How to Build a WebSocket 'Hello World' Example from Scratch?

Implementing a WebSocket "Hello World" Example from Scratch

In this article, we will explore how to create a WebSocket "Hello World" example from the ground up, addressing the issue described in the provided code snippets.

WebSocket Fundamentals

WebSockets is a standardized protocol that enables bidirectional, real-time communication between a client and a server over a single TCP connection. It relies on a complex handshake and data framing to ensure reliable, efficient data transfer.

Handshake Procedure

The handshake initiates the WebSocket connection. The client sends an HTTP request with specific headers, and the server responds with an acceptance header. This exchange is used to establish the WebSocket connection and agree on parameters such as protocol version and extensions.

Data Framing

WebSocket messages are not sent in raw format but are encapsulated within frames. Each frame consists of a header and a payload. The header contains metadata about the frame, such as its type, length, and optional masking.

Server Implementation

The provided C# server code implements basic TCP listening, but it does not contain the necessary handshake and data framing logic. To establish a proper WebSocket connection, the server needs to:

• Handle the handshake by verifying the client's request and sending an acceptable response.
• Implement data framing to receive and decode client messages.
• Implement data framing to encode and send messages to the client.

Client Implementation

The provided JavaScript code attempts to send a message to the server, but it faces issues because the server is not expecting WebSocket messages. The JavaScript client needs to:

• Implement the WebSocket API and establish a connection with the server.
• Handle the handshake by sending the appropriate HTTP request.
• Implement data framing to encode and send messages to the server.
• Handle data framing to decode incoming messages from the server.

Error Diagnosis

The issue with the original code examples is that they did not address the complexities of WebSocket. By following the steps outlined above, it is possible to implement a functional WebSocket connection where the client can send messages to the server.

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