|By Peter Bell||
|November 9, 2006 01:00 PM EST||
One of the first things that you encounter when moving to object-oriented (OO) programming are beans. Beans are simple representations of a business object (like a user or a product) that hide all of the information stored in the bean behind methods (functions) for getting and setting the information (called, unsurprisingly, getters and setters).
Typically, if you want to display a product view screen, you'll get the product information from the database, load the resulting query recordset into a bean and then, instead of displaying the variables from the query, call the methods from the bean. In the past your product view may have looked like this:
$#Price#<br /><br />
With a bean, the product view will change to the following:
$#Product.get("Price")#<br /><br />
The only difference is that you are calling a "get" method that hides (encapsulates) the way the title and the price are retrieved, but this small difference can have a big impact on the maintainability of your code. (The sharp eyed among you will have noticed that I'm using a generic getter. The sidebar explains why this might be a good idea for you to consider).
Object-oriented programming is all about writing more maintainable code. Many Object Oriented patterns take longer to code initially than a traditional procedural approach, but they are easier to maintain. Given that we tend to spend much more time maintaining than developing applications, this is usually a worthwhile trade-off.
The benefit of encapsulating business object attributes behind getters and setters is that if the logic required to calculate (or save) the attribute changes, you only have to change the code in one place. Let's say that the product price is calculated based on a sale price. In the past you might have put that logic right into the product view:
$<cfif SalePrice>#SalePrice#<cfelse>#Price#</cfif><br /><br />
The problem is, there may also be a product list screen, a product search results screen, and the cart and checkout may also need to know the price of a product, so if you changed the way you calculated the price, you would have to remember to make that change in five places. Even worse, there is the risk that you might forget to update one of the screens, so products displayed on the search screen would display a different price than when added to the basket.
With getters and setters encapsulating the logic, there would be no change at all to the display screens. They would still be:
$#Product.get("Price")#<br /><br />
The only difference is that you would change the getPrice() custom method within the product object to be something like:
<cffunction name="getPrice" returntype="numeric" access="public"
output="no" hint="I return the price to display and charge for the product">
<cfset var Local = structNew()>
<cfset Local.ReturnValue = variables.get("SalePrice")>
<cfset Local.ReturnValue = variables.Price>
So, encapsulation of getters and setters using beans is a key element of Object Oriented programming, and it is a best practice that most OO developers would use most of the time. So, what happens when we have more than one user or product or article?
The Performance Problem
In Java, this would be easy. You would take your recordset, use it to create a collection of objects (one for each record), and you would still have all of the benefits of encapsulated getting and setting of properties. Unfortunately, in ColdFusion, object creation is expensive (in terms of performance). Creating a large number of objects as part of every page load can substantially affect the performance of a ColdFusion script.
Because of this, a lot of ColdFusion developers currently use recordsets for displaying their lists, losing all of the benefits of encapsulation. If they want to change the way the price is calculated for a product list, they either need to push back the price calculation onto the database; write a script in their service object to loop through the query implementing any custom data transformations; or replicate their business logic all over their list screens.
Introducing the Iterating Business Object
The iterating business object (IBO) is a simple solution to the problem of encapsulating access to getters and setters for recordsets without sacrificing performance. It is implemented as a base class that your business objects can extend. As well as providing generic getters and setters, it can also load itself with a query, and it provides a basic set of iterating methods (first(), next(), and isLast()) for looping through the recordset.
The IBO allows you to get all of the benefits of encapsulated getting and setting of attributes - whether you are working with a single object or a collection of them. It also allows you to use exactly the same code for both your single objects and object collections. For example, it really doesn't matter whether you are viewing a single product on a product detail page or a list of products matching a search query. If you want to display the price for the product, you want to use the same business logic to calculate it in both cases. With an IBO, you always load the same object up with the results from your query, and you can maintain all of your getter and setter calculations in that one object. In addition, you are only instantiating a single object per page view, so the performance hit is nominal. You can see the code for a simple IBO in Listing 1.
Using the Iterating Business Object
When you are using the IBO to display a single record, it is exactly the same as using a bean:
$#Product.get("Price")#<br /><br />
If you want to display a list of records, it is almost as easy. You take the same basic display code and just wrap it with a loop based on the iterating methods of the object:
<cfloop condition="NOT #Product.isLast()#">
$#Product.get("Price")#<br /><br />
Improving the Object
Previously I showed an example of a custom getter for calculating the price of a product. If there was a sale price, it displayed that, otherwise it just accessed the variables scope to get the price. Well, that works for a single record, but if there are multiple records (as with the IBO), the actual code to access a particular record would be more like:
<cfset Local.ReturnValue = variables.Data[variables.IteratorCount].Price>
Where the variables.IteratorCount is a pointer to the current record within the recordset being displayed. This isn't "wrong", but over time all of the custom methods would have to include this code, and if I ever decided to change the structure of the data storage within the variables scope, all of those methods would have to be rewritten.
