Wednesday, November 03, 2004

The code from yesterday did pretty well, though there were a few errors. Overall the structure worked out, and it was just a few little things that wouldn't work. For instance, I had an array of SPLimit objects for each type, but SPObject (the parent class) will not accept a data type of TCID_FREE (0) so I had to leave that array entry at null.

The only significant issue was in a line which renames the variables of a tuples to those of the requesting constraint. Since the data has been sorted, it is contained in a HybridTuples object. It appears that the renameVariables method in this class expects to see variables which are named "Subject", "Predicate", "Object" or "Model". However, I had copied the Tuples returned from the XAStringPoolImpl which names the single column "gnodes".

While I could just fix this by renaming my single column to "Subject", I was at a loss as to why the method had previously worked on the Tuples returned from XAStringPoolImpl. I eventually realised that this was because the tuples was always renamed before being resorted into a HybridTuples, so the HybridTuples.renameVariables() method had never been called on data returned from XAStringPoolImpl before.

Looking at the code from various angles, I was able to determine that the name "gnodes" was just a convenient placeholder, and that "Subject" was not only more convenient, it also made semantic sense in the context of where this code appears.

Once it seemed to be running, I gave the code to ML to try with his code. Unfortunately there had been no unit tests for this code, and I was running a little short on time to build a comprehensive set, so letting it run in context was my best bet. There was a small bug, where I hadn't realised that the limit parameters could be set to null to indicate no limit, but I fixed this easily, and after that it worked as advertised.

Running everything in the unit tests showed up a slew of new failures in the JRDF tests. This ended up being because these tests required all new resolvers to be in the classpath, as it does reflection on each of them. Adding the nodetype resolver to its classpath fixed this. To prevent this in future, RT (who is maintaining that code) changed the build script to include the whole distribution in the classpath for that test.

Now I have to move the Remote Resolver from Kowari and into TKS, so that the distributed tests in TKS can validate this code. I've checked out TKS, and I've started exploring the paths (again). I'm not really sure what to do, but hopefully I'll figure it out early tomorrow.

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