Topic 9. Programming network applications with Socket

Goal: get to know the TCP/IP protocol stack, the TCP and UDP protocols, and the classes of the System.Net.Sockets namespace; learn to build client-server applications with asynchronous data exchange, define message boundaries and your own application protocol; master serving multiple clients, graceful shutdown, network error handling, and connection diagnostics.

Lecture contents

1. Networking, TCP, UDP, and Socket — Networking basics · The TCP and UDP protocols · The Socket class
2. TCP: client, server, and protocol — The TcpListener, TcpClient, and NetworkStream classes · The listening address and Windows Firewall · Message boundaries in a TCP stream · An application protocol
3. Serving multiple clients — Serving multiple clients
4. UDP, errors, and diagnostics — UDP and broadcast messages · Errors, timeouts, and security · Diagnosing network applications
5. Common mistakes — Common mistakes

Practice and review

• Practice — 3 worked examples with complete code
• Tasks — 30 variants, each with tasks at three difficulty levels
• Summary — conclusions, self-check questions, and useful links