Hands-On Software Engineering with Golang

Using the master as an outgoing message relay

As we saw in the RunJob method's initialization block, once we gain access to an executor instance for the graph, we register a bspgraph.Replayer instance which serves as an escape hatch for relaying messages destined for vertices, which are managed by a different graph instance.

This is how the relayNonLocalMessage helper method is implemented:

func (c *workerJobCoordinator) relayNonLocalMessage(dst string, msg message.Message) error {
    serializedMsg, err := c.cfg.serializer.Serialize(msg)
    if err != nil {
        return xerrors.Errorf("unable to serialize message: %w", err)
    }
    wMsg := &proto.WorkerPayload{Payload: &proto.WorkerPayload_RelayMessage{
        RelayMessage: &proto.RelayMessage{
 Destination: ...