This essay is the entire chapter 5 of the second volume of Exploring Requirements.
The book can be purchased as a single volume, or volumes 1 and 2 as a bundle, or as part of the People Skills bundle. It's also available from various vendors with both volumes as one bound book.
The Book of Life begins with a man and woman in a garden. It ends with Revelations.—Oscar Wilde, A Woman of No Importance
25.1 The Fear of Ending
The requirements process begins with ambiguity. It ends not with revelations, but with agreement. More important, it ends.
But how does it end? At times, the requirements process seems like Oscar Wilde when he remarked, "I was working on the proof of one of my poems all the morning and took out a comma. In the afternoon, I put it back again."
A certain percentage, far too large, of development efforts never emerge from the requirements phase. After two, or five, or even ten years, you can dip into the ongoing requirements process and watch them take out a comma in the morning and put it back again in the afternoon. Far better the comma should be killed during requirements than allowed to live such a lingering death.
Paradoxically, it is the attempt to finish the requirements work that creates this endless living death. The requirements phase ends with agreement, but the requirements work never ends until the product is finished. There simply comes a moment when you decide you have enough agreement to risk moving on into the full design phase.
25.2 The Courage to End It All
Nobody can tell you just when to step off the cliff. It's simply a matter of courage. Whenever an act requires courage, you can be sure that people will invent ways of reducing the courage needed. The requirements process is no different, and several inventions are available to diminish the courage needed to end it all.
25.2.1 Automatic design and development
One of the persistent "inventions" to substitute for courage is some form of automatic design and/or development.
In automatic development, the finished requirements are the input to an automatic process, the output of which is the finished product. There are, today, a few simple products that can be produced in approximately this way. For instance, certain optical lenses can be manufactured automatically starting from a statement of requirements.
In terms of the decision tree, automatic development is like a tree with a trunk, one limb, no branches or twigs, and a single leaf (Figure 25-1). With such a system, finishing requirements is not a problem. When you think you might be finished, you press the button and take a look at the product that emerges. If it's not right, then you weren't finished with the requirements process.
Figure 25-1. Automatic development is like a tree with a trunk, one limb, no branches or twigs, and a single leaf.
No wonder this appealing dream keeps recurring. It's exactly like the age-old story of the genie in the bottle, with no limit on the number of wishes. For those few products where such a process is in place, the only advantage of a careful requirements process is to save the time and money of wasted trial products. If trial products are cheap, then we can be quite casual about finishing requirements work.
Automatic development is, in effect, nothing but requirements work—all trunk and limb. At the other end of the spectrum is hacking, development work with no explicit requirements work. When we hack, we build something, try it out, modify it, and try it again. When we like what we have, we stop. In terms of the decision tree model, hacking is not a tree at all, but a bush: all branches, twigs, and leaves, with no trunk or major limb (Figure 25-2).
Figure 25-2. Hacking is not a tree at all, but a bush—all branches, twigs, and leaves, with no trunk or major limb.
Pure hacking eliminates the problem of ending requirements work, because there is no requirements work. On the other hand, we could conceive of hacking as pure requirements work—each hack is a way of finding out what we really want.
Almost any real project, no matter how well planned and managed, contains a certain amount of hacking, because the real world always plays tricks on our assumptions. People who abhor the idea of hacking may try to create a perfect requirements process. They are the very people who create "living death" requirements processes.
25.2.3 Freezing requirements
Paradoxically, hacking and automatic development are exactly the same process from the point of view of requirements. They are the same because they do not distinguish requirements work from development. Most real-world product development falls somewhere between pure hacking and automatic development, which is why we have to wrestle with the problem of ending.
Even when we have every requirement written down in the form of an agreement, we cannot consider the requirements process to be ended. We know those agreements will have to change because in the real world, assumptions will change. Some people have tried to combat their fear of changing assumptions by imposing a freeze on requirements. They move into the design phase with the brave declaration,
No changes to requirements will be allowed.
Those of us who understand the nature of the real world will readily understand why a freeze simply cannot work. We know of only one product development when it was even possible to enforce the freeze. In that instance, a software services company took a contract to develop an inventory application for a manufacturer. The requirements were frozen by being made part of the contract, and eighteen months later, the application was delivered. Although it met all the contracted requirements, the application was rejected.
