diff --git a/README.md b/README.md
index 5dddf84a..e967cd8a 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,8 @@ go get nhooyr.io/websocket
For a production quality example that demonstrates the complete API, see the [echo example](https://godoc.org/nhooyr.io/websocket#example-package--Echo).
+For a full stack example, see [./chat-example](./chat-example).
+
### Server
```go
diff --git a/chat-example/README.md b/chat-example/README.md
new file mode 100644
index 00000000..ef06275d
--- /dev/null
+++ b/chat-example/README.md
@@ -0,0 +1,27 @@
+# Chat Example
+
+This directory contains a full stack example of a simple chat webapp using nhooyr.io/websocket.
+
+```bash
+$ cd chat-example
+$ go run . localhost:0
+listening on http://127.0.0.1:51055
+```
+
+Visit the printed URL to submit and view broadcasted messages in a browser.
+
+
+
+## Structure
+
+The frontend is contained in `index.html`, `index.js` and `index.css`. It sets up the
+DOM with a scrollable div at the top that is populated with new messages as they are broadcast.
+At the bottom it adds a form to submit messages.
+The messages are received via the WebSocket `/subscribe` endpoint and published via
+the HTTP POST `/publish` endpoint.
+
+The server portion is `main.go` and `chat.go` and implements serving the static frontend
+assets, the `/subscribe` WebSocket endpoint and the HTTP POST `/publish` endpoint.
+
+The code is well commented. I would recommend starting in `main.go` and then `chat.go` followed by
+`index.html` and then `index.js`.
diff --git a/chat-example/chat.go b/chat-example/chat.go
new file mode 100644
index 00000000..e6e355d0
--- /dev/null
+++ b/chat-example/chat.go
@@ -0,0 +1,128 @@
+package main
+
+import (
+ "context"
+ "errors"
+ "io"
+ "io/ioutil"
+ "log"
+ "net/http"
+ "sync"
+ "time"
+
+ "nhooyr.io/websocket"
+)
+
+// chatServer enables broadcasting to a set of subscribers.
+type chatServer struct {
+ subscribersMu sync.RWMutex
+ subscribers map[chan<- []byte]struct{}
+}
+
+// subscribeHandler accepts the WebSocket connection and then subscribes
+// it to all future messages.
+func (cs *chatServer) subscribeHandler(w http.ResponseWriter, r *http.Request) {
+ c, err := websocket.Accept(w, r, nil)
+ if err != nil {
+ log.Print(err)
+ return
+ }
+ defer c.Close(websocket.StatusInternalError, "")
+
+ err = cs.subscribe(r.Context(), c)
+ if errors.Is(err, context.Canceled) {
+ return
+ }
+ if websocket.CloseStatus(err) == websocket.StatusNormalClosure ||
+ websocket.CloseStatus(err) == websocket.StatusGoingAway {
+ return
+ }
+ if err != nil {
+ log.Print(err)
+ }
+}
+
+// publishHandler reads the request body with a limit of 8192 bytes and then publishes
+// the received message.
+func (cs *chatServer) publishHandler(w http.ResponseWriter, r *http.Request) {
+ if r.Method != "POST" {
+ http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+ return
+ }
+ body := io.LimitReader(r.Body, 8192)
+ msg, err := ioutil.ReadAll(body)
+ if err != nil {
+ http.Error(w, http.StatusText(http.StatusRequestEntityTooLarge), http.StatusRequestEntityTooLarge)
+ return
+ }
+
+ cs.publish(msg)
+}
+
+// subscribe subscribes the given WebSocket to all broadcast messages.
+// It creates a msgs chan with a buffer of 16 to give some room to slower
+// connections and then registers it. It then listens for all messages
+// and writes them to the WebSocket. If the context is cancelled or
+// an error occurs, it returns and deletes the subscription.
+//
+// It uses CloseRead to keep reading from the connection to process control
+// messages and cancel the context if the connection drops.
+func (cs *chatServer) subscribe(ctx context.Context, c *websocket.Conn) error {
+ ctx = c.CloseRead(ctx)
+
+ msgs := make(chan []byte, 16)
+ cs.addSubscriber(msgs)
+ defer cs.deleteSubscriber(msgs)
+
+ for {
+ select {
+ case msg := <-msgs:
+ err := writeTimeout(ctx, time.Second*5, c, msg)
+ if err != nil {
+ return err
+ }
+ case <-ctx.Done():
+ return ctx.Err()
+ }
+ }
+}
+
+// publish publishes the msg to all subscribers.
+// It never blocks and so messages to slow subscribers
+// are dropped.
+func (cs *chatServer) publish(msg []byte) {
+ cs.subscribersMu.RLock()
+ defer cs.subscribersMu.RUnlock()
+
+ for c := range cs.subscribers {
+ select {
+ case c <- msg:
+ default:
+ }
+ }
+}
+
+// addSubscriber registers a subscriber with a channel
+// on which to send messages.
