github.com/bmhatfield/sse

Server sent events publisher in Go

Install

go get github.com/bmhatfield/sse

Usage

Import sse

import "github.com/bmhatfield/sse"

Create the event server. The event server is an async topic publisher, with events pushed to active subscribers.

// Create event server.
events := sse.NewEventServer()

// Create initial topic
events.Create("topic-name")

Create an event, and then broadcast it to subscribers. Messages will be sent to active subscribers. Broadcasts to non-existent topics will fail. Broadcasts to topics without subscribers will be dropped.

// Create an event
// See also: JSONEvent, or implement your own Event!
event := sse.NewEvent("optional-kind", []byte("hi!"))

// Broadcast!
if err := events.Broadcast("topic-name", event); err != nil {
    log.Printf("failed to broadcast: %s", err)
}

The event server is a simple HTTP handler. Use with your favorite router, or serve with the standard library.

// Serve event stream
http.Handle("/events", events)
if err := http.ListenAndServe(":8080", nil); err != nil {
    log.Fatal(err)
}

Use EventSource in js to listen for events. Clients can select their stream with the stream query param.

const stream = new EventSource("/events?stream=points");