20 Feb
2015
20 Feb
'15
2:09 p.m.
Hi Marc,
On 18 Feb 2015 at 17:19:01, Marc Sladek
(marc.sladek@synventis.com(mailto:marc.sladek@synventis.com)) wrote:
Dear XWiki devs
Within the scope of our XWiki-based project called celements, we are using
several so-called "modules", which consist of JARs, web resources
(VM/CSS/JS files) and hibernate mappings. These modules extend the
functionality of the base application and can be optionally added if
required. We need to update and migrate these modules independently from
XWiki. Therefore we require to store individual migration version numbers
in the database for each module.
XWiki's single implementation of
DataMigrationManager, HibernateDataMigrationManager, isn't intended to
store multiple version numbers with specific identifiers in the database.
There also doesn't seem to be an evident hook from XWiki to seamlessly add
own implementations of the DataMigrationManager to the application to
allow migration subsystems.
Considering the similarities of XWiki extensions to our modules, is there
already a way that we have missed to achieve independent migrations of our
modules?
I recently introduced the xwiki-platform-instance module which creates its own DB table to
store the XWiki instance id. You can do something similar for your “modules”, i.e. one
table with each row containing a module name + a module version.
Another option you have is to use the permanent directory and store the versions in a file
there (in a properties file for example to make it easy to read/write).
About hooks, there’s an Application Started Event or a Database Ready Event that you can
use to perform your checks/migrations.
If not, are there any future plans from XWiki's
side to add this
functionality?
We’ve not seen the need so far, so there’s no future plan ATM.
Now, if you’re willing to work on this, I guess it could be possible to refactor the XWiki
Migration Manager into its own module in XWiki and in addition, make it more generic so
that it can support plugging external migrations that would want to benefit from a store
and from hibernate/liquibase migrations.
It’s certainly not a priority for the xwiki dev team but if you were willing to do the
work, maybe it’s possible. Don’t know what others think about this.
We’re always happy to get more contributions in general! It would be great if the
celements team (http://www.celements.ch/Home?language=en) could contribute more stuff on
extensions.xwiki.org or participate to XWiki’s dev in one way or another! :) (having some
active committer in the project would also allow you to advertise your company/project on
xwiki.org, see http://dev.xwiki.org/xwiki/bin/view/Community/Governance).
Thanks
-Vincent
Thanks in advance
Marc Sladek
synventis gmbh