Croquet Project

The Croquet Project is a software project that was intended to promote the continued development of the Croquet open-source software development kit to create and deliver collaborative multi-user online applications. Croquet is implemented in Squeak Smalltalk.

Croquet supports communication, collaboration, resource sharing, and synchronous computation among multiple users.

Applications created with the Croquet software development kit can be used to support collaborative data visualization, virtual learning and problem solving environments, 3D wikis, online gaming environments (massively multiplayer online role-playing games (MMORPGs)), and privately maintained or interconnected multiuser virtual environments.

Further development of the technology has also branched into the Open Cobalt and Open Croquet efforts.^[2]

The most recent iteration of Croquet is a commercial product developed by Croquet Labs.^[3] This version of Croquet runs in a web browser and allows programs to be written in Javascript or WebAssembly.

Croquet is a software development kit (SDK) for use in developing collaborative virtual world applications.

Applications created using the Croquet SDK are automatically collaborative since application objects in Croquet share a common protocol allowing them to cooperate with each other by employing the principle of replicated computation (synchronization) together with a peer-based messaging protocol. The technology is designed to facilitate such replication between peers, to greatly reduce the overhead needed for widespread deployment of collaborative virtual worlds.

This efficiency, combined with the ability to deploy Croquet-based virtual worlds on consumer-level hardware, makes it possible for developers to deploy large-scale and highly participatory collaborative worlds at very low cost compared with virtual world technologies that are entirely dependent on server-based infrastructures to support the activities of their users.

The original authors of Croquet opened a commercial company named Qwaq which was later renamed to Teleplace. That technology was later sold back to a group of the original Croquet developers and became Immersive Terf.^[4][5]

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 present identity of the project has its origins in a conversation between Smith and Kay in 1990, where both expressed their frustration with the state of operating systems at the time.

In 1994, Smith built ICE, 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 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 Smith to explore the development of highly extensible collaborative interfaces to the World Wide Web. Later, in 1999, Smith built a system called OpenSpace, which was an early-bound variant of Croquet. Also in 1999, Lombardi began working with Smith on prototype implementations of highly extensible collaborative online environments based on OpenSpace. One of these implementations was a prototype implementation of ViOS, a way to spatially organize all Internet-deliverable resources (including web pages) into a massively-scaled multiuser 3D environment.

Smith and Kay officially started the Croquet Project in late 2001, and were immediately joined by David Reed and Andreas Raab. 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. Simultaneously and independently, Lombardi and McCahill began collaborating on defining and implementing highly scalable and enterprise-integrated architectures for multi-user collaboration and were invited by Kay to join the core architectural group in 2003.

From 2003 to 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–Madison, University of Minnesota, Japanese National Institute of Communication Technology (NICT), and private individuals. On April 18, 2006, the project released a beta version of the Croquet Software development kit 1.0 in the open-source. Since then, the Croquet technology infrastructure has been successfully used by private industry to build and to deploy commercial-grade closed source collaborative applications. Open source production-grade software implementations for delivering secure, interactive, persistent, virtual workspaces for education and training have at the same time been developed and deployed at the University of Minnesota, University of Wisconsin–Madison, University of British Columbia, and Duke University.

As of 2009^[update], continued development of the original Croquet technology has also taken place through the Open Cobalt and Open Croquet projects.^[2]

• It is platform and device independent
• Users and developers may freely share, modify and view the source code of the whole system, due to a liberal license
• The technology is not hosted on one organization's server, and hence not governed by any such organization
• It provides a complete professional programmer's language (Squeak Smalltalk), integrated development environment (IDE), and class library in every distributed, running participant's copy; the programming development environment itself is simultaneously shareable and extensible
• Croquet based worlds can also be updated while the system is live and running

• Open Wonderland, a Java-based open source 3D toolkit to create collaborative virtual worlds
• Unreal Engine