The HAPI server has shown that it is effective to use the timetags to indicate progress, where we know the time which will be covered so we can estimate progress by reading the time tags. With HAPI this is easy because we know where the times are, but this should be fairly easy with das2streams as well.
See https://saturn.physics.uiowa.edu/mantis/view.php?id=498 (since this is really more of a das2 request).
I'm going to implement this for TRACERS. Actually I thought there was an environment variable you could set to experiment with this, and I need to look for it.
Here's where I enabled it before: System.getProperty("timetagMonitoringDas2StreamHandler","false").startsWith("t")
This will be in the next development release.