Machine Learning Authors: Yeshim Deniz, Pat Romanski, Liz McMillan, Corey Roth, Elizabeth White

Related Topics: Machine Learning , Java IoT

Machine Learning : Article

AjaxWorld Special: Creating AJAX and Rich Internet Components with JSF

AJAX has gained momentum primarily due to the "XMLHttpRequest" browser object which supports asynchronous communication

This article is based on, and contains excerpts from, the book Pro JSF: Building Rich Internet Components by Jonas Jacobi and John Fallows, published by Apress. Book is now available on fine bookstores and Amazon as of February 25, 2006.

JavaServer Faces (JSF) standardizes the server-side component model for Web application development but doesn't standardize the presentation layer at the browser. In a series of articles we are going to look at how JSF can fulfill new presentation requirements without sacrificing application developer productivity building Rich Internet Applications (RIA).

Consumer Requirements
It's always the end user who feels the effect of any chosen technology, especially at the presentation layer. The end-user experience should be top priority for any developer building applications, whether they are Web applications or desktop applications. End users demand feature-rich and highly interactive user interfaces.

Introduction to Rich Internet Technologies
Web application developers today are faced with higher demand for richer functionality using technologies such as HTML, CSS, JavaScript, and DOM. These technologies were not developed with enterprise applications in mind and, with increasing pressure from consumers to provide applications with features not fully described or supported by these technologies, developers are looking for alternative solutions or extensions to these standards.

From a combination of both consumer requirements and developer needs, a new breed of Web technologies has evolved. Often referred to as Rich Internet Technologies, these technologies enhance the traditionally static content provided by Web applications.

In the absence of sufficiently powerful standards, new technologies such as Mozilla's XUL, Microsoft's HTC, Java applets, Flex, and OpenLaszlo have emerged to meet the requirements. Such technologies support application-specific extensions to traditional HTML markup while still leveraging the benefits of deploying an application to a central HTTP server. XMLHTTP has also returned under a newly branded name, AJAX (Asynchronous JavaScript and XML). Applications built with these technologies are often referred to as Rich Internet Applications (RIA).

In this article series we are going to focus on AJAX and XUL to illustrate the potential that JSF brings to the JavaEE developer.

AJAX has gained momentum primarily due to the XMLHttpRequest browser object, which supports asynchronous communication with any business services used by the Web application. Popular sites such as Google Mail and Google Suggest use AJAX to deliver RIA.

With the XMLHttpRequest object, developers can now send requests to the Web server to retrieve only the data needed and use JavaScript to process the response.This ability to reduce the amount of data transferred between client and Web server reduces the bandwidth to a minimum and saves processing time on the server since most of the processing is done on the client using JavaScript.

It is important to note that the XMLHttpRequest object, although widely used, could at best be called a "de facto" standard, since most browsers, including Firefox, Inter-net Explorer, Opera, and Safari, support it. It is also worth noting that the XMLHttpRequest object is not exclusive to AJAX; potentially the XMLHttpRequest object can be used by any HTML/XML-based Web technology such as XUL or HTC.

Desktop vs Web
Traditional Web applications are in most cases slower than their counterpart desktop applications. With AJAX we can now send requests to the Web server to retrieve only the data needed and use JavaScript to process the response, which leads to a more responsive Web application.

A typical AJAX application leverages standard HTML/XHTML at the presentation layer and uses JavaScript to dynamically change the DOM. This creates an effect of "richness" in the user interface with no dependency on additional browser plug-ins.

Mozilla XUL
XUL (pronounced zool) was created by the Mozilla organization (Mozilla.org) as an open source project in 1998. With XUL, developers can build rich user interfaces that may be deployed either as "thin client" Web applications, locally on a desktop, or as Internet-enabled "thick client" desktop applications. To fully provide the consumer with a rich user interfaces, XUL needs to execute in the Mozilla Gecko Runtime Environment (GRE). There are many examples of applications using XUL, including the Firefox browser, the Thunderbird e-mail client, and numerous plug-ins to each.

XUL Structure
The base idea behind XUL is to provide a markup for building user interfaces much like HTML, and to leverage technologies such as CSS for look-and-feel and JavaScript for events and behavior. There are even APIs available to access files systems and Web services over the network. As an XML language, XUL can be also be used in combination with other XML languages, such as XHTML and SVG.

XUL Components
XUL comes with a base set of components that are available through the Mozilla GRE, and has the added benefit of not needing to download components to display an application in the browser. You can also design your own components with XUL; these will need to be downloaded on request and cached in the browser.

XUL uses a language called XBL (eXtensible Binding Language) to define new components. XBL is also used to bridge the gap between XUL and HTML, making it easy to attach behavior to traditional HTML markup.

Listing 1 is a sample XUL file that embeds XUL elements and standard, name-spaced HTML elements.

