Home Page
>
Custom Networking
>
All About Datagrams
What Is a Datagram?
Clients and servers that communicate via a reliable channel, such as a
TCP socket, have a dedicated point-to-point channel between
themselves, or at least the illusion of one. To communicate, they
establish a connection, transmit the data, and then close the
connection. All data sent over the channel is received in the same
order in which it was sent. This is guaranteed by the channel.
In contrast, applications that communicate via datagrams send and
receive completely independent packets of information. These clients
and servers do not have and do not need a dedicated point-to-point
channel. The delivery of datagrams to their destinations is not
guaranteed. Nor is the order of their arrival.
Definition: A datagram is an independent,
self-contained message sent over the network whose arrival, arrival
time, and content are not guaranteed.
The java.net package contains three classes
to help you write Java programs that use datagrams
to send and receive packets over the network:
DatagramSocket,
DatagramPacket, and
MulticastSocketAn application can send and receive DatagramPackets
through a DatagramSocket.
In addition, DatagramPackets can be broadcast
to multiple recipients all listening to a MulticastSocket.
