ch11.htm

Web_Programming_with_Perl5,一个不错的Perl语言教程。

print "</form></center><hr>";

print "<center>";

# print "<table width=100%><tr><td>";

print "[ <a href=\"$base_url$edit_announce?$this_month&$this_year\">

       Add an announcement</a> for this month. ";

print "| <a href=\"$base_url$edit_announce?$this_month&$this_year&delete\">

    Delete an announcement</a> from this month." unless ($any_announce eq "no");

print " ]";

print "</center>";

print "<center>";

print "<hr>[ <a href=\"http://www.rcbowen.com/perl/HyperCal.html\">

       About HyperCal</a>.";

foreach $item (@linkto)    {

($url, $page_title)=split(/~~/,$item);

print " | <a href=\"$url\">$page_title</a>";

            }

if ($multi_user eq "yes")    {

print " | <a href=\"$base_url$change_passwd\">Change your user password</a>"}

print " ]</center><br>\n";

print "HyperCal, Version $version, Copyright © 1996, Richard Bowen.  

All rights reserved.<br>\n";

&footer;

    }    #  End of sub main

sub appoints   {

$found=0;

&julean($_[0],$_[1],$_[2]);  #  Julean date of day

for $entry (@datebook)    {

@temporary=split(/~~~/,$entry);

if (@temporary[0]==$jule)  {$found++}};

if ($found != 0) {print "   ($found)"};    }

sub goto    {

($pair1, $pair2, $pair3)=split(/&/,$args);

($junk, $month)=split(/=/, $pair1);

($junk, $year)=split(/=/, $pair2);

($junk, $this_year)=split(/=/, $pair3);

#  Need some error checking ...

if ($month eq ""){$month=1};

if ($year eq""){$year=$this_year};

if ($month>12) {$month=12};

if ($month<1) {$month=1};

if ($year<1) {$year=1};

if ($year>9999) {$year=9999};

$args="$month&$year";

&main

    }

sub personal    {

$sub=~s/personal\///;

$user_id=$ENV{`REMOTE_USER'};

$user_variables=~s/USERNAME/$user_id/;

require "$user_variables";

}

</FONT></PRE>

<P>Let's take a look at how HyperCal works. HyperCal uses a library called <TT>httools.pm</TT>,

which takes care of things like printing headers and parsing forms. CGI.pm could

be used instead of httools.pm with a few simple modifications to HyperCal's code.

The httools.pm module supports the following functions in HyperCal: <BR>

<BR>



<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><B>Function</B></TD>

		<TD ALIGN="LEFT" VALIGN="TOP"><B>Usage and Description</B></TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><TT>header</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Prints MIME content type header.</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><TT>title</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Prints title for HTML page: <TT>&amp;title(`Desired title')</TT></TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><TT>form_parse</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Parses form, places variables in <TT>$FORM{`variable_name'}</TT>.</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><TT>footer</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Prints generic footer.</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><TT>date</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Returns today's date in nicer format.</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><TT>julean</TT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Returns Julian date with Jan 1, 1995, as day 1.</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="96" ALIGN="LEFT" VALIGN="TOP"><FONT COLOR="#000000">todayjulean</FONT></TD>

		<TD ALIGN="LEFT" VALIGN="TOP"><FONT COLOR="#000000">Returns today's Julian date, calls julean.</FONT></TD>

	</TR>

</TABLE>

</P>

<P>HyperCal stores the URI encoded path info in the QUERY_STRING to a variable named

<TT>$args</TT>. Path info (variables encoded in the URI) is next filtered into the

variable <TT>$sub</TT>. The variable <TT>$sub</TT> is then evaluated to determine

what output the program should generate.</P>

<P>The hypercal.cgi program will do different things based on what variables are

present (or not present) in the QUERY_STRING (data appended to the URI) when it is

run. The principle behind this concept is simple. The HTML output (calendar) generated

by running the program contains HTML links back to the program. In other words, the

HTML calendar contains links and forms whose URIs reference back to the hypercal.cgi

script again. However, the links also contain variables appended to the URI. When

a user clicks on the URI with the appended variables, the program is run again. This

time it parses the variables in the URI and can react differently based on those

self-supplied variables. This is precisely what is happening in lines 15-17. If no

variables are found in the URI, the <TT>else</TT> statement instructs the program

to execute the <TT>&amp;main</TT> subroutine that prints the HTML for the calendar.</P>

<P>If variables are supplied to HyperCal in its URI, one of two subroutines is called

first. The <TT><BR>

&amp;personal</TT> subroutine determines if a personal calendar is being used and

alters a few variables accordingly. I'll discuss using personal calendars in more

depth in a moment. The other subroutine that may be called is <TT>&amp;goto</TT>.

