|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.
One of the bewildering things about DevOps is integrating the massive toolchain including the dozens of new tools that seem to crop up every year. Part of DevOps is Continuous Delivery and having a complex toolchain can add additional integration and setup to your developer environment. In his session at @DevOpsSummit at 18th Cloud Expo, Miko Matsumura, Chief Marketing Officer of Gradle Inc., will discuss which tools to use in a developer stack, how to provision the toolchain to minimize onboa...
Feb. 13, 2016 08:00 PM EST Reads: 145
With an estimated 50 billion devices connected to the Internet by 2020, several industries will begin to expand their capabilities for retaining end point data at the edge to better utilize the range of data types and sheer volume of M2M data generated by the Internet of Things. In his session at @ThingsExpo, Don DeLoach, CEO and President of Infobright, will discuss the infrastructures businesses will need to implement to handle this explosion of data by providing specific use cases for filte...
Feb. 13, 2016 02:00 PM EST Reads: 258
SYS-CON Events announced today that Avere Systems, a leading provider of enterprise storage for the hybrid cloud, 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. Avere delivers a more modern architectural approach to storage that doesn’t require the overprovisioning of storage capacity to achieve performance, overspending on expensive storage media for inactive data or the overbuilding of data centers ...
Feb. 13, 2016 01:30 PM EST Reads: 145
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies adopt disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevO...
Feb. 13, 2016 01:30 PM EST Reads: 285
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of 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, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management...
Feb. 13, 2016 12:45 PM EST Reads: 473
The Quantified Economy represents the total global addressable market (TAM) for IoT that, according to a recent IDC report, will grow to an unprecedented $1.3 trillion by 2019. With this the third wave of the Internet-global proliferation of connected devices, appliances and sensors is poised to take off in 2016. In his session at @ThingsExpo, David McLauchlan, CEO and co-founder of Buddy Platform, will discuss how the ability to access and analyze the massive volume of streaming data from mil...
Feb. 13, 2016 12:00 PM EST
SYS-CON Events announced today that Alert Logic, Inc., the leading provider of Security-as-a-Service solutions for the cloud, 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. Alert Logic, Inc., provides Security-as-a-Service for on-premises, cloud, and hybrid infrastructures, delivering deep security insight and continuous protection for customers at a lower cost than traditional security solutions. Ful...
Feb. 13, 2016 12:00 PM EST Reads: 474
SYS-CON Events announced today that Interoute, owner-operator of one of Europe's largest networks and a global cloud services platform, has been named “Bronze Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. Interoute is the owner-operator of one of Europe's largest networks and a global cloud services platform which encompasses 12 data centers, 14 virtual data centers and 31 colocation centers, with connections to 195 ad...
Feb. 13, 2016 12:00 PM EST Reads: 451
SYS-CON Events announced today that Men & Mice, the leading global provider of DNS, DHCP and IP address management overlay solutions, 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. The Men & Mice Suite overlay solution is already known for its powerful application in heterogeneous operating environments, enabling enterprises to scale without fuss. Building on a solid range of diverse platform support,...
Feb. 13, 2016 11:45 AM EST Reads: 278
Fortunately, meaningful and tangible business cases for IoT are plentiful in a broad array of industries and vertical markets. These range from simple warranty cost reduction for capital intensive assets, to minimizing downtime for vital business tools, to creating feedback loops improving product design, to improving and enhancing enterprise customer experiences. All of these business cases, which will be briefly explored in this session, hinge on cost effectively extracting relevant data from ...
Feb. 13, 2016 11:30 AM EST Reads: 158
WebSocket is effectively a persistent and fat pipe that is compatible with a standard web infrastructure; a "TCP for the Web." If you think of WebSocket in this light, there are other more hugely interesting applications of WebSocket than just simply sending data to a browser. In his session at 18th Cloud Expo, Frank Greco, Director of Technology for Kaazing Corporation, will compare other modern web connectivity methods such as HTTP/2, HTTP Streaming, Server-Sent Events and new W3C event APIs ...
