WebSocket API and protocol explained: How they work, are used and more

They are typically implemented using JavaScript on the client side and a server-side technology such as Node.js or Java on the server side. Normally, when a party wants to close the connection (both browser and server have equal rights), they send a “connection close frame” with a numeric code and a textual reason. The callback receives an event object and the actual message is accessible via the data property.

• Note that older versions of these browsers either don’t support WebSockets, or have limited support.
• The protocol starts with a handshake process, which is a set of HTTP requests and responses.
• The standard opcodes currently in use are defined by RFC 6455 and maintained by the Internet Assigned Numbers Authority (IANA).
• A base64-encoded one-time random value (nonce) sent by the client.
• There are also commercial solutions such as PusherApp which can be easily integrated into any web environment by providing a HTTP API to send WebSocket messages to clients.

Using extensions, it will be possible to send frames compressed, multiplexed, etc. You can find server accepted extensions by examining the extensions property of the WebSocket object after the open event. There is no officially published extensions spec just yet as of February 2012. Every frame has an opcode that determines how to interpret this frame’s
payload data. WebSocket is a framed protocol, meaning that a chunk of data (a message)
is divided into a number of discrete chunks, with the size of the chunk
encoded in the frame. The frame includes a frame type, a payload length,
and a data portion.

Are WebSockets synchronous or asynchronous?

This bit is set if
this frame is the last data to complete this message. We make it easy to build realtime experiences like live chat and multiplayer collaboration for millions of users. Companies how does websocket work like Slack, Netflix, and Uber use WebSockets to power realtime features in their apps for millions of end-users. For example, Slack uses WebSockets for instant messaging between chat users.

In December 2011, the Internet Engineering Task Force (IETF) standardized the WebSocket protocol through RFC 6455. In coordination with IETF, the Internet Assigned Numbers Authority (IANA) maintains the WebSocket Protocol Registries, which define many of the codes and parameter identifiers used by the protocol. After the protocol was shipped and enabled by default in multiple browsers, the RFC 6455 was finalized under Ian Fette in December 2011.

Frame structure

The initial HTTP handshake is used to establish the WebSocket connection. The client sends an HTTP request to the server, specifying the WebSocket protocol in the Upgrade header. The server responds with an HTTP response that includes an Upgrade header indicating that it is switching to the WebSocket protocol. The WebSocket protocol, described in the specification RFC 6455, provides a way to exchange data between browser and server via a persistent connection. The data can be passed in both directions as “packets”, without breaking the connection and the need of additional HTTP-requests.

HTTP may be more appropriate if a web application primarily sends requests to a server to retrieve data. In many cases, a combination of both technologies may be used to provide the best user experience. Well, they are a remarkable technology that powers real-time communication on the internet.

Differences Between HTTP and WebSocket Connection

WebSockets are a bidirectional communication method, allowing for multiple responses from a single server request. WebSockets are also mostly used for client-server communication, while webhooks are mostly used for server-server communication. They are widely used in gaming applications to provide real-time communication and collaboration between players. With WebSockets, game developers can build multiplayer games that run entirely within a web browser without requiring users to install any additional software or plugins.

The endpoint is terminating the connection due to a protocol error. Should be used when closing the connection and there is no expectation that a follow-up connection will be attempted (e.g., server shutting down, or browser navigating away from the page). Optional header field, initially sent from the client to the server, and then subsequently sent from the server to the client. The server needs to include this field together with one of the selected subprotocol values (the first one it supports from the list) in the response. To achieve compatibility, the WebSocket handshake uses the HTTP Upgrade header[3] to change from the HTTP protocol to the WebSocket protocol. Once the connection has been established the open event will be fired on your WebSocket instance.

What are the pros and cons of WebSockets?

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). What we really need is a way of creating a persistent, low latency connection that can support transactions initiated by either the client or server.

Unlike traditional HTTP requests, which are unidirectional and require a new connection for each request, WebSockets allow for continuous communication between the client and server. The WebSocket API is an advanced technology that makes it possible to open a two-way interactive communication session between the user’s browser and a server. With this API, you can send messages to a server and receive event-driven responses without having to poll the server for a reply. The wire protocol (a handshake and the data transfer between client and server) for WebSocket is now RFC6455.

If the server supports the WebSocket protocol, it agrees to the upgrade and communicates this through an Upgrade header in the response. Alchemy Notify can even be used to send email notifications to your dApp users, preventing frustration on the status of their transactions. This persistent connection allows data to flow in both directions at any time without the need to re-establish connections for each interaction.

They create a direct, fast, and continuous connection between your device (like a computer or phone) and a server. This connection allows for instant and efficient two-way communication, making applications more responsive and interactive. WebSockets are like a secret ingredient, making the web a more dynamic and engaging place where data flows quickly and seamlessly, making our online experiences smoother and more exciting. Unlike traditional HTTP polling or long-polling, WebSockets don’t involve unnecessary data transfer or connection overhead. This efficiency allows for instantaneous updates and interactions, making them the ideal choice for applications that require real-time responses, such as online games and chat applications. WebSockets are commonly used in chat applications to provide real-time messaging between users.

When can a Web Socket be Used?

Accepted sub-protocol can be determined by accessing protocol property of WebSocket object. Indicates a normal closure, meaning that the purpose for which the WebSocket connection was established has been fulfilled. Serves as a heartbeat mechanism ensuring the connection is still alive.