Using TCP, UDP, and Sockets
The System.Net.Sockets namespace includes types that
provide protocol-level support for TCP and UDP. These types are built on the
underlying Socket type, which is itself directly accessible for transport-level access to the network.
Two classes provide the TCP support: TcpListener and TcpClient. TcpListener listens
for incoming connections, creating Socket instances that
respond to the connection request. TcpClient connects to
a remote host, hiding the details of the underlying socket in a Stream-derived
type that allows stream I/O over the network.
A class called UdpClient provides the UDP support. UdpClient serves
as both a client and a listener, and includes multicast support, allowing individual
datagrams to be sent and received as byte arrays.
Both the TCP and the UDP classes help to access the underlying network
socket (represented by the Socket class). The Socket class
is a thin wrapper over the native Windows sockets functionality and is the
lowest level of networking accessible to managed code.
The following example is a simple implementation of the Quote of the
Day (qotd) protocol, as defined by the IETF in RFC 865. It demonstrates the
use of a TCP listener to accept incoming requests and the use of the lower-level
Socket type to fulfill the request:
// QOTDListener.cs // Run QOTDListener.exe to service incoming QOTD requests using System; using System.Net; using System.Net.Sockets; using System.Text; class QOTDListener { static string[] quotes = ...