Events received before digital twin gets updated

Gökhan Kurt 106

We have a digital twin on Azure and an event routing on property Updates to an evethub.
Then I have a console app reading from that event hub and querying the digital twin service for the node that is updated each time a message is received.
The strange thing is that when I receive an update message for a property on the event hub, the property on digital twin is actually still the old value. It takes a few seconds of sleeping before I can read the updated property.
So the question is if this is a bug or feature?

QuantumCache 20,271 Reputation points

2021-01-15T22:50:55.29+00:00

Hello @Gökhan Kurt , Thanks for posting this scenario.

Could you please provide substantial evidence so that the audience/reader can understand it better?

1) How is the console app reading from event hub & Digital Twin instance ? any code snippets (C#?), any screenshots?
2) Any timestamp recording your console app is logging? so that we know exactly how much is the lag for each service call from the console app?
3) It takes a few seconds of sleeping before I can read the updated property. how much is the few seconds? 2/3/5/10 seconds?
4) As you are talking about an End-to-End scenario and it's very difficult to say where the issue might be, so I suggest we discuss/investigate the stage which we think is causing the trouble.

Sometimes, it might be an intermittent issue, it might be a latency introduced from your network, Not using the nearest Azure Region, custom code, etc,.

Please click the reply button to comment. Be assured that we will unblock your issue!!
AshokPeddakotla-MSFT 34,701 Reputation points

2021-01-18T08:17:58.627+00:00

@Gökhan Kurt , Can you share requested information for further help?
Gökhan Kurt 106 Reputation points

2021-01-18T08:28:33.38+00:00

57546-logs.txt

57537-program.txt

Here is an extract from console output and my Program.cs contents.

The time to wait is undeterministic at least for me but varies from 3-9 seconds.

The updates are done through ADT explorer.

I first update the displayName property of a node in ADT explorer. When I get a notification in the eventhub about an update on displayName of the node, I read the same node from digital twin 5 times with 3 seconds in between. As you see in the logs, the first read which is right away always returns me the old displayName value for the node. The second or third read returns the newly updated value.

Accepted answer

Gökhan Kurt 106 Reputation points

2021-01-21T15:24:50.827+00:00

As it turned out this is most probably a feature not a bug at the end as stated as follows in the documentation (https://learn.microsoft.com/en-us/azure/digital-twins/concepts-query-language)

Timing: There may be a delay of up to 10 seconds before changes in your instance are reflected in queries. For example, if you complete an operation like creating or deleting twins with the DigitalTwins API, the result may not be immediately reflected in Query API requests. Waiting for a short period should be sufficient to resolve.
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1 person found this answer helpful.
QuantumCache 20,271 Reputation points

2021-01-26T07:01:07.703+00:00

Hello @Gökhan Kurt , Thanks for sharing your experience with this forum community.
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Events received before digital twin gets updated

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