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03/12/2021
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Hello, i'm running tests on OPCUA servers to know their capacity to send information via subscriptions. I set up on the server a variable that is supposed to change every 200 ms. Using a python script i've subscribed to this node, and on every data changes event i take the server timstamps and store it on a list. Then i calculate the interval between each timestamps to verify if the 200 ms intervals are respected. However, it happends that the interval between two successive timestamps is negative, and i can't figured out why..
Does anyone know where this might be coming from?
05/30/2017
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Client side processing of NotificationMessages often requires multiple threads. This could be DataChanges reach your code 'out of order'.
Examine your client APIs to make sure there are no possible race conditions.
If you are certain your client side is not an issue then try setting a large buffer size and a sampling rate that is faster than the publishing rate for your monitored items. This would force the server to return a block of datachanges in one message, in order.
If you see a problem with the timestamps in this scenario then there is problem with the server that needs to be taken up with the server vendor.
Also, make sure you check the ServerTimestamp and the SourceTimestamp.
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