Welcome!

Machine Learning Authors: Liz McMillan, Elizabeth White, Pat Romanski, William Schmarzo, Progress Blog

Related Topics: Machine Learning , Java IoT, PowerBuilder, Microsoft Cloud, Agile Computing, Apache

Machine Learning : Blog Feed Post

Building a Simple Peer-to-Peer WebSocket App – Part 2

A Step-by-Step Tutorial

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>Kaazing WebSocket Tutorial - JMS</title>
        <script src="http://demo.kaazing.com/lib/client/javascript/StompJms.js" type="text/javascript" language="javascript"></script>
    </head>
    <body onload="doConnect()">
        <div id="logMsgs"></div>
    </body>
</html>

 

Line 05: References the Kaazing WebSocket client libraries that ensure that communication between any Web browser and the WebSocket server is seamless, even if the browser doesn’t natively support the WebSocket API and protocol.
Line 07: Invokes the doConnect() function after the contents of the page is loaded.
Line 08: Defines a div tag that will contain the log messages. At the moment, we just have a completely empty HTML page, so there’s nothing exciting to see yet.

Let’s move on to the JavaScript code. While walking through the JavaScript code, we’ll see the power of messaging. One of the key differentiators that sets the Kaazing WebSocket Gateway apart from other WebSocket servers is its extensive support for rich business protocols and messaging APIs on top of the WebSocket standard, including XMPP, JMS, and AMQP. This tutorial focuses on the most widely used messaging API: Java Message Service (JMS).

JMS is a messaging standard that allows the loose coupling of applications by creating, sending, receiving, and reading messages. The Kaazing JMS offering extends the reach of enterprise messaging applications to the Web by providing JMS APIs in various client technologies, including Java, JavaScript, Microsoft .NET/Silverlight, as well as Flash/Flex. In this tutorial, we focus on the JavaScript JMS APIs and how you can use JMS in modern HTML5 applications.

The following code shows a simple example of a JavaScript application that uses Kaazing’s JMS APIs. Take a look at the code, then the explanations below the code snippet.

 

// Variables you can change
//
var MY_WEBSOCKET_URL = "ws://tutorial.kaazing.com/jms";
var TOPIC_NAME = "/topic/myTopic";
var IN_DEBUG_MODE = true;
var DEBUG_TO_SCREEN = true;

// WebSocket and JMS variables
//
var connection;
var session;
var wsUrl;

// JSFiddle-specific variables
//
var runningOnJSFiddle = (window.location.hostname === "fiddle.jshell.net");
var WEBSOCKET_URL = (runningOnJSFiddle ? MY_WEBSOCKET_URL : "ws://" + window.location.hostname + ":" + window.location.port + "/jms");

// Variable for log messages
//
var screenMsg = "";

// Used for development and debugging. All logging can be turned
// off by modifying this function.
//
var consoleLog = function(text) {
    if (IN_DEBUG_MODE) {
        if (runningOnJSFiddle || DEBUG_TO_SCREEN) {
            // Logging to the screen
            screenMsg = screenMsg + text + "
";
            $("#logMsgs").html(screenMsg);
        } else {
            // Logging to the browser console
            console.log(text);
        }
    }
};

var handleException = function (e) {
    consoleLog("EXCEPTION: " + e);
};

// Connecting...
//
var doConnect = function() {
    // Connect to JMS, create a session and start it.
    //
    var stompConnectionFactory = new StompConnectionFactory(WEBSOCKET_URL);
    try {
        var connectionFuture = stompConnectionFactory.createConnection(function() {
            if (!connectionFuture.exception) {
                try {
                    connection = connectionFuture.getValue();
                    connection.setExceptionListener(handleException);

                    consoleLog("Connected to " + WEBSOCKET_URL);
                    session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
                    connection.start(function() {
                        // Put any callback logic here.
                        //
                        consoleLog("JMS session created");
                    });
                } catch (e) {
                    handleException(e);
                }
            } else {
                handleException(connectionFuture.exception);
            }
        });
    } catch (e) {
        handleException(e);
    }
};
​

 

At the top of this code snippet, you can see variables that you can change.

Line 03: MY_WEBSOCKET_URL points to the WebSocket server, which in our case runs on tutorial.kaazing.com. JMS, being a messaging API, follows the publish/subscribe pattern.

Line 04: A topic in JMS is a distribution mechanism for publishing messages that are delivered to multiple subscribers. Our topic is called /topic/myTopic. You can, and probably should change the name of the topic to your liking to ensure nobody else is interfering with your experimentation. For example:

 

var TOPIC_NAME = "/topic/PeterTopic";

 

Lines 05-06: The IN_DEBUG_MODE and DEBUG_TO_SCREEN variables give you simple ways to control debugging. By default, debugging is enabled and is directed to the screen.

