6.8. PIKA-MQTT libary

6.8.1. __init__()

introduce：

Instantiate one MQTT Client

args：

serial number function types of variables comment
1 ip string required
2 port int This parameter is optional. The default value is 1883
3 clientID string This parameter is optional. The default value is mac of address
4 username string This parameter is optional. The default value is null
5 password string This parameter is optional. The default value is null
6 version string This parameter is optional. The default value is MQTT-3.1.1
7 ca string This parameter is not required and is empty by default
8 keepalive int This parameter is not required. The default value is 60 seconds

returned value：

function types of variables
mqtt event MQTT

give a typical example：

# Minimalist creation
c = MQTT("broker-cn.emqx.io")
# Create a custom port
c = MQTT("broker-cn.emqx.io", 1111)
# Create a custom clientID
c = MQTT("broker-cn.emqx.io", clientID="pikascript")
# Requires the creation of a user name and password
c = MQTT("broker-cn.emqx.io", username="pikascript123", password="123456")
# The creation of an encrypted mqtt
c = MQTT("broker-cn.emqx.io", 8883, username="pikascript123", password="123456", ca=open(cert_file).read())

6.8.2. setClientID()

introduce:

Setting clientID overrides the parameters at instantiation time parameter:

serial number function types of variables comment
1 clientid string required
function types of variables
OK:true fail:false bool

give a typical example：

c.setClientID("pikascript")

6.8.3. setUsername()

introduce：

Setting usrname overrides the instantiation parameters

parameter：

serial number function types of variables cointroducemment
1 username string required

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

c.setUsername("pikascript")

6.8.4. setPassword()

introduce：

Setting password overrides the parameter used during instantiation

parameter：

serial number function types of variables comment
1 password string required

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

c.setPassword("pikascript")

6.8.5. setVersion()

introduce：

Setting the mqtt version overrides the parameter at instantiation time

parameter：

serial number function types of variables comment
1 version string required

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

# choosable "3.1" "3.1.1"
c.setVersion("3.1")

6.8.6. setCa()

introduce：

Setting the ssl certificate overrides the parameter during instantiation Once this parameter is in effect, an ssl connection is forced

parameter：

serial number function types of variables comment
1 ca string required

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

c.setCa(open(cert_file).read())

6.8.7. setKeepAlive()

introduce：

Setting the keepalive time overrides the parameter at instantiation time

parameter：

serial number function types of variables comment
1 time int required

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

# cgs unit
c.setKeepAlive(120)

6.8.8. setWill()

introduce：

testamentary

parameter：

serial number function types of variables comment
1 topic string required
2 payload string required
3 qos int No required，defaultQOS0
4 retain bool No required，defaultFalse

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

c.setWill("/device/will", "{"name":"pikascript"}")

6.8.9. setDisconnectHandler()

introduce：

Set the disconnection callback

parameter：

serial number function types of variables comment
1 callback any required callback function

returned value：

function types of variables
OK:true fail:false bool

give a typical example：

def disconnect_cb():
    print("mqtt disconnect")

c.setDisconnectHandler(disconnect_cb)

6.8.10. connect()

introduce：

connect to server

parameter：

null

returned value：

function types of variables
OK:0 int Error code: attached one

give a typical example：

c.connect()

6.8.11. disconnect()

introduce：

Disconnect server

parameter：

null

returned value：

function types of variables
OK:0 int Error code: attached one int

give a typical example：

c.disconnect()

6.8.12. subscribe()

introduce：

Subscribe to a subject

parameter：

serial number function types of variables comment
1 topic string required
2 callback any required，回调函数
3 qos int 非required，defaultQOS0

returned value：

function types of variables
OK:0 int Error code: attached one int

give a typical example：

def sub_cb(evt):
    print(evt.msg, evt.topic)

c.subscribe("/topic/sub", sub_cb)

6.8.13. unsubscribe()

introduce：

Unsubscribe to a topic

parameter：

serial number function types of variables comment
1 topic string required

returned value

function types of variables
OK:0 int Error code: attached one

give a typical example

c.unsubscribe("/topic/sub")

6.8.14. listSubscribeTopics()

introduce

Lists the topics to which you are currently subscribed

parameter:

null

returned value

function types of variables
subject bibliography tuple

example:

t = c.listSubscribeTopics()
print(t)

6.8.15. publish()

introduce:

publish the message

parameters:

serial number function types of variables comment
1 topic string required
2 payload string required
3 qos int 非required，defaultQOS0

return values：

function types of variables
OK:0 int Error code: attached one

example：

c.publish("/topic/pub", 0, "{"msg":"hello pikascript"}")

6.8.16. Attachment 1: Error code

error code explain comment
0 STATE_SUCCESS OK
1 STATE_FAIL_UNKONW unknown cause of failure
2 STATE_FAIL_BAD_NAME_PASSWD Failed the user name and password are incorrect
3 STATE_FAIL_BAD_CLINETID Falid clientid error
4 STATE_FAIL_BAD_PROTOCOL Falid the mqtt protocol version is incorrect
5 STATE_FAIL_BAD_RCODE Falid to subsribe or ubsubscribe the server returns the operation falid
6 STATE_FAIL_PERMISSION Permissions are unreachable when a subscription or publication fails

6.8.17. Second:Comprehensive example

# coding=utf-8

def sub_test1_cb(evt):
    print("sub test1 message:", evt.msg)


def sub_test2_cb(evt):
    print("sub test2 message:", evt.msg)


def sub_test3_cb(evt):
    print("sub test3 message:", evt.msg)
    
    
def disconnect_cb():
    print("mqtt disconnect")

    
def test():
    # MQTTS
    c = MQTT("broker-cn.emqx.io", 8883,  clientID="pikaone", username="pikascript123", password="123456", ca=open("/ca.crt").read())
    
    # Test a mentary
    c.setWill("/device/will", "{"name":"pikascript"}", 0, True)
    
	# Set the dis connection callback
	c.setDisconnectHandler(disconnect_cb)
    
    # connect to server
    result = c.connect()
    if result == 0:
        print("connect success!")
    else:
        print("connect faild id={}".format(result))
        return
    
    # Subscribe to a subject
    c.subscribe("/pikascript/test1", sub_test1_cb, 0)
    c.subscribe("/pikascript/test2", sub_test2_cb, 1)
    c.subscribe("/pikascript/test3", sub_test3_cb, 2)

    print("list subscribe topics:")
    print(c.listSubscribeTopics())

    print("start publish")

    # Send topic message
    c.publish("/pikascript/test1", "{'msg'}:'hello from test1'", 0)
    c.publish("/pikascript/test2", "{'msg'}:'hello from test2'", 1)
    c.publish("/pikascript/test3", "{'msg'}:'hello from test3'", 2)

    print("end publish")

    # Discount
    result = c.disconnect()
    if result == 0:
        print("disconnect success!")
    else:
        print("disconnect faild id={}".format(result))
        return
    
# run
test()

flow chart pika-mqtt.pngmqtt