Read historian values (recorded or interpolated) from an AVEVA PI tag via PI Web API

Steps

1. Authenticate over HTTPS using Basic auth, Kerberos/Windows auth, or OAuth2 bearer token, depending on how the service is configured
2. Resolve the target WebID by path with GET /piwebapi/points?path=... for a PI point, or GET /piwebapi/attributes?path=... for an AF attribute
3. GET /piwebapi/streams/{webId}/value?selectedFields=Timestamp;Value for the current snapshot value
4. GET /piwebapi/streams/{webId}/recorded?startTime=*-2d&endTime=*-1d for compressed historian values over a time range
5. GET /piwebapi/streams/{webId}/interpolated?startTime=*-1d&endTime=*&interval=1h for evenly spaced interpolated values
6. For multiple tags in one call, use the StreamSet controller: GET /piwebapi/streamsets/recorded?webId={id1}&webId={id2}