|By Samuel Neff||
|April 3, 2003 12:00 AM EST||
Components bring to ColdFusion MX developers much of the power and practices of object-oriented programming. The component implementation in ColdFusion MX introduces us to many of the principles of OOP, including encapsulation and inheritance. One aspect of these features is the ability to create new components that inherit or extend the functionality of other components.
In order to effectively extend functionality, developers often require the ability to override existing component functions as well as still call the original functions to incorporate their programming logic. Since ColdFusion MX doesn't currently provide this ability, we'll explore a technique to work around this limitation that enables us to call a parent component's overridden method.
With component-based development, related code can easily be grouped together in a consolidated entity, giving us the ability to encapsulate data and functionality. This consolidation can be further expanded with the ability to inherit functionality from a parent component, also called extension. When one component extends another, it can both reuse the functionality of the original component and add its own functionality.
Often, the new functionality added to a component will replace its original functionality. This is an advantage to developers who utilize the component in their code since the parent and child components will each have a similar call interface, or function names. By maintaining a consistent interface, developers can write code that can use either the parent or child component interchangeably without modifying the calling code.
For an example of this, see Listing 1, which sets up two components, GreetingBase.cfc and GreetingChild.cfc. GreetingChild extends the functionality of GreetingBase, and both provide a single function, sayGreeting, which returns a greeting to the caller. The caller can use either component and call the same function to retrieve the result appropriate for the component being used, a feature known in OOP as polymorphism.
Calling Overridden Parent Component Functions
We run into a limitation when we try to utilize the parent component functionality for a function that we've overridden, in this case sayGreeting. We want to add a function sayAllGreetings, which returns the results of both the parent and the child components' sayGreeting functions. While you can create an instance of the parent component and call the new instance's sayGreeting method, this would not return accurate results in cases where the call depends on data in the component instance. Unfortunately, there is no mechanism in ColdFusion MX to call an overridden parent method and have it run in the context of the calling component instance.
Many other OOP languages, such as Java and even ActionScript, allow calling a parent class's methods through the keyword Super. While ColdFusion MX does not provide this ability, there is an often-overlooked feature that we can use to achieve the desired effect.
ColdFusion stores function references and variables equally. A function can be called by referring to the function name followed by parentheses, as you are accustomed. Additionally, the function reference can also be utilized by simply referring to the function name. The most common utilization of this feature is to copy a function to another scope, and here we'll use this ability to make a parent component's functions available to its children.
Any code that exists within the cfcomponent tags and outside of any cffunction tags is executed when the component is instantiated. This code is most often used to set up or initialize the component and is called the Constructor in OOP terms.
<!--- constructor code goes here --->
In Listing 2 we added some code to our original components. GreetingBase.cfc now has two lines of code in the constructor.
<cfset super = structNew()>
<cfset super.sayGreeting = sayGreeting>
What we've done here is set up a structure called "super", which we'll use as a holder for our parent component methods. After creating the structure we use cfset to copy a reference to the function to our structure. It's important to note here that when this code is run, the component will exist only as the parent component, so any functionality that is overridden in the child component has not yet been incorporated.
With this structure created and our parent functions safely stored, we can utilize them in the child, GreetingChild.cfc, as follows:
<cfset var greetings="Parent says '" &
"', Child says '" &
sayGreeting() & "'">
In this code we put together a string in which we call our parent component's sayGreeting function, through our super structure, and also call the current sayGreeting function as we normally would.
Super Structure Limitations
Through a little creative utilization of obscure features, we've been able to implement a very important feature common to OOP. However, our implementation is not comprehensive and does have limitations.
This technique can only be used to implement one level of parent-component calls. Since each component in the inheritance chain does not have its own data location where we can store the parent component's methods, we can only store the methods from a single parent component.
Additionally, we must recognize that this is a workaround to provide for functionality missing from ColdFusion MX. Since this feature is standard for OOP and commonly requested from developers, Macromedia will probably implement this functionality natively in a future version of ColdFusion.
When adding support for parent-component calls, Macromedia is likely to use the keyword "super" in their own implementation since this is used in both Java and ActionScript. With this change, our code will stop working since "super" will become a keyword. While this may seem like a problem, it is actually an advantage.
