6 Mail programs, mail, Mail, Columbia mm, elm, ...

World Wide Web



C H A P T E R 27



27.1 WWW

The World Wide Web (WWW) uses the HyperText Markup Language (HTML), a subset of the

Standard Generalized Markup Language (SGML), as one of its formats. This allows you publish

your own multimedia documents on the network. The Internet protocol used is HyperText Transfer

Protocol (http), which allow the client and server to negotiate the transfer representation of the

document. We’ll use this as an example of how to set up a complicated server on your workstation.



27.2 URLs

Uniform Resource Locators, URLs, reference where a resource can be found in the form:

service_scheme://machine_name[:port_number]/directory/sub-directory_list/file[?keyword]



where the items in brackets are optional. Some of the more common service_schemes are:

•

•

•

•

•



ftp - file transfer protocol, a “;type=” may be used to indicate the file type

(e.g. an “I” for image, or an “A” for text)

http - hypertext transfer protocol

gopher - gopher protocol

news - Usenet news via NNTP

telnet, rlogin, or tn3270



The service_scheme could, optionally, include a user name and password, if required for the service.

The machine_name may be followed by a decimal port_number, separated from the machine_name

by a colon, if something other than the default port number, 80, is used by the service.

The remainder of the address is the path, with subdirectories separated by “/” and ending with the

desired file name or program. The latter may optionally be followed by a “?” and a keyword that can

be used as an argument to the program. The specs for URLs can be found on:

http://www.w3c.org/Addressing/URL/Overview.html



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27.3 WWW Server

You have many choices of free servers, but one stands out; the others that were once most popular

have been discontinued because Apache is so good.

•



Apache - Hypperreal’s extensions to the original NCSA server.

http://www.apache.org/

This usually comes in source form, though binaries may be available.



27.4 WWW Browsers

There are four main browsers that you might be interested in:

•



Netscape - from Netscape Communications, Corp., the second generation browser

http://home.netscape.com/download/ - for a pre-compiled binary.



•



Mozilla - the public development version of Netscape Navigator.

http://www.mozilla.org/ - for source or binary.



•



HotJava - from Sun, written in Java and requires Java to run

Comes with Solaris 2.6+, or get it from http://java.sun.com/products/hotjava/.



•



Lynx - a powerful text only browser

http://lynx.browser.org/.



27.5 Setting up your Server

For our example we’ll use the Apache httpd server. After retrieving the source from the reference

above check out the README and src/INSTALL files for installation and configuration information.

To compile your own daemon uncompress and un-tar the source tree and edit the default control files

in the conf directory: srm.conf, access.conf, httpd.conf. Then edit the src/Configuration file to select

a compiler to use, options, and the modules to include. Some things you might change:

CC= cc

CFLAGS= -DMAXIMUM_DNS DXBITHACK

AUX_CFLAGS= -DSOLARIS2

AUX_LIBS= -lsocket -lnsl

Module agent_log_module

Module referer_log_module

Module config_log_module mod_log_config.o



or

or

or

or



CC=gcc

CFLAGS= -O2

AUX_CFLAGS= -DSUNOS4

AUX_LIBS=



You can set the paths for the various services, control files, and log files in httpd.h. Some examples

of entries you might change are:

#define HTTPD_ROOT "/usr/local/etc/httpd¨



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Setting up your Server

#define DEFAULT_ADMIN "[no address given]" -->

#define DEFAULT_PORT 80

#define DEFAULT_XFERLOG "logs/access_log"

#define DEFAULT_INDEX "index.html"

#define ACCESS_CONFIG_FILE "conf/access.conf"



"webmaster"



27.5.1 Compilation of the programs

To compile the http daemon, httpd, first go to the src subdirectory (cd src) and type "./Configure"

and respond to any questions, then type “make”. It will default to using the Makefile in that

directory. Then build any support files needed in the support directory (cd ../support) after editing

the Makefile to select the desired compiler and programs. Then install the necessary programs in

their desired directories.

The full list of steps can be found at: ftp://wks.uts.ohiostate.edu/pub/solaris2/src/UTSinfo_apache-httpd-1.0.3, along with the source and compiled binaries

in the file apache_1.0.3.tar.gz in the same directory.

WWW will support applications other than just display. There are a few sample auxiliary programs

you can compile in the cgi-src directory and install in the cgi-bin directory, which already contains a

few sample shell scripts. If you’re not going to support these services than you can ignore this step.

27.5.2 Configuration

For complete documentation on how to set up your server use netscape or mosaic to web to

http://www.apache.org/. There you can find step-by-step instructions on how to configure the server.

The configuration file can be found in the conf directory. There is an example file you can use,

httpd.conf-dist, to create your server configuration file, httpd.conf.

Some of the entries you’ll want to check out are:

ServerType standalone

Port 80

User http

Group http

ServerAdmin you@your.address

ServerRoot /usr/local/httpd



or



inetd



The latter determines the directory hierarchy for your service. It could have sub-directories such as:

cgi-bin, conf, htdocs, icons, and logs.

This is a service you don’t want to run as root, so you should create a special user and group just for

it. So in /etc/passwd you might have an entry similar to:

http:nologin:999:999:World Wide Web Server:/usr/local/http:/bin/false



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and a /etc/group entry similar to:

http:*:999:frank



You can run your server either as a standalone server, in which case you would start it up in an RC

script, or as a service controlled by inetd. In the latter case you would need an entry in /etc/services

similar to:

http



80/tcp



# WWW server



and another in /etc/inetd.conf similar to:

http stream tcp nowait http /usr/local/etc/httpd -d /usr/local/httpd -f /usr/local/httpd/conf/httpd.conf



where

-d

-f



specifies the ServerRoot and where the daemon will look for it’s configuration file

(not necessary if you use the default ServerRoot path in the configuration file.)

specifies the configuration file



To set it up as a standalone server you might put an entry similar to the following in an RC script, e.g.

/etc/rc.local for SunOS 4.1.X:

if [ -f /usr/local/etc/httpd -a -d /usr/local/httpd -a -f /usr/local/httpd/conf/httpd.conf ]; then

/usr/local/etc/httpd -d /usr/local/httpd -f /usr/local/httpd/conf/httpd.conf; echo -n ’ httpd’

fi



For SunOS 5.X set up a script to start and stop the service as you go through run level 2.

Running httpd as a standalone daemon is more efficient, but running as a service of inetd provides

greater access control. If you’re using TCPwrapper you can specify which machines or subnets have

access to your http service when each connection is controlled by inetd.



27.6 Home Page

To complete your service you’ll want to set up a Home Page on your server.

You’ll need to know a little bit about HTML and the following primer will help you get started:

http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html



A good style guide can be found at:

http://www.sun.com/styleguide/



A simple home page could be something like this one, which you could once find on

http://wks.uts.ohio-state.edu, with the following HTML:

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Home Page