UDP is a connectionless protocol that is lightweight and faster than TCP, but it's error prone because data can be lost in transmission or arrive more than once. UDP is used for streaming services such as Voice over IP, where real time matters but dropping packets just affects the sound quality.
One of the additional advantages of using UDP is the ability to broadcast or multicast data across a network. The DNS service to resolve Internet addresses and the discovery service of the Device Profile for Web Services use the broadcast feature of UDP.
With UDP, a client does not need to connect to a server. Connectionless transmission takes place with the SendTo and ReceiveFrom methods. ReceiveFrom returns an endpoint object that is populated with the actual sender information. Listing 6-4 shows a UDP client and Listing 6-5 a UDP server. They demonstrate the usage of a connectionless end-to-end transmission but are not using the broadcast feature.
If you want to send a broadcast message that theoretically all network nodes will get, you can use the IP address 255.255.255.255. There is no predefined broadcast address like Any or Loopback as there is with the full .NET Framework. You can also create a broadcast IP address object using new IPAddress(0xFFFFFFFF);.
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