Custom Metadata Transmission

In gRPC, metadata refers to key-value pairs that are attached to an RPC call, similar to HTTP headers.

Unlike the main message payload, metadata carries information about the call itself, rather than the application data being transmitted.

• It's for auxiliary data.
• It travels with requests and responses.
• It's separate from your protobuf messages.

Metadata is incredibly useful for carrying information that doesn't belong in your service's primary request or response messages.

Common use cases include:

• Authentication Tokens: Sending JWTs or API keys.
• Tracing IDs: Propagating unique request IDs for distributed tracing.
• Custom Headers: Any other contextual information needed by your services.