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Consider WriterGroups in MQTT KeepAlive calculation #3616

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Consider WriterGroups in MQTT KeepAlive calculation #3616

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30c38d6
Consider WriterGroups in MQTT KeepAlive calculation
jnsjll Mar 13, 2026
59431aa
Merge branch 'master' into jnsjll-pubsub-keep-alive-calculation
jnsjll Mar 20, 2026
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2 changes: 1 addition & 1 deletion Libraries/Opc.Ua.PubSub/IntervalRunner.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -74,7 +74,7 @@ public IntervalRunner(
public object Id { get; }

/// <summary>
/// Get/set the Interval between Runs
/// Get/set the Interval between Runs in milliseconds
/// </summary>
public double Interval
{
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14 changes: 12 additions & 2 deletions Libraries/Opc.Ua.PubSub/Transport/MqttPubSubConnection.cs
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Expand Up @@ -430,7 +430,10 @@ is not BrokerDataSetWriterTransportDataType transport ||
MqttClient publisherClient = null;
MqttClient subscriberClient = null;

TimeSpan keepAlive = CalculateMqttKeepAlive();

m_publisherMqttClientOptions ??= GetMqttClientOptions();
m_publisherMqttClientOptions.KeepAlivePeriod = keepAlive;

int nrOfPublishers = Publishers.Count;
int nrOfSubscribers = GetAllDataSetReaders().Count;
Expand Down Expand Up @@ -483,6 +486,7 @@ is BrokerDataSetReaderTransportDataType brokerTransportSettings &&
}

m_subscriberMqttClientOptions ??= GetMqttClientOptions();
m_subscriberMqttClientOptions.KeepAlivePeriod = keepAlive;

subscriberClient = (MqttClient)
await MqttClientCreator
Expand Down Expand Up @@ -730,14 +734,20 @@ private static MqttQualityOfServiceLevel GetMqttQualityOfServiceLevel(
}
}

private TimeSpan CalculateMqttKeepAlive()
{
// writer group KeepAliveTime is given in milliseconds
return TimeSpan.FromMilliseconds(GetWriterGroupsMaxKeepAlive()) +
TimeSpan.FromSeconds(m_maxKeepAliveIncrement);
}

/// <summary>
/// Get appropriate IMqttClientOptions with which to connect to the MQTTBroker
/// </summary>
private MqttClientOptions GetMqttClientOptions()
{
MqttClientOptions mqttOptions = null;
var mqttKeepAlive = TimeSpan.FromSeconds(
GetWriterGroupsMaxKeepAlive() + m_maxKeepAliveIncrement);
TimeSpan mqttKeepAlive = CalculateMqttKeepAlive();

if (ExtensionObject.ToEncodeable(PubSubConnectionConfiguration.Address)
is not NetworkAddressUrlDataType networkAddressUrlState)
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