About the Technology

From Croquet Consortium

Contents 1 Overview 2 Quotes 3 History of Croquet 3.1 Original Architects 3.2 Origins 4 Related Projects 4.1 Squeak 4.2 OpenGL 4.3 OpenAL 5 Selected Papers/Publications

Overview

Croquet is a powerful new open source software development environment for creating and deploying deeply collaborative multi-user online applications on multiple operating systems and devices. Derived from Squeak, it features a peer-based network architecture that supports communication, collaboration, resource sharing, and synchronous computation between multiple users on multiple devices. Using Croquet, software developers can create and link powerful and highly collaborative cross-platform multi-user 2D and 3D applications and simulations - making possible the distributed deployment of very large scale, richly featured and interlinked virtual environments.

Croquet is a system to synchronize identical simulations running on a distributed set of machines - so our goal is for the same thing to happen on all the machines participating in a shared, replicated space. Objects interact in croquet shared spaces by scheduling messages for future execution. The scheduling mechanism hands future-send messages off to the message router process where they are timestamped and broadcast to all participants.

On receipt of the timestamped message at a participant it is executed. If a side effect of the execution of a message was to store data - then all of the participants would write the same data for a local file. This makes it straightforward to record all interactions in a shared Croquet space - either message router or a participant add a "write timestamped messages to a file" step and generate a transcript of all object interactions. But this does nothing to simplify access to external data or metadata - Croquet is entirely about synchronizing simulations - and virtual worlds/meeting places are fundamentally simulations.

Quotes

"We've seen very few large-scale information environments recently that stretch our thinking beyond the model of the worldwide web. Croquet, however, is one such development; it integrates high end three dimensional sound and graphics, collaboration technologies, simulations and other tools to create a powerful shared space for the creation, use, and re-use of digital content. I believe that this project is important for three reasons: for what it offers directly; for the way it can expand our thinking about new information, collaboration and learning environments; and for what it can teach us about how to design new and innovative software environments that build upon, rather than directly compete with, the existing information infrastructure."

- Clifford Lynch, Director of the Coalition for Networked Information (CNI).

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"Croquet is a first in many ways. It represents a major step in our vision of computation as a communications platform and service, available anytime, anywhere, from any device. Soon, Croquet will run on everything, from a PDA through a set-top box; persistent Croquet worlds will be ubiquitous on the Internet, routed intelligently to each user through computational services overlays like PlanetLab. This will change the way people think about software and computation, from today’s device-oriented perspective to a perspective of computation as a persistent, pervasive, service."

- Patrick Scaglia, Vice President and Chief Technology Officer, Imaging and Printing Group at HP.

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"Croquet's computing model is considerably more simple, safe and powerful than current day practice. This means that bigger projects can be safely done by fewer computerists at much lower cost for both development and life-cycle maintenance."

- Alan Kay, President of Viewpoints Research Institute, Inc., winner, 2004 Draper Prize, Turing Award, and Kyoto Prize.

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"I find two aspects of Croquet particularly interesting: One is the underlying time-based computational model that Dave Reed is working on, and the other thing is the idea of providing an immersive, shared, scalable 3D environment. What Dave’s work is doing in Croquet is developing the infrastructure to build a scalable 3D environment – when you look at 3D games now, they have a scaling problem – Dave's time computation work enables that and other applications. These ideas are now motivating some of my work in the X Window System."

- Jim Gettys, primary developer of the X Window System.

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"Once you see this you realize a new kind of computing experience is coming."

- Robert Scoble, Scobleizer - Tech Geek Blog.

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“… truly mind opening.”

- Mark Prensky, Noted technology futurist, educational software developer, and author. MarkPrensky.com.

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"Croquet packs a lot of power for a little piece of software."

- Quentin Hardy, Forbes.com.

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"It's exciting to get an early glimpse of an emerging technology from another branch of the evolutionary tree. That's how I would characterize the Open Croquet Project, the most innovative-and most difficult to describe-technology I've seen all year."

