Sat, Jun
3 New Articles

A Pattern for E-business

Commerce - Other
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Quality programming is not as common as it should be. All too often, applications are hacked out that, while able to meet business requirements, contain code that is overly complex, difficult to maintain, and, the most evil of all, unable to adapt. So how is it that some code gets that “quality” label? If a group of computer scientists were to cut a dozen quality applications apart, they would find common characteristics: a simple design based on well-crafted data structures and common algorithms. Until recently, the authors of quality applications were coders who carried with them war bags full of techniques garnered from decades of experience. They can gain a difficult programming situation, see a problem that is similar to one that they’ve solved, and quickly code a simple and elegant solution.

So how do you go about filling your own war bag? Do you have to work another decade or so and hope to get the experience for solving reoccurring business problems? No. Thankfully, techniques are becoming documented using a strategy known as design patterns.


A Pattern for Design Patterns


In 1994, Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides was published. It is required reading for anyone who wants to increase his chances of designing quality software. Gamma, Helm, Johnson, and Vlissides’ book has become so well-known that they now have a nickname: “Gang of Four” or GoF.

Design Patterns lists 23 patterns, but the GoF did more than just provide a couple of dozen patterns: They created a standard strategy for describing a design pattern. They wanted industry experts to follow their lead and add to the expanding war bag of design patterns. The GoF’s strategy was constructed so that industry experts could add design patterns by documenting them by creating descriptions the have the following standard sections: Intent, Motivation, Applicability, Structure, Participants, Collaborations, Consequences, Implementation, Sample Code, Known Uses, and Related Patterns.

There are a number of books available that follow the GoF’s strategy (such as Analysis Patterns: Reusable Object Models by Martin Fowler). You should be looking for more books on design patterns that have been explicitly written for e-business applications. I happen to know that IBM Press is currently working on one such book.


Example Uses


Please realize that the use of design patterns does not require the use of an OO language. David Morris has authored several articles for Midrange Computing that show example uses of a couple of the GoF’s design patterns with an RPG application, including “RPG Building Blocks: ILE Message Handling” (November 1998).

The opportunity to use design patterns presents itself during analysis. (See “The Business Case for Use Cases” [September 2000]). In object-oriented analysis, the designers create class models to represent the business entities described in use cases. Based on a general familiarity with the ever-increasing set of design patterns, the designer looks for the opportunity to improve his object design with well-known design patterns.

I’ve used the following patterns from the GoF’s book: Command, Façade, Singleton, Bridge, Factory, and Adapter. The Command pattern works great for simple interactive Web applications. I used Façade to simplify the interface of a complex set of Java classes. Singleton worked well when I wanted to cut down the number of SQL connections to one per application. I used Bridge to create a Java class that created a common interface for both IBM’s and ASNA’s record-level access classes. I used Factory for a distributed application that used Java’s Remote Method Invocation (RMI). To be able to use RMI, you need to develop a server application that generates Java objects on command, which is where I used the Factory pattern. And, I used Adapter to write a simple set of Java classes the wrappered (albeit, not completely) IBM’s Java Toolbox for the AS/400’s data queue classes with Sun Microsystems’ Java 2 Platform, Enterprise Edition (J2EE) Java Message Service (JMS) API.


The Finder Pattern


The best place to get started with design patterns is Design Patterns. The book uses C++ in its sample code. The samples are fairly easy to follow if you know a bit of C or C++, but you may opt for James Cooper’s Java Design Patterns: A Tutorial or Mark Grand’s Patterns in Java: Volume 1, A Catalog of Reusable Design Patterns Illustrated with UML. I feel, however, that the original Design Patterns is still the best text on the subject, so you should have a copy handy in your shop. As always, the Web is the quickest way to get started, so try the Patterns home page at http://hillside.net/patterns/. The Patterns home page contains information on pattern books, articles, conferences, research projects, mailing lists, study groups, and most anything else concerning the worldwide pattern community. The use of design patterns has become so widespread that many shops now expect applicants to be familiar with, at the very least, the patterns described in Design Patterns. And so should you.




• “Developing Java Solutions Using Design Patterns,” Kelby Zorgdrager (online article available at www.developer.ibm.com/library/articles/programmer/kelby1.html)

• IBM Research Design Patterns Web page: www.research.ibm.com/ designpatterns/relatedsites.htm

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



Support MC Press Online

$0.00 Raised:

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: