Pattern Languages of Program Design 3 - Softcover

Softcover

ISBN 10: 0201310112 ISBN 13: 9780201310115

Publisher: Addison-Wesley Professional, 1997

Synopsis

The third in a series of books documenting patterns for professional software developers, this volume continues the tradition of informational excellence established by the first two volumes. Pattern Languages of Program Design 3 differs from the previous two volumes in that it includes international submissions, gathering the best papers from both PloP 96 and EuroPLoP 96. It covers a wide range of pattern-related subjects, and patterns are arranged by topic so software engineers can easily select those of greatest relevance to their needs and application domains. This book goes beyond teaching software engineers that design patterns are powerful tools to impart understanding--it shows where and when patterns are best applied.

About this title

Review

The third book in a series, Pattern Languages of Program Design 3 discusses how to catalog software patterns, which are reusable, higher-order designs. This volume presents over two dozen white papers on newly "discovered" patterns within a wide variety of contexts. The editors have grouped these patterns by topic so you can choose what interests you. Each pattern profile features a short introduction to show you what each pattern might be good for.

"General purpose" design patterns include the Null Object, the Manager, and the Product Trader patterns, and another section improves on the Visitor pattern. These patterns allow classes to borrow the methods of other classes without using inheritance. Some of the most challenging patterns in this book are good for distributed processing, including Acceptor and Connector and Object Recovery. Basic research in object-oriented design (OOD) is apparent in the Serializer pattern, which implements persistence for objects, another unusually difficult aspect of object design to get right. Another useful section introduces "domain specific" patterns--or patterns that solve particular real-world problems--with several patterns for transportation systems and fire alarms.

The book closes with more esoteric explorations of patterns for developers, including patterns for effectively designing in teams and using software testing patterns. Judging from the rich selection of the ordinary and the bizarre, there seems to be no end in sight for the business of discovering patterns. For those interested in expanding their collection of patterns, this volume offers a fascinating array of new specimens.

From the Inside Flap

This is the third in the series of PLoPD books; and it represents something of a departure from the previous two. This is the first book in the PLoPD series in which fewer than half of the papers submitted at the corresponding PLoP conferences have been published. This is also the first PLoPD book in which papers from more than one conference have been published. There were over 80 papers submitted to PLoP '96 and EuroPLoP '96 and there was no way that we could publish them all. Therefore we had the unhappy task of deciding which of those papers not to publish. This task was not easy since all the papers submitted were of very high quality (Something we have come to expect from the PLoP conferences). Fortunately, our burden was lightened by all the folks who helped out with the review and selection process.

The process of creating this book.

We recruited a veritable army of reviewers, and each of the 80+ papers was reviewed by three of them. The reviewers' recommendations were then passed on to the three editors (Dirk Riehle, Frank Buschmann, and Robert Martin). Then began a rather long and heated exchange between us. None of us had any problem being choosy; and, indeed, the three of us settled on a large core of papers to be published. But there were a few papers that we did not agree upon. And thereupon laid the long and arduous process of defining the final contents of this book. None of us think that this book is perfect; but all of us think that it is a top-notch collection of superb papers.

What were our selection criteria? The choice of papers was constrained by our target audience: software engineers. First and foremost the papers in this volume had to be of interest to this audience. Although patterns about music are interesting to musicians, we did not think that they should be included here. Secondly, the papers had to be of practical value to our audience. Although papers of abstract theory are certainly interesting, we gave preference to papers that provided techniques or tools that would be of immediate use to our audience. Finally, the papers should be patterns. There were lots of good papers that were written about software engineering, but we gave preference to those that described patterns related to software engineering.

To be sure, these criteria were not unambiguously stated up front. Like all high quality projects, the requirements evolved during development. It was during the book definition process that we learned about each other's expectations and visions for the book. And it was during this process that our own expectations and visions were changed through discussion and argument. All in all, it was a very rewarding, if somewhat exhausting, experience.

In the spirit of Ralph Johnson's suggestion to catalog patterns as design specimens, just like biology catalogs and classifies its animal and non-animal specimens, we organized the book by topic. It comprises general design patterns as well as patterns for specific technical or business domains. It also contains patterns for designing user interfaces, and helping with software processes; it even contains a chapter with patterns for writing patterns. We did not distinguish between patterns and pattern languages, but focussed on putting together patterns by topic so that you can take a look and see whether these patterns are of interest to your needs and your application domains.

Design Patterns, a 1997 perspective.

It has been two years since the publication of the GoF book. During that time interest in design patterns has increased at a phenomenal rate. Today it is very unlikely that any serious software is ignorant of the concept of design patterns. There are major magazines that run regular columns about design patterns. The C++ Report runs a monthly section about design patterns. There are several other books by major authors that have been published on the topic of design patterns. All this indicates that the concept of design patterns is a significant event in the evolution of software engineering; and that it will continue to grow in significance for several years to come.

