]
          Address: [e-mail] for CONTRIBUTIONS ONLY.
          Administration: [e-mail] (robot)
          [e-mail] (human). Description: Technical
          discussion, W3 related. Experts to experts. General questions
          to the newsgroups, please. Archive: Not currently served, but
          kept.

   [e-mail]
          Address: [e-mail]. NOT FOR GENERAL USE -
          serious low-volume announcements only. Administration:
          [e-mail] (robot),
          [e-mail] (human). Description: Low
          volume summary announcemements of product releases, etc.
          Archive: Not currently public.



                            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!

   Once you're up and running, you may wish to consult the World Wide Web
   Primer by Nathan Torkington. It is available at the URL
   http://www.vuw.ac.nz/who/Nathan.Torkington/ideas/www-primer.html .

   Later you may return to this FAQ for answers to some of the more
   advanced questions. I encourage you to check out the changes listed
   early in the document each time the FAQ appears.

                                  8: CREDITS

   Maintainer (11/93 to present): Thomas Boutell, [e-mail]

   Former Maintainer (until 11/93): Nathan Torkington,
   [e-mail]