codec

type ClientInfo struct {
	IP string `json:"ip"`
	UA string `json:"ua"`
}

type MDKey string

type MSG interface {
	Context() context.Context

	TraceID() string
	WithTraceID(s string)

	RequestTimeout() time.Duration
	WithRequestTimeout(t time.Duration)

	Namespace() string
	WithNamespace(n string)

	ServerName() string
	WithServerName(n string)

	Client() ClientInfo
	WithClient(ip, ua string)

	Metadata() metadata.MD
}