Books 


Software Reuse: Architecture, Process and Organization for Business 
Success, Ivar Jacobson, Martin Griss, and Patrik Jonsson, Addison-Wesley 
Publishing Co., Reading, MA, 1997. 497 pp. (ISBN 0-201-92476-5). 

Software reuse is an approach to development that we all cite as a best 
practice but don't really understand how to do. We know its potential for 
improving quality and productivity, but there are few large-scale examples 
to show us how good reuse should work as a long-term strategy. Often, we 
institute a trial reuse program and hold our collective breath, hoping that 
we will see some benefit and wishing that reuse becomes common, 
well-accepted practice. 

Well, now we can breathe more easily. In their book, Software Reuse: 
Architecture, Process and Organization for Business Success, Jacobson, 
Griss, and Jonsson take a broad, business view, showing us what is 
necessary to make reuse successful. They have analyzed reuse programs good 
and bad, short- and long-term, large and small. By combining good business 
sense with an understanding of architecture and technology, they make a 
series of large- and fine-grained recommendations that can help each of us 
to understand not only what makes reuse work but why. 

The authors begin by explaining that reuse is not just a technology; it is 
a business practice, and it must be embedded in the larger business 
processes that your company or organization enacts. They debunk some of the 
more grandiose claims found in the literature, and propose instead that 
reuse be adopted in small steps, each of which builds on the previous ones: 

o Informal code reuse to reduce development time 
o Black-box code reuse to reduce maintenance costs 
o Managed work product reuse to broaden coverage 
o Architected reuse to achieve interoperability and high reuse levels 
o Domain-specific reuse to achieve rapid custom product development 

Each step requires additional investment, experience, and time, but yields 
larger benefits in terms of time-to-market, cost, and quality. 

The authors distill a great deal of experience into several rules of thumb. 
For example, they list several guidelines about reuse economics (p. 23): 

o A component has to be used three to five times in application projects 
  to recover the initial cost of creating it and the ongoing cost of 
  supporting it. 
o It costs 1.5 to 3 times as much to create and support a reusable 
  component as it does to implement a similar component for a single 
  application. 
o It costs only one-quarter as much to use a reusable component as to 
  develop a new one from scratch. 
o It takes two or three product cycles--usually about three years--before 
  the benefits of reuse become significant. 

Similarly, they give us guidance on organizational principles, such as 
(p. 27): 

o Maintain top-management leadership and financial backing over the long 
  term. 
o Plan and adapt the system architecture, the development processes, and 
  the organization to the necessities of reuse in a systematic but 
  incremental fashion. Start with small pilot projects and then scale up. 
o Move to an explicitly managed reuse organization that separates the 
  creation of reusable components from their reuse in application systems 
  and provides an explicit support function. 

Unlike other reuse books and papers whose guidelines focus on similarity, 
the ones in this book target understanding the variance among components. 
"If we made no provision for variance, we would have to resign ourselves to 
the burden of a very large number of 'concrete' component systems" (p. 39). 
Consequently, Jacobson, Griss, and Jonsson describe a reuse business 
composed of application family engineering, application system engineering, 
component system engineering, and managing the reuse business. Each of 
these major activities is discussed in great detail, acknowledging that 
each is done by different participants with very different audiences and 
goals. 

For example, architectural issues are discussed in terms of variability 
mechanisms that allow common functionality and structure to be expanded in 
a carefully controlled way. Chapter 5 tells us about variation points and 
"extends" constructs that allow us to design families of similar 
components. Object-orientation, while not a necessary condition for reuse, 
is used to provide a vocabulary for discussing notions of reusable 
architectures. 

The chapters on business process are particularly useful. Jacobson, Griss, 
and Jonsson explain how to do business process engineering and how to 
organize for reuse. They emphasize that you must understand your company's 
business and its needs, purpose, players, structures, and problems before 
you can begin to think about software-based solutions. 

The authors also discuss the important role of software measurement in 
understanding reusability and in tracking the effects of reuse in the 
software and in your business. They suggest that software reuse measurement 
is useful only when you first take the time to understand the underlying 
processes and business climate. And they emphasize that a great deal of 
up-front investment is necessary for reaping long-term benefits. 

Throughout the book, the authors use a common banking example to illustrate 
their concepts. Using this example, they show how a family of similar 
applications can be designed for reuse, and how a risk analysis is 
necessary for deciding among several technology options. In addition, 
Jacobson, Griss, and Jonsson cite examples from their own experiences at 
Ericsson, Hewlett-Packard, and Rational Software, as well as from 
mainstream developers such as Microsoft and ParcPlace to make their points. 
Each chapter ends with suggestions for additional reading; these references 
point not only to the software literature but also to the business 
literature that deals with successful technology transfer. 

There is a wealth of information in the book for all of the players 
involved in reuse: requirements analysts, designers, programmers, testers, 
managers, and business strategists. Each chapter tackles a different aspect
of reuse, and all blend together to provide the most comprehensive and 
useful picture of reuse that I have found. If you are thinking about 
starting a reuse program, this book is essential reading for helping you to
understand the important variables in your decision-making process. If you 
are working to understand or improve your existing reuse efforts, this book
helps to make more visible the key elements that lead to reuse success. And
if you are recovering from a failed reuse effort, this book is useful for 
analyzing what went wrong and why you should try again. 

                                       Shari Lawrence Pfleeger 
                                       Systems/Software, Inc. 
                                       Washington, D.C. 

Note--The books reviewed are those the Editor thinks might be of interest 
to our readers. The reviews express the opinions of the reviewers.