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 Z39.50 targets (servers) in parallel.
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/.
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 SQL APIs that are available for PHP. This means that sessions are stateless but shared amongst users, thus saving the connect and initialize phase steps in most cases.
PHP/YAZ keeps track of connections with targets (Z-Associations). A positive integer represents the ID of a particular association.
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 in array host.
Example 1. YAZ()
$num_hosts = count ($host); if (empty($term) || count($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="1" name="host[]" value="z3950.bell-labs.com/books"> BELL Labs Library <br> RPN Query: <input type="text" size="30" name="term"> <input type="submit" name="action" value="Search"> '; } else { echo 'You searced for ' . htmlspecialchars($term) . '<br>'; for ($i = 0; $i < $num_hosts; $i++) { $id[] = yaz_connect($host[$i]); yaz_syntax($id[$i],"sutrs"); yaz_search($id[$i],"rpn",$term); } 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 ereg_replace("\n", "<br>\n",$rec); echo "</dd>"; } echo '</dl>'; } } |
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