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+====== Using xAP and Python ======
+{{:livebox:python-xap.jpg }} In this section we discuss how to interface with xAP devices, with a bias to the [[livebox:hah|Home Automation Hub]], using the Python programming language.  Even with very minimal skills you can modify and change the sample programs provided to create your own solutions.
+As Python run on Windows as well as Linux these programs will work on both platforms.  As well as natively on the livebox if you grab the [[development#a_native_mips_toolchain|Python for MIPS]] bundle.
+===== Simplistic samples =====
+Remember as xAP is a Broadcast protocol none of these programs need to be executed on the Livebox to interact with its hardware.  As these programs are demonstrators none of them are xAP-hub aware so only one can be ran on a computer at a time.  They demonstrate the absolute minimum amount of code that is necessary to send and receive xAP messages.
+==== xAP message snooper ====
+Listening to xAP messages on the LAN
+<code python>
+#!/usr/bin/env python
+# xAP message listener - simplistic
+import socket, traceback
+host = ''
+s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+s.bind((host, 3639))
+while 1:
+	try:
+		message, address = s.recvfrom(8192)
+		print "%s: %s" % (address, message)
+	except (KeyboardInterrupt, SystemError):
+		raise
+	except:
+		traceback.print_exc()
+</code>
+==== xAP relay toggle ====
+Toggling the relays on and off using python is very easy.  Each will go TICK on/off in sequence.
+<code python>
+import socket
+import time
+s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+s.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
+for relay in range(1,5):
+    for state in ['on','off']:
+        msg="""xap-header
+{
+v=12
+hop=1
+uid=FF000F00
+class=xAPBSC.cmd
+source=dbzoo.livebox.demo
+target=dbzoo.livebox.controller:relay.%s
+}
+output.state.1
+{
+id=*
+state=%s
+}
+"""
+        s.sendto(msg % (relay, state), ('<broadcast>', 3639))
+        time.sleep(1)
+</code>
+==== xAP LCD Clock ====
+A simplistic xAP CLOCK in python.  Every minute the LCD of the livebox will be updated.
+<code python>
+#!/usr/bin/env python
+# xAP - Simplistic LCD Clock
+from socket import *
+from time import localtime, strftime, sleep
+s = socket(AF_INET, SOCK_DGRAM)
+s.setsockopt(SOL_SOCKET, SO_BROADCAST, 1)
+while 1:
+    msg="""xap-header
+{
+v=12
+hop=1
+uid=FF000F00
+class=xAPBSC.cmd
+source=dbzoo.livebox.demo
+target=dbzoo.livebox.Controller:lcd
+}
+output.state.1
+{
+id=*
+text=%s
+}
+"""
+    t = localtime()
+    s.sendto(msg % strftime("%d %b, %H:%M", t), ('<broadcast>', 3639))
+    sleep(60 - t[5])
+</code>
+===== Need an xAP HUB =====
+Without a HUB we are only able to run a single xAP program on a computer at a time, as port 3639, the default xAP port, can only be accessed by one program.
+To get around this limitation we run an xAP hub, this performs the same function a the hardware variant of the same name.  It allows multiple xAP applications to share the 3639 port which the HUB will manage for us.
+Various hub implementations can be found on the [[http://www.xapautomation.org/index.php?title=xAP_Hub|xAP Automation site]]
+Personally I'm a fan of http://patrick.lidstone.net/haweb/hub.htm
+===== xAP support Library =====
+The support library {{xaplib.zip}} provides additional code to handle integration with a HUB.
