added tcp server and client

tcp_client.py

+import socket
+import json
+from binascii import b2a_hex
+
+# create Socket object (IP, PORT)
+ADDRESS = ('127.0.0.1', 1234)
+sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+
+# connect to a server at IP:PORT
+sock.connect(ADDRESS)
+conn = sock.makefile('rwb')
+print("Connected to [%s:%s]" % (ADDRESS[0], ADDRESS[1]))
+
+# Data to send to server (change this)
+tx_obj = [8, 10, -12, 100, 2]
+print("Sending %s to server" % type(tx_obj))
+
+# L3: convert Python object into string
+tx_str = json.dumps(tx_obj)
+print("\tjson: %s" % tx_str)
+
+# L2: convert string into binary data
+tx_data = (tx_str + '\n').encode('ascii')
+print("\tbinary: %r" % b2a_hex(tx_data))
+
+# L1: tell operating system to send data
+nbytes = conn.write(tx_data)
+conn.flush()
+
+# -------- SERVER PROCESSES MESSAGE --------
+print("waiting...")
+
+# L0: network stack waits for TCP response
+
+# L1: operating system delivers binary data
+rx_data = conn.readline()
+print("\tbinary: %r" % b2a_hex(rx_data))
+
+# L2: convert binary data into a string
+rx_str = rx_data.decode('ascii')
+print("\tjson: %s" % rx_str.rstrip())
+
+# L3: convert string into Python object
+rx_obj = json.loads(rx_str)
+print("Received %s from server" % type(rx_obj))
+
+# display result (is it correct?)
+print("Max: %d | Min %d" % (rx_obj['max'], rx_obj['min']))
+
+# close connection
+conn.close()

tcp_client_min.py

+import socket
+import json
+
+ADDRESS = ('127.0.0.1', 1234)
+sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+sock.connect(ADDRESS)
+conn = sock.makefile('rwb')
+print("Connected to [%s:%s]" % (ADDRESS[0], ADDRESS[1]))
+
+tx_obj = [8, 10, -12, 100, 2]
+print(tx_obj)
+tx_str = json.dumps(tx_obj)
+tx_data = (tx_str + '\n').encode('ascii')
+conn.write(tx_data)
+conn.flush()
+
+rx_data = conn.readline()
+rx_str = rx_data.decode('ascii')
+rx_obj = json.loads(rx_str)
+print("Max: %d | Min %d" % (rx_obj['max'], rx_obj['min']))
+
+conn.close()

tcp_server.py

+import socket
+import json
+from binascii import b2a_hex
+
+# create Socket object (IP, PORT)
+ADDRESS = ('127.0.0.1', 1234)
+sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+
+# start a server on IP:PORT combination
+sock.bind(ADDRESS)
+sock.setblocking(True)
+sock.listen(1)
+print("waiting...")
+
+# wait for a client to connect
+active_sock, address = sock.accept()
+conn = active_sock.makefile('rwb')
+print("Connection from [%s:%s]" % (address[0], address[1]))
+
+# L0: network stack waits for TCP data
+
+# L1: operating system delivers binary data
+rx_data = conn.readline()
+print("\tbinary %r" % b2a_hex(rx_data))
+
+# L2: convert binary data into a string
+rx_str = rx_data.decode('ascii')
+print("\tjson: %s" % rx_str.rstrip())
+
+# L3: convert string into Python data structure
+rx_obj = json.loads(rx_str)
+print("Received %s from client" % type(rx_obj))
+
+tx_obj = {'max': max(rx_obj),
+           'min': min(rx_obj)}
+
+input("Press [enter] to send response")
+print("Sending %s to client" % type(tx_obj))
+
+# L3: convert Python data structure into string
+tx_str = json.dumps(tx_obj)
+print("\tjson: %s" % tx_obj)
+
+# L2: convert string into binary data
+tx_data = (tx_str + '\n').encode('ascii')
+print("\tbinary: %r" % b2a_hex(tx_data))
+
+# L1: tell operating system to send data
+conn.write(tx_data)
+conn.flush()
+
+# L0: network transmits TCP data
+
+# close client connection
+conn.close()
+
+# shutdown server
+sock.close()

tcp_server_min.py

+import socket
+import json
+
+ADDRESS = ('127.0.0.1', 1234)
+sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+sock.bind(ADDRESS)
+sock.setblocking(True)
+sock.listen(1)
+active_sock, address = sock.accept()
+conn = active_sock.makefile('rwb')
+print("Connection from [%s:%s]" % (address[0], address[1]))
+
+rx_data = conn.readline()
+rx_str = rx_data.decode('ascii')
+rx_obj = json.loads(rx_str)
+
+tx_obj = {'max': max(rx_obj), 'min': min(rx_obj)}
+tx_str = json.dumps(tx_obj)
+tx_data = (tx_str + '\n').encode('ascii')
+conn.write(tx_data)
+conn.flush()
+
+conn.close()
+sock.close()