A "property push to mashup" functionality has been added in the latest release of Thingworx platform 7.2.
The property values are pushed to mashup vs. pulled using the auto-refresh widget.
Now the mashups can use a websocket connection and create subscriptions to a property.
This allows them to react responsively to property updates via the GetProperties service.
One persistent websocket connection is used and permit to retrieve automatically the property values without specifying an interval.
When using the Getproperties Service in a mashup it will display a new check box "Automatically update values when able".
This is what enable automatic receive the updates.
The GetProperties service have a ServiceInvokeCompleted service that is triggered when a new value has been received.
I hope this answer help