Welcome!

Java IoT Authors: Tim Hinds, Liz McMillan, Jonathan Fries, AppDynamics Blog, John Esposito

Related Topics: IoT User Interface, Java IoT

IoT User Interface: Article

Meet AJAX: Intelligent Web Applications with AJAX

A peek into modern technologies for browser-based applications

Browser-based applications are widely used and we like the fact that we can access them from anywhere. But from the users' perspective, the productivity level of Web applications still doesn't approximate the productivity of desktop programs. The good news is the gap is closing: the accumulated potential of multiple technologies has boosted a whole new breed of HTML-based apps that are as powerful as the desktop ones. Meet AJAX.

What Is AJAX?
The name stands for Asynchronous JavaScript + XMLHTTPRequest and means you can establish socket communication between browser-based JavaScript and the server. AJAX isn't a new technology. It's a successful branding of possibilities implanted in several technologies available in modern browsers. All AJAX applications deliver a rich UI via extensive JavaScript manipulation of the HTML Document Object Model based on the precision-pointed data retrieval via XMLHttpRequest. Typical examples of AJAX applications are Google Maps and Google Suggest from Google Labs (http://labs.google.com). These applications actively monitor user input and provide real-time page updates. Most importantly, this happens without a page refresh while the user navigates through the map or types a search string.

In fact, the technologies behind these wonders have been around for a while, although they require sophisticated skills in using browser-specific tricks. Proprietary offerings with similar capabilities - Macromedia Flash plug-in, Java Applets or .NET runtime - have been available for quite some time too. The idea of integrating a scriptable transport component talking to the server into the browser was pioneered by IE 5.0. Then Firefox and other popular browsers joined the club of browsers in supporting XMLHTTPRequest as a built-in object. With cross-browser availability, these technologies gained visibility and in March of 2004 a company called Adaptive Path introduced AJAX.

In short, backing from Google and having the right browser technologies available out-of-the-box tipped the scale: these days everyone is adding client-side technologies to Web applications for a "better user experience."

AJAX vs. Classical Applications
A classic Web application model is literally a triumph of form over substance: users are forced to submit forms in exchange for pages. That said, the form submission and page delivery aren't guaranteed: worse case the user clicks again though some pages specifically warn against that. It's quite different with AJAX, where the data travels across the wire instead of entire HTML pages. This data exchange is scripted via a specific browser object - XMLHttpRequest; the appropriate logic handles the outcome of each data request, the specific region of the page is updated instead of the entire page. The results are more speed, less traffic, and better control of information delivery.

Traditional "click-refresh" Web applications force users to interrupt the work process while waiting for the page to reload. With AJAX, a client-side script can asynchronously talk to the server while the user keeps entering data. Besides being transparent to the user, such asynchrony means more time for the server to process the request.

Classic Web applications delegate all processing to the server and force the server to manage the state. AJAX allows flexible partitioning of the application logic and state management between the client and the server. This eliminates a "click-refresh" dependency and provides better server scalability. When the state is stored on the client-side you don't have to maintain sessions across the servers or save/expire state: the lifespan is defined by client.

AJAX: Distributed MVC
Although AJAX applications rely on JavaScript for the presentation layer, the processing power and knowledge base remain on the server. For that matter, AJAX applications talk heavily to J2EE servers, feeding data to and from Web Services and servlets. The difference between J2EE applications with an AJAX-based presentation tier and standard J2EE application is that in the first case MVC is distributed over the wire. With AJAX, View is local, while Model and Controller are distributed giving the developer the flexibility to decide which components will be client-based. Specifically, a local View renders graphics by manipulating with HTML DOM; the controller handles user input locally and at the developer's discretion extends the processing to the server via HTTP requests (Web Services, XML/RPC or others); the remote part of the Model is downloaded as needed to the client achieving in-place real-time updates of the client page; and state is collected on the client.

In future AJAX articles we'll talk about each of these components in depth and provide examples of how they came to play together. Now, without further ado, let's dive into a simple AJAX example.

