# Service Latency Service latency metrics. ## Subscription Subject `$SYS.SERVER.METRIC.SERVICE.LATENCY` ## Metric Schema Metric published about sampled service requests showing request status and latencies Expand All typeconst: "io.nats.server.metric.v1.service\_latency"required idstringrequired Unique correlation ID for this event timestampstringrequired The time this event was created in RFC3339 format â–¶requestorobject Details about the service requestor â–¶responderobject Details about the service responder headerobject When header based latency is enabled, the headers that triggered the event statusintegerrequired The status of the request. 200 OK, 400 Bad Request, no reply subject. 408 Request Timeout, requester lost interest before request completed. 503 Service Unavailable. 504 Service Timeout. Allowed values:`200``400``408``503``504` errorstring A description of the status code when not 200 startstringrequired The time the request started in RFC3339 format serviceintegerrequired The time taken by the service to perform the request in nanoseconds systemintegerrequired Time spend traversing the NATS network in nanoseconds totalintegerrequired The overall request duration in nanoseconds