sink

type Client interface {
	CloseConn(ctx context.Context) error
	IsReady(ctx context.Context, in *emptypb.Empty) (bool, error)
	SinkFn(ctx context.Context, datumList []*sinkpb.Datum) ([]*sinkpb.Response, error)
}

type Datum interface {
	Value() []byte
	EventTime() time.Time
	Watermark() time.Time
	ID() string
}

type Response struct {
	// ID corresponds the ID in the message.
	ID string `json:"id"`
	// Successful or not. If it's false, "err" is expected to be present.
	Success bool `json:"success"`
	// Err represents the error message when "success" is false.
	Err string `json:"err,omitempty"`
}

type Responses []Response

type Service struct {
	sinkpb.UnimplementedUserDefinedSinkServer

	Sinker SinkHandler
}

type SinkFunc func(ctx context.Context, datumList []Datum) Responses

type SinkHandler interface {
	// HandleDo is the function to process a list of incoming messages
	HandleDo(ctx context.Context, datumList []Datum) Responses
}