[ZODB-Dev] ZODB 3.3 alpha 3 released

[Jeremy Hylton]

I'm pleased to announce the release of ZODB2 3.3 alpha 3. This release
includes support for new-style persistent classes and multi-version
concurrency control. It's an alpha release, so we could use feedback on
the new features and helping testing them.

The 3.3a3 release requires Python 2.3. It contains the code that is
slated to be in Zope 2.8.  This version of ZODB supports Zope 2 and Zope
3.

You can download a source tarball or Windows installer from
http://zope.org/Products/ZODB3.3

This release contains a lot of changes and improvements since the
previous alpha releases.  The transaction API and implementation have
been overhauled and the persistence API has seen some changes to
accommodate Zope 3.  New features include persistent weak references, an
add() method for ZODB connections, and explicit transaction manager
objects.

The news file lists the changes in more detail:
http://zope.org/Products/ZODB3.3/NEWS.html

The new features in 3.3 represent major changes to ZODB. Support for
new-style classes means that ZODB programmers can use the new class
features introduced in Python 2.2, like properties and descriptors. It
also means that ZODB no longer uses ExtensionClass, which caused many
subtle incompatibilities with other classes.

The multi-version concurrency control feature represents the end of read
conflicts. If a transaction encounters a conflict, it reads older
revisions of the object rather than raising a ReadConflictError. This
feature allows read-only transactions to see a consistent view of the
database without need to handle read conflicts and restart the
transaction.

I'd also like to include a personal note:  This is the last ZODB release
that I will be actively involved in.  I will be starting a new job next
month at Google in New York City.  I've enjoyed working with everyone in
the ZODB and Zope communities; I'll be looking forward to the ZODB 3.3
final release along with you.

Enjoy!

-- Jeremy Hylton <http://www.python.org/~jeremy/>