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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
$Id$
-->
<refentry id="fn_dav_api_lock">
<refmeta>
<refentrytitle>DAV lock manipulation functions</refentrytitle>
<refmiscinfo>ws</refmiscinfo>
</refmeta>
<refnamediv>
<refname>DAV_LOCK</refname>
<refname>DAV_UNLOCK</refname>
<refname>DAV_IS_LOCKED</refname>
<refname>DAV_LIST_LOCKS</refname>
<refpurpose>Operations on locks of DAV collections and resources</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="fsyn_dav_lock">
<funcprototype id="fproto_dav_lock">
<funcdef>integer <function>DAV_LOCK</function></funcdef>
<paramdef>in <parameter>path</parameter> varchar</paramdef>
<paramdef>in <parameter>locktype</parameter> varchar</paramdef>
<paramdef>in <parameter>scope</parameter> varchar</paramdef>
<paramdef>in <parameter>token</parameter> varchar</paramdef>
<paramdef>in <parameter>owner_name</parameter> varchar</paramdef>
<paramdef>in <parameter>owned_tokens</parameter> varchar</paramdef>
<paramdef>in <parameter>depth</parameter> varchar</paramdef>
<paramdef>in <parameter>timeout_sec</parameter> integer</paramdef>
<paramdef>in <parameter>auth_uname</parameter> varchar</paramdef>
<paramdef>in <parameter>auth_pwd</parameter> varchar</paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_dav_unlock">
<funcprototype id="fproto_dav_unlock">
<funcdef>any <function>DAV_UNLOCK</function></funcdef>
<paramdef>in <parameter>path</parameter> varchar</paramdef>
<paramdef>in <parameter>token</parameter> varchar</paramdef>
<paramdef>in <parameter>auth_uname</parameter> varchar</paramdef>
<paramdef>in <parameter>auth_pwd</parameter> varchar</paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_dav_is_locked">
<funcprototype id="fproto_dav_is_locked">
<funcdef>integer <function>DAV_IS_LOCKED</function></funcdef>
<paramdef>in <parameter>id</parameter> any</paramdef>
<paramdef>in <parameter>type</parameter> char(1)</paramdef>
<paramdef>in <parameter>owned_tokens</parameter> any := 1</paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_dav_list_locks">
<funcprototype id="fproto_dav_list_locks">
<funcdef>integer <function>DAV_LIST_LOCKS</function></funcdef>
<paramdef>in <parameter>id</parameter> any</paramdef>
<paramdef>in <parameter>type</parameter> char(1)</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="desc_dav_api_lock"><title>Description</title>
<para><function>DAV_LOCK</function> sets a new lock or refresh an existing lock or creates a lock object.</para>
<para><function>DAV_UNLOCK</function> releases a lock.</para>
<para><function>DAV_IS_LOCKED</function> reports whether the resource or collection is locked.</para>
<para><function>DAV_LIST_LOCKS</function> returns a full list of all locks on a resource or collection.</para>
<para>It is strongly recommended to carefully study DAV standards before using these functions in applications.
Improper use of DAV locks may result in subtle application errors that are hard to debug.</para>
</refsect1>
<refsect1 id="params_dav_api_lock"><title>Parameters</title>
<refsect2><title>path</title>
<para>Resource or collection path.
As usual, collection names must end with '/' and both sorts of path strings should begin with '/'.
If the path specifies a non-existing resource in an existing collection then a lock object is created and only lock owner can create a resource with this name in future.
</para>
</refsect2>
<refsect2><title>locktype</title>
<para>The type of lock. Current set of DAV standards specifies only one type of locks, called 'D:write'; the parameter value is stored 'as is' and never used, so the recommended value is an empty string.</para>
</refsect2>
<refsect2><title>scope</title>
<para>The scope of lock as a single-char string: 'S' for shared lock, 'X' for exclusive.</para>
</refsect2>
<refsect2><title>token</title>
<para>The token to update. Empty string or NULL means creation of a new lock, not an update of the existing one.</para>
</refsect2>
<refsect2><title>owner_name</title>
<para>Lock owner name as it will be displayed to other users that will query for existing locks. It is strongly recommended to provide commonly used names such as e-mails to let users ask each other to remove forgotten locks.</para>
</refsect2>
<refsect2><title>owned_tokens</title>
<para>String of tokens owned by a user, to let user ignore his own tokens. The string should match syntax of DAV HTTP 'If' parameter.
