Welcome!

You will be redirected in 30 seconds or close now.

ColdFusion Authors: Yakov Fain, Jeremy Geelan, Maureen O'Gara, Nancy Y. Nee, Tad Anderson

Related Topics: ColdFusion, Adobe Flex, Machine Learning

ColdFusion: Article

When AJAX Happens to Old Browsers

Building a single application that supports both new and old browsers

One of the latest crazes in Web development is AJAX. Unless you've been living in a cave for the last year, you've heard of this old, yet currently popular, technique for making HTTP requests to a server without refreshing the Web page. While claims of smaller bandwidth, faster response, and highly interactive user interfaces may intrigue you, one must ask, "Will it work for my user base?"

We've seen this same issue before. It's not an AJAX-specific issue; rather, it's a JavaScript issue. There are users that either by choice or mandate are stuck with an ancient Web browser. There are others who still don't have JavaScript enabled on their browsers. It's difficult to know exactly how many people don't have JavaScript turned on, but estimates range from 5%-10%.

Is 5%-10% a significant user population? It depends on who you ask. Some businesses can take a chance of alienating this user base at the prospect of wowing the remaining 90%, while for others, it's either necessary or desirable to accommodate all users. It seems that you may be left with only two options when deciding whether to implement AJAX on your site:

  • Leave the users of older browsers behind.
  • Accommodate this small user base at the expense of lesser functionality for the remaining 90%.
I'd like to propose a third option:
  • Accommodate both groups through effective planning and design.
"Accommodate both groups," you ask. "Doesn't that mean that I need to develop two separate Web applications?" With careful planning and design, you can develop a single application that provides essential functionality to all users, while providing enhanced functionality to those whose browsers can handle it.

"Essential" versus "Enhanced" Functionality
Essential functionality means providing a user with the ability to complete a task or use a service. For instance, suppose one of the services on your Web site is a weekly newsletter. To subscribe to the newsletter, a user must complete a registration form. What happens when the user clicks the submit button at the end of the form? Few things are more frustrating than completing a large form only to have the submit button "shoot blanks" because it requires JavaScript to function. Essential functionality dictates that the submit button works regardless of whether the user is using Firefox, Internet Explorer, Safari, Lynx, or a screen reader.

Enhanced functionality means adding all of the bells and whistles that really set your application apart. While such features aren't essential, adding them to an application usually provides faster ways to accomplish tasks or easier ways of doing things. Enhanced functionality includes such things as:

  • client-side form validation
  • dynamic HTML effects
  • AJAX
The strategy that I suggest for accommodating both essential and enhanced functionality is to add "bells and whistles" to a basic application. That is, we'll create an application that satisfies the essential functionality and then provide a way for enhanced functionality to be attached to the application only if the client's browser will support it.

The Sample Application: A Contact Manager
The sample application accompanying this article is a simple contact manager (see Figure 1). The goal of this application is to provide users with the ability to:

  • Add new contacts
  • Edit existing contacts
  • View all contacts
  • Delete contacts
First we'll build the application that addresses essential functionality. In the basic application, all GET and POST operations will be full-page refreshes. Later, we will add some AJAX functionality to the application. To keep the example simple, it stores all contacts in a query object in the application scope.

Coding the Basic Application
The basic application is in the /ajax/no-js/ directory of the code samples. One of the first things that I did when building the basic application was to separate queries, content sections, and controlling logic into separate templates. This is something that can be done now to prepare the application to work for both basic and advanced browsers. AJAX calls and other dynamic effects often need small segments of content, or data in XML, rather than HTML. Instead of duplicating code, we write each query and display template and include them in potentially multiple places.

Most of the business logic, or model layer, is in contactManager.cfc. It contains all of the operations needed to read and manipulate contacts. The contact listing table, contact entry and edit form, and delete confirmation page are all in separate templates. layout.cfm is a custom tag that contains the basic HTML skeleton to wrap the other content sections. Finally, index.cfm handles all of the possible actions from the browser in a <cfswitch> tag. Most of the action handlers look like the following saveRecord case:

<cfcase value="saveRecord">
<!---put the contact information in a struct --->
<cfinvoke returnvariable="contact" component="#request.manager#"
method="populateContact" argumentcollection="#form#"/>
<!--- store the contact in the database --->
<cfset request.manager.saveContact(contact)/>
<!--- retrieve an updated list of contacts --->
<cfset qContactListing = request.manager.getAll()/>
<!--- create an empty contact for the entry form --->
<cfset contact = request.manager.populateContact()/>
<cf_layout title="Contact Manager" message="Contact was successfully
saved.">
<cfinclude template="dspListing.cfm"/>
<cfinclude template="dspEntryForm.cfm"/>
</cf_layout>
</cfcase>

Each action handler case calls the business methods and includes the templates necessary to perform the action.

