minimal java8 nio secure websocket client (wss)

Tyrus client does not need to have an appserver! :)

Please see Tyrus documentation and blogpost Reducing WebSocket client jar size with ProGuard (you can get down to 500 kB with JDK 7+).

About the size - it can be minimized even more, but with some refactoring in Tyrus code. The comparison of WebSocket and plain socket is not very accurate - plain socket does not need to implement HTTP and (traditionally) did not have NIO support (that came with Java 7). Another part is the WebSocket protocol implementation, which is not that difficult but also its not just sending byte[] to the wire - there is some opening handshake, signalling frames and mandatory strict UTF-8 encoding/decoding.

So I guess you could find more simple API implementation, but sticking to something which is maintained and is part of Java EE does not seem bad to me - you have the possibility to choose the implementation (Tyrus is just one of them, there are others) and your client will be ready for inclusion to Java EE application if that would ever happen. (Editors note: I work on Tyrus, so my answer is most likely biased).

nv-websocket-client is a new WebSocket client library written in Java. It supports wss and requires just Java SE 1.5, so it can run even on Android.

The size of nv-websocket-client-1.3.jar (released on 2015-05-06) is 62,854 bytes and it does not require any external dependencies.

Below is a "wss" example.

import com.neovisionaries.ws.client.*;

public class HelloWSS
{
    public static void main(String[] args) throws Exception
    {
        // Connect to "wss://echo.websocket.org" and send "Hello." to it.
        // When a response from the WebSocket server is received, the
        // WebSocket connection is closed.
        new WebSocketFactory()
            .createSocket("wss://echo.websocket.org")
            .addListener(new WebSocketAdapter() {
                @Override
                public void onTextMessage(WebSocket ws, String message) {
                    // Received a response. Print the received message.
                    System.out.println(message);

                    // Close the WebSocket connection.
                    ws.disconnect();
                }
            })
            .connect()
            .sendText("Hello.");
    }
}

Blog
WebSocket client library (Java SE 1.5+, Android)
http://darutk-oboegaki.blogspot.jp/2015/05/websocket-client-library-java-se-15.html

GitHub
https://github.com/TakahikoKawasaki/nv-websocket-client

JavaDoc
http://takahikokawasaki.github.io/nv-websocket-client/

Maven

<dependency>
    <groupId>com.neovisionaries</groupId>
    <artifactId>nv-websocket-client</artifactId>
    <version>1.3</version>
</dependency>