+func (cs *chatServer) addSubscriber(msgs chan<- []byte) {
+ cs.subscribersMu.Lock()
+ if cs.subscribers == nil {
+ cs.subscribers = make(map[chan<- []byte]struct{})
+ }
+ cs.subscribers[msgs] = struct{}{}
+ cs.subscribersMu.Unlock()
+}
+
+// deleteSubscriber deletes the subscriber with the given msgs channel.
+func (cs *chatServer) deleteSubscriber(msgs chan []byte) {
+ cs.subscribersMu.Lock()
+ delete(cs.subscribers, msgs)
+ cs.subscribersMu.Unlock()
+}
+
+func writeTimeout(ctx context.Context, timeout time.Duration, c *websocket.Conn, msg []byte) error {
+ ctx, cancel := context.WithTimeout(ctx, timeout)
+ defer cancel()
+
+ return c.Write(ctx, websocket.MessageText, msg)
+}
diff --git a/chat-example/go.mod b/chat-example/go.mod
new file mode 100644
index 00000000..34fa5a69
--- /dev/null
+++ b/chat-example/go.mod
@@ -0,0 +1,5 @@
+module nhooyr.io/websocket/example-chat
+
+go 1.13
+
+require nhooyr.io/websocket v1.8.2
diff --git a/chat-example/go.sum b/chat-example/go.sum
new file mode 100644
index 00000000..0755fca5
--- /dev/null
+++ b/chat-example/go.sum
@@ -0,0 +1,12 @@
+github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee/go.mod h1:L0fX3K22YWvt/FAX9NnzrNzcI4wNYi9Yku4O0LKYflo=
+github.com/gobwas/pool v0.2.0/go.mod h1:q8bcK0KcYlCgd9e7WYLm9LpyS+YeLd8JVDW6WezmKEw=
+github.com/gobwas/ws v1.0.2/go.mod h1:szmBTxLgaFppYjEmNtny/v3w89xOydFnnZMcgRRu/EM=
+github.com/golang/protobuf v1.3.3/go.mod h1:vzj43D7+SQXF/4pzW/hwtAqwc6iTitCiVSaWz5lYuqw=
+github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/gorilla/websocket v1.4.1/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/klauspost/compress v1.10.0 h1:92XGj1AcYzA6UrVdd4qIIBrT8OroryvRvdmg/IfmC7Y=
+github.com/klauspost/compress v1.10.0/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
+golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+nhooyr.io/websocket v1.8.2 h1:LwdzfyyOZKtVFoXay6A39Acu03KmidSZ3YUUvPa13PA=
+nhooyr.io/websocket v1.8.2/go.mod h1:LiqdCg1Cu7TPWxEvPjPa0TGYxCsy4pHNTN9gGluwBpQ=
diff --git a/chat-example/index.css b/chat-example/index.css
new file mode 100644
index 00000000..29804662
--- /dev/null
+++ b/chat-example/index.css
@@ -0,0 +1,81 @@
+body {
+ width: 100vw;
+ min-width: 320px;
+}
+
+#root {
+ padding: 40px 20px;
+ max-width: 480px;
+ margin: auto;
+ height: 100vh;
+
+ display: flex;
+ flex-direction: column;
+ align-items: center;
+ justify-content: center;
+}
+
+#root > * + * {
+ margin: 20px 0 0 0;
+}
+
+/* 100vh on safari does not include the bottom bar. */
+@supports (-webkit-overflow-scrolling: touch) {
+ #root {
+ height: 85vh;
+ }
+}
+
+#message-log {
+ width: 100%;
+ flex-grow: 1;
+ overflow: auto;
+}
+
+#message-log p:first-child {
+ margin: 0;
+}
+
+#message-log > * + * {
+ margin: 10px 0 0 0;
+}
+
+#publish-form-container {
+ width: 100%;
+}
+
+#publish-form {
+ width: 100%;
+ display: flex;
+ height: 40px;
+}
+
+#publish-form > * + * {
+ margin: 0 0 0 10px;
+}
+
+#publish-form input[type="text"] {
+ flex-grow: 1;
+
+ -moz-appearance: none;
+ -webkit-appearance: none;
+ word-break: normal;
+ border-radius: 5px;
+ border: 1px solid #ccc;
+}
+
+#publish-form input[type="submit"] {
+ color: white;
+ background-color: black;
+ border-radius: 5px;
+ padding: 5px 10px;
+ border: none;
+}
+
+#publish-form input[type="submit"]:hover {
+ background-color: red;
+}
+
+#publish-form input[type="submit"]:active {
+ background-color: red;
+}
diff --git a/chat-example/index.html b/chat-example/index.html
new file mode 100644
index 00000000..76ae8370
--- /dev/null
+++ b/chat-example/index.html
@@ -0,0 +1,25 @@
+
+
+
+
+ nhooyr.io/websocket - Chat Example
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/chat-example/index.js b/chat-example/index.js
new file mode 100644
index 00000000..8fb3dfb8
--- /dev/null
+++ b/chat-example/index.js
@@ -0,0 +1,62 @@
+;(() => {
+ // expectingMessage is set to true
+ // if the user has just submitted a message
+ // and so we should scroll the next message into view when received.
