Your answer can be done the quickest with direct API web-hooks that call your Service Now Instance directly to POST parameters from a Pi code process. This will Update data on a CMDB CI or Custom Table. But a MID-server and a CMDB Custom Class is the...

Many ways to process payloads for producing records from the examples others have provided. But your original question was how to determine if a CI is operational or not from that REST integration. This is something that can be exposed as a single qu...