Zip Codes Validation and Lookup
We'll create an HTML page containing three INPUT fields: Zip, City, and State. We'll make sure that as soon as the user enters the first three digits of the zip code, the state will get populated with the first matching state value. Once the user types in all five zip digits, we'll instantly determine and populate the appropriate city. If the zip code isn't valid (not found in the server's database), we'll turn the zip's border color to red. Such visual clues are helpful to users and have become standard in modern browsers (as an example, Firefox finds matching words in an HTML page by highlighting them in the browser search field while you type).

Let's start with a simple HTML containing three input fields: zip, city, and state. Please note that the method zipChanged() is called as soon as a character is entered in the zip field. In turn, the JavaScript function zipChanged() (see below) calls the function updateState() when the zip length is three and up-dateCity() when the length of the zip is five. Both updateCity() and updateState() delegate most of the work to another function - ask().

Zip:<input id="zipcode" type="text" maxlength="5" onKeyUp="zipChanged()"
style="width:60"/>
City: <input id="city" disabled maxlength="32" style="width:160"/>
State:<input id="state" disabled maxlength="2" style="width:30"/>

<script src="xmlhttp.js"></script>
<script>
var zipField = null;
function zipChanged(){
zipField = document.getElementById("zipcode")
var zip = zipField.value;
zip.length == 3?updateState(zip):zip.length == 5?updateCity(zip):"";

}
function updateState(zip) {
var stateField = document.getElementById("state");
ask("resolveZip.jsp?lookupType=state&zip="+zip, stateField, zipField);
}
function updateCity(zip) {
var cityField = document.getElementById("city");
ask("resolveZip.jsp? lookupType=city&zip="+zip, cityField, zipField);
}
</script>

More Stories By Victor Rasputnis

Dr. Victor Rasputnis is a Managing Principal of Farata Systems. He's responsible for providing architectural design, implementation management and mentoring to companies migrating to XML Internet technologies. He holds a PhD in computer science from the Moscow Institute of Robotics. You can reach him at [email protected]

More Stories By Anatole Tartakovsky

Anatole Tartakovsky is a Managing Principal of Farata Systems. He's responsible for creation of frameworks and reusable components. Anatole authored number of books and articles on AJAX, XML, Internet and client-server technologies. He holds an MS in mathematics. You can reach him at [email protected]

More Stories By Igor Nys

Igor Nys is a Director of Technology Solutions at EPAM Systems, Inc, a company combining IT consulting expertise with advanced onshore-offshore software development practices. Igor has been working on many different computer platforms and languages including Java, C++, PowerBuilder, Lisp, Assembler since the mid 80's. Igor is currently managing a number of large distributed projects between US and Europe. In addition Igor is the author of the award-winning freeware system-management tools, and he was closely involved in the development of XMLSP technology - one of the AJAX pioneers.

Comments (8) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
SYS-CON India News Desk 02/19/06 07:05:30 PM EST

Browser-based applications are widely used and we like the fact that we can access them from anywhere. But from the users' perspective, the productivity level of Web applications still doesn't approximate the productivity of desktop programs. The good news is the gap is closing: the accumulated potential of multiple technologies has boosted a whole new breed of HTML-based apps that are as powerful as the desktop ones. Meet AJAX.

Anatole Tartakovsky 12/26/05 06:15:32 PM EST

I received number of questions on the future of the AJAX recently - tried to give my personal view on the possible development in the blog - http://anatolet.blogspot.com

Frank 12/19/05 07:04:50 PM EST

You mention the need to destroy the request and callback objects, but my O'Reilly reference says there is no need to clean up in javascript. Which is correct.

How do you destroy the request and especially the callback objects (can I destroy the callback in the callback!!!)?

Halans 10/15/05 06:25:27 PM EDT

Nice, to the point, Ajax article.
Though some comments (nitpicking)... Wasn't the term 'Ajax' introduced in the Adaptive Path article from february 2005, not march 2004?
You add style attributes with values 'width:30', but you should add 'px' ('width:30px') to make it standards compliant and make firefox display it correctly (IE is way too lax).
Wouldn't you best upon readyState==4 also check the http status 200 before continuing?
You should best add an existing default url to the iframe (ex 'blank.html'), because when you would do this over https (without a url to begin with) you would get an ugly security message in IE, making you pull your hair out to solve this (I lost a bunch one time).
While you did the iframe example, you might have integrated it with the xmlhttprequest for gracefull degradation in an (corporate) IE environment with ActiveX disabled, no?
But like I said, nitpicking.
Looking forward for the upcoming Ajax articles.

