Virtuoso – Once More With Feeling

The Virtuoso backend for Soprano and, thus, Nepomuk can be seen as rather stable now. So now the big tests can begin as the goal is to make it the standard in KDE 4.4. Let me summarize the important information again:

Step 1

Get Virtuoso 5.0.12 from the Sourceforge download page. Virtuoso 6 is NOT supported. (not yet anyway)

Step 2

Hints for packagers: Soprano only needs two files: the virtuoso-t binary and the virtodbc_r(.so) ODBC driver. Everything else is optional. (For the self-compiling folks out there: –disable-all-vads is your friend.)

Step 3

Install libiodbc which is what the Soprano build will look for (Virtuoso is simply a run-time dependency.)

Step 4

Rebuild Soprano from current svn trunk (Remember: Redland is still mandatory. Its memory storage is used all over Nepomuk!)

Step 5

Edit ${KDEHOME}/share/config/nepomukserverrc with your favorite editor. In the “[Basic Settings]” section add “Soprano Backend=virtuosobackend”. Do not touch the main repository settings!

Step 6

Restart Nepomuk. I propose the following procedure to gather debugging information in case something goes wrong:
Shutdown Nepomuk completely:

 # qdbus org.kde.NepomukServer /nepomukserver org.kde.NepomukServer.quit

Restart it by piping the output into a temporary file (bash syntax):

 # nepomukserver 2> /tmp/nepomuk.stderr

Step 7

Wait for Nepomuk to convert your data. If you are running KDE trunk you even get a nice progress bar in the notification area (BTW: does anyone know why it won’t show the title?)

And Now?

That is already it. Now you can enjoy the new Virtuoso backend.

The development has taken a long time. But I want to thank OpenLink and especially Patrick van Kleef who helped a lot by fixing the last little tidbits in Virtuoso 5 for my unit tests to pass. Next step is Virtuoso 6.

Redland 1.0.9 breaks Nepomuk

This is how Soprano (and with it Nepomuk) goes down when run against Redland 1.0.9:

symbol lookup error: /usr/lib64/redland/ undefined symbol: librdf_storage_register_factory

Redland 1.0.8 works without problems. This is mainly for informational purposes and to propose to distributors to downgrade. I will also post a bug report with Redland and try to figure out what the problem is. But in the meantime it might make sense to not live on the edge for once. ;)