NATS

The github.com/dygoframework/dygo/micro/nats module carries the app’s message handlers over NATS. Patterns are NATS subjects, so wildcards such as orders.* and audit.> work.

type UsersHandlers struct{}

func (h *UsersHandlers) Patterns(r micro.Router) {
  r.Message("users.get", micro.Handle(h.get))
}

func (h *UsersHandlers) get(_ context.Context, in GetUser) (*User, error) {
  return &User{ID: in.ID, Name: "Ada"}, nil
}

func UsersService(url string) *dygo.Module {
  return &dygo.Module{
    Name:      "users",
    Providers: []dygo.Provider{dygo.Value(&UsersHandlers{})}, // found by their Patterns method
    Imports:   []*dygo.Module{nats.ClientModule(nats.ClientOptions{URL: url})},
  }
}

func serveOverNATS(ctx context.Context, app *dygo.HTTPApp, url string) error {
  app.ConnectMicroservice(nats.NewServer(nats.Options{URL: url, Queue: "users"}))
  return app.Listen(ctx, ":0") // HTTP and NATS in one process
}

• Queue is the queue group. Instances in the same group share the messages. Leave it empty to send every message to every instance.
• Concurrency limits how many messages are handled at once. The default is 100.
• nats.ClientModule provides a *micro.Client. It connects when the client is built and closes at shutdown.

Call a handler from another service:

u, err = micro.Send[*User](ctx, client, "users.get", GetUser{ID: 7})