Home > Articles > Programming

Software Development Methodology Today

This introductory chapter reviews the leading models for software development and proposes a robust software development model based on the best practices of the past, while incorporating the promise of more recent programming technology.
This chapter is from the book

Cease dependence on inspection to achieve quality.

—W. Edwards Deming

Quality is a many-splendored thing, and every improvement of its attributes is at once an advance and an advantage.

—C. V. Ramamoorthy


Both personal productivity and enterprise server software are routinely shipped to their users with defects, called bugs from the early days of computing. This error rate and its consequent failures in operation would not be tolerated for any manufactured or "hardware" product sold today. But software is not a manufactured product in the same sense as a mechanical device or household appliance, even a desktop computer. Since programming began as an intellectual and economic activity with the ENIAC in 1946, a great deal of attention has been given to making software programs as reliable as the computer hardware they run on. Unlike most manufactured goods, software undergoes continual redesign and upgrading in practice because the system component adapts the general-purpose computer to its varied and often-changing, special-purpose applications. As needs change, so must the software programs that were designed to meet them. A large body of technology has developed over the past 50 years to make software more reliable and hence trustworthy. This introductory chapter reviews the leading models for software development and proposes a robust software development model based on the best practices of the past, while incorporating the promise of more recent programming technology. The Robust Software Development Model (RSDM) recognizes that although software is designed and "engineered," it is not manufactured in the usual sense of that word. Furthermore, it recognizes an even stronger need in software development to address quality problems upstream, because that is where almost all software defects are introduced. Design for Trustworthy Software (DFTS) addresses the challenges of producing trustworthy software using a combination of the iterative Robust Software Development Model, Software Design Optimization Engineering, and Object-Oriented Design Technology.

Chapter Outline

  • Software Development: The Need for a New Paradigm

  • Software Development Strategies and Life-Cycle Models

  • Software Process Improvement

  • ADR Method

  • Seven Components of the Robust Software Development Process

  • Robust Software Development Model

  • Key Points

  • Additional Resources

  • Internet Exercises

  • Review Questions

  • Discussion Questions and Projects

  • Endnotes

Software Development: The Need for a New Paradigm

Computing has been the fastest-growing technology in human history. The performance of computing hardware has increased by more than a factor of 1010 (10,000 million times) since the commercial exploitation of the electronic technology developed for the ENIAC 50 years ago, first by Eckert and Mauchly Corp., later by IBM, and eventually by many others. In the same amount of time, programming performance, a highly labor-intensive activity, has increased by about 500 times. A productivity increase of this magnitude for a labor-intensive activity in only 50 years is truly amazing, but unfortunately it is dwarfed by productivity gains in hardware. It’s further marred by low customer satisfaction resulting from high cost, low reliability, and unacceptable development delays. In addition, the incredible increase in available computer hardware cycles has forced a demand for more and better software. Much of the increase in programming productivity has, as you might expect, been due to increased automation in computer software production. Increased internal use of this enormous hardware largesse to offset shortcomings in software and "manware" have accounted for most of the gain. Programmers are not 500 times more productive today because they can program faster or better, but because they have more sophisticated tools such as compilers, operating systems, program development environments, and integrated development environments. They also employ more sophisticated organizational concepts in the cooperative development of programs and employ more sophisticated programming language constructs such as Object-Oriented Programming (OOP), class libraries, and object frameworks. The first automation tools developed in the 1950s by people such as Betty Holburton1 at the Harvard Computation Laboratory (the sort-merge generator) and Mandalay Grems2 at the Boeing Airplane Company (interpretive programming systems) have emerged again. Now they take the form of automatic program generation, round-tripping, and of course the ubiquitous Java Virtual Machine, itself an interpretive programming system.

Over the years, a number of rules of thumb or best practices have developed among enterprise software developers, both in-house and commercial or third-party vendors. Enterprise software is the set of programs that a firm, small or large, uses to run its business. It is usually conceded that it costs ten times as much to prepare (or "bulletproof") an enterprise application for the marketplace as it costs to get it running in the "lab." It costs another factor of 2 from that point to market a software package to the break-even point. The high cost of software development in both time and dollars, not to mention political or career costs (software development is often referred to as an "electropolitical" problem, and a high-risk project as a "death march"), has encouraged the rise of the third-party application software industry and its many vendors. Our experience with leading both in-house and third-party vendor enterprise software development indicates that the cost of maintaining a software system over its typical five-year life cycle is equal to its original development cost.

Each of the steps in the software life cycle, as shown in Figure 1.1, is supported by numerous methods and approaches, all well-documented by textbooks and taught in university and industrial courses. The steps are also supported by numerous consulting firms, each having a custom or proprietary methodology, and by practitioners well-trained in it. In spite of all of this experience supported by both computing and organizational technology, the question remains: "Why does software have bugs?" In the past two decades it has been popular to employ an analogy between hardware design and manufacture and software design and development. Software "engineering" has become a topic of intense interest in an effort to learn from the proven practices of hardware engineering—that is, how we might design and build bug-free software. After all, no reputable hardware manufacturer would ship products known to have flaws, yet software developers do this routinely. Why?

Figure 1.1

Figure 1.1 Essential Steps in the Traditional Enterprise Software Development Process

One response is that software is intrinsically more complex than hardware because it has more states, or modes of behavior. No machine has 1,000 operating modes, but any integrated enterprise business application system is likely to have 2,500 or more input forms. Software complexity is conventionally described as proportional to some factor—say, N—depending on the type of program, times the number of inputs, I, multiplied by the number of outputs, O, to some power, P. Thus

software complexity = N*I*OP

This can be thought of as increasing with the number of input parameters but growing exponentially with the number of output results.

Computers, controlled by software, naturally have more states—that is, they have larger performance envelopes than do other, essentially mechanical, systems. Thus, they are more complex.

Although software engineering has become a popular subject of many books and is taught in many university computing curricula, we find the engineering/manufacturing metaphor to be a bit weak for software development. Most of a hardware product’s potential problems become apparent in testing. Almost all of them can be corrected by tuning the hardware manufacturing process to reduce product and/or process variability. Software is different. Few potential problems can be detected in testing due to the complexity difference between software and hardware. None of them can be corrected by tuning the manufacturing process, because software has no manufacturing process! Making copies of eight CD-ROMs for shipment to the next customer along with a box of installation and user manuals offers little chance for fine-tuning and in any case introduces no variability. It is more like book publishing, in which you can at most slip an errata sheet into the misprinted book before shipping, or, in the case of software, an upgrade or fix-disk.

So, what is the solution? Our contention is that because errors in software are almost all created well upstream in the design process, and because software is all design and development, with no true manufacturing component, everything that can be done to create bug-free software must be done as far upstream in the design process as possible. Hence our advocacy of Taguchi Methods (see Chapters 2, 15, and 17) for robust software architecture. Software development is an immensely more taxing process than hardware development. Although there is no silver bullet, we contend that the Taguchi Methods described in the next chapter can be deployed as a key instrument in addressing software product quality upstream at the design stage. Processes are often described as having upstream activities such as design and downstream activities such as testing. This book advocates moving the quality-related aspects of development as far upstream in the development process as possible. The RSDM presented in this book provides a powerful framework to develop trustworthy software in a time- and cost-effective manner.

This introductory chapter is an overview of the software development situation today in the view of one of the authors. Although he has been developing both systems and applications software since 1957, no single individual’s career can encompass the entire spectrum of software design and development possibilities. We have tried in this chapter to indicate when we are speaking from personal experience and sharing our personal opinions, and when we are referring to the experience of others.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020