sse

Documentation

Overview

Package sse serves Server-Sent Events: a one-way text/event-stream from server to client. Handler wraps a streaming writer; the supplied function owns the send loop and returns to end the stream.

Index

• func Handler(fn func(c *fiber.Ctx, s *Stream)) fiber.Handler
• type Event
• type Stream
  • func (s *Stream) Comment(text string) error
  • func (s *Stream) Event(e Event) error
  • func (s *Stream) Send(event string, data any) error
  • func (s *Stream) SendRaw(event, data string) error

Examples

• Handler

Functions

func Handler

func Handler(fn func(c *fiber.Ctx, s *Stream)) fiber.Handler

Handler returns a Fiber handler that streams events. fn is called with a Stream; when fn returns, the stream closes. fn owns its own loop and should stop when a Send returns an error (client gone) or the request context is done.

Example

package main

import (
	"time"

	"github.com/gofiber/fiber/v2"
	"github.com/rahmadafandi/fibr/sse"
)

func main() {
	app := fiber.New()
	app.Get("/events", sse.Handler(func(c *fiber.Ctx, s *sse.Stream) {
		ticker := time.NewTicker(time.Second)
		defer ticker.Stop()
		for n := 0; ; n++ {
			if err := s.Send("tick", map[string]int{"n": n}); err != nil {
				return // client disconnected
			}
			select {
			case <-c.Context().Done():
				return
			case <-ticker.C:
			}
		}
	}))
	_ = app
}

Types

type Event

type Event struct {
	ID    string
	Name  string
	Data  any
	Retry int // reconnection hint, milliseconds
}

Event is a fully specified SSE event. Data is JSON-encoded unless it is a string or []byte, which are written verbatim.

type Stream

type Stream struct {
	// contains filtered or unexported fields
}

Stream writes SSE frames to a single client connection.

func (*Stream) Comment

func (s *Stream) Comment(text string) error

Comment writes an SSE comment line (": text"), commonly used as a keepalive.

func (*Stream) Event

func (s *Stream) Event(e Event) error

Event writes a fully specified event and flushes. A flush error indicates the client disconnected.

func (*Stream) Send

func (s *Stream) Send(event string, data any) error

Send writes a named event with JSON-encoded data and flushes.

func (*Stream) SendRaw

func (s *Stream) SendRaw(event, data string) error

SendRaw writes a named event with a pre-formatted string payload.