This can be also an integer, this will work as empty list of tokens.</para>
</refsect2>
<refsect2><title>depth</title>
<para>This specifies the recursive depth of the lock.
The string can be '0' to lock the specified collection only, '1' to lock the collection and its subcollections, 'infinity' to lock the whole subtree.
When the lock is added to a resource, the value '0' is used, for obvious reason.
If NULL is passed to the function then the effective value is 'infinity' for collection lock or '0' for resource lock.</para>
</refsect2>
<refsect2><title>timeout_sec</title>
<para>Expiration interval for the lock, in seconds. If 0 or NULL is passed then HTTP DAV default is used that is equal to 604800 seconds (one week).</para>
</refsect2>
<refsect2><title>auth_uname</title>
<para>DAV user name to authenticate access. Lock, Lock refresh and unlock operations on existing resource or collection require write permission.
To create a lock object in a collection, user should have write permission on that collection.
This may cause problem when user first locks a resource and then loose write permission for some reason: the user is unable to remove his own lock.
Default is NULL that means public access.
</para>
</refsect2>
<refsect2><title>auth_pwd</title>
<para>User password. Default is NULL.</para>
</refsect2>
<refsect2><title>id</title>
<para>Internal identifier of a resource or collection as returned by DAV_SEARCH_ID().</para>
</refsect2>
</refsect1>
<refsect1 id="examples_dav_api_lock"><title>Examples</title>
<example id="ex_dav_api_lock_1"><title>Two concurrent users</title>
<para>The following example shows how two users can prevent each other from undesired operations.</para>
<para>The sample function DAV_LOCK_DEMO() uses a function DUMP_VEC() that print the content of vector in Virtuoso/PL syntax.
Yon can find the implementation of this function as one of examples for <link linkend="fn_vector"><function>vector()</function></link> Virtuoso/PL function.</para>
<screen><![CDATA[
create procedure DAV_LOCK_DEMO (in dav_passwd varchar := 'dav')
{
declare ACTION, RETVAL, token_s1, token_s2, token_x varchar;
result_names (ACTION, RETVAL);
result ('Adding group lock_demo_grp:',
DAV_ADD_GROUP ('lock_demo_grp', 'dav', dav_passwd) );
result ('Adding user lock_u1:',
DAV_ADD_USER ('lock_u1', 'lock_u1_pwd', 'lock_demo_grp', '110110000T', 0, '/DAV/lock_demo_u1_home/', 'First User of lock demo', 'lock_u1@localhost', 'dav', dav_passwd) );
result ('Adding user lock_u2:',
DAV_ADD_USER ('lock_u2', 'lock_u2_pwd', 'lock_demo_grp', '110110000T', 0, '/DAV/lock_demo_u2_home/', 'Second User of lock demo', 'lock_u2@localhost', 'dav', dav_passwd) );
result ('Adding a collection:',
DAV_COL_CREATE ('/DAV/lock_demo/', '110110000R', 'lock_u1', 'lock_demo_grp', 'dav', dav_passwd) );
result ('Uploading /DAV/lock_demo/sample.htm:',
DAV_RES_UPLOAD ('/DAV/lock_demo/sample.htm', '<html><body>This is /DAV/lock_demo/sample.htm</body></html>', 'text/plain', '110110000R', 'lock_u1', 'lock_demo_grp', 'lock_u1', 'lock_u1_pwd') );
token_s1 := DAV_LOCK ('/DAV/lock_demo/sample.htm', '', 'S', NULL, 'user1@example.com', '', '0', NULL, 'lock_u1', 'lock_u1_pwd');
