Week 0

UDP

• stands for User Datagram Protocol
• The sender won’t wait to make sure the recipient received the packet — it will just continue sending the next packets.
• when speed is desirable and error correction isn’t necessary
• no point in requesting the old packets if you missed them

Programming with UDP/IP sockets

There are a few steps involved in using sockets:

1. Create the socket

2. Identify the socket (name it)

create the data packet

3. On the server, wait for a message

4. On the client, send a message

5. Send a response back to the client (optional)

6. Close the socket

As shown in the Figure,

the steps of establishing a UDP socket communication on the client side are as follows:

• Create a socket using the socket() function;

• Send and receive data by means of the recvfrom() and sendto() functions.

The steps of establishing a UDP socket communication on the server side are as follows:

• Create a socket with the socket() function;

• Bind the socket to an address using the bind() function;

• Send and receive data by means of recvfrom() and sendto().

• UDP is connection-less. You do not connect or disconnect. All you do is to send and receive (must specify destination each time).