We have an application that accesses data from multiple PI servers from a PIWEBAPI service. This application queries data from several TAGs in sequence and when it finishes processing the last TAG, returns to the beginning, in a continuous repetition.
After running normally for some time, all requests suddenly return "No Data" instead of the TAG values. The system reads the data through PIWEBAPI's recordedData method. The problem presents itself in different TAGs and has also occurred on different PI servers. Once the system receives the first "No Data", all subsequent requests will return "No Data". Through the browser, the same query that is performed by the system returns valid data.
When I restart the system, it resumes processing the TAGs normally. There are no log occurrences on the system, but I have detected occurrences in the PIWEBAPI server PI SDK log with the following content:
- Information, Deleting connection: New Connection, Remote Connection failed.  No connection could be made because the target machine actively refused it.
- Information, Deleting connection: New Connection, Remote Connection failed.  A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
This issue is occurring in version 1.7.0, but we also installed version 1.11.1 and the same issue occurred.
It appears that this issue is related to a temporary unavailability of any of the PI servers queried. I would like to know if there is a way to get the service to return data without having to force a restart of the application.