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# CLXXVII. YAZ Functions

# 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/.

> Note: This extension has been moved to the PECL repository and is no longer bundled with PHP as of PHP 5.0.0.

# Installation

Obtain YAZ (ANSI/NISO Z39.50 support) and install it. YAZ can be fetched in source or in various prebuilt packages from the YAZ archive. Systems such as Debian GNU/Linux, Suse Linux, FreeBSD also has YAZ as part of their distribution.

For the PHP 4 series, the YAZ extension is bundled (but not YAZ itself) Build PHP with your favorite modules and add option --with-yaz[=DIR].

Example 1. YAZ compilation for PHP 4 on Unix

    gunzip -c php-4.4.X.tar.gz|tar xf -
    gunzip -c yaz-2.1.8.tar.gz|tar xf -
    cd yaz-2.1.8
    ./configure --prefix=/usr
    make
    sudo make install
    cd ../php-4.4.X.
    ./configure --with-yaz=/usr/bin
    make
    sudo make install

For PHP 5, the YAZ extension is in PECL and is installed as a shared object/dll. If you have pear installed the easiest way to download, configure and install the YAZ extension is by using the pear command.

Example 2. Installation of PECL YAZ on GNU/Debian Linux

On a Debian GNU/Linux system the following installs YAZ and PECL YAZ:

    sudo apt-get install libyaz-dev
    sudo pear install yaz

On Windows, `php_yaz.dll` depend on `yaz.dll`. The `yaz.dll` is part of the Win32 ZIP from the PHP site. It is also part of the Windows YAZ install available from the YAZ WIN32 area.

Warning
The PHP 5.0.5 Win32 zip includes a too old version of `yaz.dll` (version 1.9.1 < required version 2.0.13). If that's the case use the `yaz.dll` from a newer YAZ WIN32 install.

On windows, don't forget to add the PHP directory to the PATH, so that the `yaz.dll` file can be found by the system.

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

    extension=yaz.so

And for Windows:

    extension=php_yaz.dll

Warning
The IMAP, recode, YAZ and Cyrus extensions cannot be used in conjuction, because they both share the same internal symbol.

> Note: The above problem is solved in version 2.0 of YAZ.

# Runtime Configuration

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

Table 1. YAZ configuration options

Name | Default | Changeable | Changelog
--- | --- | --- | ---
yaz.max_links | "100" | PHP_INI_ALL | Available since PHP 4.3.0.
yaz.log_file | NULL | PHP_INI_ALL | Available since PHP 4.3.0.

For further details and definitions of the PHP_INI_* constants, see the Appendix G.

# 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 3. 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>';
}
}
?>`

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