02
Sat, Nov
2 New Articles

Extreme Programming

General
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

The first time I heard the phrase Extreme Programming, I had visions of all-night coding sessions with cans of Jolt cola and Mountain Dew strewn about. Far from it, Extreme Programming (XP), the latest craze in software construction methodologies, actually advocates a 40-hour workweek. The term “extreme” comes from XP’s radical departure from the complex, time-consuming techniques of well-known and long-accepted methodologies.

Consider this quote from one of Kent Beck’s XP converts: “XP matches observations of programmers in the wild.” (Beck is the author of Xtreme Programming Xplained—Embrace Change.) So yes, XP is radical, and the best way that I can describe XP is to list its practices and then summarize XP’s project cycle.

XP Practices

• Planning—Determine the scope of the next release by combining business priorities with technical estimates made by coders.

• Small releases—Use iterative development where each release is delivered in one to three weeks.

• Metaphor—Start with a simple, shared story of how the system is to work.

• Simple design—Follow the doctrine of, as Beck says, “extracomplexity removed as soon as it is discovered,” but strive not to use complex designs in the first place.

• Testing—Have coders write unit tests for all methods and customers write functional tests for the application.

• Refactoring—Continually strive to remove duplicate code and find ways to simplify code while adding flexibility—i.e., “do over.”

• Pair-programming—All production code is done by two coders sharing one workstation.

• Collective ownership—Allow anyone to be able to change any code anywhere in the system at any time.


• Continuous integration—Build and completely test the system several times a day.

• 40-hour week—It is an absolute rule that you can’t go over 40 hours two weeks in a row.

• On-site customer—Have a user expert on the team full time to develop functional tests and provide continuous feedback.

• Coding standards—Because everyone owns all the code of the system, it must all look the same throughout the system.

XP Project Cycle

An XP project seeks to deliver the system every one to three weeks. The idea is to drop grandiose design schemes and replace them with a simple story of the system that everyone understands and agrees on. The project starts with the most basic of the requirements for thesystems. The design is done using the simple strategy of 3 x 5 Class-Responsibility- Collaborator (CRC) cards. (To get a better idea how CRC cards are used to design object- oriented systems, read c2.com/doc/oopsla89/paper.html.) After the “hyper” design phase is done, coders select 3 x 5 cards, estimate the amount of time to deliver, select a partner, and begin coding. One coder is the driver, and the other is the planner. The driver fleshes out the code for the task, and the planner looks for coding errors while planning how to test the code and improve the overall design.

Pair Programming

This pair programming goes against common coding practices, and my first thought about it was that it would result in less code. But studies have shown that pair programming always results in cleaner and more concise code. Quality code means fewer bugs and, after coders become comfortable with pair programming, output catches up with “cave coding” anyway.

One of the immediate benefits of pair programming is continuous code reviews. I’ve always been an advocate of code reviews, but, because they burn up lots of time and resources, code reviews are often skipped. With XP, code reviews go on constantly (because you always work in pairs), and therefore are extremely effective.

Testing and Collective Ownership

Testing is the name of the game with XP. Coders become “test infected” because they won’t add a feature unless they can test that feature. Unit tests provide instant gratification while establishing coder confidence. The XP team customer is responsible for adding functional tests as features are added to the systems.

As a coding pair completes a task, it integrates its code to the system. At this point, the coding pair not only tests its new code but also runs the automated tests for the entire system. If any test fails, the coding pair is to fix any code that fails—even if it didn’t code it. That’s called collective ownership—all the coders are responsible for all the code in the system.

Iterative Development

After a one- to three-week phase is complete, the system is delivered to the customer. Feedback is instantaneous, and a subsequent project cycle begins. Features are added and designs are changed. In other words, the scope of the project evolves after each iteration.

Is XP for You?


Should you be using XP? First, remember that XP is a radical new methodology. Your company’s coders and management must be willing to try a completely new way of designing, coding, and delivering systems. XP’s use of numerous releases and continual evolution of a project may not work in your business environment. Note, too, that XP works best for small projects, ones with two to 10 coders. And last, XP is dependant on modular programming, if not object-oriented programming. The continual integration and system testing of XP require a programming language that supports fast builds and automated unit tests. XP success stories were built using C++, Java, and Smalltalk.


Don Denoncourt

Don Denoncourt is a freelance consultant. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..


MC Press books written by Don Denoncourt available now on the MC Press Bookstore.

Java Application Strategies for iSeries and AS/400 Java Application Strategies for iSeries and AS/400
Explore the realities of using Java to develop real-world OS/400 applications.
List Price $89.00

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: