java BIRT grouping

Answer 1

You should be able to create and populate the summary table using the built-in aggregation tool. On the Control palette look toward the bottom for "Aggregation". From there you can set up your aggregation data items. In your case probably a count on the OS data item.

Then to add them to the report, you can move the data item itself anywhere you want in a given table. TO avoid it repeating (and to ensure it can see all the data in a given group) you would probably add a summary table to the group footer, and then add your aggregations to that summary table.