For 50 years we've been developing a science and practice of software based on understandings and explorations of software systems of modest size-centering on systems of a few tens of thousands of lines of code but extending up to about 50 million lines. Scale makes a difference: scale of time and of size. The prospect of ultra large scale software systems-systems with perhaps trillions of lines of code encompassing millions of processors, ranging from sensors the size of dust to the largest servers, with much of it with real-time requirements-will change everything. Imagine, if you can, how such systems will be made. Can they truly be said to be designed at all? The realities of such systems will force us to re-examine the very foundations of computing and software engineering; our concepts of abstraction, modularity, information hiding, pure static typing, and many other things will need to be refined, expanded, or reformulated. Consider, further, that such systems in normal circumstances cannot be routinely re-installed nor globally rebooted, and when used in life-critical situations, they must not stop. Data must be readable and usable for decades, even as standards and hardware changes.

This talk will examine the nature of such systems, especially how they are designed, built, and what is needed to keep them running. We'll take both a philosophical and technical look at some of the aspects of ultra large scale software that make us need to revise our foundations and what those revisions will be like.

Richard P. Gabriel is a Distinguished Engineer at IBM Research, looking into the architecture, design, and implementation of extraordinarily large, self-sustaining systems. He is the award-winning author of four books and a poetry chapbook. He lives in California.

The chimpanzees and the bonobos are the animals whose genetic make-up is closest to that of human beings, but their ""cultures"" (and, yes, these animals definitely have well-defined cultures) are very different. The chimpanzees are aggressive, and operate in a strict, alpha-male-dominated hierarchy, while the bonobos are gentle and promiscuous! What sort of tie-could this have for those of us who favor agile development over plan-driven?

Linda Rising has a Ph.D. from Arizona State University in the field of object-based design metrics and a background that includes university teaching and industry work in telecommunications, avionics, and strategic weapons systems. An internationally known presenter on topics related to patterns, retrospectives, agile development approaches, and the change process, Linda is the author of numerous articles and four books---Design Patterns in Communications, The Pattern Almanac 2000, A Patterns Handbook, and Fearless Change: Patterns for Introducing New Ideas, written with Mary Lynn Manns. Find more information about Linda at www.lindarising.org.

Several books document parts of the emerging standard architectural style for building enterprise computing systems using OO technology. Martin Fowler's book "Patterns of Enterprise Application Architecture" is the most well-known, but Eric Evan's "Domain Driven Design" describes some key aspects of this style that Martin Fowler does not describe, and is closely related. Both of these books emphasize the importance of the domain model, but neither describe the patterns of the domain model. These patterns are described in other books, such as Fowler's "Analysis Patterns", Silverston's "The Data Model Resource Book" and Hay's "Data Model Patterns". This talk will show how these books are related and what is still missing to document the architectural style of building enterprise applications based on object-oriented domain models.

Ralph Johnson is Research Associate Professor at the University of Illinois at Urbama-Champaign. He is one of the four co-authors of "Design Patterns" and the conference chair of the first PLoP. He has been to every PLoP since, in large part because they have been close to his home and organized by his students and ex-students. He is an editor of the new Transactions on Pattern Languages of Programming and will be twisting arms at PLoP to get people to help.