This frozen product was totally unusable because in eighteen months it had become totally removed from what was really required in the here-and-now. The customer refused to pay, and the software services company threatened legal action. The customer pointed out how embarrassing it would be to a professional software company to have its "freeze fantasy" exposed in a public courtroom.
Eventually, the two parties sat down to negotiate, and the customer paid about one-fourth of the software firm's expenses. At the end of this bellicose negotiation, someone pointed out how with far less time negotiating, they could have renegotiated the requirements as they went along, and both parties would have been happy.
25.2.4 The renegotiation process
The freeze idea is just a fantasy, designed to help us cope with our fear of closure. But we cannot fearlessly close the requirements phase unless we know there is some renegotiation process available. That's why agreeing to a renegotiation process is the last step in the requirements process.
Working out the renegotiation process is also a final test of the requirements process itself. If the requirements process has been well done, the foundation has been laid for the renegotiation process. The people have all been identified, and they know how to work well together. They have mastered all the techniques they will need in renegotiation, because they are the same techniques the participants needed to reach agreement in the first place.
25.2.5 The fear of making assumptions explicit
The agreement about renegotiation must, of course, be written down, and this act itself may strike fear in some hearts. Another way to avoid ending requirements is to avoid written agreements at the end of the requirements phase. Some designers are afraid of ending requirements because the explicit agreements would make certain assumptions explicit. An example may serve to make this surprising observation more understandable.
While working with the highway department of a certain state, we encountered the problem of what to do about a particularly dangerous curve on one of the state highways (see Figure 25-3). In an average year, about six motorists missed the curve and went to their death over a cliff. Because it was a scenic highway, it was neither practical nor desirable to eliminate the curve, but highway design principles indicated that a much heavier barrier would prevent wayward cars from going over the cliff.
Figure 25-3. What should be done about this dangerous curve?
Building the barrier seems an obvious decision, but there was another factor to consider. Perhaps once every three years, with a heavy barrier in place, one of these wayward cars would bounce off the barrier into a head-on collision with an oncoming vehicle. The collision would likely be fatal for all involved.
Now, on average, the number of people killed with the barrier in place would be perhaps one-fifth of those killed without the barrier, but the highway designers had to think of another factor. When a solo driver goes over the cliff, the newspapers will probably blame the driver. But what if a drunk driver bounces off the barrier and kills a family of seven who just happened to be driving in the wrong place at the wrong time? The headlines would shout about how the barrier caused the deaths of innocent people, and the editorials would scream for heads to roll at the highway department.
So, it's no wonder the highway engineers didn't want anything documented about their decision not to build the barrier. They were making life-and-death decisions in a way that covered their butts, and they could protect themselves by taking the position, "If I never thought about it, I'm not responsible for overlooking it in the design." And, if it was never written down, who could say they had thought of it?
25.3 The Courage to Be Inadequate
Most engineers and designers react to this story by citing similar stories of their own to prove, yes, indeed, there are decisions it's better not to write down. We believe, however, this kind of pretense is an abuse of professional power, an abuse not necessary if we remember the proper role of the requirements process.
It's not for the designers to decide what is wanted, but only to assist the customers in discovering what they want. The highway designers should have documented the two sides of the issue, then gone to the elected authorities for resolution of this open requirements question. With guidance from those charged with such responsibilities, the engineers could have designed an appropriate solution.
But suppose the politicians came back with an impossible requirement, such as,
The highway curve must be redesigned so there will be no fatalities in five years.
Then the engineers would simply go back to their customers and state they knew of no solution that fit this requirement, except perhaps for a barricade preventing cars from using the highway. Yes, they might lose their jobs, but that's what it means to be a professional—never to promise what you know in advance you can't deliver.
The purpose of requirements work is to avoid making mistakes, and to do a complete job. In the end, however, you can't avoid all mistakes, and you can't be omniscient. If you can't risk being wrong—if you can't risk being inadequate to the task you've taken on—you will never succeed in requirements work. If you want the reward, you will have to take the risk.