Refactoring and additions

2025-02-27 22:44:18 +01:00
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+---
+banner_title: "Flash - Websockets"
+banner_description: "Learn how to create and manage server-side Websockets in Flash."
+---
+
+# 🌐 Websockets
+
+In this section, we illustrate how to create and manage Websockets in Flash, which are used to establish a bidirectional communication channel between the client and the server.
+
+## Understanding Websockets
+
+Websockets are a communication protocol that provides full-duplex communication channels over a single TCP connection.
+Unlike HTTP, which is a request-response protocol, Websockets allow for real-time, low-latency communication between the client and the server.
+
+Imagine a scenario where you need to send real-time updates to the client, such as a chat application or a live feed: if you were to use HTTP,
+you would need to poll the server at regular intervals to check for updates, which is inefficient and resource-intensive.
+
+## Creating a Websocket
+
+To create a Websocket in Flash, you need to extend the `WebsocketHandler` class and override the `onOpen`, `onMessage`, `onClose`, and `onError` methods.
+These methods are called when the Websocket connection is opened, a message is received, the connection is closed, and an error occurs, respectively,
+and they provide you with an instance of the `WebSocketSession` object to be able to interact with it.
+
+```java
+public class MyWebsocketHandler extends WebsocketHandler {
+    @Override
+    public void onOpen(WebSocketSession session) {
+        System.out.println("WebSocket connection opened");
+    }
+
+    @Override
+    public void onClose(WebSocketSession session, int statusCode, String reason) {
+        System.out.println("WebSocket connection closed");
+    }
+
+    @Override
+    public void onMessage(WebSocketSession session, String message) {
+        System.out.println("Received message: " + message);
+
+        //optionally send a reponse back to the client
+        session.sendMessage("I received your message!");
+    }
+
+    @Override
+    public void onError(WebSocketSession session, Throwable error) {
+        System.out.println("WebSocket error: " + error.getMessage());
+    }
+}
+```
+
+To register your Websocket handler with the server, you can use the `server.ws()` method:
+
+```java
+public class Example {
+    public static void main(String[] args) {
+        FlashServer server = new FlashServer(8080);
+
+        server.ws("/ws")
+            .register(new MyWebsocketHandler());
+
+        server.start();
+    }
+}
+``` 
+
+## Interacting with Websockets sessions
+
+The `WebSocketSession` object provides methods to interact with the Websocket session, such as sending messages, closing the connection, and getting the remote address and session ID.
+
+| Method             | Params           | Description                                                                                                                                      |
+|--------------------|------------------|--------------------------------------------------------------------------------------------------------------------------------------------------|
+| `getChannel()`     | `none`           | Returns an instance of `AsynchronousSocketChannel` useful for retrieving info about the client   .                                               |
+| `getRequestInfo()` | `none`           | Returns an instance of `RequestInfo` containing all sorts of information about the request (headers, method, path etc.) .                        |
+| `getPath()`        | `none`           | Returns the path to the websocket endpoint as a `String`.                                                                                        |
+| `getId()`          | `none`           | Returns the id of the websocket session as a `String`, useful if you want to keep track of the connected clients in a custom manager.            |
+| `getBuffer()`      | `none`           | Returns the ByteBuffer for that session.                                                                                                         |
+| `sendMessage()`    | `String message` | Sends the `message` to the client as a `String`. it's up to the developer to stringify and de-stringify any data you want to send back and forth |
+| `close()`          | `none`           | Closes the websocket session.                                                                                                                    |
+
+::: warning NOTE
+`WebsocketHandler` includes a `setId(String id)` method for overriding the default session ID. Unless you have a specific reason to change it, it's best to leave it as is.
+
+Similarly, the `setBuffer(ByteBuffer buffer)` method allows you to override the default buffer. If you're unsure about this, it's recommended to keep the default setting.
+:::
+