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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.14 $ -->
<!-- splitted from ./en/functions/session.xml, last change in rev 1.23 -->
<refentry id="function.session-set-save-handler">
<refnamediv>
<refname>session_set_save_handler</refname>
<refpurpose>
Sets user-level session storage functions
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<methodsynopsis>
<type>bool</type><methodname>session_set_save_handler</methodname>
<methodparam><type>callback</type><parameter>open</parameter></methodparam>
<methodparam><type>callback</type><parameter>close</parameter></methodparam>
<methodparam><type>callback</type><parameter>read</parameter></methodparam>
<methodparam><type>callback</type><parameter>write</parameter></methodparam>
<methodparam><type>callback</type><parameter>destroy</parameter></methodparam>
<methodparam><type>callback</type><parameter>gc</parameter></methodparam>
</methodsynopsis>
<para>
<function>session_set_save_handler</function> sets the user-level
session storage functions which are used for storing and
retrieving data associated with a session. This is most useful
when a storage method other than those supplied by PHP sessions
is preferred. i.e. Storing the session data in a local database.
&return.success;
</para>
<note>
<para>
The "write" handler is not executed until after the output
stream is closed. Thus, output from debugging statements in the
"write" handler will never be seen in the browser. If debugging
output is necessary, it is suggested that the debug output be
written to a file instead.
</para>
</note>
<para>
The following example provides file based session
storage similar to the PHP sessions default save handler
<parameter>files</parameter>. This example could easily be
extended to cover database storage using your favorite PHP
supported database engine.
</para>
<para>
Read function must return string value always to make save
handler work as expected. Return empty string if there is no data
to read. Return values from other handlers are converted to
boolean expression. &true; for success, &false; for failure.
</para>
<warning>
<para>
Write and Close handlers are called after destructing objects since PHP
5.0.5. Thus destructors can use sessions but session handler can't use
objects. In prior versions, they were called in the opposite order. It
is possible to call <function>session_write_close</function> from the
destructor to solve this chicken and egg problem.
</para>
</warning>
<para>
<example>
<title>
<function>session_set_save_handler</function> example
</title>
<programlisting role="php">
<![CDATA[
<?php
function open($save_path, $session_name)
{
global $sess_save_path;
$sess_save_path = $save_path;
return(true);
}
function close()
{
return(true);
}
function read($id)
{
global $sess_save_path;
$sess_file = "$sess_save_path/sess_$id";
return (string) @file_get_contents($sess_file);
}
function write($id, $sess_data)
{
global $sess_save_path;
$sess_file = "$sess_save_path/sess_$id";
if ($fp = @fopen($sess_file, "w")) {
$return = fwrite($fp, $sess_data);
fclose($fp);
return $return;
} else {
return(false);
}
}
function destroy($id)
{
global $sess_save_path;
$sess_file = "$sess_save_path/sess_$id";
return(@unlink($sess_file));
}
function gc($maxlifetime)
{
global $sess_save_path;
foreach (glob("$sess_save_path/sess_*") as $filename) {
if (filemtime($filename) + $maxlifetime < time()) {
@unlink($filename);
}
}
return true;
}
session_set_save_handler("open", "close", "read", "write", "destroy", "gc");
session_start();
// proceed to use sessions normally
?>
]]>
</programlisting>
</example>
</para>
<para>
See also the <link linkend="ini.session.save-handler">session.save_handler</link>
configuration directive.
</para>
</refsect1>
</refentry>
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