Building Data Mining Tools Using JDM - Java Data Mining: Strategy, Standard, and Practice - page 351

30. "RetrieveStatsDS", NamedObject.physicalDataSet);

31. }

32. return null;

33.}

Line 2 checks if the PhysicalDataSet named RetrieveStatsDS exists
in the MOR. If it does, we retrieve the PhysicalDataSet and check that
its URI is the same as the one of the current console, which is stored
in the member variable mBuildData . If so, we return the restored
PhysicalDataSet that should contain statistical information from a
previous execution of the ComputeStatisticsTask object.
When the PhysicalDataSet called RetrieveStatsDS does not match,
we save a new version of the PhysicalDataSet named RetrieveStatsDS
in the repository (note the last argument on line 14 overwrites any
previous version). We then create the ComputeStatisticsTask associ-
ated with this dataset and save, verify, and execute. Note that the
PhysicalDataSet was saved before task creation because the Compute-
StatisticsTaskFactory needs a named PhysicalDataSet, as shown in line
16. When the task successfully completes, it saves a new version of
this PhysicalDataSet with the statistical information.
In JDM, vendors are required to support synchronous execution;
while asynchronous execution is optional. We have chosen to illustrate
asynchronous execution for our tool examples. We monitor task exe-
cution using the method monitorTaskExecution for all tasks executed
from the JDMConsole . The code for this method is provided here:

1. protected boolean monitorTaskExecution(ExecutionHandle iExecHandle)
2. throws JDMException {

3. ExecutionState lState iExecHandle.getLatestStatus().getState();

4. boolean lIsTerminated false;

5. while (!lIsTerminated) {

6. lState iExecHandle.getLatestStatus().getState();

7. lIsTerminated (lState.equals(ExecutionState.success)

8. || lState.equals(ExecutionState.error));

9. try {

10. Thread.sleep(100);

11. } catch (InterruptedException lException) {

12. JOptionPane.showMessageDialog(this,

13. "InterruptedException Occured: "

14. lException.getMessage());

15. }

16. }

17. return lState.equals(ExecutionState.success);

18.}