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IPoll Contract
This interface is composed of methods called by the client to poll the
server for data, alarms, and events.
Methods
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PollDataChanges
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This method is used to poll the endpoint for changes to a
specific data list.
Changes consists of:
- values for data objects that were added to the list,
- values for data objects whose current values have changed
since the last time they were reported to the client via this
interface. If a deadband filter has been defined for the list,
floating point values are not considered to have changed unless
they have changed by the deadband amount.
- historical values that meet the list filter criteria,
including the deadband.
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PollEventChanges
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This method is used to poll the endpoint for changes to a
specific event list. Event messages are sent when there has been a
change to the specified event list. A new alarm or event that has
been added to the list, a change to an alarm already in the list, or
the deletion of an alarm from the list constitutes a change to the
list.
Once an event has been reported from the list, it is automatically
deleted from the list. Alarms are only deleted from the list when
they transition to inactive and acknowledged.
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