Python script examples

Script template

Use the following Python script template to write a data parsing script.

# Transforms custom data from a device into the Alink protocol format. This function is called when a device uploads data to IoT Platform.
# Input parameter: rawData. A list of integers. Cannot be empty.
# Response parameter: jsonObj. A dictionary. Cannot be empty.
def raw_data_to_protocol(rawData):
    jsonObj = {}
    return jsonObj

# Transforms data in the Alink protocol format into a custom format that a device can understand. This function is called when IoT Platform sends data to a device.
# Input parameter: jsonData. A dictionary. Cannot be empty.
# Response parameter: rawdata. A list of integers. The value of each element must be between 0 and 255. Cannot be empty.
def protocol_to_raw_data(jsonData):
    rawData = []
    return rawData

Notes on writing scripts

• Avoid using global variables to prevent inconsistent execution results.
• The script processes data using two's complement. The two's complement for the range [-128, 127] is [0, 255]. For example, the two's complement of -1 is 255 in decimal.
• The `raw_data_to_protocol` function parses data uploaded by a device. Its input parameter is an integer array. Perform a bitwise AND operation with 0xFF to obtain the two's complement.
• The `protocol_to_raw_data` function parses data sent from the IoT Platform. It returns an array of integers with values from 0 to 255.

Script examples

The following script is based on the properties and communication protocols defined in Examples of data parsing for TSL models.

# coding=UTF-8
import struct

COMMAND_REPORT = 0x00  # Report properties.
COMMAND_SET = 0x01  # Set properties.
COMMAND_REPORT_REPLY = 0x02  # // Response to reported data.
COMMAND_SET_REPLY = 0x03  # // Response from the device to a property setting command.
COMMAD_UNKOWN = 0xff  # // Unknown command.
ALINK_PROP_REPORT_METHOD = 'thing.event.property.post'  # IoT Platform topic for devices to upload property data to the cloud.
ALINK_PROP_SET_METHOD = 'thing.service.property.set'  # // IoT Platform topic for the cloud to send property control instructions to devices.
ALINK_PROP_SET_REPLY_METHOD = 'thing.service.property.set'  # // IoT Platform topic for devices to report the results of property settings to the cloud.


# Sample data:
# Data reported by the device
# Input parameter ->
#    0x000000000100320100000000
# Output result ->
#    {"method":"thing.event.property.post","id":"1","params":{"prop_float":0,"prop_int16":50,"prop_bool":1},"version":"1.0"}
# Response to a property setting command
# Input parameter ->
#    0x0300223344c8
# Output result ->
#    {"code":"200","data":{},"id":"2241348","version":"1.0"}

def raw_data_to_protocol(bytes):
    uint8Array = []
    for byteValue in bytes:
        uint8Array.append(byteValue & 0xff)

    fHead = uint8Array[0]
    jsonMap = {}
    if fHead == COMMAND_REPORT:
        jsonMap['method'] = ALINK_PROP_REPORT_METHOD
        jsonMap['version'] = '1.0'
        jsonMap['id'] = str(bytes_to_int(uint8Array[1:5]))
        params = {}
        params['prop_int16'] = bytes_to_int(uint8Array[5:7])
        params['prop_bool'] = bytes_to_int(uint8Array[7: 8])
        params['prop_float'] = bytes_to_int(uint8Array[8:])
        jsonMap['params'] = params
    elif fHead == COMMAND_SET_REPLY:
        jsonMap['version'] = '1.0'
        jsonMap['id'] = str(bytes_to_int(uint8Array[1:5]))
        jsonMap['code'] = str(bytes_to_int(uint8Array[5:]))
        jsonMap['data'] = {}

    return jsonMap


# Sample data:
# Set properties
# Input parameter ->
#    {"method":"thing.service.property.set","id":"12345","version":"1.0",
#    "params":{"prop_float":123.452, "prop_int16":333, "prop_bool":1}}
# Output result ->
#    0x0100003039014d0142f6e76d
# Response to reported data
# Input data ->
#    {"method":"thing.event.property.post","id":"12345","version":"1.0","code":200,"data":{}}
# Output result ->
#    0x0200003039c8
def protocol_to_raw_data(json):
    method = json.get('method', None)
    id = json.get('id', None)
    version = json.get('version', None)
    payload_array = []

    if method == ALINK_PROP_SET_METHOD:
        params = json.get('params')
        prop_float = params.get('prop_float', None)
        prop_int16 = params.get('prop_int16', None)
        prop_bool = params.get('prop_bool', None)

        payload_array = payload_array + int_8_to_byte(COMMAND_SET)
        payload_array = payload_array + int_32_to_byte(int(id))
        payload_array = payload_array + int_16_to_byte(prop_int16)
        payload_array = payload_array + int_8_to_byte(prop_bool)
        payload_array = payload_array + float_to_byte(prop_float)

    elif method == ALINK_PROP_REPORT_METHOD:
        code = json.get('code', None)
        payload_array = payload_array + int_8_to_byte(COMMAND_REPORT_REPLY)
        payload_array = payload_array + int_32_to_byte(int(id))
        payload_array = payload_array + int_8_to_byte(code)
    else:
        code = json.get('code')
        payload_array = payload_array + int_8_to_byte(COMMAD_UNKOWN)
        payload_array = payload_array + int_32_to_byte(int(id))
        payload_array = payload_array + int_8_to_byte(code)

    return payload_array


# Converts a byte array to an integer.
def bytes_to_int(bytes):
    data = ['%02X' % i for i in bytes]
    return int(''.join(data), 16)


# Converts a byte array to a float without precision.
def bytes_to_float(bytes):
    data = []
    for i in bytes:
        t_value = '%02X' % i
        if t_value % 2 != 0:
            t_value += 0
        data.append(t_value)
    hex_str = ''.join(data)
    return struct.unpack('!f', hex_str.decode('hex'))[0]


# Converts an 8-bit integer to a byte array.
def int_8_to_byte(value):
    t_value = '%02X' % value
    if len(t_value) % 2 != 0:
        t_value += '0'

    return hex_string_to_byte_array(t_value)


# Converts a 32-bit integer to a byte array.
def int_32_to_byte(value):
    t_value = '%08X' % value
    if len(t_value) % 2 != 0:
        t_value += '0'

    return hex_string_to_byte_array(t_value)


# Converts a 16-bit integer to a byte array.
def int_16_to_byte(value):
    t_value = '%04X' % value
    if len(t_value) % 2 != 0:
        t_value += '0'

    return hex_string_to_byte_array(t_value)


# Converts a float to a byte array.
def float_to_byte(param):
    return hex_string_to_byte_array(struct.pack(">f", param).encode('hex'))


# Converts a hexadecimal string to a byte array.
def hex_string_to_byte_array(str_value):
    if len(str_value) % 2 != 0:
        return None

    cycle = len(str_value) / 2

    pos = 0
    result = []
    for i in range(0, cycle, 1):
        temp_str_value = str_value[pos:pos + 2]
        temp_int_value = int(temp_str_value, base=16)

        result.append(temp_int_value)
        pos += 2
    return result