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Some cosmetics.

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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@20310 c90b9560-bf6c-de11-be94-00142212c4b1
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Egon Schmid 2000-02-24 07:03:05 +00:00
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452
functions/session.xml
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@ -1,24 +1,23 @@
<reference id="ref.session">
<title>Session handling functions</title>
<titleabbrev>Sessions</titleabbrev>
<partintro>
<para>
Session support in PHP consists of a way to preserve certain data
across subsequent accesses. This enables you to build more
customized applications and increase the appeal of your web site.
</para>
<para>
If you are familiar with the session management of PHPLIB, you will notice
that some concepts are similar to PHP's session support.
If you are familiar with the session management of PHPLIB, you
will notice that some concepts are similar to PHP's session
support.
</para>
<para>
A visitor accessing your web site is assigned an unique id, the
so-called session id. This is either stored in a cookie on the
user side or is propagated in the URL.
</para>
<para>
The session support allows you to register arbitrary numbers of
variables to be preserved across requests. When a visitor accesses
@ -29,14 +28,12 @@
id has been sent with the request. If this is the case, the prior
saved environment is recreated.
</para>
<para>
All registered variables are serialized after the request
finishes. Registered variables which are undefined are marked as
being not defined. On subsequent accesses, these are not defined
by the session module unless the user defines them later.
</para>
<para>
<literal>track_vars</literal> and <literal>gpc_globals</literal>
configuration settings influence how the session variables get
@ -48,24 +45,27 @@
both of these settings are enabled, then the globals variables and
the $HTTP_STATE_VARS entries will reference the same value.
</para>
<para>
There are two methods to propagate a session id:
<itemizedlist>
<listitem><simpara>
Cookies</simpara></listitem>
<listitem><simpara>
URL parameter</simpara></listitem>
</itemizedlist></para>
<listitem>
<simpara>
Cookies
</simpara>
</listitem>
<listitem>
<simpara>
URL parameter
</simpara>
</listitem>
</itemizedlist>
</para>
<para>
The session module supports both methods. Cookies are optimal, but
since they are not reliable (clients are not bound to accept
them), we cannot rely on them. The second method embeds the
session id directly into URLs.
</para>
<para>
PHP is capable of doing this transparently when compiled with
<literal>--enable-trans-sid</literal>. If you enable this option,
@ -76,32 +76,28 @@
the form <literal>session_name=session_id</literal> or is an empty
string.
</para>
<para>
The following example demonstrates how to register a variable, and
how to link correctly to another page using SID.
<example>
<title>Counting the number of hits of a single user</title>
<programlisting>
<example>
<title>Counting the number of hits of a single user</title>
<programlisting role="php">
&lt;?php
session_register("count");
$count++;
?&gt;
Hello visitor, you have seen this page &lt;? echo $count; ?&gt; times.&lt;p&gt;
&lt;?
&lt;php?
# the &lt;?=SID?&gt; is necessary to preserve the session id
# in the case that the user has disabled cookies
?&gt;
To continue, &lt;A HREF="nextpage.php?&lt;?=SID?&gt;"&gt;click here&lt;/A&gt;
</programlisting></example></para>
To continue, &lt;A HREF="nextpage.php?&lt;?=SID?&gt;"&gt;click here&lt;/A&gt;
</programlisting>
</example>
</para>
<para>
To implement database storage you need PHP code and a user level
function <function>session_set_save_handler</function>. You would
@ -116,12 +112,12 @@ Hello visitor, you have seen this page &lt;? echo $count; ?&gt; times.&lt;p&gt;
<programlisting role="php">
&lt;?php
function open ( $save_path, $session_name ) {
function open ($save_path, $session_name) {
echo "open ($save_path, $session_name)\n";
return true;
}
function close () {
function close() {
echo "close\n";
return true;
}
@ -144,7 +140,7 @@ function gc ($maxlifetime) {
return true;
}
session_set_save_handler("open", "close", "read", "write", "destroy", "gc");
session_set_save_handler ("open", "close", "read", "write", "destroy", "gc");
session_start();
@ -154,11 +150,9 @@ $foo++;
</programlisting>
</example>
</para>
<para>
Will produce this results:
</para>
<para>
<programlisting>
$ ./php save_handler.php
@ -171,104 +165,120 @@ write (f08b925af0ecb52bdd2de97d95cdbe6b, foo|i:2;)
close
</programlisting>
</para>
<para>
The <literal>&lt;?=SID?&gt;</literal> is not necessary, if
<literal>--enable-trans-sid</literal> was used to compile PHP.