- Marshall Breeding, Director for Innovative Technologies and Research for the Heard Library at Vanderbilt University

History of Croquet

Original Architects

Croquet represents the combined visions of its original architects: Alan Kay, David P. Reed, Andreas Raab, Julian Lombardi, Mark P. McCahill, Andreas Raab, and its lead system architect David A. Smith - all of whom believed that the time was right to fully bring to bear the underlying power of modern computers and network connectivities in the open source. Through the public release of this software, they intend to harness the creative power of a larger community of software developers and content creators and seed the development of technologies that will transform the way we use computers.

Alan Kay

Alan Kay, President of Viewpoints Research Institute, Inc., is best known for the ideas of personal computing, the intimate laptop computer, and the inventions of the now ubiquitous overlapping-window interface and modern object-oriented programming. His deep interests in children and education were the catalysts for these ideas, and they continue to be a source of inspiration to him. One of the founders of the Xerox Palo Alto Research Center, (PARC) he led one of the several groups that together developed modern workstations (and the forerunners of the Macintosh), Smalltalk, the overlapping window interface, Desktop Publishing, the Ethernet, Laser printing, and network "client-servers." Prior to his work at Xerox, Dr. Kay was a member of the University of Utah ARPA research team that developed 3-D graphics. There he earned a doctorate (with distinction) in 1969 for the development of the first graphical object-oriented personal computer. He holds undergraduate degrees in mathematics and molecular biology from the University of Colorado. Kay also participated in the original design of the ARPANet, which later became the Internet. After Xerox PARC, Kay was Chief Scientist of Atari, a Fellow of Apple Computer for 12 years, 5 years as Vice President of Research and Development at The Walt Disney Company and 3 years as Sr. Fellow at the Hewlett-Packard Company. In 2001 he founded Viewpoints Research Institute, a non-profit organization located in Glendale, CA, and continues as the organization’s President. Dr. Kay has received numerous honors, including the ACM Software Systems Award, the ACM Outstanding Educator Award, the ACM Turing Award (2003), the J-D Warnier Prix D'Informatique and the NEC C&C Prize 2001. He has been elected a Fellow of the American Academy of Arts and Sciences, the National Academy of Engineering, the Royal Society of Arts, and the Computer Museum History Center. He is a recipient of the ZeroOne Award from the University of Berlin, and recently received an honorary doctorate degree from the Royal Institute of Technology (KTH). He was inducted into the Utah Information Technology Association (UITA) as a “Hall of Fame Member, November 2003. He was awarded the Draper Prize by the National Academy of Engineering in February 2004. Most recently he was designated laureate (in Advanced Technology) by the Inamori Foundation and was awarded the 2004 Kyoto Prize.

Julian Lombardi

Julian Lombardi has long been interested in developing simulation-based social software systems. He brings his background in developmental and evolutionary biology, complexity theory, and in the study of emergent properties in biological systems to his work in information technology. Dr. Lombardi has long been fascinated by the transformative potential of new interface technologies. In the late 1980s, and while at The University of North Carolina, he developed instructional software for biological and medical education. In 1995, he combined his interests in information technology and evolutionary/developmental biology and developed systems and methods for enabling representations of network-deliverable resources to self organize and optimize within the framework of social computing systems. In 1999, he founded ViOS, Inc. and served as ViOS's first CEO and then Chief Creative Officer/Chief Software Architect. Over an eighteen-month period, he oversaw the successful completion of the company's core technology leading to the launch of a user-friendly knowledge management and social computing platform with an industry award-winning interface. Dr. Lombardi has also provided executive management and consulting services for emerging IT companies and from 2002-2005 he managed a software R&D group at the University of Wisconsin-Madison. Since 2005, Dr. Lombardi has been serving as Duke University’s Assistant Vice President of Academic Services and Technology Support. He is also a Senior Research Scholar with Duke University’s program in Information Science + Information Studies and an adjunct professor with Duke University’s Department of Computer Science.

