Replace Websocket with SSE with Mercure

In this article we'll see why the Send Event Server (SSE) is more suitable than Websocket.

Websocket

WebSockets enable a full-duplex connection to be established over a single TCP connection, facilitating two-way communication between client and server. This technology is particularly well suited to applications requiring real-time updates, such as online games, live chat or trading platforms.

SSE

Server-Sent Events (SSE) is a technology that enables the server to push updates to the browser via a standard HTTP connection. Unlike WebSockets, SSE is designed for one-way communication, from server to client. This makes it ideal for use cases such as notifications or real-time data updates.

A common example where the use of SSE is relevant is a web page displaying data that needs to update automatically on the user's screen whenever an action occurs on the application's backend.

Why use SSE instead of Websocket?

First of all, it depends on your needs. If you need complex bidirectional communication, consider Websocket. Otherwise, use SSE.

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Using SSE

To use the SSE, we need a server to send events. I recommend using Mercure developed by the symfony corp.
Here's an example of how to use it.

const eventSource = new EventSource('https://serverMercure/topic');

eventSource.onmessage = function(event) {
    console.log('Data received:', JSON.parse(event.data));
};

eventSource.onerror = function(error) {
    console.error('SSE error', error);
};

Conclusion

In conclusion, WebSockets and Server-Sent Events (SSE) are two distinct technologies, each addressing specific client-server communication needs. WebSockets are ideal for bidirectional interactions and instantaneous updates, making them a preferred choice for real-time interactive applications. On the other hand, SSE, with its unidirectional communication, is particularly suited to scenarios where the server needs to send real-time updates to the client, as in the case of notifications or dynamic data updates. The choice between these two technologies therefore depends on the specific requirements of the application and the type of communication needed.