</para>
<para>
The session management system supports a number of configuration
options which you can place in your php.ini file. We will give a
short overview.
<itemizedlist>
<listitem><simpara>
<literal>session.save_handler</literal> defines the name of the
handler which is used for storing and retrieving data associated
with a session. Defaults to
<literal>files</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.save_path</literal> defines the argument which
is passed to the save handler. If you choose the default files
handler, this is the path where the files are created. Defaults
to <literal>/tmp</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.name</literal> specifies the name of the
session which is used as cookie name. It should only contain
alphanumeric characters. Defaults to
<literal>PHPSESSID</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.auto_start</literal> specifies whether the
session module start a session automatically on request
startup. Defaults to <literal>0</literal>
(disabled).</simpara></listitem>
<listitem><simpara>
<literal>session.lifetime</literal> specifies the lifetime of
the cookie in seconds which is sent to the browser. The value 0
means "until the browser is closed." Defaults to
<literal>0</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.serialize_handler</literal> defines the name of
the handler which is used to serialize/deserialize
data. Currently, a PHP internal format (name
<literal>php</literal>) and WDDX is supported (name
<literal>wddx</literal>). WDDX is only available, if PHP is
compiled with <link linkend="ref.wddx">WDDX
support</link>. Defaults to
<literal>php</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.gc_probability</literal> specifies the
probability that the gc (garbage collection) routine is started
on each request in percent. Defaults to
<literal>1</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.gc_maxlifetime</literal> specifies the number
of seconds after which data will be seen as 'garbage' and
cleaned up.</simpara></listitem>
<listitem><simpara>
<literal>session.referer_check</literal> determines
whether session ids referred to by external sites will be
eliminated. If session ids are propagated using the URL method,
users not knowing about the impact might publish session
ids. This can lead to security problems which this check tries
to defeat. Defaults to
<literal>0</literal>.</simpara></listitem>
<listitem><simpara>
<literal>session.entropy_file</literal> gives a path to an
external resource (file) which will be used as an additional
entropy source in the session id creation process. Examples are
<literal>/dev/random</literal> or
<literal>/dev/urandom</literal> which are available on many Unix
systems.</simpara></listitem>
<listitem><simpara>
<literal>session.entropy_length</literal> specifies the number
of bytes which will be read from the file specified
above. Defaults to <literal>0</literal>
(disabled).</simpara></listitem>
<listitem><simpara>
<literal>session.use_cookies</literal> specifies whether the
module will use cookies to store the session id on the client
side. Defaults to <literal>1</literal>
(enabled).</simpara></listitem>
<listitem>
<simpara>
<literal>session.save_handler</literal> defines the name of the
handler which is used for storing and retrieving data
associated with a session. Defaults to
<literal>files</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.save_path</literal> defines the argument which
is passed to the save handler. If you choose the default files
handler, this is the path where the files are created.
Defaults to <literal>/tmp</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.name</literal> specifies the name of the
session which is used as cookie name. It should only contain
alphanumeric characters. Defaults to
<literal>PHPSESSID</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.auto_start</literal> specifies whether the
session module start a session automatically on request
startup. Defaults to <literal>0</literal> (disabled).
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.lifetime</literal> specifies the lifetime of
the cookie in seconds which is sent to the browser. The value 0
means "until the browser is closed." Defaults to
<literal>0</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.serialize_handler</literal> defines the name
of the handler which is used to serialize/deserialize
data. Currently, a PHP internal format (name
<literal>php</literal>) and WDDX is supported (name
<literal>wddx</literal>). WDDX is only available, if PHP is
compiled with <link linkend="ref.wddx">WDDX
support</link>. Defaults to <literal>php</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.gc_probability</literal> specifies the
probability that the gc (garbage collection) routine is started
on each request in percent. Defaults to <literal>1</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.gc_maxlifetime</literal> specifies the number
of seconds after which data will be seen as 'garbage' and
cleaned up.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.referer_check</literal> determines whether
session ids referred to by external sites will be
eliminated. If session ids are propagated using the URL method,
users not knowing about the impact might publish session
ids. This can lead to security problems which this check tries
to defeat. Defaults to <literal>0</literal>.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.entropy_file</literal> gives a path to an
external resource (file) which will be used as an additional
entropy source in the session id creation process. Examples are
<literal>/dev/random</literal> or
<literal>/dev/urandom</literal> which are available on many
Unix systems.
