ch10.htm

Web_Programming_with_Perl5,一个不错的Perl语言教程。

<BR>

<BR>

To search using GlimpseHTTP, view the ghindex.html file that has been generated in

each directory. The ghindex.html page has a search form which you can use search

that particular subdirectory of the archive.</P>

<P>GlimpseHTTP allows you to integrate search with browsing. If you have several

nested directories which the user may browse, you can include the Glimpse interface

in each document such that only the relevant directories will be included in the

search. More details are given below.</P>

<P>The current version of GlimpseHTTP was tested under httpd 1.2 HTML server from

NCSA, and works on Apache and other Web servers.</P>

<P>Some features of GlimpseHTTP include:



<UL>

	<LI>Combined browsing and searching; first, you locate the directory where the relevant

	information might be located, then you can use search to locate specific files. The

	result of a search is nicely formatted hypertext with hyperlinks to matching documents.

	<P>

	<LI>Easy generation of search pages

	<P>

	<LI>Configurable search pages

	<P>

	<LI>Well-documented scripts and complete online documentation

	<P>

	<LI>Easy installation

	<P>

	<LI>Non-centralized archive management, allowing separate users to maintain separate

	archives with no special permissions needed

	<P>

	<LI>Uses the Glimpse search engine, which provides some unique features:

</UL>







<BLOCKQUOTE>

	<P>Uses a very small index (3 to 5 percent of the total text) Very fast search Searches

	for approximate match, allowing errors



</BLOCKQUOTE>



<H3 ALIGN="CENTER"><A NAME="Heading6"></A><FONT COLOR="#000077">Search the Web with

WWW::Search</FONT></H3>

<P>For searching outside of your site, a set of modules called WWW::Search has been

written by John Heidemann. WWW::Search is a collection of Perl modules which provides

a common API to most popular WWW search engines. As of this writing, there are modules

which support AltaVista, Yahoo!, Lycos, Hotbot, and WebCrawler. The author is currently

developing more modules for other search engines and more sophisticated clients and

examples. The latest version of the WWW::Search module can be found at:</P>

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

</FONT><A HREF="javascript:if(confirm('http://www.isi.edu/lsam/tools/WWW_SEARCH/  \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://www.isi.edu/lsam/tools/WWW_SEARCH/'" tppabs="http://www.isi.edu/lsam/tools/WWW_SEARCH/"><FONT COLOR="#0066FF">http://www.isi.edu/lsam/tools/WWW_SEARCH/</FONT></A><FONT

COLOR="#0066FF">

</FONT></PRE>

<P>Installation of the module requires Perl5 version 5.003, and is very straightforward.

Using the module to generate custom queries to a search engine is very simple.</P>

<P>First, the type of search engine must be defined. Check the documentation to see

if the search engine you wish to query is supported, then create a new search:</P>

<PRE><FONT COLOR="#0066FF">$search = new WWW::Search(`SearchEngineName');

</FONT></PRE>

<P>An example would be:</P>

<PRE><FONT COLOR="#0066FF">$search = new WWW::Search(`AltaVista');

</FONT></PRE>

<P>Then specify the query string. This string is made up of some specific name value

pairs, and is URI encoded.</P>

<PRE><FONT COLOR="#0066FF">$search-&gt;native_query(`search-engine-specific+query+string');

</FONT></PRE>

<P>Here's a documented example which performs an AltaVista search, then prints the

URIs resulting from the search. Note that you could easily add nice custom formatting

of the results in the while loop.</P>

<PRE><FONT COLOR="#0066FF">my($search) = new WWW::Search::AltaVista;

$search-&gt;native_query(WWW::Search::escape_query($query));

my($result);

while ($result = $search-&gt;next_result()) {

print $result-&gt;url, &quot;\n&quot;;

};

</FONT></PRE>

<P>Listing 10.1 is code from search.PL, a small example included with the WWW::Search

distribution. This example illustrates the usage of the Search Library. Figure 10.2

depicts an example of output that could easily be generated by search.PL.

<H3 ALIGN="CENTER"><A NAME="Heading7"></A><FONT COLOR="#000077">Listing 10.1. search.PL</FONT></H3>

<H3 ALIGN="CENTER"><A NAME="Heading8"></A><FONT COLOR="#000077">; real world example

of WWW::Search.</FONT></H3>

<PRE><FONT COLOR="#0066FF"># Copyright (c) 1996 University of Southern California.

# All rights reserved.



use strict;



&amp;usage if ($#ARGV == -1);

&amp;usage if ($#ARGV &gt;= 0 &amp;&amp; $ARGV[0] eq `-?');



use WWW::Search;

use Getopt::Long;



my(%opts);

&amp;GetOptions(\%opts, qw(v a e=s o=s@)); # i.e -v -e=&lt;string&gt; -o=&lt;options&gt;



&amp;usage if ($#ARGV == -1); # we MUST have one left, the query



my($verbose) = $opts{`v'};

my($all) = $opts{`a'};



&amp;main(join(&quot; &quot;, @ARGV));



exit 0;



sub print_result {

  my($result, $count) = @_;



  my($prefix) = &quot;&quot;;

  $prefix = &quot;[$count] &quot; if defined($verbose);



  if ($all) {

    foreach ($result-&gt;urls()) {

      print &quot;$prefix$_\n&quot;;

      $prefix = &quot;      &quot;;

    };

  } else {

    print $prefix, $result-&gt;url, &quot;\n&quot;;

  };

}



sub main {

  my($query) = @_;

  my($count) = &quot;001&quot; if defined($verbose);

  my($search) = new WWW::Search($opts{e});

  my($query_options_ref);



  if (defined($opts{`o'})) {

    $query_options_ref = {};

    foreach (@{$opts{`o'}}) {

      my($key, $value) = m/^([^=]+)=(.*)$/;

      $query_options_ref-&gt;{$key} = WWW::Search::escape_query($value);

    };

  };



  $search-&gt;native_query(WWW::Search::escape_query($query), $query_options_ref);



  my($way) = 0; # 0=piecemeal, 1=all at once

  my($result);

  if ($way) { # return all at once.

    foreach $result ($search-&gt;results()) {

      print_result($result, $count++);

    };

  } else { # return page by page

    while ($result = $search-&gt;next_result()) {

      print_result($result, $count++);

    };

  };

};

</FONT></PRE>

<P><A HREF="11wpp02.jpg" tppabs="http://210.32.137.15/ebook/Web%20Programming%20with%20Perl%205/11wpp02.jpg"><TT><B>Figure 10.2.</B></TT></A> Output possible

from search.PL.

<H3 ALIGN="CENTER"><A NAME="Heading9"></A><FONT COLOR="#000077">Summary</FONT></H3>

<P>Adding a search engine to your site with Glimpse greatly increases the usefulness

and functionality of your service. Whether you have an online catalog or are just

providing information, Glimpse is an easy way to make your information more accessible.

The WWW::Search module is a good way to provide a seamless link from your on-site

search to information resources elsewhere on the Internet.<BR>



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