Implementing TCP Communication in Node.js

Working with TCP servers involves creating low-level network applications that enable reliable, ordered, and continuous data exchange between clients and servers using Node.js.

• Uses the TCP protocol for reliable communication.
• Implemented in Node.js using the net module.
• Suitable for non-GUI and real-time applications.

Setting Up a Basic TCP Server in Node.js

Node.js offers the net module for creating TCP servers. This module helps build server-client connections, allowing data to be transferred between them.

Import the net module:

const net = require('net');

Create the TCP server: Use net.createServer() to create a server that listens for incoming connections.

Run the server:

node tcpServer.js

• The server listens on port 8080 and waits for client connections.
• Connecting to the TCP Server Using Telnet

Since TCP doesn't use a graphical interface like a web browser, you can connect to the server using a command-line tool like Telnet:

Open a command prompt (CMD or PowerShell) and enter:

telnet localhost 8080

After connecting, type messages (e.g., "Hi Nicol"), which the server will receive and log.

The server will display the data as received from the client, confirming the transmission order is maintained (TCP ensures data is received correctly).

Reliability: If any data packet fails to be received, TCP will automatically retry sending the packet to ensure reliable data transfer

File Transfer Using TCP

File transfer using TCP in Node.js leverages streams to send file data reliably from a server to a client, ensuring ordered and complete delivery of the file.

• Uses TCP streams for reliable file transmission.
• Implemented with Node.js net and fs modules.
• Sends files as continuous data streams.

Create a TCP server that reads a file and sends it to the client:

Run command:

node tcpFileServer.js

A client can connect to this server using Telnet or a custom TCP client, and the file data will be received as a stream.

Client-Side TCP Implementation

The client-side TCP implementation focuses on connecting to a TCP server, receiving streamed data, and saving it locally using Node.js.

• Connects to the server using the TCP protocol.
• Implemented with Node.js net module.
• Receives data as a stream.
• Writes incoming data to a file.
• Closes the connection after transfer completes.

On the client side, you can set up a TCP client that connects to the server and writes the received data to a file:

Run command:

node tcpclient.js

When this client connects to the server, the file content sent over TCP will be written to received.txt.