Mark P. McCahill

Mark McCahill got his start in computing in the early 1970s when the first teletype terminals and timesharing systems accessible to students arrived at his junior high school. After staying after school for several weeks to teach himself how to program applications in BASIC, he was presented with the delightful opportunity to be the programming instructor for a few days in math class, because the math teacher was unsure how to program. After receiving a B.A. in Chemistry at the University of Minnesota, Mark took a job doing analytical chemistry and analyzing the results on the campus mainframe with the unfortunate result of some shockingly large computer time bills. Others on the project forcefully suggested moving the data analysis to a newly acquired Apple ][. This experience ultimately lead to a programming position at the University computer center specializing in early microcomputers. In 1989, Mark lead a team at the University of Minnesota that developed one of the first popular Internet e-mail clients (POPmail) for the Macintosh (and later the PC). In 1991, Mark led the original Internet Gopher development team and helped invent a simple way to navigate distributed information resources on the Internet. Internet Gopher's menu-based hypermedia paved the way for the popularization of the Web and was the de-facto standard for Internet information systems in the early to mid 1990s. In 1994-95 Mark's team developed GopherVR, a 3D user interface to Internet Gopherspace. Mark's current interest is in applying the lessons learned from the first generation Internet information systems to Croquet. Mark is a senior systems architect with Duke University's Office of Information Technology.

Andreas Raab

Andreas Raab attended the University of Magdeburg (Germany) where in 1994 he received a Diplom-Informatiker (equivalent to a M.S in Computer Science) and in 1998 a Ph.D. in Computer Science. His main background is in Computer Graphics and Interactive Systems. During his doctoral research he developed various new techniques for analyzing geometric models (global shape estimation operators), visualizing 3D models (based on real-time non-photorealistic techniques), as well as new interaction metaphors for 3D models (e.g., using zoom techniques for inplace interaction and emphasis in 3D models). While at Disney he concentrated on implementing real-time graphics capabilities into Squeak, including support for real-time vector graphics (Flash), real-time 3D graphics, advanced 3D modelling techniques (Teddy), as well as integrating these components into the "eToy" environment (the kids scripting environment). Besides the work done in the area of Computer Graphics, Dr. Raab also developed an extensive expertise in the area of designing and implementing object-oriented systems. Until recently, Dr. Raab was working at HP-Labs in the above areas. He is now working on commercial Croquet-based applications at Qwaq Inc.

David P. Reed

David P. Reed's research focuses on designing systems that manage, communicate, and manipulate information shared among people. He is well known as a pioneer in the design and construction of the Internet protocols, distributed data storage, and PC software systems and applications. He is best known for co-developing the Internet design principle known as the "end-to-end argument" (with MIT Professors J.H. Saltzer and David D. Clark), and "Reed's Law," which describes the economics of group formation in networks. Dr. Reed splits his working time between HP Laboratories, where he is an HP Fellow, and the MIT Media Laboratory, where he is an adjunct professor. His research at HP Labs is focused on highly scalable, decentralized, interactive computing systems built as a loose federation of end-user resources. In particular, his research involves the concepts underlying Croquet as a computing platform based on temporal reflection and replication of computation. At the Media Lab, he co-leads the Lab's Viral Communications Program, exploring new approaches to achieve adaptive, scalable, and evolving wireless network architectures, and is a founder of the MIT Communications Futures Program, which explores the technical and business disruptions that are driven by fundamental changes in the basic communications technologies. He has consulted widely to the computer industry, and has served as senior research scientist at Interval Research Corporation and as vice president and chief scientist for Lotus Development Corporation. Previously he was vice president of research and development and chief scientist at Software Arts. Dr. Reed was a faculty member in MIT's Department of Electrical Engineering and Computer Science (EECS) from 1978 to 1983, working in the Laboratory for Computer Science (LCS). He also earned his BS, MS, EE, and PhD degrees in EECS while conducting research at LCS and its predecessor, Project MAC. During his early academic career at MIT, he helped to shape the early design of LANs and their communication protocols. He participated in the design of the protocol suite now used in the Internet and also worked on systems architectures for confederated networks of interconnected personal computers. As a student at MIT, Dr. Reed also was involved in developing commercial implementations of MACLISP and MACSYMA. As a teacher, he helped develop undergraduate and graduate courses in computer and communication systems design, and programming language implementation and design.