To encapsulate that change, I added one more pair of generic methods to the base IBO: access() and mutate(). Accessors and mutators are alternate terms for getters and setters, but these methods are private and are only to be used by the customer getters and setters to access the underlying data structure, so if I ever wished to change the structure, I would only have to change those two methods. Below is simplified code for the access() method (the full code is available in Listing 1):
<cffunction name="access" returntype="any" access="private" output="no"
hint="I encapsulate access to the attribute values within this object,
accepting an attribute name and returning the appropriate attribute value.">
<cfargument name="AttributeName" type="string" required="yes"
hint="I am the name of the attribute to return the value for">
<cfset var Local = structNew()>
<cfset Local.ReturnValue = variables.Data[variables.IteratorCount][arguments.AttributeName] >
With this in place, we can now simplify the data access in the custom methods to just:
<cfset Local.ReturnValue = variables.access("Price")>
I have used the IBO on a number of production projects over the last couple of months. One project in particular required almost daily changes to the (very complex) object model as we continually added new attributes and changed the rules for calculating existing attributes. I found the application extremely easy to maintain and it is now in production, powering over 20 different sites and performing very well under load.
If you don't have any calculations for getting or setting any of your object attributes and really don't expect any in the future, any kind of encapsulation is overkill, and you would be better just to display using recordsets and cfoutput - for one record or for many. If you do have calculated fields, give the IBO a try and see how it works for your projects.
|Peter Bell 01/02/07 07:19:46 PM EST|
Good catch! That was indeed a little messy and is something I plan to clean up later this month. if you're interested, I'll be reposting code on my Blog. I'm probably going to use isDone(), but will take a little time to look at some other iterators to see what syntax is most popular.
|Michael Long 11/26/06 07:49:10 PM EST|
Could just be me, but I'd expect a function named "isLast" to return true if I'm actually on the last record. Which would in turn lead to an off-by-one error, as the loop would terminate early.
Better, perhaps, would be isEOF, or isDone, either of which would be true if the current record count is greater than the actual record count.
With 15% of enterprises adopting a hybrid IT strategy, you need to set a plan to integrate hybrid cloud throughout your infrastructure. In his session at 18th Cloud Expo, Steven Dreher, Director of Solutions Architecture at Green House Data, discussed how to plan for shifting resource requirements, overcome challenges, and implement hybrid IT alongside your existing data center assets. Highlights included anticipating workload, cost and resource calculations, integrating services on both sides...
Jul. 26, 2016 09:00 PM EDT Reads: 2,014
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, discussed how leveraging the Industrial Internet a...
Jul. 26, 2016 08:00 PM EDT Reads: 278
Big Data engines are powering a lot of service businesses right now. Data is collected from users from wearable technologies, web behaviors, purchase behavior as well as several arbitrary data points we’d never think of. The demand for faster and bigger engines to crunch and serve up the data to services is growing exponentially. You see a LOT of correlation between “Cloud” and “Big Data” but on Big Data and “Hybrid,” where hybrid hosting is the sanest approach to the Big Data Infrastructure pro...
Jul. 26, 2016 07:15 PM EDT Reads: 1,927
"My role is working with customers, helping them go through this digital transformation. I spend a lot of time talking to banks, big industries, manufacturers working through how they are integrating and transforming their IT platforms and moving them forward," explained William Morrish, General Manager Product Sales at Interoute, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
Jul. 26, 2016 06:30 PM EDT Reads: 2,114
A critical component of any IoT project is what to do with all the data being generated. This data needs to be captured, processed, structured, and stored in a way to facilitate different kinds of queries. Traditional data warehouse and analytical systems are mature technologies that can be used to handle certain kinds of queries, but they are not always well suited to many problems, particularly when there is a need for real-time insights.
Jul. 26, 2016 05:45 PM EDT Reads: 1,822
The best-practices for building IoT applications with Go Code that attendees can use to build their own IoT applications. In his session at @ThingsExpo, Indraneel Mitra, Senior Solutions Architect & Technology Evangelist at Cognizant, provided valuable information and resources for both novice and experienced developers on how to get started with IoT and Golang in a day. He also provided information on how to use Intel Arduino Kit, Go Robotics API and AWS IoT stack to build an application tha...
Jul. 26, 2016 04:30 PM EDT Reads: 1,081
IoT generates lots of temporal data. But how do you unlock its value? You need to discover patterns that are repeatable in vast quantities of data, understand their meaning, and implement scalable monitoring across multiple data streams in order to monetize the discoveries and insights. Motif discovery and deep learning platforms are emerging to visualize sensor data, to search for patterns and to build application that can monitor real time streams efficiently. In his session at @ThingsExpo, ...
Jul. 26, 2016 04:30 PM EDT Reads: 1,012
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 ...