Victor Rasputnis 10/04/05 08:04:22 AM EDT

Anand, you are right. The example was meant to be the most obvious, to avoid problems with getRealPath() or explanation around getResourseAsStream() etc. You have a good eye :), thanks again.

Anand 10/03/05 01:42:54 PM EDT

Thanks Victor. I had figured out application instead of using getServletContext() on BEA. However my problem was with the

properties.load(new java.io.FileInputStream(key + ".property"));

I had the file in the same folder and thought that I did not need to provide it with an explicit path such as c:\\ but I guess that is not the case. Also one more change to the html file that I figured in the line:
zip.length = 3 ? updateState(zip) : zip.length == 5 ? updateCity(zip):"";

should be

zip.length == 3 ? updateState(zip) : zip.length == 5 ? updateCity(zip):"";

Victor Rasputnis 09/30/05 10:31:34 PM EDT

Anand, getServletContext() is available in Tomcat JSP, but not in WebLogic (WL -getServletConfig().getServletContext()). Anyway, I replaced gSC() to _application_ for simplicity. Please download again. Most importantly, please also download the DATA files or ZIP will remain red, no matter what :).

Kind Regards,
Victor Rasputnis

Anand 09/29/05 08:42:16 AM EDT

I tried doing this sample using both IE 6 and Firefox. Everytime I type in 3 digits (valid zip code) it paints the box red. It does not populate the city and state. Using BEA I got an error on the JSP page saying that getServletContext() was not recognized. On Tomcat I did not get any error but the program won't work.
Any suggestions ?

