bus

Simple message bus that supports synchronous and asynchronous message processing. It is intended to be used within a single application to help implement loosely coupled components.

msgBus := bus.New()

Publish

Publish a message to the bus.

msgBus.Publish(context.Background(), Message{Content: "hello"})

Subscribe

Subscribe to a message by its type.

msgBus.Subscribe(func(ctx context.Context, message Message) error {
    message.Result = "1234"
    return nil
})

The subscriber is run synchronously. A common pattern is to mutate the message in the subscriber, allowing the publisher to access the return value. For example

b := bus.New()
b.Subscribe(func(ctx context.Context, query *GetUserQuery) {
    query.Result = UserResult{
        Name:  "Jan",
        Email: "[email protected]",
    }
})

query := GetUserQuery{ID: "1234"}
b.Publish(context.Background(), &query)

fmt.Println(query.Result.Name) // prints Jan 

SubscribeAsync

Subscribe to a message by its type. The handler is invoked in a separate go routine and doesn't block the calling go routine.

msgBus.SubscribeAsync(func(ctx context.Context, message Message) {
    fmt.Println(message.Content) 
})