result ('First user set a shared lock:', token_s1);
token_s2 := DAV_LOCK ('/DAV/lock_demo/sample.htm', '', 'S', NULL, 'user2@example.com', '', '0', NULL, 'lock_u2', 'lock_u2_pwd');
result ('Second user set a shared lock:', token_s2);
token_x := DAV_LOCK ('/DAV/lock_demo/sample.htm', '', 'X', NULL, 'user1@example.com', token_s1, '0', NULL, 'lock_u1', 'lock_u1_pwd');
result ('Lock dump',
DUMP_VEC (DAV_LIST_LOCKS (DAV_SEARCH_ID ('/DAV/lock_demo/sample.htm', 'R'), 'R')) );
result ('First user tries to set an exclusive lock:', token_x);
result ('Second user releases his lock:',
DAV_UNLOCK ('/DAV/lock_demo/sample.htm', token_s2, 'lock_u2', 'lock_u2_pwd') );
token_x := DAV_LOCK ('/DAV/lock_demo/sample.htm', '', 'X', NULL, 'user1@example.com', token_s1, '0', NULL, 'lock_u1', 'lock_u1_pwd');
result ('First user sets an exclusive lock:', token_x);
result ('First user releases his lock:',
DAV_UNLOCK ('/DAV/lock_demo/sample.htm', token_s1, 'lock_u1', 'lock_u1_pwd') );
token_x := DAV_LOCK ('/DAV/lock_demo/sample.htm', '', 'X', NULL, 'user1@example.com', token_s1, '0', NULL, 'lock_u1', 'lock_u1_pwd');
result ('First user sets an exclusive lock:', token_x);
result ('Second user tries to add a property to the resource:',
DAV_PROP_SET ('/DAV/lock_demo/sample.htm', 'sample_prop', 'sample value', 'lock_u2', 'lock_u2_pwd') );
result ('First user releases his shared:',
DAV_UNLOCK ('/DAV/lock_demo/sample.htm', token_x, 'lock_u1', 'lock_u1_pwd') );
result ('Second user adds a property to the resource:',
DAV_PROP_SET ('/DAV/lock_demo/sample.htm', 'sample_prop', 'sample value', 'lock_u2', 'lock_u2_pwd') );
}
DAV_LOCK_DEMO ();
ACTION RETVAL
VARCHAR VARCHAR
_______________________________________________________________________________
Adding group lock_demo_grp: 107
Adding user lock_u1: 108
Adding user lock_u2: 109
Adding a collection: 171
Uploading /DAV/lock_demo/sample.htm: 1103
First user set a shared lock: 1545ce54-3599-11da-8697-8f3efbd86ef2
Second user set a shared lock: 15460590-3599-11da-8697-8f3efbd86ef2
Lock dump
vector (
vector ('', 'S', '1545ce54-3599-11da-8697-8f3efbd86ef2', 604800, 108, 'user1@example.com'),
vector ('', 'S', '15460590-3599-11da-8697-8f3efbd86ef2', 604800, 109, 'user2@example.com'))
First user tries to set an exclusive lock: -8
Second user releases his lock: 15460590-3599-11da-8697-8f3efbd86ef2
First user sets an exclusive lock: -8
First user releases his lock: 1545ce54-3599-11da-8697-8f3efbd86ef2
First user sets an exclusive lock: 1547251a-3599-11da-8697-8f3efbd86ef2
Second user tries to add a property to the resource: -8
First user releases his shared: 1547251a-3599-11da-8697-8f3efbd86ef2
Second user adds a property to the resource: 1321
]]>
</screen>
</example>
</refsect1>
<refsect1 id="seealso_dav_api_add"><title>See Also</title>
<para><link linkend="fn_dav_api_add">DAV content add/update/delete functions</link></para>
<para><link linkend="fn_dav_api_change">DAV content manipulation functions</link></para>
<para><link linkend="fn_dav_api_search">DAV search functions</link></para>
<para><link linkend="fn_dav_api_user">DAV user management functions</link></para>
</refsect1>
</refentry>
|
