add example tcp/udp communication using socket

socket/UdpMulticastSender.py

@@ -0,0 +1,39 @@
+import socket
+import struct
+import sys
+
+message = 'very important data'
+multicast_group = ('224.3.29.71', 10000)
+
+# Create the datagram socket
+sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+
+# Set a timeout so the socket does not block indefinitely when trying
+# to receive data.
+sock.settimeout(0.2)
+
+# Set the time-to-live for messages to 1 so they do not go past the
+# local network segment.
+ttl = struct.pack('b', 1)
+sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl)
+
+try:
+
+    # Send data to the multicast group
+    print >>sys.stderr, 'sending "%s"' % message
+    sent = sock.sendto(message, multicast_group)
+
+    # Look for responses from all recipients
+    while True:
+        print >>sys.stderr, 'waiting to receive'
+        try:
+            data, server = sock.recvfrom(16)
+        except socket.timeout:
+            print >>sys.stderr, 'timed out, no more responses'
+            break
+        else:
+            print >>sys.stderr, 'received "%s" from %s' % (data, server)
+
+finally:
+    print >>sys.stderr, 'closing socket'
+    sock.close()