With this growth in awareness and significance comes a danger. It would be easy to switch our enthusiasm from the patterns themselves to the concept of patterns in general. This, in our opinion, would be a mistake. The use of well-worn design patterns in a given project can be of great benefit. But the force fit of lots of different patterns into the same project would be worse than useless. Just because a pattern exists, does not mean the pattern should be used. A particular pattern fits into a project when there is a problem to be solved, and when that pattern properly balances the forces that impinge upon that problem. One cannot justify the use of a particular pattern just because it is a pattern. For example, an engineer can not justify the use of the Visitor pattern simply because it is a pattern in the GoF book. Design patterns are tools to be used by engineers who understand where and when those tools are best applied.

Where are your weapons?

Dr. Who is an old English science fiction television series. In the episode entitled "Hand of Destiny" a silicon based life-form is escorted into the Tardis (Dr. Who's space ship. An acronym which stands for: Time And Relative Dimensions In Space) by the Doctor. The life form looks around and exclaims: "Impressive! But where are its weapons?" The Doctor stares the silicon based life form right in the eyes, points at his temple, and says: "Here!"

Once one of us (Robert) spoke at a conference in Chicago to a rather large audience regarding design patterns. He asked all of them who had purchased the GoF book to raise their hands. About 80% of the hands went up. Then he asked everyone who had not read what they had bought to put their hands down. About half the hands went down. Then he asked everyone who could not explain the Visitor pattern to put their hands down. Nearly all the hands went down.

The patterns in this book, or in any of the excellent patterns books that have been published since 1995, do you no good if they remain in the book. They have to get into your head for them to be of real use. Some folks like to think that they can use the various patterns books as a catalog in which to look up solutions when they have problems; but this is not likely to be an effective practice. Instead, you must study the patterns and integrate them into your mental model of software design. Then, when you are designing software, the patterns will present themselves before you even know you have a design problem.

So read the patterns. Read them carefully. Make sure your weapons for attacking software design are firmly ensconced within your brain.

Acknowledgements

First of all, a very special thanks to the Hillside group for sponsoring the PLoP conferences, and for providing the motive force for these books. Without their effort and dedication there might not be any PLoPD books at all.

Thanks to Doug Schmidt whose sanity is contagious.

Thanks to Jim Coplien (cope) who reminded us that our work has a moral, as well as technological, imperative.

Thanks to John Vlissides, the series editor, for keeping his hand on the tiller while the storm raged.

Thanks to Walter Tichy for keeping us humble.

Finally, from Bob a personal thanks to Dirk Riehle and Frank Buschmann for keeping him from bouncing too far off the wall.

We would also like to thank all the authors who submitted papers to PLoP and EuroPLoP '96, the shepherds who helped guide those papers to the conference, and the reviewers who helped the editors make the hard choices. Their names follow:

Alan O'Callaghan, Alejandra Garrido, Alistair Cockburn, Amiram Yehudai, Amnon H. Eden, Amund Aarsten, Andreas R¸ping, AntÛnio Rito Silva, Becky Fletcher, BenoÓt Garbinato, Bernd-Uwe Pagel, Bindu Rama Rao, Bjˆrn Eiderb‰ck, Bobby Woolf, Bran Selic, Brian Foote, Bruce Anderson, Bruce Lombardi, Charles D. Knutson, Charles Weir, Chris Cleeland, Chrystalla C. Alexandrou, Clazien Wezeman, Curtis R. Cook, D Janaki Ram, D. Schwabe, Daniel A. Rawsthorne, Daniel Megert, David E. DeLano, Davide Brugali, Dirk B‰umer, Don Roberts, Douglas C. Schmidt, Edward J. Posnak, Elizabeth A. Kendall, Erich Gamma, Eugene Wallingford, Eyun Eli Jacobsen, Fernando das Neves,

G. Rossi, George A. Papadopoulos, Gerard Meszaros, Giuseppe Menga, Hans Rohnert, Harrick M. Vin, Heinz Z¸llighoven, Ilir Kondo, Irfan Pyarali, James Noble, Jan Newmarch, Jean Tessier, Jean-Lin Pacherie, Jean-Marc JÈzÈquel, Jens Coldewey, Jim Doble, Jim Lee, Jo„o Pereira, John Brant, John Vlissides, John W. Gilbert, JosÈ Alves Marques, Joseph Gil, Joseph Yoder, K N Anantha Raman, K N Guruprasad, Ken Auer, Kent Beck, Kyle Brown, Lennart Ohlsson, Leonor Barroca, Linda Rising, Lipling Zhao, Lizette Vel·zquez, Lorraine L. Boyd, Margaret T. Malkoun, Mario Winte

Edition details

• Publisher: Addison-Wesley Professional
• Publication date: 1997
• ISBN 10: 0201310112
• ISBN 13: 9780201310115
• Binding: Paperback
• Language: English
• Edition number: 1
• Number of pages: 632
• Editor: Martin Robert C., Riehle Dirk, Buschmann Frank