IPoll contract

This interface is composed of methods called by the client to poll the server for data, alarms, and events.

Method	Explanation
PollDataChanges	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.
PollEventChanges	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.

Method

Explanation

PollDataChanges

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.

PollEventChanges

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.