David A. Smith

David A. Smith is the chief system architect for Croquet. The Croquet project is the culmination of David's work on 3D component-based architectures for the development and deployment of complex peer-to-peer environments including interactive entertainment. His first experiments in multi-user systems and interactive environments laid the groundwork for much of the architecture and user interface of Croquet. David is a co-founder and CTO of Qwaq, Inc., a Croquet Internet services company. He is also co-founder and CTO of 3Dsolve, Inc., the Simulation and Learning company. David created a number of ground-breaking interactive 3D applications including: “The Colony”, the very first 3D interactive game and precursor to today's "first person shooters" like Quake... except Colony ran on a Macintosh in 1987. "The Colony" won the "Best Adventure Game of the Year" award from MacWorld Magazine and was declared one of the "Top 10 Mac Gaming Thingies of the Past 1,000 Years". In 1989, David used the technologies developed for the game to create a virtual set and virtual camera system that was used by Jim Cameron for the movie “The Abyss”. Based upon this experience, David founded Virtus Corporation in 1990 and developed Virtus Walkthrough, the first real-time 3D design application for personal computers. Walkthrough won the very first "Breakthrough Product of the Year" from MacUser Magazine, and Best Drawing Package from PC Computing Magazine. David co-founded Red Storm Entertainment with Tom Clancy, and Timeline Computer Entertainment with Michael Crichton. He also co-founded Neomar, a wireless enterprise infrastructure company. David is now the the CTO at Qwaq, Inc.

Origins

Croquet is the confluence of several independent lines of work that were being carried out by its six principal architects, Alan Kay, David A. Smith. David P. Reed, Andreas Raab, Julian Lombardi, and Mark McCahill. The project has its origins in a conversation between David A. Smith and Alan Kay in 1990, where both expressed their frustration with the state of operating systems at the time.

In 1994 Smith built a working prototype of a two user collaborative system that was a predecessor of the core of what Croquet is today. Also in 1994 Mark P. McCahill's team at the University of Minnesota developed GopherVR, a 3D user interface to Internet Gopher to explore how spatial metaphors could be used to organize information and create social spaces. In 1996 Julian Lombardi approached David A. Smith to explore the development of highly extensible collaborative interfaces to the WWW. Later, in 1999, David A. Smith built a system called OpenSpace, which along with Smith's earlier work on a multi-user shared component environment that he called the Interactive Collaboration Environment (ICE), acted as an important guide to the development of Croquet. Also in 1999, Julian Lombardi began working with David A. Smith to experiment with prototype implementations of highly extensible collaborative online environments based on OpenSpace. One of these implementations was a prototype implementation of ViOS, a way of spatially organizing all Internet-deliverable resources (including web pages) into a massively-scaled multiuser 3D wiki-like collaboration environment.

David A. Smith and Alan Kay officially started the Croquet Project in late 2001 and were immediately joined by David P. Reed and Andreas Raab. David P. Reed brought to the project his longstanding work on massively scalable peer-to-peer messaging architectures in a form deriving from his doctoral dissertation that was published in 1978. The first working Croquet code was developed in January 2002 under the technical direction of David A. Smith. Simultaneously, Julian Lombardi and Mark P. McCahill began independently collaborating on defining and implementing highly scalable architectures for multi-user collaboration and were invited by Alan Kay to join the core architectural group in 2003.

From 2003-2006 the technology was developed under the leadership of its six principal architects with financial support from Hewlett-Packard, Viewpoints Research Institute Inc., The University of Wisconsin, The University of Minnesota, the Japanese National Institute of Communication Technology (NICT) and private individuals. In 2007, HP and Duke University announced the formation of the Croquet Consortium, a not-for-profit organization dedicated to the continued development and refinement of the Croquet open source platform. In 2008, Duke University and other members of the consortium developed the first pre-alpha build of the Croquet-based Cobalt application intended to serve as a focal point for the development of a metaverse browser.

Related Projects

Squeak

Croquet is built on top of Squeak, a 21st century dynamic-object wide-spectrum operating and authoring environment derived from the 1970s Xerox PARC Smalltalk system. Squeak represents a powerful, cross-platform, and open alternative to the traditional multimedia and exploratory languages and is gaining wide acceptance as an agile solution for high quality computation. Several of the authors of Squeak were principals at Xerox and were co-creators of many of the PARC inventions which include overlapping window GUIs, desktop publishing, media authoring, and many other familiar software systems.

Visit http://www.squeak.org for more information.