Since we no longer need our workaround once parent component calls are implemented in ColdFusion, we want to ensure that we can easily remove this workaround when it becomes obsolete. To accomplish this, wrap all of the super workaround code, the parent-component constructor, inside consistent comments as shown in Listing 3.
With these comments, we can utilize the Regular Expression replace in either ColdFusion Studio or Dreamweaver to remove all of the super structures from our code. As long as the keyword super is used for this functionality natively, the rest of our code will continue to work.
Component-based development brings to ColdFusion MX many of the features of OOP. By using a structure and function references, we were able to bring a common feature of OOP to ColdFusion, albeit with limitations. In recognizing these limitations, we can write our code in a forward-thinking manner and facilitate future changes to the code when they come in conflict with possible new functionality.
“In the past year we've seen a lot of stabilization of WebRTC. You can now use it in production with a far greater degree of certainty. A lot of the real developments in the past year have been in things like the data channel, which will enable a whole new type of application," explained Peter Dunkley, Technical Director at Acision, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 19, 2014 06:00 PM EST Reads: 1,137
The BPM world is going through some evolution or changes where traditional business process management solutions really have nowhere to go in terms of development of the road map. In this demo at 15th Cloud Expo, Kyle Hansen, Director of Professional Services at AgilePoint, shows AgilePoint’s unique approach to dealing with this market circumstance by developing a rapid application composition or development framework.
Dec. 19, 2014 04:45 PM EST Reads: 767
The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com), moderated by Ashar Baig, Research Director, Cloud, at Gigaom Research, Nate Gordon, Director of T...
Dec. 19, 2014 11:30 AM EST Reads: 2,283
"BSQUARE is in the business of selling software solutions for smart connected devices. It's obvious that IoT has moved from being a technology to being a fundamental part of business, and in the last 18 months people have said let's figure out how to do it and let's put some focus on it, " explained Dave Wagstaff, VP & Chief Architect, at BSQUARE Corporation, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 19, 2014 11:00 AM EST Reads: 1,843
SYS-CON Events announced today that Windstream, a leading provider of advanced network and cloud communications, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Windstream (Nasdaq: WIN), a FORTUNE 500 and S&P 500 company, is a leading provider of advanced network communications, including cloud computing and managed services, to businesses nationwide. The company also offers broadband, phone and digital TV services to consumers primarily in rural areas.
Dec. 19, 2014 07:00 AM EST Reads: 2,156
The Internet of Things is not new. Historically, smart businesses have used its basic concept of leveraging data to drive better decision making and have capitalized on those insights to realize additional revenue opportunities. So, what has changed to make the Internet of Things one of the hottest topics in tech? In his session at @ThingsExpo, Chris Gray, Director, Embedded and Internet of Things, discussed the underlying factors that are driving the economics of intelligent systems. Discover how hardware commoditization, the ubiquitous nature of connectivity, and the emergence of Big Data a...
Dec. 19, 2014 06:30 AM EST Reads: 2,148
ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ -- IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's platform-as-a-service. The new platform enables developers to build ap...
Dec. 19, 2014 05:00 AM EST Reads: 1,965
SYS-CON Events announced today that IDenticard will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. IDenticard™ is the security division of Brady Corp (NYSE: BRC), a $1.5 billion manufacturer of identification products. We have small-company values with the strength and stability of a major corporation. IDenticard offers local sales, support and service to our customers across the United States and Canada. Our partner network encompasses some 300 of the world's leading systems integrators and security s...
Dec. 19, 2014 04:00 AM EST Reads: 1,962
DevOps Summit 2015 New York, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete at launch. DevOps may be disruptive, but it is essential.
Dec. 18, 2014 09:45 PM EST Reads: 988
"People are a lot more knowledgeable about APIs now. There are two types of people who work with APIs - IT people who want to use APIs for something internal and the product managers who want to do something outside APIs for people to connect to them," explained Roberto Medrano, Executive Vice President at SOA Software, in this SYS-CON.tv interview at Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 18, 2014 09:00 AM EST Reads: 1,275
Nigeria has the largest economy in Africa, at more than US$500 billion, and ranks 23rd in the world. A recent re-evaluation of Nigeria's true economic size doubled the previous estimate, and brought it well ahead of South Africa, which is a member (unlike Nigeria) of the G20 club for political as well as economic reasons. Nigeria's economy can be said to be quite diverse from one point of view, but heavily dependent on oil and gas at the same time. Oil and natural gas account for about 15% of Nigera's overall economy, but traditionally represent more than 90% of the country's exports and as...
