====
ZODB
====

Introduction
============

The ZODB  package provides a  set of tools  for using the  Zope Object
Database (ZODB).  The components you  get with the ZODB release are as
follows:

- Core ZODB, including the persistence machinery
- Standard storages such as FileStorage
- The persistent BTrees modules
- ZEO, for scalability needs
- documentation (needs a lot more work)

Our primary development platforms are Linux, Mac OS X, and Windows
XP.  The test suite should pass without error on all of these
platforms, although it can take a long time on Windows -- longer if
you use ZoneAlarm.  Many particularly slow tests are skipped unless
you pass --all as an argument to test.py.

Compatibility
=============

ZODB 3.9 requires Python 2.4.2 or later.

Note --
   When using ZEO and upgrading from Python 2.4, you need to upgrade
   clients and servers at the same time, or upgrade clients first and
   then servers.  Clients running Python 2.5 or 2.6 will work with
   servers running Python 2.4.  Clients running Python 2.4 won't work
   properly with servers running Python 2.5 or later due to changes in
   the way Python implements exceptions.

ZODB ZEO clients from ZODB 3.2 on can talk to ZODB 3.9 servers.  ZODB
ZEO Clients can talk to ZODB 3.8 and 3.9 ZEO servers.

Prerequisites
=============

You must have Python installed. If you're using a system Python
install, make sure development support is installed too.

You also need the transaction, zc.lockfile, ZConfig, zdaemon,
zope.event, zope.interface, zope.proxy and zope.testing packages.  If
you don't have them and you can connect to the Python Package Index,
then these will be installed for you if you don't have them.

Installation
============

ZODB is released as a distutils package.  The easiest ways to build
and install it are to use `easy_install
<http://peak.telecommunity.com/DevCenter/EasyInstall>`_, or
`zc.buildout <http://www.python.org/pypi/zc.buildout>`_.

To install by hand, first install the dependencies, ZConfig, zdaemon,
zope.interface, zope.proxy and zope.testing.  These can be found
in the `Python Package Index <http://www.python.org/pypi>`_.

To run the tests, use the test setup command::

  python setup.py test

It will download dependencies if needed.  If this happens, ou may get
an import error when the test command gets to looking for tests.  Try
running the test command a second time and you should see the tests
run.

::

  python setup.py test

To install, use the install command::

  python setup.py install


Testing for Developers
======================

The ZODB checkouts are `buildouts <http://www.python.org/pypi/zc.buildout>`_.
When working from a ZODB checkout, first run the bootstrap.py script
to initialize the buildout:

    % python bootstrap.py

and then use the buildout script to build ZODB and gather the dependencies:

    % bin/buildout

This creates a test script:

    % bin/test -v

This command will run all the tests, printing a single dot for each
test.  When it finishes, it will print a test summary.  The exact
number of tests can vary depending on platform and available
third-party libraries.::

    Ran 1182 tests in 241.269s

    OK

The test script has many more options.  Use the ``-h`` or ``--help``
options to see a file list of options.  The default test suite omits
several tests that depend on third-party software or that take a long
time to run.  To run all the available tests use the ``--all`` option.
Running all the tests takes much longer.::

    Ran 1561 tests in 1461.557s

    OK


Maintenance scripts
-------------------

Several scripts are provided with the ZODB and can help for analyzing,
debugging, checking for consistency, summarizing content, reporting space used
by objects, doing backups, artificial load testing, etc.
Look at the ZODB/script directory for more informations.


History
=======

The historical version numbering schemes for ZODB and ZEO are complicated.
Starting with ZODB 3.4, the ZODB and ZEO version numbers are the same.

In the ZODB 3.1 through 3.3 lines, the ZEO version number was "one smaller"
than the ZODB version number; e.g., ZODB 3.2.7 included ZEO 2.2.7.  ZODB and
ZEO were distinct releases prior to ZODB 3.1, and had independent version
numbers.

Historically, ZODB was distributed as a part of the Zope application
server.  Jim Fulton's paper at the Python conference in 2000 described
a version of ZODB he called ZODB 3, based on an earlier persistent
object system called BoboPOS.  The earliest versions of ZODB 3 were
released with Zope 2.0.

Andrew Kuchling extracted ZODB from Zope 2.4.1 and packaged it for
use by standalone Python programs.  He called this version
"StandaloneZODB".  Andrew's guide to using ZODB is included in the Doc
directory.  This version of ZODB was hosted at
http://sf.net/projects/zodb.  It supported Python 1.5.2, and might
still be of interest to users of this very old Python version.

Zope Corporation released a version of ZODB called "StandaloneZODB
1.0" in Feb. 2002.  This release was based on Andrew's packaging, but
built from the same CVS repository as Zope.  It is roughly equivalent
to the ZODB in Zope 2.5.

Why not call the current release StandaloneZODB?  The name
StandaloneZODB is a bit of a mouthful.  The standalone part of the
name suggests that the Zope version is the real version and that this
is an afterthought, which isn't the case.  So we're calling this
release "ZODB". We also worked on a ZODB4 package for a while and
made a couple of alpha releases.  We've now abandoned that effort,
because we didn't have the resources to pursue ot while also maintaining
ZODB(3).

License
=======

ZODB is distributed under the Zope Public License, an OSI-approved
open source license.  Please see the LICENSE.txt file for terms and
conditions.

The ZODB/ZEO Programming Guide included in the documentation is a
modified version of Andrew Kuchling's original guide, provided under
the terms of the GNU Free Documentation License.


More information
================

We maintain a Wiki page about all things ZODB, including status on
future directions for ZODB.  Please see

    http://wiki.zope.org/ZODB/FrontPage

and feel free to contribute your comments.  There is a Mailman mailing
list in place to discuss all issues related to ZODB.  You can send
questions to

    zodb-dev@zope.org

or subscribe at

    http://lists.zope.org/mailman/listinfo/zodb-dev

and view its archives at

    http://lists.zope.org/pipermail/zodb-dev

Note that Zope Corp mailing lists have a subscriber-only posting policy.

Andrew's ZODB Programmers Guide is made available in several
forms, including DVI and HTML.  To view it online, point your
browser at the file Doc/guide/zodb/index.html


Bugs and Patches
================

Bug reports and patches should be added to the Launchpad:

    https://launchpad.net/zodb


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