Add client_server example files.

Author: peterhinch

client_server/uclient.py

@@ -0,0 +1,47 @@
+# uclient.py Demo of simple uasyncio-based client for echo server
+
+# Released under the MIT licence
+# Copyright (c) Peter Hinch 2019
+
+import usocket as socket
+import uasyncio as asyncio
+import ujson
+server = '192.168.0.32'
+port = 8123
+
+async def run():
+    sock = socket.socket()
+    def close():
+        sock.close()
+        print('Server disconnect.')
+    try:
+        serv = socket.getaddrinfo(server, port)[0][-1]
+        sock.connect(serv)
+    except OSError as e:
+        print('Cannot connect to {} on port {}'.format(server, port))
+        sock.close()
+        return
+    while True:
+        sreader = asyncio.StreamReader(sock)
+        swriter = asyncio.StreamWriter(sock, {})
+        data = ['value', 1]
+        while True:
+            try:
+                await swriter.awrite('{}\n'.format(ujson.dumps(data)))
+                res = await sreader.readline()
+            except OSError:
+                close()
+                return
+            try:
+                print('Received', ujson.loads(res))
+            except ValueError:
+                close()
+                return
+            await asyncio.sleep(2)
+            data[1] += 1
+
+loop = asyncio.get_event_loop()
+try:
+    loop.run_until_complete(run())
+except KeyboardInterrupt:
+    print('Interrupted')  # This mechanism doesn't work on Unix build.

client_server/userver.py

@@ -0,0 +1,71 @@
+# userver.py Demo of simple uasyncio-based echo server
+
+# Released under the MIT licence
+# Copyright (c) Peter Hinch 2019
+
+import usocket as socket
+import uasyncio as asyncio
+import uselect as select
+import ujson
+
+class Server:
+    @staticmethod
+    async def flash():  # ESP8266 only: demo that it is nonblocking
+        from machine import Pin
+        pin = Pin(2, Pin.OUT)
+        while True:
+            pin(not pin())
+            await asyncio.sleep_ms(100)
+
+    async def run(self, loop, port=8123, led=True):
+        addr = socket.getaddrinfo('0.0.0.0', port, 0, socket.SOCK_STREAM)[0][-1]
+        s_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  # server socket
+        s_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        s_sock.bind(addr)
+        s_sock.listen(5)
+        self.socks = [s_sock]  # List of current sockets for .close()
+        print('Awaiting connection on port', port)
+        poller = select.poll()
+        poller.register(s_sock, select.POLLIN)
+        client_id = 1  # For user feedback
+        if led:
+            loop.create_task(self.flash())
+        while True:
+            res = poller.poll(1)  # 1ms block
+            if res:  # Only s_sock is polled
+                c_sock, _ = s_sock.accept()  # get client socket
+                loop.create_task(self.run_client(c_sock, client_id))
+                client_id += 1
+            await asyncio.sleep_ms(200)
+
+    async def run_client(self, sock, cid):
+        self.socks.append(sock)
+        sreader = asyncio.StreamReader(sock)
+        swriter = asyncio.StreamWriter(sock, {})
+        print('Got connection from client', cid)
+        try:
+            while True:
+                res = await sreader.readline()
+                if res == b'':
+                    raise OSError
+                print('Received {} from client {}'.format(ujson.loads(res.rstrip()), cid))
+                await swriter.awrite(res)  # Echo back
+        except OSError:
+            pass
+        print('Client {} disconnect.'.format(cid))
+        sock.close()
+        self.socks.remove(sock)
+
+    def close(self):
+        print('Closing {} sockets.'.format(len(self.socks)))
+        for sock in self.socks:
+            sock.close()
+
+loop = asyncio.get_event_loop()
+server = Server()
+try:
+    loop.run_until_complete(server.run(loop))
+except KeyboardInterrupt:
+    print('Interrupted')  # This mechanism doesn't work on Unix build.
+finally:
+    server.close()