FromChain creates an endpoint Sink that sends calls between multiple middlewares for things like counting traces in between.

NextWrap wraps a NextSink to make it usable by MiddlewareConstructor.

ValidJSON is useful for testing.

DefaultLogger is used by package structs that don't have a default logger set.

Annotation associates an event that explains latency with a timestamp.

Endpoint is the network context of a node in the service graph.

Span defines a span.

NextSink is a special case of a sink that forwards to another sink.

A Sink is an object that can accept traces and do something with them, like forward them to some endpoint.

A MiddlewareConstructor is used by FromChain to chain together a bunch of sinks that forward to each other.

Trace is a list of spans.