Day: February 6, 2008

Finding Sessions

Clusters can making finding where a user was working a clusterf***. Users end up on a node, but they don’t know which node. Heck, we are ahead of the curve to get user name, date, and time. Usually checking all the nodes in the past few days can net you the sessions. Capturing the session ids in the web server logs usually leads to finding an error in the webct logs. Though not always. Digging through the web server logs to find where the user was doing something similar to the appropriate activity consumes days.

Blackboard Vista captures node information for where the action took place. Reports against the tracking data provide more concise, more easily understood, and more quickly compiled. They are fantastic for getting a clear understanding of what steps a user took.

Web server logs contain every hit which includes every page view (well, almost, the gap is another post). Tracking data represents at best 25% of the page views. This problem is perhaps the only reason I favor logs over tracking data. More cryptic data usually means a slower resolution time not faster.

Another issue with tracking is the scope. When profiling student behavior, it is great. The problem is only okay data can be located for instructors while designers and administrators are almost totally under the radar. With the new outer join, what we can get for these oblivious roles has been greatly expanded.

Certainly, I try not to rely too much on a single source of data. Even I sometimes forget to do so.

Tweets for Today

  • 08:57 If Google is the new Microsoft, then does that make the founders Darth Page and Darth Brin? tinyurl.com/3yh3yz #
  • 09:42 You can't make this stuff up: "should [the fire alarm] go off for some reason there is no reason to be alarmed." #
  • 09:58 @dgcombs True… Stock in them is cool. A drop in quality of their applications sux. #
  • 10:10 Nice… Flubbed the query against 17 nodes. It gave me the most recent not long running requests. Re-running it now…… #
  • 10:56 Vista tracking files on nodes are not so much a log… as… cached data pre-inclusion to db. Not sure what corruption at power fail means. #
  • 16:29 Wonder how many Americans actually keep their votes secret? For example, people tweet their votes to @ivoted. How easily do people fess up? #
  • 18:15 From @SuperTuesday: Apparently Virginia voters are showing up at the polls – but they don't open for another week. tinyurl.com/36eyh2 #
  • 22:47 Wow… a ton ofelection tweets… #
  • 22:52 Last Cricket game @ dart practice was a monster. Scored 11 triples against GH. Threw well @ cricket all night. Not so well @ 301. #

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User Interface v. SQL Reports and Tracking

Blackboard Vista tracks student activity. This tracking data is viewed as a critical feature of Vista. Our instructors depended on the information until we revoked their ability to run reports themselves due to performance issues. Campus administrators can still generate reports (though some still fail). We doubt the solution to this is Blackboard improving the queries to create the reports. We favor deleting tracking data (data preserved outside of Vista) to resolve the performance issues.

We developed SQL reports to look at the tracking data where the user in question was not a student. Yes, the data is limited, but in determining when and where a user was active, can help determine where to look in logs. When we hit the performance issues we started using these reports where the user interface reports failed to generate.

My understanding was the user interface and SQL reports on tracking were the same. Both looked at the same data. The user interface reports were just sexier wrapped in HTML and using icons. I compared a user interface report to a SQL report. Just prior to doing this, I was thinking, WebCT was stupid for not tracking when students look at the list of assessments. Turns out “Assessment list viewed” was tracked in the user interface all along but was missing in our sqlplus queries. WTF?

The data has to be there. The problem has to be our approach in sqlplus is inadvertently excluding the information from the reports. Because these reports must be accurate, I’ll crack this nut… Or become nuts myself.

CRACKED THE NUT: So, part of the data WebCT collected was the name of pages. There is a page name table which was inner joined to the user action table. So pages without a name were not reported. George suggested an outer join. I placed it on the page name table which now lets us see the formerly missing tracked actions. For the specific case where I found this, I now get all the missing actions.

Considering a Blackboard (it’s their problem now) feature request to ensure every page in the application has a title. I consider it developer laziness (someone else said worthlessness) that some pages might not have something so core and simple.

ANOTHER TRICK: Oracle’s NVL function displays a piece of text instead of a null value. Awesome for the above.