In this section, we’ll quickly scaffold perfect-cursors before going back to Home.jsx to import and use it. With perfect-cursors, it becomes possible to gently animate the cursor from [0, 0] to [0, 500] basically giving the illusion that the cursor is updated in true realtime. If not for useRef (useCallback would work as well by the way), we would be calling throttle every time the renders (this happens many times per second). This isn’t only quite inefficient, but it would break the throttle function because we would also be starting the internal 50ms timer from scratch every render.

There are numerous scenarios where fragmenting a WebSocket message into multiple frames is required (or at least desirable). Without fragmentation, an endpoint would have to buffer the entire message before sending it. With fragmentation, the endpoint can choose a reasonably sized buffer, and when that is full, send subsequent frames as a continuation. The receiving endpoint then assembles the frames to recreate the WebSocket message. The table below describes the headers used by the client and the server during the opening handshake – both the required ones (illustrated in the code snippets above) and the optional ones.

WebSocket FAQs

WebSocket is a realtime technology that enables bidirectional, full-duplex communication between client and server over a persistent, single-socket connection. The WebSocket connection is kept alive for as long as needed (in theory, it can last forever), allowing the server and the client to send data at will, with minimal overhead. Historically, creating web apps that needed real-time data required an abuse of HTTP protocol to establish bidirectional data transfer. There were multiple methods used to achieve real-time capabilities by enabling a way to send data directly from the server to clients, but none of them were as efficient as WebSocket. HTTP polling, HTTP streaming, Comet, and SSE  (server-sent events) all have their drawbacks. The WebSocket protocol enables ongoing, full-duplex, bidirectional communication between a web client and a web server over an underlying TCP connection.

Finally, if you ever need to troubleshoot an issue with your Websocket connection, having logs will be invaluable. For example, an attacker could use a WebSocket to inject malicious JavaScript what is websocket into a web page, which would then be executed by the victim’s browser. Or, an attacker could use a WebSocket to launch a denial-of-service attack by flooding the server with requests.

How do WebSockets work?

The messages can be text or binary, and they can have any size and content. The protocol allows us to send and receive messages as binary data or UTF-8 (N.B., transmitting and converting UTF-8 has less overhead). Try inspecting WebSocket messages by using Chrome DevTools to see sent/received messages, as shown in the preview above. This isn’t a post about Spaces (I just think realtime cursors are cool) but we apply that learning here by creating a custom function called sendJsonMessageThrottled.

• Serves as a heartbeat mechanism ensuring the connection is still alive.
• In this tutorial, we showed you how easy it is to create WebSockets in a React Native apps.
• Remember to always test your implementation thoroughly and keep up with the latest developments in WebSocket technology.
• We make it easy to build realtime experiences like live chat and multiplayer collaboration for millions of users.
• So, if your app doesn’t need a fallback transport method, selecting React useWebSocket is a good decision.
• Ordinarily, if you move your cursor from [0, 0] to [0, 500], it would appear to jump across the screen.

Ordinarily, if you move your cursor from [0, 0] to [0, 500], it would appear to jump across the screen. Sending a cursor update every time the cursor twitches isn’t sustainable, so we throttle the update by 50 milliseconds. This isn’t strictly necessary for this project, however, I include to illustrate a key feature of useWebSocket that will probably be of use in your project. It would make a lot of sense to abstract that code away in a hook instead of convoluting your components and risking messy code duplication. As mentioned earlier, WebSocket is a simple and minimal API and there’s always more work to do on top to achieve a minimum-viable production implementation. At a minimum, a custom WebSocket hook would provide an idiomatic way to abstract your WebSocket-related code in a single place.

The Ably Platform

In the sample project, I used the popular ws library to attach a WebSocket server instance to an HTTP server instance. Once the WebSocket server is attached to the HTTP server instance, it will accept the incoming WebSocket connection requests by upgrading the protocol from HTTP to WebSocket. This mechanism saved the pain of network latency because the initial request is kept open indefinitely.

So, if your app doesn’t need a fallback transport method, selecting React useWebSocket is a good decision. You can also drop React useWebSocket to make a more lightweight app bundle by using the native WebSocket browser API. Choose a library or use the native browser API according to your preference. For example, we used the React useWebSocket library with React to connect to the WebSocket server writing less implementation code.

WebSocket

This is a generic status code; it should be used when other status codes are not suitable, or if there is a need to hide specific details about the policy. WebSocket programming follows an asynchronous, event-driven programming model. As long as a WebSocket connection is open, the client and the server simply listen for events in order to handle incoming data and changes in connection status (with no need for polling).

It also supports message protocol integration with Fast Binary Encoding, ensuring that the asynchronous socket server is ultra-fast and has low latency. There is a workaround for this called long-polling, but it makes the HTTP request with a long time-out period. The server uses the long timeout to wait and push the data without a new HTTP request. Technically, WebSocket provides full-duplex communication between the server and the client, which allows real-time data transfer.

Sockette

Note that older versions of these browsers either don’t support WebSockets, or have limited support. At the time of writing (25th of April 2023), Opera Mini is the only modern browser that doesn’t support WebSockets. The connection will be rejected if the Origin indicated is unacceptable to the server. Optional header field, initially sent from the client to the server, and then subsequently sent from the server to the client. Optional header field, containing a list of values indicating which subprotocols the client wants to speak, ordered by preference. Indicates that the server is willing to initiate the WebSocket connection.

The protocol is designed to allow clients and servers to communicate in realtime, allowing for efficient and responsive data transfer in web applications. In a nutshell, WebSocket is a realtime technology that enables bidirectional, full-duplex communication between web clients and web servers over persistent connections. A WebSocket connection is kept alive for as long as needed (in theory, it can last forever), allowing the server and the client to send data at will, with minimal overhead. If you’re just getting started with WebSockets and you’re looking to build your first realtime app powered by WebSockets, check out this step-by-step tutorial. It teaches you how to develop an interactive cursor position-sharing demo using two simple open-source WebSocket libraries.

Support

Note that the WebSocket protocol doesn’t prescribe any particular way for servers to authenticate clients. For example, you can handle authentication during the opening handshake, by using cookie headers. Another option is to manage authentication (and authorization) at the application level, by using techniques such as JSON Web Tokens. The process of closing a WebSocket connection is known as the closing handshake. In addition to the opcode, the close frame may contain a body that indicates the reason for closing. This body consists of a status code (integer) and a UTF-8 encoded string (the reason).