How to implement "real-time" report with automatic refresh/update?

We need to create a report that queries a real-time database and automatically refreshes data on an administered schedule, as frequently as every 3 seconds.  How can this be done in a Crystal report launched from the Crystal report server?

Also, the report will have at least 2 sub-reports, 1 query for 1 sub-report, 2 queries for the other sub-report.

Thanks!