python: added example client application which uses Protobuf and UDP / domain sockets to communicate with VILLASnode

clients/python/villas.py

@@ -0,0 +1,64 @@
+# -*- coding: utf-8 -*-
+import villas_pb2
+import time, socket, errno, sys, os, os.path
+
+layer = sys.argv[1] if len(sys.argv) == 2 else 'udp'
+
+if layer not in ['udp', 'unix']:
+	raise Exception('Unsupported socket type')
+
+if layer == 'unix':
+	local  = '/var/run/villas-node.client.sock'
+	remote = '/var/run/villas-node.server.sock'
+
+	skt = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+
+	# Delete stale sockets
+	if os.path.exists(local):
+		os.unlink(local)
+elif layer == 'udp':
+	local  = ('0.0.0.0', 12001)
+	remote = ('127.0.0.1', 12000)
+
+	skt = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+
+print('Start client...')
+
+skt.bind(local)
+
+# Try to connect in case Unix domain socket does not exist yet..
+connected = False
+while not connected:
+	try:
+		skt.connect(remote)
+	except socket.error as serr:
+		if serr.errno not in [ errno.ECONNREFUSED, errno.ENOENT ]:
+			raise serr
+			
+		print('Not connected. Retrying in 1 sec')
+		time.sleep(1)
+	else:
+		connected = True
+
+print('Ready. Ctrl-C to quit.')
+
+msg = villas_pb2.Message()
+
+while True:
+	try:
+		dgram = skt.recv(1024)
+		if not dgram:
+			break
+		else:
+			msg.ParseFromString(dgram)
+			print(msg)
+			
+			skt.send(msg.SerializeToString())
+
+	except KeyboardInterrupt:
+		print('Shutting down.')
+		break
+
+skt.close()
+
+print('Bye.')

etc/example.conf

@@ -99,8 +99,8 @@ nodes = {
 		type	= "socket",
 		layer	= "unix",			# Datagram UNIX domain sockets require two endpoints
 		
-		local	= "/var/run/villas/node/node.sock",
-		remote	= "/var/run/villas/node/client.sock"
+		local	= "/var/run/villas-node/node.sock",
+		remote	= "/var/run/villas-node/client.sock"
 	},
 	opal_node = {					# The server can be started as an Asynchronous process
 		type	= "opal",			# from within an OPAL-RT model.