The <TT>&amp;goto</TT> subroutine directs HyperCal to display a specific month. The

month and year must be supplied in the URI, in the following format:</P>

<PRE><A HREF="javascript:if(confirm('http://uri/hypercal.cgi/goto?month=9&year=1999&this_year=1996  \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address.  \n\nDo you want to open it from the server?'))window.location='http://uri/hypercal.cgi/goto?month=9&year=1999&this_year=1996'" tppabs="http://uri/hypercal.cgi/goto?month=9&year=1999&this_year=1996"><FONT

COLOR="#0066FF">http://URI/hypercal.cgi/goto?month=9&amp;year=1999&amp;this_year=1996

</FONT></A><FONT COLOR="#0066FF"></FONT></PRE>

<P>The <TT>&amp;goto</TT> subroutine reads the three name/value pairs, trashes the

names, and stores the values to <TT>$month</TT>, <TT>$year</TT>, and <TT>$this_year</TT>.

The month and year are then stored in <TT>$args</TT>, and the main subroutine is

called to display the requested month. Note that if <TT>$args</TT> does not contain

a prespecified month, the current month is used.</P>

<P>Using multiple users requires a few extra steps. In the configuration file (discussed

next), the <TT>$multi_user</TT> variable must be set to <TT>yes</TT>. Note that in

the <TT>&amp;main</TT> subroutine in hypercal.cgi, if this variable is set to <TT>yes</TT>,

a button <TT>Go To Personal Calendar</TT> is displayed.</P>

<P>Personal calendars are protected by restricting access to the user directory in

which HyperCal keeps the user data using the <TT>.htgroup</TT> and <TT>.htpasswd</TT>

file. The usage of <TT>.htpasswd</TT> is discussed more thoroughly in Chapter 3.

The cal_admin.cgi program is used to add users and passwords to the <TT>.htpasswd</TT>

file, essentially adding users to the calendar. To set up HyperCal in multi-user

mode, variables in the config file need to be set.

<CENTER>

<H4><A NAME="Heading5"></A><FONT COLOR="#000077">Configuration of HyperCalThe Variables

File</FONT></H4>

</CENTER>

<P>All of HyperCal's configuration variables are located in a separate file named

&quot;variables.&quot; By carefully reading over the configuration file, you can

get an idea of what HyperCal does and how to configure it. Listing 11.2 shows the

&quot;variables&quot; file for HyperCal.

<CENTER>

<H3><A NAME="Heading6"></A><FONT COLOR="#000077">Listing 11.2. Variables and configuration

file for HyperCal.</FONT></H3>

</CENTER>

<PRE><FONT COLOR="#0066FF">

$version=&quot;2.3&quot;;

#  Names of the various program files

#  Some sites only allow cgi's with a .cgi extension

#  so you might need to change your file names

$add_date=&quot;add_date.cgi&quot;;

$del_date=&quot;del_date.cgi&quot;;

$disp_day=&quot;disp_day.cgi&quot;;

$edit_announce=&quot;edit_announce.cgi&quot;;

$hypercal=&quot;hypercal.cgi&quot;;

$cal_admin=&quot;cal_admin.cgi&quot;;

$personal=&quot;personal.cgi&quot;;

$change_passwd=&quot;change.password&quot;;

# Other files

$datebook=&quot;datebook&quot;;

$hypercal_id=&quot;hypercal_id&quot;;

$announce=&quot;announce&quot;;

$users_dir=&quot;/www/cgi-bin/datebook/users/&quot;;

$user_variables=&quot;/www/cgi-bin/datebook/users/USERNAME/variables&quot;;

