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<html><head><title>Running CGI Scripts with mod_perl (Perl in a Nutshell, 2nd Edition)</title><link rel="stylesheet" type="text/css" href="../style/style1.css" /><meta name="DC.Creator" content="Stephen Spainhour" /><meta name="DC.Format" content="text/xml" scheme="MIME" /><meta name="DC.Language" content="en-US" /><meta name="DC.Publisher" content="O'Reilly & Associates, Inc." /><meta name="DC.Source" scheme="ISBN" content="0596002416L" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="Perl in a Nutshell, 2nd Edition" /><meta name="DC.Type" content="Text.Monograph" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Java and XSLT" /><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch11_03.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228" /><td align="right" valign="top" width="228"><a href="ch11_05.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">11.4. Running CGI Scripts with mod_perl</h2><p><a name="INDEX-1724" /><a name="INDEX-1725" /><a name="INDEX-1726" />What most people wantto do with <em class="emphasis">mod_perl</em> is improve CGI performance.The <em class="emphasis">mod_perl</em> installation assumes this requestby enabling the <tt class="literal">PerlHandler</tt> callback hook bydefault and by installing the Apache::Registry module.<tt class="literal">PerlHandler</tt> is the handler used for the contentretrieval stage of the server transaction. Apache::Registry is thePerl module that emulates the CGI environment so you can use"standard" Perl CGI scripts with<em class="emphasis">mod_perl</em> without having to rewrite them (much).This is by far the cheapest way to get improved CGI performance.</p><p>With Apache::Registry, each individual CGI program is compiled andcached the first time it is called (or whenever it is changed) andremains available for all subsequent instances of that CGI script.This process avoids the costs of startup time.</p><p><a name="INDEX-1727" />Whereas most CGI scripts are kept in<em class="emphasis">cgi-bin</em>, scripts that use Apache::Registry areplaced in a separate directory, e.g., <em class="emphasis">perl-bin</em>.The <em class="emphasis">access.conf</em> Apache configuration file needsto point to this directory by setting an alias and defining a handlerfor this new location:</p><blockquote><pre class="code">Alias /perl-bin/ /usr/local/apache/perl-bin/<Location /perl-bin>SetHandler perl-scriptPerlHandler Apache::RegistryPerlSendHeader OnOptions ExecCGI</Location></pre></blockquote><p><a name="INDEX-1728" />Instead of using the<tt class="literal">cgi-script</tt> handler, we use the<tt class="literal">perl-script</tt> handler to give control to<em class="emphasis">mod_perl</em>. Next, the<tt class="literal">PerlHandler</tt> directive tells<em class="emphasis">mod_perl</em> that the Apache::Registry module shouldbe used for serving all files in thatdirectory.<tt class="literal">PerlSendHeader</tt> is another<em class="emphasis">mod_perl</em>-specific directive; in this case, ittells <em class="emphasis">mod_perl</em> to send response lines and commonheaders—by default, none are sent. (For NPH scripts,you'll want to turn this feature off again.)<tt class="literal">Options ExecCGI</tt> is a standard Apache header thatis needed to tell Apache to treat the script as a CGI script.</p><p>If you want to load Perl modules in addition to Apache::Registry, youcan use the PerlModule directive<a name="INDEX-1729" />:</p><blockquote><pre class="code">PerlModule CGI</pre></blockquote><p>If you include this line, you shouldn't need toexplicitly <tt class="literal">use CGI</tt> in each Perl CGI scriptanymore, since CGI.pm will be loaded directly from the Apache server.Up to ten modules can be listed with the<tt class="literal">PerlModule</tt> directive.</p><p>CGI scripts in the new directory should work now. However, if youhave problems, the <em class="emphasis">mod_perl</em> manpage offers somewords of wisdom:</p><ul><li><p>Always use <tt class="literal">use strict</tt>. Standard CGI scripts startwith a clean slate every time. When switching to<em class="emphasis">mod_perl</em>, CGI programmers are often surprised tolearn how often they take advantage of this fact. <tt class="literal">usestrict</tt> tells you when your variableshaven't been properly declared and might inheritvalues from previous invocations of the script.</p></li><li><p><a name="INDEX-1730" />Don'tcall <tt class="literal">exit( )</tt>. Calling <tt class="literal">exit( )</tt>at the end of every program is a habit of many programmers. Whileoften totally unnecessary, it usually doesn't hurt .. . except with <em class="emphasis">mod_perl</em>. Ifyou're using <em class="emphasis">mod_perl</em> withoutApache::Registry, <tt class="literal">exit( )</tt> kills the serverprocess. If <tt class="literal">exit( )</tt> is the last function call, youcan just remove it. If the structure of your program is such that itis called from the middle of the script, you can just put a label atthe end of the script and use <tt class="literal">goto( )</tt>.There's also an <tt class="literal">Apache->exit()</tt> call you can use if you're reallyattached to <tt class="literal">exit( )</tt> s.</p><p>If you're using Apache::Registry, youdon't have to worry about this problem.Apache::Registry is smart enough to override all <tt class="literal">exit()</tt> calls with <tt class="literal">Apache->exit( )</tt>.</p></li></ul><p>In addition, it is recommended that you should use recent versions ofPerl and CGI.pm. You should scan the <em class="emphasis">mod_perl</em>documentation for the latest compatibility news.<a name="INDEX-1731" /><a name="INDEX-1732" /><a name="INDEX-1733" /></p><hr width="684" align="left" /><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch11_03.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch11_05.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">11.3. mod_perl Handlers</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">11.5. Server-Side Includes with mod_perl</td></tr></table></div><hr width="684" align="left" /><img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" /><p><p><font size="-1"><a href="copyrght.htm">Copyright © 2002</a> O'Reilly & Associates. All rights reserved.</font></p><map name="library-map"><area shape="rect" coords="1,0,85,94" href="../index.htm"><area shape="rect" coords="86,1,178,103" href="../lwp/index.htm"><area shape="rect" coords="180,0,265,103" href="../lperl/index.htm"><area shape="rect" coords="267,0,353,105" href="../perlnut/index.htm"><area shape="rect" coords="354,1,446,115" href="../prog/index.htm"><area shape="rect" coords="448,0,526,132" href="../tk/index.htm"><area shape="rect" coords="528,1,615,119" href="../cookbook/index.htm"><area shape="rect" coords="617,0,690,135" href="../pxml/index.htm"></map></body></html>?? 快捷鍵說明
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