+ let expectingMessage = false
+ function dial() {
+ const conn = new WebSocket(`ws://${location.host}/subscribe`)
+
+ conn.addEventListener("close", ev => {
+ console.info("websocket disconnected, reconnecting in 1000ms", ev)
+ setTimeout(dial, 1000)
+ })
+ conn.addEventListener("open", ev => {
+ console.info("websocket connected")
+ })
+
+ // This is where we handle messages received.
+ conn.addEventListener("message", ev => {
+ if (typeof ev.data !== "string") {
+ console.error("unexpected message type", typeof ev.data)
+ return
+ }
+ const p = appendLog(ev.data)
+ if (expectingMessage) {
+ p.scrollIntoView()
+ expectingMessage = false
+ }
+ })
+ }
+ dial()
+
+ const messageLog = document.getElementById("message-log")
+ const publishForm = document.getElementById("publish-form")
+ const messageInput = document.getElementById("message-input")
+
+ // appendLog appends the passed text to messageLog.
+ function appendLog(text) {
+ const p = document.createElement("p")
+ // Adding a timestamp to each message makes the log easier to read.
+ p.innerText = `${new Date().toLocaleTimeString()}: ${text}`
+ messageLog.append(p)
+ return p
+ }
+ appendLog("Submit a message to get started!")
+
+ // onsubmit publishes the message from the user when the form is submitted.
+ publishForm.onsubmit = ev => {
+ ev.preventDefault()
+
+ const msg = messageInput.value
+ if (msg === "") {
+ return
+ }
+ messageInput.value = ""
+
+ expectingMessage = true
+ fetch("/publish", {
+ method: "POST",
+ body: msg,
+ })
+ }
+})()
diff --git a/chat-example/main.go b/chat-example/main.go
new file mode 100644
index 00000000..2a520924
--- /dev/null
+++ b/chat-example/main.go
@@ -0,0 +1,47 @@
+package main
+
+import (
+ "errors"
+ "log"
+ "net"
+ "net/http"
+ "os"
+ "time"
+)
+
+func main() {
+ log.SetFlags(0)
+
+ err := run()
+ if err != nil {
+ log.Fatal(err)
+ }
+}
+
+// run initializes the chatServer and routes and then
+// starts a http.Server for the passed in address.
+func run() error {
+ if len(os.Args) < 2 {
+ return errors.New("please provide an address to listen on as the first argument")
+ }
+
+ l, err := net.Listen("tcp", os.Args[1])
+ if err != nil {
+ return err
+ }
+ log.Printf("listening on http://%v", l.Addr())
+
+ var ws chatServer
+
+ m := http.NewServeMux()
+ m.Handle("/", http.FileServer(http.Dir(".")))
+ m.HandleFunc("/subscribe", ws.subscribeHandler)
+ m.HandleFunc("/publish", ws.publishHandler)
+
+ s := http.Server{
+ Handler: m,
+ ReadTimeout: time.Second * 10,
+ WriteTimeout: time.Second * 10,
+ }
+ return s.Serve(l)
+}
diff --git a/ci/fmt.mk b/ci/fmt.mk
index f313562c..3512d02f 100644
--- a/ci/fmt.mk
+++ b/ci/fmt.mk
@@ -13,7 +13,7 @@ goimports: gen
goimports -w "-local=$$(go list -m)" .
prettier:
- prettier --write --print-width=120 --no-semi --trailing-comma=all --loglevel=warn $$(git ls-files "*.yml" "*.md")
+ prettier --write --print-width=120 --no-semi --trailing-comma=all --loglevel=warn $$(git ls-files "*.yml" "*.md" "*.js" "*.css" "*.html")
gen:
stringer -type=opcode,MessageType,StatusCode -output=stringer.go
diff --git a/conn_test.go b/conn_test.go
index a7bfba0a..64e6736f 100644
--- a/conn_test.go
+++ b/conn_test.go
@@ -329,7 +329,7 @@ func newConnTest(t testing.TB, dialOpts *websocket.DialOptions, acceptOpts *webs
}
t.Helper()
- ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+ ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
tt = &connTest{t: t, ctx: ctx}
tt.appendDone(cancel)