Event Handling and Messaging

So far, we have set up a basic WebSocket server and tested the connections between the server and the client. In this chapter, we will delve deeper into how to handle various events and messages to build a more robust and functional application.

WebSocket Events

There are multiple events you can use to manage WebSocket connections. Here are some of the most common ones:

1. connection: Triggered when a client connects to the server.
2. message: Triggered when a message is received from a client.
3. close: Triggered when a connection is closed.
4. error: Triggered when an error occurs in the connection.

We will adjust our server to handle these events appropriately.

Handling the Connection Event

The connection event is handled as we did in the previous chapter. We can add additional features, such as tracking active connections:

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Here, we maintain a Set of connected clients and update this set when a client connects or disconnects.

Handling the Message Event

We handle incoming communications through the message event. For example, we can broadcast messages to all connected clients:

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In this code, we broadcast received messages to all clients except the sender. This is useful for applications like real-time chats.

Handling the Close Event

Client disconnection management was partially covered earlier. Here it is more elaborated:

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The disconnected client is removed from the Set of active clients and the disconnection is logged.

Handling the Error Event

To handle errors in connections:

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With this, we can log errors that occur during the WebSocket connection.

Business Logic

We can manage the business logic that we need to apply to these events according to the use case of our application. For example:

Message Broadcasting

We can adjust our message handling to include a broadcasting mechanism:

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Placeholder Image: [Flowchart showing the process of handling events and broadcasting messages to multiple clients.]

Targeted Messaging

We can send messages to specific clients using unique identifiers. For example:

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Pings and Pongs

We can use pings and pongs to check the health of the connections:

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With all this, we are able to effectively manage events and messages to build robust applications with WebSockets and Node.js. Let's keep exploring more features in the next chapter! 🚀