The Ultimate Guide to WebSocket Message Format

WebSocket message format is an essential part of the WebSocket protocol. It is a structured way of exchanging data between the client and the server in real-time. Understanding the WebSocket message format is crucial for building real-time applications such as chat applications, online gaming, stock market applications, and more.

What is WebSocket Protocol?

WebSocket protocol is a computer communication protocol that provides full-duplex communication channels over a single TCP connection. It enables two-way communication between the client and the server in real-time. The WebSocket protocol is designed to work over the same ports as HTTP and HTTPS (port 80 and 443). It allows web servers to push data to a client instantly rather than waiting for the client to request data.

WebSocket Message Format

The WebSocket message format is a structured way of exchanging data between the client and the server. The WebSocket protocol defines two types of messages: control messages and data messages. Control messages are used for managing the WebSocket connection, while data messages are used for exchanging information between the client and the server.

Data Messages

Data messages are used for exchanging information between the client and the server. They can be of two types: text messages and binary messages.

Text Messages

Text messages are used for exchanging textual data between the client and the server. A text message is encoded as UTF-8 text and consists of one or more frames. Each frame can be up to 125 bytes in length, but longer messages can be split into multiple frames.

Binary Messages

Binary messages are used for exchanging binary data between the client and the server. A binary message consists of one or more frames. Each frame can be up to 125 bytes in length, but longer messages can be split into multiple frames.

Control Messages

Control messages are used for managing the WebSocket connection. They can be of several types:

• Close: Used to close the WebSocket connection.
• Ping: Used to test whether the connection is still alive.
• Pong: Used to respond to a Ping message.
• Binary: Used to indicate that the message is a binary message.
• Text: Used to indicate that the message is a text message.

WebSocket Message Framing

WebSocket messages are framed to ensure that they are transmitted over the network efficiently. Each message consists of one or more frames. The first frame in a message is called the control frame, and it contains the message type and the length of the message. The following frames are called data frames, and they contain the actual data.

Control Frame

The control frame contains the message type and the length of the message. The message type indicates whether the message is a data message or a control message. The length of the message is the length of the data in the message.

Data Frame

The data frame contains the actual data that is being transmitted. The data can be split into multiple frames to ensure that the message is transmitted efficiently over the network.

WebSocket Message Examples

Here are some examples of WebSocket messages:

Text Message

1. The client sends a text message to the server:
2. Message Type: Text
3. Length: 12
4. Data: Hello World!

Binary Message

1. The client sends a binary message to the server:
2. Message Type: Binary
3. Length: 4
4. Data: 0x01 0x02 0x03 0x04

Close Message

1. The server sends a close message to the client:
2. Message Type: Close
3. Length: 0
4. Data: None

WebSocket Message Security

WebSocket messages can be secured using SSL/TLS encryption. This provides an additional layer of security to prevent eavesdropping and tampering of WebSocket messages.

WebSocket Message Performance

WebSocket messages are designed to be transmitted efficiently over the network. They are optimized for low latency and high throughput, making them ideal for real-time applications.

FAQ

What is the maximum size of a WebSocket message?

The maximum size of a WebSocket message is 2^63-1 bytes. However, most web servers and browsers have a limit on the size of WebSocket messages. The default limit in most web browsers is 4MB.

Can WebSocket messages be compressed?

Yes, WebSocket messages can be compressed using the WebSocket permessage-deflate extension. This reduces the size of WebSocket messages, making them faster to transmit over the network.

What is the difference between a text message and a binary message?

A text message is used for exchanging textual data between the client and the server, while a binary message is used for exchanging binary data. Text messages are encoded as UTF-8 text, while binary messages can contain any binary data.

What is the purpose of control messages?

Control messages are used for managing the WebSocket connection. They are used for opening and closing the connection, testing whether the connection is still alive, and indicating the type of message being transmitted.

Is WebSocket message format compatible with HTTP?

Yes, WebSocket message format is compatible with HTTP. WebSocket messages are transmitted over the same ports as HTTP and HTTPS (port 80 and 443), and the WebSocket handshake is based on HTTP.

What is the difference between WebSocket and HTTP?

WebSocket is a protocol for providing full-duplex communication channels over a single TCP connection, while HTTP is a protocol for transferring data over the web. WebSocket enables real-time communication between the client and the server, while HTTP is designed for request-response communication.