Wirepas MQTT Library¶
This Python wheel is designed to ease the development of tools on top of Wirepas Gateway to backend Api (MQTT with protobuf payloads).
Connection through MQTT is wrapped and messages in protobuf format are generated and parsed for you.
Its main focus is to control a full network without to handle individually the connection to every gateways.
Most api can be used in a synchronous or asynchronous way to feat your design.
Automatically generated documentation is hosted here.
Install from PyPi¶
This package is available from PyPi.
pip install wirepas-mqtt-library
From the source¶
This wheel can be install from source directly if you need modifications.
pip install -e .
Steps to write a script to send a message¶
Import the module¶
Once the wheel is installed, you can import the module easily
from wirepas_mqtt_library import WirepasNetworkInterface
Create a Wirepas Network Interface object¶
wni = WirepasNetworkInterface(host, port, username, password)
This object will allow you to interact with the network. For example, you can retrieve the list of gateways
Or print the list of sinks for a given network
line = "" for gw, sink, config in wni.get_sinks(): line += "[%s:%s] " % (gw, sink) print(line)
Send a message with broadcast address from all sinks of a given network¶
for gw, sink, config in wni.get_sinks(): try: res = wni.send_message(gw, sink, 0xFFFFFFFF, 1, 1, "This is a test message".encode()) if res != wmm.GatewayResultCode.GW_RES_OK: print("Cannot send data to %s:%s res=%s" % (gw, sink, res)) except TimeoutError: print("Cannot send data to %s:%s", gw, sink)
When creating a WirepasNetworkInterface object, few threads will be involved.
Network (MQTT) thread: all the internal MQTT operations will happen on this dedicated thread but no code from your application will be executed on it
- Worker thread(s): these threads will be used to call all your callbacks.It can be either asynchronous reception of gateway responses or the data you have registered to.If long operation are expected in your callback (like IO operation), you can specify the number of threads to use when creatingyour WirepasNetworkInterface object to avoid a bottleneck. In fact, multiple threads will allow to handlea new callback if another one is executing long operations.By default there is a single thread.
Your calling thread: Any call made in synchronous mode (cb=None) will lock your calling thread until it a response is receive or a timeout has elapsed
Synchronous vs Asynchronous¶
Most of the WirepasNetworkInterface methods can be called synchronously or asynchronously. When synchronous, answer from the gateway is awaited before returning. from the gateway and a TimeoutError Exception will be generated if the gateway doesn’t answer within the default 2s timeout.
# Send a message as broadcast from sink sink_id attached to gateway gw_id on endpoint 1 # in a synchronous way res = wni.send_message(gw, sink, 0xFFFFFFFF, 1, 1, "This is a test message".encode()) if res != wmm.GatewayResultCode.GW_RES_OK: print("Sending data synchronously failed: res=%s" % res)
But if you specify a callback, it will be called when the answer is received or never if the gateway doesn’t answer.
def on_message_sent_cb(res, param): if res != wmm.GatewayResultCode.GW_RES_OK: print("Sending data asynchronously failed: res=%s. Caller param is %s" % (res, param)) param = 1234 # Send a message as broadcast from sink sink_id attached to gateway gw_id on endpoint 1 # in an asynchronous way wni.send_message(gw_id, sink_id, 0xFFFFFFFF, 1, 1, "This is a test message".encode(), cb=on_message_sent_cb, param=param)
Licensed under the Apache License, Version 2.0.