requestid

RequestId is a unique identifier assigned to a single request as it moves through a system, enabling traceability and correlation of events across components. It is commonly used in web services, APIs, and distributed architectures to link log entries, metrics, and traces that originate from the same user action or operation.

In practice, the RequestId is generated at the edge of a system or at the first service that handles the request and then propagated downstream. HTTP applications often rely on headers such as X-Request-Id or Request-Id, with some ecosystems using Trace-Id or framework-specific properties like HttpContext.TraceIdentifier. The token is typically a UUID/GUID or another unique string.

The primary uses of a RequestId are logging and tracing. By including the RequestId in log lines across services and machines, operators can correlate entries from different components to reconstruct the path of a request, diagnose failures, measure latency, and troubleshoot user-reported issues. It also supports monitoring and analytics by aggregating metrics for a single request lineage.

Implementation considerations include ensuring reliable propagation across service boundaries, choosing a suitable generation method, and deciding whether the header is mandatory or optional. Privacy and security should be considered to avoid exposing sensitive internal details. Proxies and gateways can affect propagation, so designs often require explicit forwarding of the RequestId. Related concepts include correlation IDs and distributed tracing, such as OpenTelemetry traces.