websockets are great

Tests/test-websocket.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+# WS server example
+
+import asyncio
+import websockets
+
+async def hello(websocket, path):
+    name = await websocket.recv()
+    print(f"< {name}")
+
+    greeting = f"Hello {name}!"
+
+    await websocket.send(greeting)
+    print(f"> {greeting}")
+
+start_server = websockets.serve(hello, "localhost", 8765)
+
+asyncio.get_event_loop().run_until_complete(start_server)
+asyncio.get_event_loop().run_forever()

WebSocket/browserbased-client-v2.html

@@ -0,0 +1,80 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <title>WebSocket demo</title>
+        <style type="text/css">
+            body {
+                font-family: "Courier New", sans-serif;
+                text-align: center;
+            }
+            .buttons {
+                font-size: 4em;
+                display: flex;
+                justify-content: center;
+            }
+            .button, .value {
+                line-height: 1;
+                padding: 2rem;
+                margin: 2rem;
+                border: medium solid;
+                min-height: 1em;
+                min-width: 1em;
+            }
+            .button {
+                cursor: pointer;
+                user-select: none;
+            }
+            .minus {
+                color: red;
+            }
+            .plus {
+                color: green;
+            }
+            .value {
+                min-width: 2em;
+            }
+            .state {
+                font-size: 2em;
+            }
+        </style>
+    </head>
+    <body>
+        <div class="buttons">
+            <div class="minus button">-</div>
+            <div class="value">?</div>
+            <div class="plus button">+</div>
+        </div>
+        <div class="state">
+            <span class="users">?</span> online
+        </div>
+        <script>
+            var minus = document.querySelector('.minus'),
+                plus = document.querySelector('.plus'),
+                value = document.querySelector('.value'),
+                users = document.querySelector('.users'),
+                websocket = new WebSocket("ws://127.0.0.1:6789/");
+            minus.onclick = function (event) {
+                websocket.send(JSON.stringify({action: 'minus'}));
+            }
+            plus.onclick = function (event) {
+                websocket.send(JSON.stringify({action: 'plus'}));
+            }
+            websocket.onmessage = function (event) {
+                data = JSON.parse(event.data);
+                switch (data.type) {
+                    case 'state':
+                        value.textContent = data.value;
+                        break;
+                    case 'users':
+                        users.textContent = (
+                            data.count.toString() + " user" +
+                            (data.count == 1 ? "" : "s"));
+                        break;
+                    default:
+                        console.error(
+                            "unsupported event", data);
+                }
+            };
+        </script>
+    </body>
+</html>

WebSocket/browserbased-client.html

@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <title>WebSocket demo</title>
+    </head>
+    <body>
+        <script>
+            var ws = new WebSocket("ws://127.0.0.1:5678/"),
+                messages = document.createElement('ul');
+            ws.onmessage = function (event) {
+                var messages = document.getElementsByTagName('ul')[0],
+                    message = document.createElement('li'),
+                    content = document.createTextNode(event.data);
+                message.appendChild(content);
+                messages.appendChild(message);
+            };
+            document.body.appendChild(messages);
+        </script>
+    </body>
+</html>

WebSocket/browserbased-server-v2.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python
+
+# WS server example that synchronizes state across clients
+
+import asyncio
+import json
+import logging
+import websockets
+
+logging.basicConfig()
+
+STATE = {"value": 0}
+
+USERS = set()
+
+
+def state_event():
+    return json.dumps({"type": "state", **STATE})
+
+
+def users_event():
+    return json.dumps({"type": "users", "count": len(USERS)})
+
+
+async def notify_state():
+    if USERS:  # asyncio.wait doesn't accept an empty list
+        message = state_event()
+        await asyncio.wait([user.send(message) for user in USERS])
+
+
+async def notify_users():
+    if USERS:  # asyncio.wait doesn't accept an empty list
+        message = users_event()
+        await asyncio.wait([user.send(message) for user in USERS])
+
+
+async def register(websocket):
+    USERS.add(websocket)
+    await notify_users()
+
+
+async def unregister(websocket):
+    USERS.remove(websocket)
+    await notify_users()
+
+
+async def counter(websocket, path):
+    # register(websocket) sends user_event() to websocket
+    await register(websocket)
+    try:
+        await websocket.send(state_event())
+        async for message in websocket:
+            data = json.loads(message)
+            if data["action"] == "minus":
+                STATE["value"] -= 1
+                await notify_state()
+            elif data["action"] == "plus":
+                STATE["value"] += 1
+                await notify_state()
+            else:
+                logging.error("unsupported event: {}", data)
+    finally:
+        await unregister(websocket)
+
+
+start_server = websockets.serve(counter, "localhost", 6789)
+
+asyncio.get_event_loop().run_until_complete(start_server)
+# asyncio.get_event_loop().run_forever()

WebSocket/browserbased-server.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+
+# WS server that sends messages at random intervals
+
+import asyncio
+import datetime
+import random
+import websockets
+
+async def time(websocket, path):
+    while True:
+        now = datetime.datetime.utcnow().isoformat() + "Z"
+        await websocket.send('moche')
+        await asyncio.sleep(2)
+
+start_server = websockets.serve(time, "127.0.0.1", 5678)
+
+asyncio.get_event_loop().run_until_complete(start_server)
+asyncio.get_event_loop().run_forever()

WebSocket/client.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+
+# WS client example
+
+import asyncio
+import websockets
+
+async def hello():
+    uri = "ws://localhost:8765"
+    async with websockets.connect(uri) as websocket:
+        name = input("What's your name? ")
+
+        await websocket.send(name)
+        print(f"> {name}")
+
+        greeting = await websocket.recv()
+        print(f"< {greeting}")
+
+asyncio.get_event_loop().run_until_complete(hello())

WebSocket/server.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+# WS server example
+
+import asyncio
+import websockets
+
+async def hello(websocket, path):
+    name = await websocket.recv()
+    print(f"< {name}")
+
+    greeting = f"Hello {name}!"
+
+    await websocket.send(greeting)
+    print(f"> {greeting}")
+
+start_server = websockets.serve(hello, "localhost", 8765)
+
+asyncio.get_event_loop().run_until_complete(start_server)
+asyncio.get_event_loop().run_forever()