SubscriptionQuantumLimit Element (ADF)
Specifies how far the logical (quantum) clock can fall behind the real-time clock before skipping subscription rule firings.
Syntax
<ApplicationExecutionSettings>
...
<SubscriptionQuantumLimit>
Element Characteristics
| Characteristic | Description |
|---|---|
Data type |
Non-negative integer. |
Default value |
30 quanta, which is 30 minutes, assuming a QuantumDuration value of 1 minute. |
Occurrence |
Optional once per ApplicationExecutionSettings element. |
Updates |
Can be added, deleted, and modified when updating the application. |
Element Relationships
| Relationship | Elements |
|---|---|
Parent element |
|
Child elements |
None. |
Remarks
Notification Services uses a quantum clock to schedule rule firings. If the Notification Services engine that runs the application was down, or if the workload is causing the application to fall behind, the quantum clock can fall behind the real-time clock. This means that Notification Services falls behind on maintaining the running subscription rules.
Quantum limits ensure that the application does not fall too far behind the real-time clock, helping to ensure that newer data is processed in a timely manner.
To determine the value for this element, determine your application's maximum lag time between the quantum clock and the real-time clock and then divide that time by the quantum duration. For example, if you want a maximum lag time of 2 hours, and your quantum duration is 5 minutes, divide 120 by 5 and then set this element to the result (24).
If you set this value to 0 (zero), there is no subscription quantum limit. Monitor your application using a report such as NSSnapshotApplications (Transact-SQL) to ensure that data is being processed in a timely manner.
If you do not specify a value for the SubscriptionQuantumLimit element, remove the element from the ADF. The system default is used in this case.
Example
The following example shows a SubscriptionQuantumLimit element that sets the quantum limit to 10 quanta. If the logical clock that keeps track of quanta falls 10 quantum intervals behind the real-time clock, the application will skip subscription rule firings to catch up to the 10 quanta limit.
<SubscriptionQuantumLimit>10</SubscriptionQuantumLimit>
See Also
Reference
Application Definition File Reference
Other Resources
Specifying Quantum Limits
Updating Instances and Applications