Finally, I made sure that the markup was clean and simple, and that all visual styling was placed in a stylesheet. Clean markup provides three benefits, regardless of whether the application will be using AJAX:

  1. It's easier to work with the HTML structure using JavaScript DOM APIs. and stylesheets.
  2. It usually means less data is sent back to the client at one time, since unnecessary elements and attributes are eliminated. When we send HTML segments to the client using AJAX, those responses will be even smaller.
  3. The HTML is often easier to read and maintain.
Try out the sample application so you understand how it works. At this point, the basic application works reliably and provides essential functionality. Because, it's not very exciting, it's time to add some enhanced functionality.

Grafting In the Enhancements
The enhanced application is in the /ajax/with-js/ directory of the code samples. In this version of the application, we're going to add some AJAX calls. This means replacing any of the pages exit points - the edit links, delete links, and save button - with JavaScript calls to actions in the ColdFusion application. A common way to do this is to make the necessary onclick event handler an attribute on the anchor tag or submit button like so:

<a href="index.cfm?action=editRecord...." onClick="lookupContact();">edit</a>

Rather than cluttering up the HTML with event handlers, I prefer to attach them to the elements using JavaScript calls in the header. The calls are usually invoked as part of the browser window's onload event. This keeps the HTML content and JavaScript code clearly separated. To make it easy to attach events using this method, let's make two quick changes to the code:

  1. Add class attributes to the edit and delete links, and an id attribute to the submit button. This will make it easier to find the elements using JavaScript.
  2. Move the HTML contact table to a separate template (dspListingContent.cfm) and include it in the original template using <cfinclude/>. The HTML table is a key page fragment that we'll want to return to the client using AJAX.

More Stories By Jeremy Lund

Jeremy Lund is the manager of the Web Resource Center at University Health Care in Salt Lake City, Utah (http://uuhsc.utah.edu/wrc/). As the manager he coordinates development efforts, designs their Web architecture, and, in the time left, develops Web applications. He has worked with Internet technologies for over seven years, and enjoys working not only with ColdFusion, Java, and Perl, but is also an advocate of using XHTML and CSS. Jeremy received a bachelor's degree in computer engineering from the University of Utah, and is a Sun Certified Programmer for the Java 2 platform.

Comments (1)

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.


IoT & Smart Cities Stories
The deluge of IoT sensor data collected from connected devices and the powerful AI required to make that data actionable are giving rise to a hybrid ecosystem in which cloud, on-prem and edge processes become interweaved. Attendees will learn how emerging composable infrastructure solutions deliver the adaptive architecture needed to manage this new data reality. Machine learning algorithms can better anticipate data storms and automate resources to support surges, including fully scalable GPU-c...
Machine learning has taken residence at our cities' cores and now we can finally have "smart cities." Cities are a collection of buildings made to provide the structure and safety necessary for people to function, create and survive. Buildings are a pool of ever-changing performance data from large automated systems such as heating and cooling to the people that live and work within them. Through machine learning, buildings can optimize performance, reduce costs, and improve occupant comfort by ...
The explosion of new web/cloud/IoT-based applications and the data they generate are transforming our world right before our eyes. In this rush to adopt these new technologies, organizations are often ignoring fundamental questions concerning who owns the data and failing to ask for permission to conduct invasive surveillance of their customers. Organizations that are not transparent about how their systems gather data telemetry without offering shared data ownership risk product rejection, regu...
René Bostic is the Technical VP of the IBM Cloud Unit in North America. Enjoying her career with IBM during the modern millennial technological era, she is an expert in cloud computing, DevOps and emerging cloud technologies such as Blockchain. Her strengths and core competencies include a proven record of accomplishments in consensus building at all levels to assess, plan, and implement enterprise and cloud computing solutions. René is a member of the Society of Women Engineers (SWE) and a m...
Poor data quality and analytics drive down business value. In fact, Gartner estimated that the average financial impact of poor data quality on organizations is $9.7 million per year. But bad data is much more than a cost center. By eroding trust in information, analytics and the business decisions based on these, it is a serious impediment to digital transformation.
Digital Transformation: Preparing Cloud & IoT Security for the Age of Artificial Intelligence. As automation and artificial intelligence (AI) power solution development and delivery, many businesses need to build backend cloud capabilities. Well-poised organizations, marketing smart devices with AI and BlockChain capabilities prepare to refine compliance and regulatory capabilities in 2018. Volumes of health, financial, technical and privacy data, along with tightening compliance requirements by...
Predicting the future has never been more challenging - not because of the lack of data but because of the flood of ungoverned and risk laden information. Microsoft states that 2.5 exabytes of data are created every day. Expectations and reliance on data are being pushed to the limits, as demands around hybrid options continue to grow.
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
Enterprises have taken advantage of IoT to achieve important revenue and cost advantages. What is less apparent is how incumbent enterprises operating at scale have, following success with IoT, built analytic, operations management and software development capabilities - ranging from autonomous vehicles to manageable robotics installations. They have embraced these capabilities as if they were Silicon Valley startups.
As IoT continues to increase momentum, so does the associated risk. Secure Device Lifecycle Management (DLM) is ranked as one of the most important technology areas of IoT. Driving this trend is the realization that secure support for IoT devices provides companies the ability to deliver high-quality, reliable, secure offerings faster, create new revenue streams, and reduce support costs, all while building a competitive advantage in their markets. In this session, we will use customer use cases...