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.
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:
And for Windows:
| 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.
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.
This extension has no resource types defined.
This extension has no constants defined.
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>';
}
}
?>
|
|
