I am implementing a HistoryQueryExecutor. How do I get the timezone? It could be different between client / designer / gateway.
You shouldn’t need it. The java.util.Date objects you get in any scope have already taken care of that. java.util.Date contains UTC milliseconds upon creation, and that absolute time is maintained through serialization (client-gateway RPC). The t_stamp column in Ignition’s historian tables is UTC milliseconds as a long integer. You should do the same.