Receiving Structured Data

Client libraries may provide tools to help receive structured data, like JSON. The core traffic to the NATS server will always be opaque byte arrays. The server does not process message payloads in any form. For libraries that don't provide helpers, you can always encode and decode data before sending the associated bytes to the NATS client.

For example, to receive JSON you could do:

nc, err := nats.Connect("",
    nats.ErrorHandler(func(nc *nats.Conn, s *nats.Subscription, err error) {
        if s != nil {
        log.Printf("Async error in %q/%q: %v", s.Subject, s.Queue, err)
        } else {
        log.Printf("Async error outside subscription: %v", err)
if err != nil {
defer nc.Close()
ec, err := nats.NewEncodedConn(nc, nats.JSON_ENCODER)
if err != nil {
defer ec.Close()

// Define the object
type stock struct {
    Symbol string
    Price  int

wg := sync.WaitGroup{}

// Subscribe
// Decoding errors will be passed to the function supplied via
// nats.ErrorHandler above, and the callback supplied here will
// not be invoked.
if _, err := ec.Subscribe("updates", func(s *stock) {
    log.Printf("Stock: %s - Price: %v", s.Symbol, s.Price)
}); err != nil {

// Wait for a message to come in

Last updated