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QuotaFolder - Quota support for Zope
What is it?
-----------
QuotaFolder is a folder-ish object that restricts the total number of objects,
their total size and their individual maximum size. QuotaFolder takes
subfolders (recursively) into account, so it should not be possible to escape
the quota restrictions.
The basic goal of QuotaFolder is not to put an absolute limit on ZODB usage
- it is impossible to determine this. For example, each object may have
several revisions in the ZODB, and some of the internal state of the object
is stored in the ZODB that's not returned by get_size(). The goal is to
limit the use of objects in general, to prevent people from offering large
files or using up resources with enormous amounts of objects.
How does it work?
-----------------
QuotaFolder 'MonkeyPatches (tm)' some of the internal Zope components such
as ObjectManager, File, Image, DTMLMethod, DTMLDocument and more. The patching
constist of making the components 'quota aware'. This basically means the
objects will track changes and report them to parent folders. If one if the
parent folders is a QuotaFolder, and the QuotaFolder detects that the change
will exceed the quota, a QuotaExceededException is raised, and the transaction
is rolled back.
At this moment, if an object supports the get_size() method, it's used. The
value reported by this method will not take all usage (i.e. properties) into
account, so this may be changed in the future.
Supported products
------------------
The QuotaFolder product knows how to account File, Image, DTMLMethod,
DTMLDocument and PythonScript objects. It also understands ObjectManager
based products such as Folder and BTreeFolder (TransparentFolder is not
thoroughly tested, but it seems to work well)
Most products (i.e. FLE, Squishdot, PhotoFolder, ZWiki) exist of ObjectManagers
with subobjects, and QuotaFolder knows how to handle these quite well.
Unknown objects who's size (and changes in size) cannot be determined are
accounted as 1 object with size 0. If this is not satisfactory (for example,
it's not at this moment for TinyTablePlus), extra support can be built in for
these objects (as has been done with, for example, ZPT).
QuotaFolder also supports .zexp imports and copy/paste operations.
QuotaFolder has been tested with Zope 2.4.3, 2.4.4b1 and 2.5.0. It has not
been tested in ZEO setups.
Installing
----------
**WARNING**
This product patches classes in your Zope server. Please test the code on
a test-server or shadow server first! This code has been known to work
succesfully with Zope 2.4.x and Zope 2.5. Use this product at your own
risk, and backup your Data.fs first!
Install the QuotaFolder product by simply unpacking into your Products
directory (either in your SOFTWARE_HOME or your INSTANCE_HOME) and restart
your Zope server. The QuotaFolder product should appear in
/Control_Panel/Products, and it should also be available in the products
dropdown.
When creating (or editting) a QuotaFolder, you will be presented with the
following fields:
id
title
Quota size in bytes - this is the maximum total size of all objects
that's allowed to be created
Maximum object size in bytes - The maximum allowed total size for single
objects
Maximum number of objects - this is the maximum number of objects that's
allowed to be created
Require manager role in parent context?
- If this setting is enabled, a user must be
manager in the folder context *above* the
quotafolder itself to be able to edit the
quota. If you want to limit your users in their
usage, you don't want them to be able to edit
their quota themselves, do you?
After creation, you will get the same contents view as with a standard folder,
but with an extra tab to the right where you can view and (optionally edit)
the quota.
When visiting the quota tab, you will see an extra button 'Sync'. Pressing
this button will cause the QuotaFolder to recalculate all usage. Usually,
the folder shouldn't be out of sync. If you manage to get a QuotaFolder
out of sync, please contact me.
Migrating
---------
There are two ways to migrate a standard folder to a QuotaFolder:
- Create a new QuotaFolder, copy all objects from the old folder, paste
them into the QuotaFolder and rename the folders. This will probably not
work if you have versions (cut/paste may work with versions)
- Use the builtin _replaceFolder method. I.e. create the following external
method:
from Products.QuotaFolder.QuotaFolder import _replaceFolder
def replace(self, name, quota_bytes, quota_objects, quota_maxsize, REQUEST):
_replaceFolder(self, name, quota_bytes, quota_objects, quota_maxsize)
return "%s converted" % name
Create an appropriate external method object in your zope server and invoke
it with an appropriately formatted url or create a dtml form.
Hacking contest!
----------------
QuotaFolder has been thoroughly tested, and seems very stable and compatible.
However, every now and then, new situations seem to appear where it's possible
to use more objects or space than the QuotaFolder should enforce. This may
be through unsupported objects (though these should generaly not make it
possible to create more free space for other objects), or using trickery
with PythonScripts, etc.
If anyone finds issues like this, please contact me (info below), so we can
make this product even more stable and robust :)
Please check the file KNOWNBUGS before reporting issues.
Release info
------------
0.1 Initial version, basic support for quota
Future plans
------------
- Support soft and hardlimit quota, with configurable timeleft
- Restrict installable metatypes
- Limit number of certain metatypes
Contact/License
---------------
QuotaFolder is partially based on ideas by Andrew Kenneth, though most of his
old QuotaFolder has disappeared.
QuotaFolder is written by Ivo van der Wijk as part of Amaze Internet Service's
FreeZope.org Free Zope hosting environment.
I can be contacted through ivo@amaze.nl or on IRC as VladDrac / VladDrak @ OPN
Recent versions of QuotaFolder and other Zope products can be found at:
http://www.zope.org/Members/ivo
http://vanderijk.info/
QuotaFolder is (c) 2002 Ivo van der Wijk / Amaze Internet Services
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