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.entropy_length</literal> specifies the number
of bytes which will be read from the file specified
above. Defaults to <literal>0</literal> (disabled).
</simpara>
</listitem>
<listitem>
<simpara>
<literal>session.use_cookies</literal> specifies whether the
module will use cookies to store the session id on the client
side. Defaults to <literal>1</literal> (enabled).
</simpara>
</listitem>
</itemizedlist>
<note>
<para>
Session handling was added in PHP 4.0.</para>
</note></para>
<note>
<para>
Session handling was added in PHP 4.0.
</para>
</note>
</para>
</partintro>
<refentry id="function.session-start">
@ -287,10 +297,12 @@ close
the current one based on the session id being passed via a GET
variable or a cookie).</simpara>
<simpara>
This function always returns true.</simpara>
This function always returns true.
</simpara>
<note>
<para>
This function was added in PHP 4.0.</para>
This function was added in PHP 4.0.
</para>
</note>
</refsect1>
</refentry>
@ -308,12 +320,15 @@ close
</funcsynopsis>
<simpara>
<function>session_destroy</function> destroys all of the data
associated with the current session.</simpara>
associated with the current session.
</simpara>
<simpara>
This function always returns true.</simpara>
This function always returns true.
</simpara>
<note>
<para>
This function was added in PHP 4.0.</para>
This function was added in PHP 4.0.
</para>
</note>
</refsect1>
</refentry>
@ -327,36 +342,41 @@ close
<title>Description</title>
<funcsynopsis>
<funcdef>string <function>session_name</function></funcdef>
<paramdef>string <parameter><optional>name</optional></parameter></paramdef>
<paramdef>string
<parameter><optional>name</optional></parameter>
</paramdef>
</funcsynopsis>
<para>
<function>session_name</function> returns the name of the current
session. If <parameter>name</parameter> is specified, the name of
the current session is changed to its value.</para>
the current session is changed to its value.
</para>
<para>
The session name references the session id in cookies and URLs. It should
contain only alphanumeric characters; it should be short and descriptive
(i.e. for users with enabled cookie warnings). The session name is
resetted to the default value stored in <literal>session.name</literal>
at request startup time. Thus, you need to call
<function>session_name</function> for every request (and before
<function>session_start</function> or
<function>session_register</function> are called).</para>
The session name references the session id in cookies and
URLs. It should contain only alphanumeric characters; it should
be short and descriptive (i.e. for users with enabled cookie
warnings). The session name is resetted to the default value
stored in <literal>session.name</literal> at request startup
time. Thus, you need to call <function>session_name</function>
for every request (and before <function>session_start</function>
or <function>session_register</function> are called).
</para>
<example>
<title><function>session_name</function> examples</title>
<programlisting>
<programlisting role="php">
&lt;?php
# set the session name to WebsiteID
$previous_name = session_name("WebsiteID");
$previous_name = session_name ("WebsiteID");
echo "The previous session name was $previous_name&lt;p&gt;";
</programlisting>
</example>
<note>
<para>
This function was added in PHP 4.0.</para>
This function was added in PHP 4.0.
</para>
</note>
</refsect1>
</refentry>
@ -370,16 +390,20 @@ echo "The previous session name was $previous_name&lt;p&gt;";
<title>Description</title>
<funcsynopsis>
<funcdef>string <function>session_module_name</function></funcdef>
<paramdef>string <parameter><optional>module</optional></parameter></paramdef>
<paramdef>string
<parameter><optional>module</optional></parameter>
</paramdef>
</funcsynopsis>
<para>
<function>session_module_name</function> returns the name of the current
session module. If <parameter>module</parameter> is specified, that
module will be used instead.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
<function>session_module_name</function> returns the name of the
current session module. If <parameter>module</parameter> is
specified, that module will be used instead.