+<code python>
+#!/usr/bin/env python
+#
+# XAP support library
+import socket, traceback, time
+class Xap:
+        def __init__(self, uid, source):
+                self.heartbeat_tick = 0;
+                self.uid = uid
+                self.source = source
+                self.port = 0
+                self.running = 1
+        def run(self, func):
+                self.connect()
+                while self.running:
+                        if self.port:
+                                self.heartbeat(60)
+                        try:
+                                func(self)
+                        except KeyboardInterrupt:
+                                self.done()
+                                pass
+                        except socket.timeout:
+                                pass
+                        except:
+                                traceback.print_exc()
+                                self.done()
+        def done(self):
+                self.gout.close()
+                self.gin.close()
+                self.running = 0
+        def connect(self):
+                host = ''
+                self.gin = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+                self.gin.settimeout(60)
+                try:
+                        self.gin.bind((host, 3639))
+                except socket.error, msg:
+                        print "Broadcast socket port 3639 in use"
+                        print "Assuming a hub is active"
+                        host = '127.0.0.1'
+                        for self.port in range(3639,4639):
+                                try:
+                                        self.gin.bind((host, self.port))
+                                except socket.error, msg:
+                                        print "Socket port %s in use" % self.port
+                                        continue
+                                print "Discovered port %s" % self.port
+                                break
+                self.gout = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+                self.gout.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
+        def send(self ,msg):
+                self.gout.sendto(msg, ('<broadcast>', 3639))
+        def sendMsg(self, clazz, target, msg):
+                msg = """xap-header
+{
+v=12
+hop=1
+uid=%s
+class=%s
+source=%s
+target=%s
+}
+%s""" % (self.uid, clazz, self.source, target, msg)
+                self.send(msg)
+        def sendLCDMsg(self, msg):
+                msg = "output.state.1\n{\nid=*\ntext=%s\n}" % msg
+                self.sendMsg("xAPBSC.cmd","dbzoo.livebox.Controller:lcd", msg)
+        def sendSMS(self, num, msg):
+                msg = "outbound\n{\nnum=%s\nmsg=%s\n}" % (num, msg)
+                self.sendMsg("sms.message","dbzoo.livebox.sms", msg)
+        def receive(self):
+                try:
+                        return self.gin.recvfrom(8192)
+                except KeyboardInterrupt:
+                        self.done()
+                        pass
+# The HUB won't relay messages to us until it see's our heartbeat knows our listening port.
+# This must be periodically sent to keep it active on the HUB.
+        def heartbeat(self, interval):
+                now = time.time()
+                if now - self.heartbeat_tick > interval or self.heartbeat_tick == 0:
+                        self.heartbeat_tick = now
+                        msg="""xap-hbeat
+{
+nv=12
+hop=1
+uid=%s
+class=xap-hbeat-alive
+source=%s
+interval=%s
+port=%s
+}"""
+                        self.send(msg % (self.uid, self.source, interval, self.port))
+</code>
+===== HUB aware samples =====
+The support library greatly simplifies the process of writing a small xaplet.
+==== xAP message snoop ====
+A message snooper is now trivially implemented
+<code python>
+#!/usr/bin/env python
+# xAP message listener - HUB aware
+from xaplib import Xap
+def snoopTraffic(xap):
+    print "MSG: %s ADDR: %s" % xap.receive()
+Xap("FF000F00","dbzoo.livebox.Snoop").run(snoopTraffic)
+</code>
+==== xAP LCD Clock ====
+Revisiting our simplistic clock we can rewrite the code using fewer lines and at the same time making it hub friendly.
+<code python>
+#!/usr/bin/env python
+# LCD Clock
+from xaplib import Xap
+from time import localtime, strftime, sleep
+def clock(xap):
+    t = localtime()
+    xap.sendLCDMsg( strftime("%d %b, %H:%M", t) )
+    sleep(60 - t[5])
+Xap("FF000F00","dbzoo.livebox.demo").run(clock)
+</code>
+====== Demo code ======
+Some other samples which might be useful
+  * {{xap-sms-event.zip}} - Watch out for an RF or RELAY event when one if detected send an SMS of the change
+  * {{xap-sms-lcd.zip}} - Watch out for inbound SMS messages when one if detected display the message on the livebox LCD
+  * {{xap-input-smtp.zip}} - Send an email on an input event
+{{tag>livebox xap python programming}}