Some Programming Principles: Products



Watts S. Humphrey

This library item is related to the following area(s) of work:

Process Improvement

This article was originally published in News at SEI on: March 1, 2003

This is the second in a series of columns on programming principles. The first column discussed those principles that relate to program requirements and why requirements must change throughout the development process. The conclusion was that we must use development processes that recognize the inevitability of requirements changes and that will work effectively even in the face of frequent and often substantial changes. In this column, I review those product-related principles that govern our work in developing software-intensive systems and the unique challenges we face in doing software work.

The Nature of Computer Programs

Computer programs are fundamentally different from other types of products. Software doesn’t wear out, rot, or deteriorate. Once a program works and as long as its operating conditions remain the same, it will continue to work indefinitely. Software products can be reproduced for essentially nothing and distributed worldwide in seconds. From a business perspective, software is almost an ideal product. It is the most economical way to implement most logic and it is the only way to implement complex logic. As an intellectual product, software can be legally protected almost indefinitely and this makes software products potentially very profitable. These basic software characteristics provide great opportunities. However, they also present us with six major challenges. To properly address these challenges, we must substantially change the way we do our work and the methods we use to run our projects.

The First Challenge: Software Work Is Intellectual

Because software work is intellectual and our products are intangible, we cannot easily describe what we do or demonstrate our results. This makes it extremely difficult for non-software people to manage software groups or even to understand what we do. As more people get involved with and become knowledgeable about software, this will be less of a problem. However, today, few customers, managers, or executives have an intuitive feeling for the software business. The problem is that you can’t touch, see, or feel software. When we tell them that the product is nearly ready to ship, they have no real appreciation for what we are saying. We can’t take them out into the laboratory and show them the first software model being assembled, describe which parts must be added before final test, or show them parts being welded, machined, or painted.

The problem here is trust. Businesses run on trust, but many managers follow the maxim: “Trust but verify.” Unfortunately, with software, management can only verify what we say by asking another software person who they hope is more trustworthy. Since we typically don’t have any way to prove that what we say is true, management can only tell if we are telling an accurate story by relating what we currently tell them with what we have said before and how that turned out. Unfortunately, the abysmal history of most software operations is such that very few if any software developers or managers have any credibility with their more senior management.

The result is a critical challenge for the software community: we work in an environment where senior management doesn’t really believe what we tell them. This means that, almost invariably, management will push for very aggressive development schedules in the hopes that we will deliver sooner than we otherwise would. To maintain this schedule pressure, management is not very receptive to pleas for more time. Furthermore, even when we break our humps and actually deliver a product on the requested schedule, management isn’t very impressed. After all, that is only what we said we would do. Other groups do that all the time.

The Second Challenge: Software Is Not Manufactured

Because software can be reproduced automatically, no manufacturing process is required. This means that there is no need for a manufacturing release process and therefore that there is no external process to discipline our design work. When I used to run systems development projects, the hardware had to be manufactured in IBM’s plants. Before I could get a cost estimate signed off or get a price and product forecast, I needed agreement from the manufacturing and service groups. This required that the product’s design be released to manufacturing. In this release process, the manufacturing engineers reviewed the design in great detail and decided whether or not they could manufacture the product for the planned costs, in the volumes required, and on the agreed schedules. We also had to get service to agree that the spare parts plan was adequate, that the replacement rate was realistic, and that the service labor costs were appropriate.

As you might imagine, release-to-manufacturing meetings were extremely detailed and often took several days. The development engineers had to prove that their designs were complete enough to be manufactured and that the cost estimates were realistic and accurate. While these release meetings were grueling and not something that the development engineers enjoyed, once you passed one, you had a design that the manufacturing people could build and everybody knew precisely where your program stood.

Unfortunately, software development does not require such a release process. The consequence is that design completion is essentially arbitrary and we have no consistent or generally-accepted criteria that defines what a complete design must contain. The general result is poor software-design practices, incomplete designs, and poor-quality products. The challenge here is that, without any external forces that require us to use disciplined design practices, we must discipline ourselves. This is difficult in any field, but especially for software, since we have not yet learned how to reliably and consistently do disciplined software work.

The Third Challenge: The Major Software Activities Are Creative

Because software can be reproduced automatically, a traditional manufacturing process is not required and no manufacturing resources are needed. This is a major change from more traditional products where the manufacturing costs are often more than ten times the development expenses. In software, the principal resources are development and test. This mix imposes a new set of demands on management: they must now learn to manage large-scale intellectual work.

In the past, large-scale activities have generally concerned military operations or manufacturing processes. Typically, large numbers of people have been needed only for repetitive or routine activities like reproducing already-designed products. In software, large-scale efforts are often required to develop many of the products. In directing large numbers of people, management has typically resorted to autocratic methods like unilaterally establishing goals, setting and controlling the work processes, and managing with simplistic measures. The problem here is that large-scale intellectual work is quite different from any other kind of large-scale activity. Autocratic practices do not produce quality intellectual work and they are counterproductive for software. In fact, such practices often antagonize the very people whose creative energies are most needed.

To address this challenge, management must understand the problem and they must also get guidance on what to do and how to do it. While the proper management techniques are not obvious, they are not very complex or difficult. And once they are mastered, these management techniques can be enormously effective.

The Fourth Challenge: Software Lives Forever

Because software essentially lives forever, product managers face an entirely new and unique set of strategic issues. For example, how can they continue to make money from essentially stable products, and what can they do to sustain a business in the face of rampant piracy? The problem is that immortal products that can be reproduced for essentially nothing will soon lose their unique nature and cease to be protectable assets. While this is not a severe problem when the software is frequently enhanced, once products stabilize, they will be exceedingly hard and often impossible to protect, at least for anything but very short periods.

