Version: v3.0.2+incompatible Latest Latest

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Published: Nov 11, 2021 License: BSD-3-Clause Imports: 14 Imported by: 57


see README for proper import paths





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var DefaultOptions = Options{
	Websocket:         true,
	RawWebsocket:      false,
	JSessionID:        nil,
	SockJSURL:         "//",
	HeartbeatDelay:    25 * time.Second,
	DisconnectDelay:   5 * time.Second,
	ResponseLimit:     128 * 1024,
	WebsocketUpgrader: nil,

DefaultOptions is a convenient set of options to be used for sockjs

View Source
var (
	// ErrSessionNotOpen error is used to denote session not in open state.
	// Recv() and Send() operations are not suppored if session is closed.
	ErrSessionNotOpen = errors.New("sockjs: session not in open state")
View Source
var WebSocketReadBufSize = 4096

WebSocketReadBufSize is a parameter that is used for WebSocket Upgrader.

View Source
var WebSocketWriteBufSize = 4096

WebSocketWriteBufSize is a parameter that is used for WebSocket Upgrader


func DefaultJSessionID

func DefaultJSessionID(rw http.ResponseWriter, req *http.Request)

DefaultJSessionID is a default behaviour function to be used in options for JSessionID if JSESSIONID is needed

func NewHandler

func NewHandler(prefix string, opts Options, handleFunc func(Session)) http.Handler

NewHandler creates new HTTP handler that conforms to the basic net/http.Handler interface. It takes path prefix, options and sockjs handler function as parameters

Example (DefaultMux)
package main

import (


func main() {
	handler := sockjs.NewHandler("/echo", sockjs.DefaultOptions, func(session sockjs.Session) {
		for {
			if msg, err := session.Recv(); err == nil {
				if session.Send(msg) != nil {
			} else {
	// need to provide path prefix for http.Mux
	http.Handle("/echo/", handler)
	http.ListenAndServe(":8080", nil)

Example (Simple)
package main

import (


func main() {
	handler := sockjs.NewHandler("/echo", sockjs.DefaultOptions, func(session sockjs.Session) {
		for {
			if msg, err := session.Recv(); err == nil {
				if session.Send(msg) != nil {
			} else {
	http.ListenAndServe(":8080", handler)


type Options

type Options struct {
	// Transports which don't support cross-domain communication natively ('eventsource' to name one) use an iframe trick.
	// A simple page is served from the SockJS server (using its foreign domain) and is placed in an invisible iframe.
	// Code run from this iframe doesn't need to worry about cross-domain issues, as it's being run from domain local to the SockJS server.
	// This iframe also does need to load SockJS javascript client library, and this option lets you specify its url (if you're unsure,
	// point it to the latest minified SockJS client release, this is the default). You must explicitly specify this url on the server
	// side for security reasons - we don't want the possibility of running any foreign javascript within the SockJS domain (aka cross site scripting attack).
	// Also, sockjs javascript library is probably already cached by the browser - it makes sense to reuse the sockjs url you're using in normally.
	SockJSURL string
	// Most streaming transports save responses on the client side and don't free memory used by delivered messages.
	// Such transports need to be garbage-collected once in a while. `response_limit` sets a minimum number of bytes that can be send
	// over a single http streaming request before it will be closed. After that client needs to open new request.
	// Setting this value to one effectively disables streaming and will make streaming transports to behave like polling transports.
	// The default value is 128K.
	ResponseLimit uint32
	// Some load balancers don't support websockets. This option can be used to disable websockets support by the server. By default websockets are enabled.
	Websocket bool
	// This option can be used to enable raw websockets support by the server. By default raw websockets are disabled.
	RawWebsocket bool
	// Provide a custom Upgrader for Websocket connections to enable features like compression.
	// See for more details.
	WebsocketUpgrader *websocket.Upgrader
	// WebsocketWriteTimeout is a custom write timeout for Websocket underlying network connection.
	// A zero value means writes will not time out.
	WebsocketWriteTimeout time.Duration
	// In order to keep proxies and load balancers from closing long running http requests we need to pretend that the connection is active
	// and send a heartbeat packet once in a while. This setting controls how often this is done.
	// By default a heartbeat packet is sent every 25 seconds.
	HeartbeatDelay time.Duration
	// The server closes a session when a client receiving connection have not been seen for a while.
	// This delay is configured by this setting.
	// By default the session is closed when a receiving connection wasn't seen for 5 seconds.
	DisconnectDelay time.Duration
	// Some hosting providers enable sticky sessions only to requests that have JSessionID cookie set.
	// This setting controls if the server should set this cookie to a dummy value.
	// By default setting JSessionID cookie is disabled. More sophisticated behaviour can be achieved by supplying a function.
	JSessionID func(http.ResponseWriter, *http.Request)
	// CORS origin to be set on outgoing responses. If set to the empty string, it will default to the
	// incoming `Origin` header, or "*" if the Origin header isn't set.
	Origin string
	// CheckOrigin allows to dynamically decide whether server should set CORS
	// headers or not in case of XHR requests. When true returned CORS will be
	// configured with allowed origin equal to incoming `Origin` header, or "*"
	// if the request Origin header isn't set. When false returned CORS headers
	// won't be set at all. If this function is nil then Origin option above will
	// be taken into account.
	CheckOrigin func(*http.Request) bool

Options type is used for defining various sockjs options

type Session

type Session interface {
	// Id returns a session id
	ID() string
	// Request returns the first http request
	Request() *http.Request
	// Recv reads one text frame from session
	Recv() (string, error)
	// Send sends one text frame to session
	Send(string) error
	// Close closes the session with provided code and reason.
	Close(status uint32, reason string) error
	//Gets the state of the session. SessionOpening/SessionActive/SessionClosing/SessionClosed;
	GetSessionState() SessionState

Session represents a connection between server and client.

type SessionState

type SessionState uint32

SessionState defines the current state of the session

const (
	// brand new session, need to send "h" to receiver
	SessionOpening SessionState = iota
	// active session
	// session being closed, sending "closeFrame" to receivers
	// closed session, no activity at all, should be removed from handler completely and not reused

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