This blog will demonstrate how to a build and run a WebSocket based microservice. Here is what the blog will cover at a high level


  • Overview of WebSocket and the sample Java application
  • Continuous Integration setup: from source code in the IDE to a build artifact in Oracle Developer Cloud
  • Continuous Deployment setup: from a build artifact in Developer Cloud Service to an application running in Oracle Application Container Cloud
  • Testing the application





WebSocket: the standard


WebSocket is an IETF standard recognized by RFC 6455 and has the following key characteristics which make it great fit for real time applications

  • Bi-directional: both server and client an initiate a communication
  • Full duplex: once the WebSocket session is established, both server and client can communicate independent of each other
  • Less verbose (compared to HTTP)


A deep dive into the protocol is out of scope of this blog. Please refer to the RFC for further details


Java Websocket API


A standard Java equivalent (API) for this technology is defined by JSR 356. It is backed by a specification which makes it possible to have multiple implementations of the same. JSR 356 is also included as a part of the Java Enterprise Edition 7 (Java EE 7) Platform. This includes a pre-packaged (default) implementation of this API as well as integration with other Java EE technologies like EJB, CDI etc.




Tyrus is the reference implementation of the Java Websocket API. It is the default implementation which is packaged with Java EE 7 containers like Weblogic 12.2.1 (and above) and Glassfish (4.x). It provides both server and client side API for building web socket applications.


Tyrus grizzly module


Tyrus has a modular architecture i.e. it has different modules for server, client implementations, a SPI etc. It supports the notion of containers (you can think of them as connectors) for specific runtime support (these build on the modular setup). Grizzly is one of the supported containers which can be used for server or client (or both) modes as per your requirements (the sample application leverages the same)


About the sample application


The sample is a chat application – a canonical use case for WebSockets (this by no means a full-blown chat service). Users can

  • Join the chat room (duplicate usernames not allowed)
  • Get notified about new users joining
  • Send public messages
  • Send private messages
  • Leave the chat room (other users get notified)


The application is quite simple

  • It has a server side component which is a (fat) JAR based Java application deployed to Application Container Cloud
  • The client can be any component which has support for the WebSocket API e.g. your browser . The unit tests use the Java client API implementation of Tyrus



















Here is a summary of the various classes and their roles










It contains the core business logic of the application



Manages bootstrap and shutdown process of the WebSocket container


DuplicateUserNotification, LogOutNotification,




Domain objects

Simple POJOs to model the application level entities



Converts chats sent by users into Java (domain) object which can be used within the application

DuplicateUserMessageEncoder, LogOutMessageEncoder,





Converts Java (domain) objects into native (text) payloads which can be sent over the wire using the WebSocket protocol


Here is the WebSocket endpoint implementation (


        value = "/chat/{user}/",
        encoders = {ReplyEncoder.class, 
        decoders = {ChatMessageDecoder.class}

public class ChatServer {

    private static final Set<String> USERS = new ConcurrentSkipListSet<>();
    private String user;
    private Session s;
    private boolean dupUserDetected;

    public void userConnectedCallback(@PathParam("user") String user, Session s) {
        if (USERS.contains(user)) {
            try {
                dupUserDetected = true;
                s.getBasicRemote().sendText("Username " + user + " has been taken. Retry with a different name");
            } catch (IOException ex) {
                Logger.getLogger(ChatServer.class.getName()).log(Level.SEVERE, null, ex);

        this.s = s;
        s.getUserProperties().put("user", user);
        this.user = user;


    private void welcomeNewJoinee() {
        try {
            s.getBasicRemote().sendObject(new WelcomeMessage(this.user));
        } catch (Exception ex) {
            Logger.getLogger(ChatServer.class.getName()).log(Level.SEVERE, null, ex);

    private void announceNewJoinee() {
                .filter((sn) -> !sn.getUserProperties().get("user").equals(this.user))
                //.filter((s) -> s.isOpen())
                .forEach((sn) -> sn.getAsyncRemote().sendObject(new NewJoineeNotification(user, USERS)));

    public static final String LOGOUT_MSG = "[logout]";

    public void msgReceived(ChatMessage msg, Session s) {
        if (msg.getMsg().equals(LOGOUT_MSG)) {
            try {
            } catch (IOException ex) {
                Logger.getLogger(ChatServer.class.getName()).log(Level.SEVERE, null, ex);
        Predicate<Session> filterCriteria = null;
        if (!msg.isPrivate()) {
            //for ALL (except self)
            filterCriteria = (session) -> !session.getUserProperties().get("user").equals(user);
        } else {
            String privateRecepient = msg.getRecepient();
            //private IM
            filterCriteria = (session) -> privateRecepient.equals(session.getUserProperties().get("user"));

                //.forEach((session) -> session.getAsyncRemote().sendText(msgContent));
                .forEach((session) -> session.getAsyncRemote().sendObject(new Reply(msg.getMsg(), user, msg.isPrivate())));


    public void onCloseCallback() {

    private void processLogout() {
        try {
                    .filter((sn) -> sn.isOpen())
                    .forEach((session) -> session.getAsyncRemote().sendObject(new LogOutNotification(user)));

        } catch (Exception ex) {
            Logger.getLogger(ChatServer.class.getName()).log(Level.SEVERE, null, ex);



Setting up Continuous Integration & Deployment


The below sections deal with the configurations to made within the Oracle Developer Cloud service


Project & code repository creation


Please refer to the Project & code repository creation section in the Tracking JUnit test results in Developer Cloud service blog or check the product documentation for more details


Configure source code in Git repository


Push the project from your local system to your Developer Cloud Git repo you just created. We will do this via command line and all you need is Git client installed on your local machine. You can use Git or any other tool of your choice


cd <project_folder> 
git init  
git remote add origin <developer_cloud_git_repo>  
git add .  
git commit -m "first commit"  
git push -u origin master  //Please enter the password for your Oracle Developer Cloud account when prompted


Configure build


Create a New Job



Select JDK




Continuous Integration (CI)


Choose Git repo




Set build trigger - this build job will be triggered in response to updated within the Git repository (e.g. via git push)




Add Maven Build Step




Activate the following post build actions

  • Archive the Maven artifacts (contains deployable zip file)
  • Publish JUnit test result reports




Execute Build & check JUnit test results


Before configuring deployment, we need to trigger the build in order to produce the artifacts which can be referenced by the deployment configuration




After the build is complete, you can

  • Check the build logs
  • Check JUnit test results
  • Confirm archived Maven artifacts





Test results




Build logs





Continuous Deployment (CD) to Application Container Cloud


Create a New Confguration for deployment




Enter the required details and configure the Deployment Target




Configure the Application Container Cloud instance






Configure Automatic deployment option on the final confirmation page




Confirmation screen





Test the CI/CD flow


Make some code changes and push them to the Developer Cloud service Git repo. This should


  • Automatically trigger the build, which once successful will
  • Automatically trigger the deployment process








Check your application in Application Container Cloud






Here is the detailed view







You would need a WebSocket client for this example. I would personally recommend using the client which can be installed into Chrome browser as a plugin – Simple WebSocket Client. See below snapshot for a general usage template of this client




The following is a template for the URL of the WebSocket endpoint


e.g. wss://



Test transcript


Here is a sequence of events which you can execute to test things out


Users foo and bar join the chatroom







foo gets notified about bar





User john joins






foo and bar are notified






foo sends a message to everyone (public)




Both bar and john get the message



bar sends a private message to foo



Only foo gets it



In the meanwhile, john gets bored and decides to leave the chat room




Both foo and bar get notified




That's all folks !


**The views expressed in this post are my own and do not necessarily reflect the views of Oracle.