Programming Network Applications in Java

Create a simple tcp server in java by building a server socket on port 2020, accepting a client, and exchanging messages using buffered input and print writer output.

This lesson shows a simple Java tcp client that connects to localhost:2020, reads the server's welcome message, sends Thanks!, and closes the socket.

Learn how a simple tcp program uses the main method, server socket setup, and buffered input/output streams to handle client connections, exchange welcome and thanks messages, and close the sockets.

This lesson extends the simple tcp program by enabling the client to send a custom message and participate in a number guessing game with the server.

Observe a live TCP exchange in Wireshark: a three-way handshake, a 10-byte 'Welcome!' message with the push flag, followed by the client 'Thanks!' and socket closure.

Create a simple TCP server in Java that handles multiple clients by opening a socket on port 2020 and spawning a new thread per connection with a ServerThread implementing Runnable.

Advance the multithreaded tcp program by moving the client counter to the server main, exposing getClientNumber and printing 'client n has connected' and 'client n has disconnected'.

Explore bonus network tasks including a server that echoes text in upper case, reverses text, and a number guessing game from 1 to 20 for multiple clients, with solutions attached.

Explore UDP socket programming in Java by building a receiver that handles datagrams, explains the difference between TCP and UDP, uses DatagramSocket and DatagramPacket, and demonstrates sending and receiving messages.

Describe the sender side of a simple UDP program, prompting for a message, sending a DatagramPacket via a socket, and receiving via a buffer, noting UDP has no prior connection.

Add an indefinite while(true) loop in a new simple_udp2 package to enable continuous sender–receiver UDP communication using DatagramSocket, packets, and payloads.