MQTT: allow publish and subscribe from user python code.
# mqtt/client.py
from __future__ import absolute_import
import os
from POULibrary import POULibrary
import util.paths as paths
mqtt_python_lib_code = """
def MQTT_publish(clientname, topic, payload, QoS = 1, Retained = False):
c_function_name = "__mqtt_python_publish_" + clientname
c_function = getattr(PLCBinary, c_function_name)
c_function.restype = ctypes.c_int # error or 0
c_function.argtypes = [
ctypes.c_char_p, # topic
ctypes.c_char_p, # data
ctypes.c_uint32, # datalen
ctypes.c_uint8, # QoS
ctypes.c_uint8, # Retained
]
res = c_function(topic, payload, len(payload), QoS, Retained)
return res
# C per client CallBack type for __mqtt_python_subscribe_{name}
c_cb_type = ctypes.CFUNCTYPE(ctypes.c_int, # return
ctypes.c_char_p, # topic
ctypes.POINTER(ctypes.c_char), # data
ctypes.c_uint32) # data length
# CallBacks management
# - each call to MQTT_subscribe registers a callback
MQTT_subscribers_cbs = {}
# - one callback registered to C side per client
MQTT_client_cbs = {}
def per_client_cb_factory(client):
def per_client_cb(topic, dataptr, datalen):
payload = ctypes.string_at(dataptr, datalen)
subscriber = MQTT_subscribers_cbs[client].get(topic, None)
if subscriber:
subscriber(topic, payload)
return 0
return 1
return per_client_cb
def MQTT_subscribe(clientname, topic, cb, QoS = 1):
global MQTT_client_cbs, MQTT_subscribers_cbs
c_function_name = "__mqtt_python_subscribe_" + clientname
c_function = getattr(PLCBinary, c_function_name)
c_function.restype = ctypes.c_int # error or 0
c_function.argtypes = [
ctypes.c_char_p, # topic
ctypes.c_uint8] # QoS
MQTT_subscribers_cbs.setdefault(clientname, {})[topic] = cb
c_cb = MQTT_client_cbs.get(clientname, None)
if c_cb is None:
c_cb = c_cb_type(per_client_cb_factory(clientname))
MQTT_client_cbs[clientname] = c_cb
register_c_function = getattr(PLCBinary, "__mqtt_python_callback_setter_"+clientname )
register_c_function.argtypes = [c_cb_type]
register_c_function(c_cb)
res = c_function(topic, QoS)
return res
"""
class MQTTLibrary(POULibrary):
def GetLibraryPath(self):
return paths.AbsNeighbourFile(__file__, "pous.xml")
def Generate_C(self, buildpath, varlist, IECCFLAGS):
runtimefile_path = os.path.join(buildpath, "runtime_00_mqtt.py")
runtimefile = open(runtimefile_path, 'w')
runtimefile.write(mqtt_python_lib_code)
runtimefile.close()
return ((["mqtt"], [], False), "",
("runtime_00_mqtt.py", open(runtimefile_path, "rb")))