Jul. 26, 2016 04:00 PM EDT Reads: 1,029
Extracting business value from Internet of Things (IoT) data doesn’t happen overnight. There are several requirements that must be satisfied, including IoT device enablement, data analysis, real-time detection of complex events and automated orchestration of actions. Unfortunately, too many companies fall short in achieving their business goals by implementing incomplete solutions or not focusing on tangible use cases. In his general session at @ThingsExpo, Dave McCarthy, Director of Products...
Jul. 26, 2016 03:45 PM EDT Reads: 1,716
Amazon has gradually rolled out parts of its IoT offerings in the last year, but these are just the tip of the iceberg. In addition to optimizing their back-end AWS offerings, Amazon is laying the ground work to be a major force in IoT – especially in the connected home and office. Amazon is extending its reach by building on its dominant Cloud IoT platform, its Dash Button strategy, recently announced Replenishment Services, the Echo/Alexa voice recognition control platform, the 6-7 strategic...
Jul. 26, 2016 03:15 PM EDT Reads: 358
WebRTC is bringing significant change to the communications landscape that will bridge the worlds of web and telephony, making the Internet the new standard for communications. Cloud9 took the road less traveled and used WebRTC to create a downloadable enterprise-grade communications platform that is changing the communication dynamic in the financial sector. In his session at @ThingsExpo, Leo Papadopoulos, CTO of Cloud9, discussed the importance of WebRTC and how it enables companies to focus...
Jul. 26, 2016 03:15 PM EDT Reads: 925
Verizon Communications Inc. (NYSE, Nasdaq: VZ) and Yahoo! Inc. (Nasdaq: YHOO) have entered into a definitive agreement under which Verizon will acquire Yahoo's operating business for approximately $4.83 billion in cash, subject to customary closing adjustments. Yahoo informs, connects and entertains a global audience of more than 1 billion monthly active users** -- including 600 million monthly active mobile users*** through its search, communications and digital content products. Yahoo also co...
Jul. 26, 2016 02:30 PM EDT Reads: 527
"There's a growing demand from users for things to be faster. When you think about all the transactions or interactions users will have with your product and everything that is between those transactions and interactions - what drives us at Catchpoint Systems is the idea to measure that and to analyze it," explained Leo Vasiliou, Director of Web Performance Engineering at Catchpoint Systems, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York Ci...
Jul. 26, 2016 01:45 PM EDT Reads: 1,996
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
Jul. 26, 2016 10:15 AM EDT Reads: 1,191
Is your aging software platform suffering from technical debt while the market changes and demands new solutions at a faster clip? It’s a bold move, but you might consider walking away from your core platform and starting fresh. ReadyTalk did exactly that. In his General Session at 19th Cloud Expo, Michael Chambliss, Head of Engineering at ReadyTalk, will discuss why and how ReadyTalk diverted from healthy revenue and over a decade of audio conferencing product development to start an innovati...
Jul. 26, 2016 09:15 AM EDT Reads: 1,020
It’s 2016: buildings are smart, connected and the IoT is fundamentally altering how control and operating systems work and speak to each other. Platforms across the enterprise are networked via inexpensive sensors to collect massive amounts of data for analytics, information management, and insights that can be used to continuously improve operations. In his session at @ThingsExpo, Brian Chemel, Co-Founder and CTO of Digital Lumens, will explore: The benefits sensor-networked systems bring to ...
Jul. 26, 2016 08:45 AM EDT Reads: 1,555
SYS-CON Events announced today that 910Telecom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Housed in the classic Denver Gas & Electric Building, 910 15th St., 910Telecom is a carrier-neutral telecom hotel located in the heart of Denver. Adjacent to CenturyLink, AT&T, and Denver Main, 910Telecom offers connectivity to all major carriers, Internet service providers, Internet backbones and ...
Jul. 26, 2016 08:45 AM EDT Reads: 634
SYS-CON Events announced today that Venafi, the Immune System for the Internet™ and the leading provider of Next Generation Trust Protection, will exhibit at @DevOpsSummit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Venafi is the Immune System for the Internet™ that protects the foundation of all cybersecurity – cryptographic keys and digital certificates – so they can’t be misused by bad guys in attacks...
Jul. 26, 2016 08:45 AM EDT Reads: 1,325
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...
Jul. 26, 2016 06:15 AM EDT Reads: 1,439
SYS-CON Events has announced today that Roger Strukhoff has been named conference chair of Cloud Expo and @ThingsExpo 2016 Silicon Valley. The 19th Cloud Expo and 6th @ThingsExpo will take place on November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. "The Internet of Things brings trillions of dollars of opportunity to developers and enterprise IT, no matter how you measure it," stated Roger Strukhoff. "More importantly, it leverages the power of devices and the Interne...
Jul. 26, 2016 05:15 AM EDT Reads: 2,130