Introduction

This extension offers a PHP interface to the YAZ toolkit that implements the Z39.50 Protocol for Information Retrieval. With this extension you can easily implement a Z39.50 origin (client) that searches or scans Z39.50 targets (servers) in parallel.

The module hides most of the complexity of Z39.50 so it should be fairly easy to use. It supports persistent stateless connections very similar to those offered by the various RDB APIs that are available for PHP. This means that sessions are stateless but shared among users, thus saving the connect and initialize phase steps in most cases.

YAZ is available at http://www.indexdata.dk/yaz/. You can find news information, example scripts, etc. for this extension at http://www.indexdata.dk/phpyaz/.

Installation

Compile YAZ (ANSI/NISO Z39.50 support) and install it. Build PHP with your favourite modules and add option --with-yaz[=DIR]. Your task is roughly the following:

Example 1. YAZ compilation gunzip -c php-4.3.X.tar.gz|tar xf - gunzip -c yaz-2.0.tar.gz|tar xf - cd yaz-2.0 ./configure --prefix=/usr make make install cd ../php-4.3.X. ./configure --with-yaz=/usr/bin make make install

If you are using YAZ as a shared extension, add (or uncomment) the following line in php.ini on Unix:

extension=php_yaz.so

And for Windows:

extension=php_yaz.dll

On Windows, php_yaz.dll depend on yaz.dll. You'll find yaz.dll in sub directory dlls in the Win32 zip archive. Copy yaz.dll to a directory in your PATH environment (c:\winnt\system32 or c:\windows\system32).

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Resource Types

This extension has no resource types defined.

Predefined Constants

This extension has no constants defined.

Examples

PHP/YAZ keeps track of connections with targets (Z-Associations). A resource represents a connection to a target.

The script below demonstrates the parallel searching feature of the API. When invoked with no arguments it prints a query form; else (arguments are supplied) it searches the targets as given in array host.

Example 2. Parallel searching using Yaz <?php $host=$_REQUEST[host]; $query=$_REQUEST[query]; $num_hosts = count($host); if (empty($query) || count($host) == 0) {     echo '<form method="get">     <input type="checkbox"     name="host[]" value="bagel.indexdata.dk/gils" />         GILS test     <input type="checkbox"     name="host[]" value="localhost:9999/Default" />         local test     <input type="checkbox" checked="checked"     name="host[]" value="z3950.loc.gov:7090/voyager" />         Library of Congress     <br />     RPN Query:     <input type="text" size="30" name="query" />     <input type="submit" name="action" value="Search" />     </form>     ';         } else {     echo 'You searched for ' . htmlspecialchars($query) . '<br />';     for ($i = 0; $i < $num_hosts; $i++) {         $id[] = yaz_connect($host[$i]);     yaz_syntax($id[$i], "usmarc");         yaz_range($id[$i], 1, 10);         yaz_search($id[$i], "rpn", $query);     }     yaz_wait();     for ($i = 0; $i < $num_hosts; $i++) {         echo '<hr />' . $host[$i] . ':';         $error = yaz_error($id[$i]);         if (!empty($error)) {             echo "Error: $error";         } else {             $hits = yaz_hits($id[$i]);             echo "Result Count $hits";         }         echo '<dl>';         for ($p = 1; $p <= 10; $p++) {             $rec = yaz_record($id[$i], $p, "string");             if (empty($rec)) continue;             echo "<dt><b>$p</b></dt><dd>";             echo nl2br($rec);             echo "</dd>";         }         echo '</dl>';     } } ?>