# variables

#  Are you running a secure site with personal accounts?

$multi_user=&quot;no&quot;;

$personal_on=&quot;no&quot;;

$old=370;

#  Number of days to keep past dates

# Your info goes here - dont make this me, please

$admin=&quot;Richard Bowen&quot;;

$admin_mail=&quot;rbowen\@databeam.com&quot;;

$admin_uid=&quot;rbowen&quot;;

# Person to contact with problems

$base_url=&quot;/scripts/hypercal/&quot;;

# URL of the directory in which these files live

$title=&quot;HyperCal&quot;;

# Title of the calendar.

$htpass=&quot;/www/passwd/.htpasswd&quot;;

$htgroup=&quot;/www/passwd/.htgroup&quot;;

#  Location of the .htpasswd and .htgroup files

#  This will be used only if you are running the security part

@linkto=(&quot;http://www.mk.net/~~MK.net Home Page&quot;, &quot;/perl/~~My Perl archive&quot;);

#  Places to provide links to on each page.

#  This array contains the locations of images for the various

#  months.  The format is:

#  &quot;url_for_icon~~url_for_background~~bgcolor~~link~~visited link&quot;

#  This array must contain 12 elements. Any field where you have

#  no preference, indicate by &quot;none&quot;

@month_images=(&quot;images/january.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/february.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/march.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/april.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/may.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/june.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/july.gif~~none~~none~~none~~none~~none&quot;,

    &quot;none~~none~~none~~none~~none~~none&quot;,

    &quot;none~~none~~none~~none~~none~~none&quot;,

    &quot;images/october.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/november.gif~~none~~none~~none~~none~~none&quot;,

    &quot;images/december.gif~~none~~none~~none~~none~~none&quot;);

1;

</FONT></PRE>

<P>Notice which elements of the program are located in the configuration file. The

first two blocks define the names of the supplementary programs and the names and

locations of various configuration files. These locations are different on different

software platforms and flavors of UNIX, so placing them in a configuration file instead

of hard coding them into your code significantly increases your ability to easily

get your CGI running on different servers. In general, anything that you might want

to change, or will change based on the software environment of your CGI, should be

defined in a configuration file.</P>

<P>Arrays are a great way to store variables with multiple elements, like the <TT>month_images</TT>

in the <BR>

preceding example. Notice that the last line of code uses a return value to verify

the successful loading of the file to the main program.

<CENTER>

<H4><A NAME="Heading8"></A><FONT COLOR="#000077">Displaying Appointments on a Specific

Day: disp_day.cgi</FONT></H4>

</CENTER>

<P>Each day in the calendar is a link to disp_day.cgi, along with the date URI encoded.

For example, a link to June 25, 1997, looks like this:</P>

<PRE><FONT COLOR="#0066FF">http://myserver.com/hypercal/disp_day.cgi?6&amp;25&amp;1997

</FONT></PRE>

<P>The disp_day.cgi script, shown in Listing 11.3, simply reads the day from the

URI, reads the datebook database, looks up the Julian date to reference the database

entry, and formats an HTML page based on the contents of the database (if any) on

that day.

<CENTER>

<H3><A NAME="Heading9"></A><FONT COLOR="#000077">Listing 11.3. disp_day.cgi.</FONT></H3>

</CENTER>

<PRE><FONT COLOR="#0066FF">#!/usr/bin/perl

#  Display Day.  Reads in database and prints appointments for the

#  selected day.  Allows option of adding new appointment.

#

require `variables';

require `httools.pl';

&amp;header;

#  Determine if this is a personal calendar;

($sub=$ENV{`PATH_INFO'})=~s#^/##;

if ($sub=~/personal/){require $personal};

#   Read date from QUERY_STRING

$info=$ENV{`QUERY_STRING'};

($month,$day,$year)=split(/&amp;/,$info);

#  Print titles to html page

&amp;month_txt(&quot;$month&quot;);

&amp;title(&quot;Appointments for $month_txt $day, $year.&quot;);

print &quot;&lt;h2&gt;Appointments for $month_txt $day, $year.&lt;/h2&gt;&lt;hr&gt;&quot;;