This may not seem like a serious problem today, but it soon will be. A large but ultimately limited number of basic functions will be required to provide future users with a stable, convenient, accessible, reliable, and secure computing capability. While such functional needs have evolved rapidly over the last 50 years, the rate of change will inevitably slow. This fact, coupled with the users’ growing needs for safety, security, reliability, and stability, will require that the rate of change for many of our products be sharply reduced. This in turn will make it vastly more difficult to protect these products.

The reason that this is important to programmers is that if the uniqueness of our products cannot be protected, our organizations will be unable to make money from the products we produce. They will then no longer be able to pay us to develop these products.

Lest this prediction sound too dire, the programming business will not wither away. I am only suggesting that the part of the programming business that provides basic system facilities will almost certainly have to change. On the other hand, I cannot visualize a time when application programming will not be a critical and valuable part of the world economy. In fact, I believe that skilled application programming will become so important that the programming profession as we now know it will no longer exist: every professional will have to be a skilled application programmer.

The Fifth Challenge: Software Provides Product Uniqueness

Because software contains the principal logic for most products, it provides the essential uniqueness for those products. This means that the software’s design is an essential product asset and that the key to maintaining a competitive product line is maintaining a skilled and capable software staff. This is an entirely new consideration for a management group that has viewed software as an expense to be limited, controlled, and even outsourced, rather than as an asset to be nurtured, protected, and grown. The pressure to limit software expenses is what caused IBM to lose control of the PC business. Management was unwilling to devote the modest resources needed to develop the initial PC software systems. This gave Bill Gates and Microsoft the opportunity to replace IBM as the leader of the software industry.

As software becomes a more important part of many products, whole industries are likely to lose control of their products’ uniqueness. This control will be in the hands of the programmers in India or China or whoever else offered the lowest-cost bids for outsourcing the needed software work. In effect, these industries are paying their contractors to become experts on their products’ most unique features. Ultimately, these contractors will very likely become their most dangerous competitors. Over time, these industries may well find themselves in a position much like IBM’s in the PC business: manufacturing low-profit commodity-like hardware to run somebody else’s high-margin software.

The Sixth Challenge: Software Quality is Critical

Because software controls an increasing number of the products we use in our daily lives, quality, safety, security, and privacy are becoming largely software issues. These increasing quality needs will put enormous pressure on software businesses and on software professionals. The reason is that software safety, security, and privacy are principally software design issues. Without a complete, fully-documented, and competently reviewed design, there is practically no way to ensure that software is safe, secure, or private. This is a problem of development discipline: since we don’t have to release our products to a manufacturing or implementation group, there is no objective way to tell whether or not we have produced a complete and high-quality design.

This development discipline problem has several severe consequences. First, it has never been necessary for software people to define what a complete software design must contain. This means that most software engineers stop doing design work when they believe that they know enough to start writing code. However, unless they have learned how to produce complete and precise designs, most software engineers have only a vague idea of what a design should contain.

With the poor state of software design and the growing likelihood of serious incidents that are caused by poor-quality, insecure, or unsafe software, we can expect increased numbers of life-critical or business-critical catastrophes. It won’t take many of these catastrophes to cause a public outcry and a political demand for professional software engineering standards. This will almost certainly lead to the mandatory certification of qualified software engineers. Then, the challenge for us will be to determine what is required to be a qualified software engineer and how such qualification can be measured.


Since we have been living with all of these problems for many years, you might ask why we should worry about them now. The reason is that the size and scope of the software business has been growing while software engineering practices have not kept pace. As the scale and criticality of software work expands, the pressures on all of us will increase. Until we learn to consistently produce safe, secure, and high-quality software on predictable schedules, we will not be viewed as responsible professionals. As the world increasingly depends on our work, we must either learn how to discipline our own practices or expect others to impose that discipline on us. Unfortunately, in the absence of agreed and demonstrably effective standards for sound software engineering practices, government-imposed disciplines will not likely be very helpful and they could even make our job much more difficult.


In writing papers and columns, I make a practice of asking associates to review early drafts. For this column, I particularly appreciate the helpful comments and suggestions of Marsha Pomeroy-Huff, Bill Peterson, and Alan Willett.

In closing, an invitation to readers. . .

In these columns, I discuss software issues and the impact of quality and process on engineers and their organizations. However, I am most interested in addressing the issues that you feel are important. So, please drop me a note with your comments, questions, or suggestions. I will read your notes and consider them when planning future columns.

Thanks for your attention and please stay tuned in.

Watts S. Humphrey

1 See my book, Winning with Software: an Executive Strategy. Reading, Mass., Addison Wesley, 2002.

About the Author

Watts S. Humphrey founded the Software Process Program at the SEI. He is a fellow of the institute and is a research scientist on its staff. From 1959 to 1986, he was associated with IBM Corporation, where he was director of programming quality and process. His publications include many technical papers and several books. His most recent books are Introduction to the Team Software Process (2000) and Winning With Software: An Executive Strategy (2002). He holds five U.S. patents. He is a member of the Association for Computing Machinery, a fellow of the Institute for Electrical and Electronics Engineers, and a past member of the Malcolm Baldrige National Quality Award Board of Examiners. He holds a BS in physics from the University of Chicago, an MS in physics from the Illinois Institute of Technology, and an MBA from the University of Chicago.

The views expressed in this article are the author's only and do not represent directly or imply any official position or view of the Software Engineering Institute or Carnegie Mellon University. This article is intended to stimulate further discussion about this topic.

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