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
@ -392,23 +416,28 @@ echo "The previous session name was $previous_name&lt;p&gt;";
<title>Description</title>
<funcsynopsis>
<funcdef>string <function>session_save_path</function></funcdef>
<paramdef>string <parameter><optional>path</optional></parameter></paramdef>
<paramdef>string
<parameter><optional>path</optional></parameter>
</paramdef>
</funcsynopsis>
<para>
<function>session_save_path</function> returns the path of the current
directory used to save session data. If <parameter>path</parameter>
is specified, the path to which data is saved will be changed.
<note>
<para>
On some operating systems, you may want to specify a path on
a filesystem that handles lots of small files efficiently. For
example, on Linux, reiserfs may provide better performance than
ext2fs.</para>
</note>
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
<note>
<para>
On some operating systems, you may want to specify a path on a
filesystem that handles lots of small files efficiently. For
example, on Linux, reiserfs may provide better performance than
ext2fs.
</para>
</note>
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
@ -424,27 +453,34 @@ echo "The previous session name was $previous_name&lt;p&gt;";
<paramdef>string <parameter><optional>id</optional></parameter></paramdef>
</funcsynopsis>
<para>
<function>session_id</function> returns the session id for the current
session. If <parameter>id</parameter> is specified, it will replace
the current session id.</para>
<function>session_id</function> returns the session id for the
current session. If <parameter>id</parameter> is specified, it
will replace the current session id.
</para>
<para>
directory used to save session data. If <parameter>path</parameter>
is specified, the path to which data is saved will be changed.</para>
directory used to save session data. If
<parameter>path</parameter> is specified, the path to which data
is saved will be changed.
</para>
<para>
The constant <systemitem>SID</systemitem> can also be used to retrieve
the current name and session id as a string suitable for adding to
URLs.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
The constant <systemitem>SID</systemitem> can also be used to
retrieve the current name and session id as a string suitable for
adding to URLs.
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
<refentry id="function.session-register">
<refnamediv>
<refname>session_register</refname>
<refpurpose>Register one or more variables with the current session</refpurpose>
<refpurpose>
Register one or more variables with the current session
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
@ -460,21 +496,26 @@ echo "The previous session name was $previous_name&lt;p&gt;";
variable name or an array consisting of such variable names or
other arrays. For each encountered variable name,
<function>session_register</function> registers the global
variable named by it with the current session.</para>
variable named by it with the current session.
</para>
<para>
This function returns true when the variable is successfully
registered with the session.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
<refentry id="function.session-unregister">
<refnamediv>
<refname>session_unregister</refname>
<refpurpose>Unregister a variable from the current session</refpurpose>
<refpurpose>
Unregister a variable from the current session
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
@ -485,21 +526,26 @@ echo "The previous session name was $previous_name&lt;p&gt;";
<para>
<function>session_unregister</function> unregisters (forgets)
the global variable named <parameter>name</parameter> from the
current session.</para>
current session.
</para>
<para>
This function returns true when the variable is successfully
unregistered from the session.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
<refentry id="function.session-is-registered">
<refnamediv>
<refname>session_is_registered</refname>
<refpurpose>Find out if a variable is registered in a session</refpurpose>
<refpurpose>
Find out if a variable is registered in a session
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
@ -509,12 +555,14 @@ echo "The previous session name was $previous_name&lt;p&gt;";
</funcsynopsis>
<para>
<function>session_is_registered</function> returns true if there
is a variable with the name <parameter>name</parameter> registered
in the current session.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
is a variable with the name <parameter>name</parameter>
registered in the current session.
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
@ -533,17 +581,21 @@ echo "The previous session name was $previous_name&lt;p&gt;";
<function>session_decode</function> decodes the session data in
<parameter>data</parameter>, setting variables stored in the
session.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>
<refentry id="function.session-encode">
<refnamediv>
<refname>session_encode</refname>
<refpurpose>Encodes the current session data as a string</refpurpose>
<refpurpose>
Encodes the current session data as a string
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
@ -554,10 +606,12 @@ echo "The previous session name was $previous_name&lt;p&gt;";
<para>
<function>session_encode</function> returns a string with the
contents of the current session encoded within.
<note>
<para>
This function was added in PHP 4.0.</para>
</note></para>
<note>
<para>
This function was added in PHP 4.0.
</para>
</note>
</para>
</refsect1>
</refentry>