XUL Event Handling
Using XUL event handling is not that different from using HTML event handling. The GRE implementation supports DOM Level 2 (and partially DOM Level 3) and is virtually the same for HTML and XUL, and changes to the state and events are propagated through a range of DOM calls. XUL elements come with predefined event handlers, much like the event handlers provided with the standard HTML elements (see Listing 2).

As in HTML, developers can use JavaScript functions located in external libraries, or embedded in the page.

<script type="text/javascript"src="http://

There is a large set of built-in XUL components, each with its own set of event handler attributes. For example, the XUL window element delivers events such as load and paint.

Creating Custom XUL Components Using XBL
XBL is an XML language that allows developers to extend XUL by adding "custom" components to the extensive set of existing XUL elements. In XUL, developers can define the look and feel using CSS, and they can define the behavior using XBL.

Developers can look at XUL as the "implementation" that comes with a pre-set of components, or tag libraries that can be used to build a user interface, much like the JSF Reference Implementation. XBL is the language developers use to extend XUL components and enable integration with HTML, in much the same way that Java is used to extend JSF components.

XBL Structure
An XBL file contains a set of bindings, each describing the behavior, properties, and methods of an XUL component.

A quick look at Listing 3 shows the root <bindings> element containing two binding elements. A <bindings> element can contain any number of <binding> elements. The namespace in the <bindings> element defines which syntax will be used, and in Listing 3 it is XBL - xmlns=http://www.mozilla.org/xbl. The file also contains a combination of XUL and HTML elements <xul:text/> and <html:input/>. This is extremely useful for simplifying development by encapsulating several components as a single, reusable component. The xbl:inherits attribute allows the text element to inherit values from the bound element by defining a variable called name and assigns it to the value attribute. If no value is defined when the component is used in a page, the text field's value will default to "Guest".

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.

More Stories By John Fallows

John brings to Kaazing his 17 years’ experience in technology development and software design, and is considered a pioneer in the field of rich and highly interactive user interfaces. As CTO he formulates Kaazing Corporation’s vision of enabling mobile users, marketplaces and machines to connect and communicate in real-time, more reliably and at unprecedented scale. He defines the architecture of the Kaazing product suite and oversees its development. Prior to co-founding Kaazing, John served as Architect for Brane Corporation, a startup company based in Redwood City, California. Before joining Brane, he was a Consulting Member of Technical Staff for Server Technologies at Oracle Corporation. During his last five years at Oracle, he focused on designing, developing, and evolving Oracle ADF Faces to fully integrate Ajax technologies. Originally from Northern Ireland, he received his MA in Computer Science from Cambridge University in the United Kingdom and has written several articles for leading IT magazines such as Java Developer’s Journal, AjaxWorld Magazine, and JavaMagazine (DE), and is a popular speaker at international conferences. He is co-author of the bestselling book Pro JSF and Ajax: Building Rich Internet Components (Apress).

Comments (5)

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.

CloudEXPO Stories
When applications are hosted on servers, they produce immense quantities of logging data. Quality engineers should verify that apps are producing log data that is existent, correct, consumable, and complete. Otherwise, apps in production are not easily monitored, have issues that are difficult to detect, and cannot be corrected quickly. Tom Chavez presents the four steps that quality engineers should include in every test plan for apps that produce log output or other machine data. Learn the steps so your team's apps not only function but also can be monitored and understood from their machine data when running in production.
Wooed by the promise of faster innovation, lower TCO, and greater agility, businesses of every shape and size have embraced the cloud at every layer of the IT stack – from apps to file sharing to infrastructure. The typical organization currently uses more than a dozen sanctioned cloud apps and will shift more than half of all workloads to the cloud by 2018. Such cloud investments have delivered measurable benefits. But they’ve also resulted in some unintended side-effects: complexity and risk. End users now struggle to navigate multiple environments with varying degrees of performance. Companies are unclear on the security of their data and network access. And IT squads are overwhelmed trying to monitor and manage it all.
Is it possible to migrate 100% of your data ecosystem to the cloud? Join Joe Caserta as he takes you on a complete journey to digital transformation mapping out on-prem data footprint and walking it to the cloud. Joe will also explain how the modern ecosystem supports Artificial Intelligence and will include business use cases to back each of his insights.
Your job is mostly boring. Many of the IT operations tasks you perform on a day-to-day basis are repetitive and dull. Utilizing automation can improve your work life, automating away the drudgery and embracing the passion for technology that got you started in the first place. In this presentation, I'll talk about what automation is, and how to approach implementing it in the context of IT Operations. Ned will discuss keys to success in the long term and include practical real-world examples. Get started on automating your way to a brighter future!
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things'). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing. IoT is not about the devices, its about the data consumed and generated. The devices are tools, mechanisms, conduits. This paper discusses the considerations when dealing with the massive amount of information associated with these devices. Ed presented sought out sessions at CloudEXPO Silicon Valley 2017 and CloudEXPO New York 2017. He is a regular contributor to Cloud Computing Journal.