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Tuesday 6 April 2021

java-WebSocket

 Here some more details about protocol versions/drafts.

##Build You can build using Ant or Maven but there is nothing against just putting the source path src/main/java on your applications buildpath.

###Ant

ant 

will create the javadoc of this library at doc/ and build the library itself: dest/java_websocket.jar

The ant targets are: compilejardoc and clean

###Maven

To use maven just add this dependency to your pom.xml:

<dependency>
    <groupId>org.java-websocket</groupId>
    <artifactId>Java-WebSocket</artifactId>
    <version>1.3.0</version>
</dependency> 

Running the Examples

Note: If you're on Windows, then replace the : (colon) in the classpath in the commands below with a ; (semicolon).

After you build the library you can start the chat server (a WebSocketServer subclass):

java -cp build/examples:dist/java_websocket.jar ChatServer

Now that the server is started, you need to connect some clients. Run the Java chat client (a WebSocketClient subclass):

java -cp build/examples:dist/java_websocket.jar ChatClient

The chat client is a simple Swing GUI application that allows you to send messages to all other connected clients, and receive messages from others in a text box.

In the example folder is also a simple HTML file chat client chat.html, which can be opened by any browser. If the browser natively supports the WebSocket API, then it's implementation will be used, otherwise it will fall back to a Flash-based WebSocket Implementation.

Writing your own WebSocket Server

The org.java_websocket.server.WebSocketServer abstract class implements the server-side of the WebSocket Protocol. A WebSocket server by itself doesn't do anything except establish socket connections though HTTP. After that it's up to your subclass to add purpose.

Writing your own WebSocket Client

The org.java_websocket.client.WebSocketClient abstract class can connect to valid WebSocket servers. The constructor expects a valid ws:// URI to connect to. Important events onOpenonCloseonMessage and onIOError get fired throughout the life of the WebSocketClient, and must be implemented in your subclass.

WSS Support

This library supports wss. To see how to use wss please take a look at the examples.

If you do not have a valid certificate in place then you will have to create a self signed one. Browsers will simply refuse the connection in case of a bad certificate and will not ask the user to accept it. So the first step will be to make a browser to accept your self signed certificate. ( https://bugzilla.mozilla.org/show_bug.cgi?id=594502 ).
If the websocket server url is wss://localhost:8000 visit the url https://localhost:8000 with your browser. The browser will recognize the handshake and allow you to accept the certificate. This technique is also demonstrated in this video.

The vm option -Djavax.net.debug=all can help to find out if there is a problem with the certificate.

It is currently not possible to accept ws and wss connections at the same time via the same websocket server instance.

For some reason firefox does not allow multible connections to the same wss server if the server uses a different port than the default port(443).

If you want to use wss on the android platfrom you should take a look at this.

I ( @Davidiusdadi ) would be glad if you would give some feedback whether wss is working fine for you or not.

Minimum Required JDK

Java-WebSocket is known to work with:

  • Java 1.5 (aka SE 6)
  • Android 1.6 (API 4)

Other JRE implementations may work as well, but haven't been tested.

from https://github.com/Toastbro/WebSocks/tree/master/TooTallNate-Java-WebSocket-58d1778

(https://github.com/TooTallNate/java-WebSocket)


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