Dec. 18, 2014 06:00 AM EST Reads: 806
The Internet of Things is a misnomer. That implies that everything is on the Internet, and that simply should not be - especially for things that are blurring the line between medical devices that stimulate like a pacemaker and quantified self-sensors like a pedometer or pulse tracker. The mesh of things that we manage must be segmented into zones of trust for sensing data, transmitting data, receiving command and control administrative changes, and peer-to-peer mesh messaging. In his session at @ThingsExpo, Ryan Bagnulo, Solution Architect / Software Engineer at SOA Software, focused on desi...
Dec. 17, 2014 11:15 PM EST Reads: 1,313
"At our booth we are showing how to provide trust in the Internet of Things. Trust is where everything starts to become secure and trustworthy. Now with the scaling of the Internet of Things it becomes an interesting question – I've heard numbers from 200 billion devices next year up to a trillion in the next 10 to 15 years," explained Johannes Lintzen, Vice President of Sales at Utimaco, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 17, 2014 11:00 PM EST Reads: 1,371
"For over 25 years we have been working with a lot of enterprise customers and we have seen how companies create applications. And now that we have moved to cloud computing, mobile, social and the Internet of Things, we see that the market needs a new way of creating applications," stated Jesse Shiah, CEO, President and Co-Founder of AgilePoint Inc., in this SYS-CON.tv interview at 15th Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 17, 2014 08:00 PM EST Reads: 1,349
SYS-CON Events announced today that Gridstore™, the leader in hyper-converged infrastructure purpose-built to optimize Microsoft workloads, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Gridstore™ is the leader in hyper-converged infrastructure purpose-built for Microsoft workloads and designed to accelerate applications in virtualized environments. Gridstore’s hyper-converged infrastructure is the industry’s first all flash version of HyperConverged Appliances that include both compute and storag...
Dec. 17, 2014 06:30 PM EST Reads: 1,248
Today’s enterprise is being driven by disruptive competitive and human capital requirements to provide enterprise application access through not only desktops, but also mobile devices. To retrofit existing programs across all these devices using traditional programming methods is very costly and time consuming – often prohibitively so. In his session at @ThingsExpo, Jesse Shiah, CEO, President, and Co-Founder of AgilePoint Inc., discussed how you can create applications that run on all mobile devices as well as laptops and desktops using a visual drag-and-drop application – and eForms-buildi...
Dec. 17, 2014 11:45 AM EST Reads: 1,474
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
Dec. 16, 2014 11:45 PM EST Reads: 1,312
Code Halos - aka "digital fingerprints" - are the key organizing principle to understand a) how dumb things become smart and b) how to monetize this dynamic. In his session at @ThingsExpo, Robert Brown, AVP, Center for the Future of Work at Cognizant Technology Solutions, outlined research, analysis and recommendations from his recently published book on this phenomena on the way leading edge organizations like GE and Disney are unlocking the Internet of Things opportunity and what steps your organization should be taking to position itself for the next platform of digital competition.
Dec. 15, 2014 11:45 PM EST Reads: 1,673
The 3rd International Internet of @ThingsExpo, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that its Call for Papers is now open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
Dec. 15, 2014 10:30 AM EST Reads: 6,877
As the Internet of Things unfolds, mobile and wearable devices are blurring the line between physical and digital, integrating ever more closely with our interests, our routines, our daily lives. Contextual computing and smart, sensor-equipped spaces bring the potential to walk through a world that recognizes us and responds accordingly. We become continuous transmitters and receivers of data. In his session at @ThingsExpo, Andrew Bolwell, Director of Innovation for HP's Printing and Personal Systems Group, discussed how key attributes of mobile technology – touch input, sensors, social, and ...
Dec. 15, 2014 10:00 AM EST Reads: 1,958