Method Signature/Syntax:
socket.recvfrom(bufsize[, flags])
Parameters:
bufsize - The number of bytes to be read from the UDP socket.
flags - This is an optional parameter. As supported by the operating system. Multiple values combined together using bitwise OR. The default value is zero.
Return Value:
Returns a bytes object read from an UDP socket and the address of the client socket as a tuple.
Overview:
- The recvfrom() method Python's socket class, reads a number of bytes sent from an UDP socket.
- Like sendto(), the recvfrom() method as well is to be called on a UDP socket.
- Unlike sendto(), the method recvfrom() does not take an IP address and port as a parameter.
- The recvfrom() method can be used with an UDP server to receive data from a UDP client or it can be used with an UDP client to receive data from a UDP server.
Example – An UDP server that serves price information:
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# ----- An example UDP client in Python that uses recvfrom() method ----- import socket import random
# Give price def getPrice(corpName): if(corpName == "Example Corporation"): price = random.uniform(27.0, 29.0); return price; else: return "NA";
# Create an UDP based server socket socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM); socket.bind(("127.0.0.1", 4141));
while(True): msgAndAddress = socket.recvfrom(1024); incName = msgAndAddress[0].decode(); print(incName);
price = getPrice(incName); print(price) priceStr = "%.2f"%price; socket.sendto(priceStr.encode(), msgAndAddress[1]); |
Output:
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Example Corporation 2019-06-30 01:35:58.801308 28.44 Example Corporation 2019-06-30 01:36:00.150010 28.88 |
Example – An UDP client that asks for price information:
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# ----- An example UDP client in Python that uses recvfrom() method ----- import socket
# Number of bytes to get numBytes2Get = 1024;
# Create a UDP socket. UDP is datagram based. destination = ("127.0.0.1", 4141); udpClientSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM);
# Send quote request sentBytesCount = udpClientSocket.sendto("Example Corporation".encode(), destination);
# Use receivefrom() to get quote receivedBytes = udpClientSocket.recvfrom(numBytes2Get);
# Print the quote print(receivedBytes[0].decode()); |
Output:
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28.88 |