Over the Thanksgiving break, I wrote the database plugin [1]. The goal
of this effort is:
- Define a common abstraction for plugins that want external database
connectivity.
The plugin defines the Database class, which represents a capsule
around JDBC DataSource. The Database class is Describable, because
it's meant to be configured by admins for plugins that use them.
The immediate driver for this was Jenkow plugin, which embeds a
workflow engine that stores stuff in RDBMS. So the admin would tell
this plugin what database to connect to, via GUI, and this is just a
matter of having a property whose type is Database [3].
The plugin then uses Database.getDataSource() to retrieve DataSource,
then use it.
- I want to create a global Database instance that's available to
plugins for use. I think some plugins would find such a storage
useful, and I think it's better for the admin to configure it once
and let all interested plugins use it, as opposed to every plugin
coming up with its own places to store stuff.
- I want to also create a per-job file-backed embedded Database
instance that plugins can use to store job-scoped stuff (like test
reports and analysis results.)
This appeals to me because the ultimate data store for this is still
under $JENKINS_HOME/jobs/foo/, just that some data are now binary and
not in XML.
I think the first feature is non-controversial, and this is already
implemented, along with several database driver plugins (H2 for
embedded, MySQL and Postgres because I can!)
But the 2nd and the 3rd ones open up a lot of questions for which I have
no answer --- name collisions of tables among different plugins, how
schemas kept in sync with plugin versions, whether they should be higher
level abstractions to deal with these. Right now, it's just you and
Connection (with which anyone can execute any SQL.)
Are these interesting? Would any plugin developers interested in using
this? Any suggestion for abstraction improvements before I release the
first version of the plugin?
[1] https://wiki.jenkins-ci.org/display/JENKINS/Database+Plugin
[2] https://github.com/jenkinsci/database-plugin
[3]
https://github.com/jenkinsci/database-plugin/blob/master/src/test/java/org/jenkinsci/plugins/database/Sample.java
--
Kohsuke Kawaguchi http://kohsuke.org/
