Sending Messages

NATS sends and receives messages using a protocol that includes a target subject, an optional reply subject and an array of bytes. Some libraries may provide helpers to convert other data formats to and from bytes, but the NATS server will treat all messages as opaque byte arrays.

All of the NATS clients are designed to make sending a message simple. For example, to send the string “All is Well” to the “updates” subject as a UTF-8 string of bytes you would do:

Go

nc, err := nats.Connect("demo.nats.io", nats.Name("API PublishBytes Example"))
if err != nil {
    log.Fatal(err)
}
defer nc.Close()

if err := nc.Publish("updates", []byte("All is Well")); err != nil {
    log.Fatal(err)
}

Java

Connection nc = Nats.connect("nats://demo.nats.io:4222");

nc.publish("updates", "All is Well".getBytes(StandardCharsets.UTF_8));

JavaScript

const sc = StringCodec();
nc.publish("updates", sc.encode("All is Well"));

Python

nc = NATS()

await nc.connect(servers=["nats://demo.nats.io:4222"])

await nc.publish("updates", b'All is Well')

C#

// dotnet add package NATS.Net
using NATS.Net;

await using var client = new NatsClient(url: "demo.nats.io", name: "API Publish String Example");

// The default serializer uses UTF-8 encoding for strings
await client.PublishAsync<string>(subject: "updates", data: "All is Well");

Ruby

require 'nats/client'

NATS.start(servers:["nats://127.0.0.1:4222"]) do |nc|
  nc.publish("updates", "All is Well")
end