A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); }
A pointer from the current span to another span in the same trace or in a different trace. For example, this can be used in batching operations, where a single batch handler processes multiple requests from different traces or when the handler receives a request from a different project.
A span represents a single operation within a trace. Spans can be nested to form a trace tree. Often, a trace contains a root span that describes the end-to-end latency, and one or more subspans for its sub-operations. A trace can also contain multiple root spans, or none at all. Spans do not need to be contiguous. There might be gaps or overlaps between spans in a trace.
The Status type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by gRPC. Each Status message contains three pieces of data: error code, error message, and error details. You can find out more about this error model and how to work with it in the API Design Guide.
A collection of TimeEvents. A TimeEvent is a time-stamped annotation on the span, consisting of either user-supplied key:value pairs, or details of a message sent/received between Spans.