Cited from RFC 2518, chapter 3 "Terminology": "Null Resource - A resource which responds with 404 (Not Found) to any HTTP/1.1 or DAV method except for PUT, MKCOL, OPTIONS and LOCK. A Null Resource MUST NOT appear as a member of its parent collection."

Cited from RFC 2518, chapter 7.4 "Write Locks and Null Resources": "It is possible to assert a write lock on a null resource in order to lock the name. A write locked null resource, referred to as a lock-null resource, MUST respond with a 404 (Not Found) or 405 (Method Not Allowed) to any HTTP71.1 or DAV methods except for PUT, MKCOL, OPTIONS, PROPFIND, LOCK and UNLOCK. A lock-null resource MUST appear as a member of its parent collection. Additionally the lock-null resource MUST have defined on it all mandatory DAV properties. Most of these properties such as all the get properties, will have no value as a lock-null resource does not support the GET method. Lock-Null resources MUST have defined values for lockdiscovery and supportedlock properties. Until a method such as PUT or MKCOL is successfully executed on the lock-null resource the resource MUST stay in the lock-null state. However, once a PUT or MKCOL is successfully executed on a lock-null resouce the resource ceases to be in the lock-null state. If the resource is unlocked, for any reason, without a PUT, MKCOL, or similar method having been successfully executed upon it then the resource MUST return to the null state."

Null-resources are used by class.ilDAVSerrev.php for the following use cases:

Use case 1: Creating a new file resource

Client sends a PROPFIND request on the name of the resource
Server returns 404 (Not Found)
Client sends a LOCK request on the name of the resource.
Server creates a Null Resource and a Lock on the name.
Client sends a PUT request on the name and passes the resource content along
Server converts the Null Resource into a File resource and stores the resource content
Client sends an UNLOCK request on the name of the resource
Server deletes the Lock.

Use case 2: Creating a new collection resource

Client sends a PROPFIND request on the name of the resource
Server returns 404 (Not Found)
Client sends a LOCK request on the name of the resource.
Server creates a Null Resource and a Lock on the name.
Client sends a MKCOL request on the name
Server converts the Null Resource into a Collection resource and stores the resource content
Client sends an UNLOCK request on the name of the resource
Server deletes the Lock.

Use case 3: Locking and Unlocking a null resource

Client sends a LOCK request on the name of the resource for some reason.
Server creates a Null Resource and a Lock on the name.
(Some time later) Client sends a UNLOCK request on the name of the resource
Server deletes the Null Resource
Server deletes the Lock.

Use case 4: Locking and timeout on lock on a null resource

Client sends a LOCK request on the name of the resource for some reason.
Server creates a Null Resource and a Lock on the name.
(Some time later) the lock times out.
Server deletes the Null Resource
Server deletes the Lock.

Author: Werner Randelshofer, Hochschule Luzern, werne.nosp@m.r.ra.nosp@m.ndels.nosp@m.hofe.nosp@m.r@hsl.nosp@m.u.ch

Version

Id:: class.ilObjNull.php,v 1.0 2005/01/31 10:01:10 wrandels Exp

-core

Author: Sascha Hofmann shofm.nosp@m.ann@.nosp@m.datab.nosp@m.ay.d.nosp@m.e

Version: $Id$

-setup

this file helps setting up ilias main purpose is writing the ilias.ini to the filesystem it can set up the database to if the settings are correct and the dbuser has the rights