QOS Property

The messages QoS level.

Data Type

Integer

This property should be set to publish or receive messages at the specified QOS level.

QoS values set the service level for delivery of a message. Values range from 0 to 2 and have the following meanings:


Value	Description
0	At most once delivery - The published message is sent once, and if it does not arrive it is lost.
1	At least once delivery - Guarantees that the published message arrives, but there may be duplicates.
2	Exactly once delivery - Guarantees that the publish message arrives and that there are no duplicates.