Lines 16-17: If the app is running outside of the context of JSFiddle, the WebSocket URL is constructed dynamically, pointing back to the same server where the HTML page was downloaded from.

Line 21: The screenMsg variable holds the log messages.
Note: When this variable grows big, the performance of the application may degrade significantly. If you’re seeing increased latency, disabling logging of the application often helps.

Line 26: The consoleLog() function is used for logging. It honors the preferences set through the logging variables, specified in lines 05-06.

Line 45: The doConnect() function is in charge of establishing the WebSocket connection.

Line 48: Next, we create a StompConnectionFactory, allowing us to create a connection with a JMS provider via a WebSocket connection.

Line 50: Then, we create a connection, where ConnectionFuture handles the returned result.

Line 57: Finally, we create a session. Optionally, you can use sessions to handle transactions. This tutorial doesn’t use transactions.

When you run this code, the Result pane in the bottom right displays the following log messages:

 

Connected to ws://tutorial.kaazing.com/jms
JMS session created

 

In Part 3 (coming soon), we will evolve our application.


Read the original blog entry...

More Stories By Kaazing Blog

Kaazing is helping define the future of the event-driven enterprise by accelerating the Web for the Internet of Things.

@CloudExpo Stories
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
"Codigm is based on the cloud and we are here to explore marketing opportunities in America. Our mission is to make an ecosystem of the SW environment that anyone can understand, learn, teach, and develop the SW on the cloud," explained Sung Tae Ryu, CEO of Codigm, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"We're developing a software that is based on the cloud environment and we are providing those services to corporations and the general public," explained Seungmin Kim, CEO/CTO of SM Systems Inc., in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"We're focused on how to get some of the attributes that you would expect from an Amazon, Azure, Google, and doing that on-prem. We believe today that you can actually get those types of things done with certain architectures available in the market today," explained Steve Conner, VP of Sales at Cloudistics, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Enterprises are moving to the cloud faster than most of us in security expected. CIOs are going from 0 to 100 in cloud adoption and leaving security teams in the dust. Once cloud is part of an enterprise stack, it’s unclear who has responsibility for the protection of applications, services, and data. When cloud breaches occur, whether active compromise or a publicly accessible database, the blame must fall on both service providers and users. In his session at 21st Cloud Expo, Ben Johnson, C...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
WebRTC is great technology to build your own communication tools. It will be even more exciting experience it with advanced devices, such as a 360 Camera, 360 microphone, and a depth sensor camera. In his session at @ThingsExpo, Masashi Ganeko, a manager at INFOCOM Corporation, introduced two experimental projects from his team and what they learned from them. "Shotoku Tamago" uses the robot audition software HARK to track speakers in 360 video of a remote party. "Virtual Teleport" uses a multip...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"The reason Tier 1 companies are coming to us is we're able to narrow the gap where custom applications need to be built. They provide a lot of services, like IBM has Watson, and they provide a lot of hardware but how do you bring it all together? Bringing it all together they have to build custom applications and that's the niche that we are able to help them with," explained Peter Jung, Product Leader at Pulzze Systems Inc., in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2,...
While some developers care passionately about how data centers and clouds are architected, for most, it is only the end result that matters. To the majority of companies, technology exists to solve a business problem, and only delivers value when it is solving that problem. 2017 brings the mainstream adoption of containers for production workloads. In his session at 21st Cloud Expo, Ben McCormack, VP of Operations at Evernote, discussed how data centers of the future will be managed, how the p...
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Data scientists must access high-performance computing resources across a wide-area network. To achieve cloud-based HPC visualization, researchers must transfer datasets and visualization results efficiently. HPC clusters now compute GPU-accelerated visualization in the cloud cluster. To efficiently display results remotely, a high-performance, low-latency protocol transfers the display from the cluster to a remote desktop. Further, tools to easily mount remote datasets and efficiently transfer...
High-velocity engineering teams are applying not only continuous delivery processes, but also lessons in experimentation from established leaders like Amazon, Netflix, and Facebook. These companies have made experimentation a foundation for their release processes, allowing them to try out major feature releases and redesigns within smaller groups before making them broadly available. In his session at 21st Cloud Expo, Brian Lucas, Senior Staff Engineer at Optimizely, discussed how by using ne...
"We work around really protecting the confidentiality of information, and by doing so we've developed implementations of encryption through a patented process that is known as superencipherment," explained Richard Blech, CEO of Secure Channels Inc., in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
The question before companies today is not whether to become intelligent, it’s a question of how and how fast. The key is to adopt and deploy an intelligent application strategy while simultaneously preparing to scale that intelligence. In her session at 21st Cloud Expo, Sangeeta Chakraborty, Chief Customer Officer at Ayasdi, provided a tactical framework to become a truly intelligent enterprise, including how to identify the right applications for AI, how to build a Center of Excellence to oper...
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...