OpenGL

OpenGL is a widely used and supported 2D and 3D graphics application programming interface (API) that has brought thousands of applications to a wide variety of computer platforms. OpenGL fosters innovation and speeds application development by incorporating a broad set of rendering, texture mapping, special effects, and other powerful visualization functions. Developers are able to leverage the power of OpenGL across all popular desktop and workstation platforms. For more information on OpenGL, click here.

Please note that graphics cards and their drivers are crucial to Croquet's compatibility and performance. Be sure that your graphics card is OpenGL 1.3 or higher compliant AND that you have appropriate OpenGL hardware drivers installed. Windows users should be aware that upgrading your DirectX versions through Microsoft's web site often overwrites existing hardware OpenGL drivers with software OpenGL->DirectX wrappers (killing performance, if not compatibility). The fix is to re-install the video card manufacturer's drivers after any DirectX install procedure. Also keep in mind that the fastest new computer/processor won't run Croquet at all with older graphics cards.

OpenAL

OpenAL is a cross-platform 3D audio API developed for use with gaming and other applications. For more information on OpenAL, click here. In order to run applications that use spatialized sound, you must also install OpenAL. Recent versions of Macintosh OSX include the OpenAL libraries as a standard part of the system. PC users may also find that their sound card came with an OpenAL driver as well. If you need to install OpenAL, you may download the installer for your system here.

Selected Papers/Publications

Click on titles to view the entire resource.

• 2006. Extending Croquet Spaces with Virtual Presence, Vehicles, and Vector Fields - a paper by Mark P. McCahill, Peter Moore, Liz Wendland, Anthony Zampogna

• 2006. Simplified Distributed Authoring Via Component-based Object Construction and Deconstruction in Collaborative Croquet Spaces - a paper by Howard Stearns, Joshua Gargus, Martin Schuetze and Julian Lombardi

• 2006. A Language Supporting Direct Manipulation of Component-based Object Construction and Deconstruction in Collaborative Croquet Spaces - a paper by Howard Stearns, Joshua Gargus, Martin Schuetze and Julian Lombardi

• 2006. 3D Model Annotation from Multiple Viewpoints for Croquet - a paper by Rieko Kadobayashi, Julian Lombardi, Mark P. McCahill, Howard Stearns, Katsumi Tanaka, and Alan Kay

• 2005. Filters and Tasks in Croquet - a paper by David A. Smith, Andreas Raab, Yoshiki Ohshima, David P. Reed, and Alan Kay

• 2005. Annotation Authoring in Collaborative 3D Virtual Environments - a paper by Rieko Kadobayashi, Julian Lombardi, Mark P. McCahill, Howard Stearns, Katsumi Tanakaa, and Alan Kay

• 2005. Hedgehog Architecture' - a PowerPoint presentation by David A. Smith, Andreas Raab, David P. Reed, and Alan Kay

• 2005. TeaTime: Designing the Architectural Framework for Croquet - a PowerPoint presentation by David P. Reed

• 2005. Standing on the Plateau Looking Forward: The Croquet Project - a paper by Marilyn M. Lombardi

• 2005. Croquet Learning Environments: Extending the Value of Campus Life into the Online Experience - a paper by Marilyn M. Lombardi and Julian Lombardi

• 2004. In All Possible Worlds: A radical new technology has arrived and the world will never be the same - a posting by Max Borders

• 2004. Enabling Social Dimensions of Learning Through a Persistent, Unified, Massively Multi-User, and Self-Organizing Virtual Environment - a paper by Julian Lombardi and Mark P. McCahill

• 2004. Design for an Extensible Croquet-Based Framework to Deliver a Persistent, Unified, Massively Multi-User, and Self-Organizing Virtual Environment - a paper by Mark P. McCahill and Julian Lombardi

• 2004. Croquet: A Menagerie of New User Interfaces - a paper by David A. Smith, Andreas Raab, David P. Reed, and Alan Kay

• 2004. Croquet, Anyone? Designing a more Responsive Online Learning Environment - paper by Marilyn M. Lombardi

• 2004. Application of 3D GUI based Object Modeling Environment for Embedded System Design Process a paper by M. Sakai, Y. Ishizaki, A. Togawa, and T. Yamamoto

• 2003. Croquet – A Collaboration System Architecture - a paper by David A. Smith, Alan Kay, Andreas Raab, and David P. Reed