1 # mqtt/client.py

     2 

     3 from __future__ import absolute_import

     4 

     5 import os

     6 

     7 from POULibrary import POULibrary

     8 import util.paths as paths

     9 

    10 mqtt_python_lib_code = """

    11 def MQTT_publish(clientname, topic, payload, QoS = 1, Retained = False):

    12     c_function_name = "__mqtt_python_publish_" + clientname

    13     c_function = getattr(PLCBinary, c_function_name)

    14     c_function.restype = ctypes.c_int # error or 0

    15     c_function.argtypes = [

    16         ctypes.c_char_p,  # topic

    17         ctypes.c_char_p,  # data

    18         ctypes.c_uint32,  # datalen

    19         ctypes.c_uint8,   # QoS

    20         ctypes.c_uint8,   # Retained

    21     ]

    22     res = c_function(topic, payload, len(payload), QoS, Retained)

    23     return res

    24 

    25 # C per client CallBack type for __mqtt_python_subscribe_{name}

    26 c_cb_type = ctypes.CFUNCTYPE(ctypes.c_int,                   # return

    27                              ctypes.c_char_p,                # topic

    28                              ctypes.POINTER(ctypes.c_char),  # data

    29                              ctypes.c_uint32)                # data length

    30 

    31 # CallBacks management

    32 # - each call to MQTT_subscribe registers a callback

    33 MQTT_subscribers_cbs = {}

    34 

    35 # - one callback registered to C side per client

    36 MQTT_client_cbs = {}

    37 

    38 def per_client_cb_factory(client):

    39     def per_client_cb(topic, dataptr, datalen):

    40         payload = ctypes.string_at(dataptr, datalen)

    41         subscriber = MQTT_subscribers_cbs[client].get(topic, None)

    42         if subscriber:

    43             subscriber(topic, payload)

    44             return 0

    45         return 1

    46     return per_client_cb

    47     

    48 def MQTT_subscribe(clientname, topic, cb, QoS = 1):

    49     global MQTT_client_cbs, MQTT_subscribers_cbs

    50     c_function_name = "__mqtt_python_subscribe_" + clientname

    51     c_function = getattr(PLCBinary, c_function_name)

    52     c_function.restype = ctypes.c_int # error or 0

    53     c_function.argtypes = [

    54         ctypes.c_char_p,  # topic

    55         ctypes.c_uint8]   # QoS

    56 

    57     MQTT_subscribers_cbs.setdefault(clientname, {})[topic] = cb

    58 

    59     c_cb = MQTT_client_cbs.get(clientname, None)

    60     if c_cb is None:

    61         c_cb = c_cb_type(per_client_cb_factory(clientname))

    62         MQTT_client_cbs[clientname] = c_cb

    63         register_c_function = getattr(PLCBinary, "__mqtt_python_callback_setter_"+clientname )

    64         register_c_function.argtypes = [c_cb_type]

    65         register_c_function(c_cb)

    66 

    67     res = c_function(topic, QoS)

    68     return res

    69 

    70 """

    71 

    72 class MQTTLibrary(POULibrary):

    73     

    74     def GetLibraryPath(self):

    75         return paths.AbsNeighbourFile(__file__, "pous.xml")

    76 

    77     def Generate_C(self, buildpath, varlist, IECCFLAGS):

    78 

    79         runtimefile_path = os.path.join(buildpath, "runtime_00_mqtt.py")

    80         runtimefile = open(runtimefile_path, 'w')

    81         runtimefile.write(mqtt_python_lib_code)

    82         runtimefile.close()

    83         return ((["mqtt"], [], False), "",

    84                 ("runtime_00_mqtt.py", open(runtimefile_path, "rb")))