Method Signature/Syntax:
sendto(bytes, flags, address)
Parameters:
bytes - The data to be sent in bytes format. If the data is in string format, str.encode() method can be used to convert the strings to bytes.
flags - As supported by the operating system, multiple values can be combined using bitwise OR. This optional parameter has a default value of 0.
address - A tuple consisting of IP address and port number.
Return Value:
Returns the number of bytes sent.
Overview:
- The method sendto() of the Python's socket class, is used to send datagrams to a UDP socket.
- The communication could be from either side. It could be from client to server or from the server to client.
- For sendto() to be used, the socket should not be in already connected state.
Example – UDP server that uses sendto() function:
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# ----- An UDP server in Python that receives temperature values from clients----- import socket import datetime
# Define the IP address and the Port Number ip = "127.0.0.1"; port = 7070; listeningAddress = (ip, port);
# Create a datagram based server socket that uses IPv4 addressing scheme datagramSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM); datagramSocket.bind(listeningAddress);
while(True): tempVal, sourceAddress = datagramSocket.recvfrom(128); print("Temperature at %s is %s"%(sourceAddress, tempVal.decode())); response = "Received at: %s"%datetime.datetime.now(); datagramSocket.sendto(response.encode(), sourceAddress); |
Output:
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Temperature at ('127.0.0.1', 64164) is 61.65 Temperature at ('127.0.0.1', 56309) is 61.66 |
Example – UDP client that uses sendto() function:
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# ----- An UDP client in Python that sends temperature values to server----- import socket import random
# Get temperature def getTemp(): temp = random.uniform(60.0, 62.0); return temp;
# A tuple with server ip and port serverAddress = ("127.0.0.1", 7070);
# Create a datagram socket tempSensorSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM);
# Get temperature temperature = getTemp(); tempString = "%.2f"%temperature;
# Socket is not in connected state yet...sendto() can be used # Send temperature to the server tempSensorSocket.sendto(tempString.encode(), ("127.0.0.1",7070));
# Read UDP server's response datagram response = tempSensorSocket.recv(1024); print(response); |
Output:
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b'Received at: 2019-06-28 23:12:49.262979' |