Feb. 13, 2016 11:30 AM EST
SYS-CON Events announced today that iDevices®, the preeminent brand in the connected home industry, 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. iDevices, the preeminent brand in the connected home industry, has a growing line of HomeKit-enabled products available at the largest retailers worldwide. Through the “Designed with iDevices” co-development program and its custom-built IoT Cloud Infrastruc...
Feb. 13, 2016 11:00 AM EST Reads: 154
Companies can harness IoT and predictive analytics to sustain business continuity; predict and manage site performance during emergencies; minimize expensive reactive maintenance; and forecast equipment and maintenance budgets and expenditures. Providing cost-effective, uninterrupted service is challenging, particularly for organizations with geographically dispersed operations.
Feb. 13, 2016 11:00 AM EST
There will be new vendors providing applications, middleware, and connected devices to support the thriving IoT ecosystem. This essentially means that electronic device manufacturers will also be in the software business. Many will be new to building embedded software or robust software. This creates an increased importance on software quality, particularly within the Industrial Internet of Things where business-critical applications are becoming dependent on products controlled by software. Qua...
Feb. 13, 2016 11:00 AM EST
Join us at Cloud Expo | @ThingsExpo 2016 – June 7-9 at the Javits Center in New York City and November 1-3 at the Santa Clara Convention Center in Santa Clara, CA – and deliver your unique message in a way that is striking and unforgettable by taking advantage of SYS-CON's unmatched high-impact, result-driven event / media packages.
Feb. 13, 2016 10:00 AM EST Reads: 104
As enterprises work to take advantage of Big Data technologies, they frequently become distracted by product-level decisions. In most new Big Data builds this approach is completely counter-productive: it presupposes tools that may not be a fit for development teams, forces IT to take on the burden of evaluating and maintaining unfamiliar technology, and represents a major up-front expense. In his session at @BigDataExpo at @ThingsExpo, Andrew Warfield, CTO and Co-Founder of Coho Data, will dis...
Feb. 13, 2016 09:45 AM EST Reads: 234
Silver Spring Networks, Inc. (NYSE: SSNI) extended its Internet of Things technology platform with performance enhancements to Gen5 – its fifth generation critical infrastructure networking platform. Already delivering nearly 23 million devices on five continents as one of the leading networking providers in the market, Silver Spring announced it is doubling the maximum speed of its Gen5 network to up to 2.4 Mbps, increasing computational performance by 10x, supporting simultaneous mesh communic...
Feb. 13, 2016 05:00 AM EST
Eighty percent of a data scientist’s time is spent gathering and cleaning up data, and 80% of all data is unstructured and almost never analyzed. Cognitive computing, in combination with Big Data, is changing the equation by creating data reservoirs and using natural language processing to enable analysis of unstructured data sources. This is impacting every aspect of the analytics profession from how data is mined (and by whom) to how it is delivered. This is not some futuristic vision: it's ha...
Feb. 13, 2016 04:45 AM EST Reads: 475
The cloud promises new levels of agility and cost-savings for Big Data, data warehousing and analytics. But it’s challenging to understand all the options – from IaaS and PaaS to newer services like HaaS (Hadoop as a Service) and BDaaS (Big Data as a Service). In her session at @BigDataExpo at @ThingsExpo, Hannah Smalltree, a director at Cazena, will provide an educational overview of emerging “as-a-service” options for Big Data in the cloud. This is critical background for IT and data profes...
Feb. 13, 2016 03:45 AM EST Reads: 256
With the Apple Watch making its way onto wrists all over the world, it’s only a matter of time before it becomes a staple in the workplace. In fact, Forrester reported that 68 percent of technology and business decision-makers characterize wearables as a top priority for 2015. Recognizing their business value early on, FinancialForce.com was the first to bring ERP to wearables, helping streamline communication across front and back office functions. In his session at @ThingsExpo, Kevin Roberts...
Feb. 12, 2016 12:45 AM EST Reads: 430