@ThingsExpo Stories
We're entering the post-smartphone era, where wearable gadgets from watches and fitness bands to glasses and health aids will power the next technological revolution. With mass adoption of wearable devices comes a new data ecosystem that must be protected. Wearables open new pathways that facilitate the tracking, sharing and storing of consumers’ personal health, location and daily activity data. Consumers have some idea of the data these devices capture, but most don’t realize how revealing and...
Digital payments using wearable devices such as smart watches, fitness trackers, and payment wristbands are an increasing area of focus for industry participants, and consumer acceptance from early trials and deployments has encouraged some of the biggest names in technology and banking to continue their push to drive growth in this nascent market. Wearable payment systems may utilize near field communication (NFC), radio frequency identification (RFID), or quick response (QR) codes and barcodes...
Artificial Intelligence has the potential to massively disrupt IoT. In his session at 18th Cloud Expo, AJ Abdallat, CEO of Beyond AI, will discuss what the five main drivers are in Artificial Intelligence that could shape the future of the Internet of Things. AJ Abdallat is CEO of Beyond AI. He has over 20 years of management experience in the fields of artificial intelligence, sensors, instruments, devices and software for telecommunications, life sciences, environmental monitoring, process...
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
The IETF draft standard for M2M certificates is a security solution specifically designed for the demanding needs of IoT/M2M applications. In his session at @ThingsExpo, Brian Romansky, VP of Strategic Technology at TrustPoint Innovation, will explain how M2M certificates can efficiently enable confidentiality, integrity, and authenticity on highly constrained devices.
There is an ever-growing explosion of new devices that are connected to the Internet using “cloud” solutions. This rapid growth is creating a massive new demand for efficient access to data. And it’s not just about connecting to that data anymore. This new demand is bringing new issues and challenges and it is important for companies to scale for the coming growth. And with that scaling comes the need for greater security, gathering and data analysis, storage, connectivity and, of course, the...
A critical component of any IoT project is the back-end systems that capture data from remote IoT devices and structure it in a way to answer useful questions. Traditional data warehouse and analytical systems are mature technologies that can be used to handle large data sets, but they are not well suited to many IoT-scale products and the need for real-time insights. At Fuze, we have developed a backend platform as part of our mobility-oriented cloud service that uses Big Data-based approache...
The IoTs will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, will demonstrate how to move beyond today's coding paradigm and share the must-have mindsets for removing complexity from the development proc...
trust and privacy in their ecosystem. Assurance and protection of device identity, secure data encryption and authentication are the key security challenges organizations are trying to address when integrating IoT devices. This holds true for IoT applications in a wide range of industries, for example, healthcare, consumer devices, and manufacturing. In his session at @ThingsExpo, Lancen LaChance, vice president of product management, IoT solutions at GlobalSign, will teach IoT developers how t...
Manufacturers are embracing the Industrial Internet the same way consumers are leveraging Fitbits – to improve overall health and wellness. Both can provide consistent measurement, visibility, and suggest performance improvements customized to help reach goals. Fitbit users can view real-time data and make adjustments to increase their activity. In his session at @ThingsExpo, Mark Bernardo Professional Services Leader, Americas, at GE Digital, will discuss how leveraging the Industrial Interne...
Increasing IoT connectivity is forcing enterprises to find elegant solutions to organize and visualize all incoming data from these connected devices with re-configurable dashboard widgets to effectively allow rapid decision-making for everything from immediate actions in tactical situations to strategic analysis and reporting. In his session at 18th Cloud Expo, Shikhir Singh, Senior Developer Relations Manager at Sencha, will discuss how to create HTML5 dashboards that interact with IoT devic...
SYS-CON Events announced today that Ericsson has been named “Gold Sponsor” of SYS-CON's @ThingsExpo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. Ericsson is a world leader in the rapidly changing environment of communications technology – providing equipment, software and services to enable transformation through mobility. Some 40 percent of global mobile traffic runs through networks we have supplied. More than 1 billion subscribers around the world re...
We’ve worked with dozens of early adopters across numerous industries and will debunk common misperceptions, which starts with understanding that many of the connected products we’ll use over the next 5 years are already products, they’re just not yet connected. With an IoT product, time-in-market provides much more essential feedback than ever before. Innovation comes from what you do with the data that the connected product provides in order to enhance the customer experience and optimize busi...
The increasing popularity of the Internet of Things necessitates that our physical and cognitive relationship with wearable technology will change rapidly in the near future. This advent means logging has become a thing of the past. Before, it was on us to track our own data, but now that data is automatically available. What does this mean for mHealth and the "connected" body? In her session at @ThingsExpo, Lisa Calkins, CEO and co-founder of Amadeus Consulting, will discuss the impact of wea...
In his session at @ThingsExpo, Chris Klein, CEO and Co-founder of Rachio, will discuss next generation communities that are using IoT to create more sustainable, intelligent communities. One example is Sterling Ranch, a 10,000 home development that – with the help of Siemens – will integrate IoT technology into the community to provide residents with energy and water savings as well as intelligent security. Everything from stop lights to sprinkler systems to building infrastructures will run ef...
Whether your IoT service is connecting cars, homes, appliances, wearable, cameras or other devices, one question hangs in the balance – how do you actually make money from this service? The ability to turn your IoT service into profit requires the ability to create a monetization strategy that is flexible, scalable and working for you in real-time. It must be a transparent, smoothly implemented strategy that all stakeholders – from customers to the board – will be able to understand and comprehe...
You deployed your app with the Bluemix PaaS and it's gaining some serious traction, so it's time to make some tweaks. Did you design your application in a way that it can scale in the cloud? Were you even thinking about the cloud when you built the app? If not, chances are your app is going to break. Check out this webcast to learn various techniques for designing applications that will scale successfully in Bluemix, for the confidence you need to take your apps to the next level and beyond.
SYS-CON Events announced today that Peak 10, Inc., a national IT infrastructure and cloud services provider, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Peak 10 provides reliable, tailored data center and network services, cloud and managed services. Its solutions are designed to scale and adapt to customers’ changing business needs, enabling them to lower costs, improve performance and focus inter...
So, you bought into the current machine learning craze and went on to collect millions/billions of records from this promising new data source. Now, what do you do with them? Too often, the abundance of data quickly turns into an abundance of problems. How do you extract that "magic essence" from your data without falling into the common pitfalls? In her session at @ThingsExpo, Natalia Ponomareva, Software Engineer at Google, will provide tips on how to be successful in large scale machine lear...
SYS-CON Events announced today that Fusion, a leading provider of cloud services, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Fusion, a leading provider of integrated cloud solutions to small, medium and large businesses, is the industry's single source for the cloud. Fusion's advanced, proprietary cloud service platform enables the integration of leading edge solutions in the cloud, including cloud...