The record of most development groups is poor, but the record of software groups is particularly bad. The Standish Group reports that more than half of all software projects are seriously late and over budget, and that nearly one-quarter of them are cancelled without being finished. 1 Under 30% of the projects were considered successful. Most of the software developers I know are well aware of these problems and can even explain their causes: unrealistic schedules, inadequate resources, and unstable requirements. Although these problems are common and not hard to solve, few developers know how. It is tempting to blame others for our difficulties, but a victimlike attitude doesn't solve problems. When you approach these software management problems in the proper way, you can generally solve them. However, this requires skills and practices that you may not have learned. It also requires dealing with management on management's terms. You can gain the required practices with the Personal Software Process (PSP). 2 This book describes the PSP and explains the practices and methods you will need to deliver quality products on predictable schedules. After learning these skills, you will be qualified to participate on a team that uses the Team Software Process (TSP). Such teams are called self-directed because they define their own working practices and negotiate their plans and schedules with management. The final chapter of the book describes the TSP and how it helps to put you in charge of your own work. Being a Software Engineer An engineer is someone who knows how to consistently and predictably do quality work. Many of the states in the United States have regulations governing the practice of engineering and they do not allow people to call themselves engineers unless they have demonstrated competence in their professional specialty. Most engineering fields were originally established because the public demanded protection from unqualified work, particularly in building construction, steam power plants, and the like. Without such licensing, steam boilers frequently exploded and bridges collapsed. Although licensing did not magically solve all of these problems, it has been a big help. Licensed engineers use known and proven methods, they are tested to ensure that they consistently do quality work, and they are required to demonstrate their competence at producing safe products. The difference between a licensed engineer and any other technical worker is that the engineer knows the proper ways to do his or her job and is required by law to work that way regardless of management, customer, or other pressures. If we are to call ourselves engineers, we must learn to produce quality products on predictable schedules. This requires that we learn how to consistently meet our commitments and that we know how to handle the normal challenges of creative development work. Software development is the most challenging professional occupation I know of and we must all consistently use the best available methods to meet our management's and our customers' needs. Quality Problems Poor quality management causes many of today's software problems. Most software professionals spend nearly half of their time testing and fixing their products during development and final testing. Poor quality also leads to schedule problems, with defective products delivered long after they were committed. Although fixing a few defects may seem inconvenient, even fairly small programs can have hundreds of defects, and finding and fixing them can take many weeks or even months. Software quality starts with the individual developer. If any of the program modules that we develop have numerous defects, they will be hard to test, take time to integrate into larger systems, and be troublesome for our users. Most of us can be highly productive when writing very small programs. However, our productivity falls off sharply when we develop larger programs. Although developing bigger systems involves some added architectural and design work, most of the added effort is caused by defects. The average amount of time it takes to find and fix each defect increases exponentially as programs become larger. However, if you can consistently write high-quality module-size programs, you will produce better products and improve your and your organization's productivity. A disciplined software engineering process includes effective defect management, comprehensive planning, and precise project tracking and reporting. This book shows you how to use these disciplines to do better development work as an individual and as a TSP team member. It also shows why these practices are essential if you want to manage your own work. The Benefits of Being a Software Engineer As our lives increasingly depend on software, the demands for safety, security, and quality will only increase. This means that the demand for capable software professionals will also increase. Unfortunately, few software developers have any way to distinguish themselves from the many programmers who bang out poor-quality code. With PSP training, you can apply to the Software Engineering Institute to become a PSP-certified software professional. This will distinguish you from the many developers who have no unique qualifications. PSP training will also qualify you to participate on a TSP team, and PSP certification will assure potential employers that you are a professional who is capable of producing high-quality software for predictable costs and on committed schedules. Other personal benefits of PSP certification are the added recognition of being a skilled software professional and easier access to more responsible and higher-paying positions. Developers with such qualifications are now widely sought and will be increasingly needed in the future. Who Should Learn the PSP? Modern technical work involves many specialties, and the people who participate in developing modern products and systems now come from a wide range of disciplines. To produce quality products on predictable schedules, all of the work that these people do must be planned, managed, and quality-controlled. This means that just about everyone associated with system development must know how to do disciplined engineering work. It also means that just about anyone doing such work would benefit from learning the PSP. Although the examples and exercises in this book concern developing small programs, this is only because, even for small programs, software development is a marvelously rich process that can be measured and analyzed. This makes the software process particularly suitable for teaching disciplined engineering practices. Most modern professionals in almost any technical field now learn to write programs during their education, so the PSP course is appropriate for almost anyone planning an engineering or technical career, and it is particularly appropriate for anyone planning to work in product or system development. The Approach Taken by This Book With the growing importance of software and software products, organizations will increasingly need software engineers who consistently use disciplined personal practices. To meet this need, we must learn and consistently practice these disciplines with every program we write. If we don't use sound development practices when writing module-size programs, there is little chance that we will use them when writing large programs. When students start to program, they generally begin by learning a programming language. They practice on toy problems and develop the personal skills to deal with issues at this toy level. As they take more courses, they build their personal skills and can soon develop fairly large programs relatively quickly. These programming-in-the-small skills, however, are inherently limited. Although they may suffice on small-scale individual tasks, they do not provide an adequate foundation for solving the problems of large-scale, multiperson, distributed project teams. This book follows a fundamentally different strategy. It scales down industrial software practices to fit the needs of module-size program development. It then walks you through a progressive sequence of software processes that provide a sound foundation for large-scale software development. By doing the exercises and using the methods described in this book, you will learn how to use the methods for yourself. Once you have learned and used these practices on module-size programs, you will have the skills to use them on larger projects. Although some additional requirements, design, implementation, and testing methods are needed for developing large programs, the basic software engineering disciplines taught by this book apply directly to large-scale system development. The reason, of course, is that large systems are built from collections of program modules that are much like the programs you develop in the PSP course. The principal goal of this book is to guide you in developing the personal software engineering skills that you need to perform at your very best. Consider the challenge of improving personal performance. In sports, for example, runners know the length of the track, their personal time, their fastest time, and the record time for each event. With proper coaching and guidance, they learn their personal strengths and weaknesses and see how to improve. In software, without clear performance measures, few of us can understand our personal strengths and weaknesses or see how to improve. The methods in this book will help you to assess your own performance, to identify ways to improve, and to guide your improvement efforts. In addition to helping you improve your personal performance, this book will also help you build the engineering skills needed for large-scale software work. You will learn how to make accurate plans, how to estimate the accuracy of these plans, and how to track your performance against them. You will use defect management, design and code reviews, design templates, and process analysis. You will do th...