WebSocket

What is WebSocket?

WebSocket is a distinct computer communications protocol, providing full-duplex communication channels over a single TCP connection.

Unlike HTTP, which is request-response (the client asks, the server answers), WebSocket allows both the client and server to send data at any time. This persistence makes it the standard for real-time applications like chat apps, live gaming, and trading platforms.

How it Works (The Handshake)

WebSocket starts as a standard HTTP request. The client asks to "Upgrade" the connection:

Client Request:

Server Response (101 Switching Protocols):

Once this handshake is complete, the HTTP connection is replaced by the WebSocket connection, which stays open indefinitely.

Code Example: JavaScript Client

Modern browsers have built-in WebSocket support:

Comparisons: HTTP vs. WebSocket

Feature	HTTP	WebSocket
Connection	Short-lived (Request/Response)	Persistent (Keep-alive)
Direction	Half-duplex (Client starts)	Full-duplex (Bi-directional)
Overhead	High (Headers per request)	Low (Headers only at start)
Latency	Higher (Connect time)	Lowest (Always connected)

Debugging WebSocket in Apidog

Debugging persistent connections requires a different UI than standard HTTP requests.

1. Establish Connection

Create a New WebSocket API in Apidog.

Enter the URL (starts with ws:// or wss://).

Click Connect.

Apidog will perform the handshake and show the "Connected" status.

2. Send and Receive Messages

Message Types: You can send Text (JSON, String) or Binary content.

Message Stream: All sent and received messages appear in a chronological timeline view.

Formatting: Use the internal JSON formatter to make complex message payloads readable.

3. Handling Variables

You can use Apidog variables (e.g., {{token}}) in the:

Handshake URL.

Handshake Headers / Params.

Example Messages you save for reuse.

See details WebSocket

Key Takeaways

Full-Duplex: WebSocket enables real-time, two-way communication between client and server over a single persistent connection.

Low Latency: Once established, data frames are exchanged without the overhead of repeated HTTP headers.

Stateful: Unlike stateless REST, the server knows who is connected, making it perfect for chat apps and games.

Timeline Debugging: Apidog provides a real-time timeline view to track sent and received messages in chronological order.

Continue with → Socket.IO

What is WebSocket?#

How it Works (The Handshake)#

Code Example: JavaScript Client#

Comparisons: HTTP vs. WebSocket#

Debugging WebSocket in Apidog#

1. Establish Connection#

2. Send and Receive Messages#

3. Handling Variables#

Key Takeaways#