Getting started with Croquet and the Collaborative code.

I’ve been getting a lot of “getting started as newbie developers” questions lately. I know I’ve got to get this cleaned up, but better to share what I’ve got as is…

  • The CroquetCollaborative is running a version a tiny little bit further along than the SDK. You can use the SDK and update your image using the public code repository. But since you’re just starting, it’s easier to get a pre-loaded version. [N.B.: Some errors that you can encounter have been fixed. If you connect using an older version and hit one of these, you break the server for everyone. Yes, the server should check that you’re current. Do we have a volunteer?…] The blue button on the first page of the CroquetCollaborative image runs the KAT demo — same as if you were running that demo out of the object browser. Everything else about the image is the same as the SDK (except for being a newer version).
  • In the KAT, if you accept the default when prompted for a place to connect to, it will attempt to connect to a router on a hosting service in Madison, WI. If the screen just stays red, then someone has done something in the “welcome” world or “commons” that has broken it. Please notify us by email. (These days, it can take a while to connect…)
  • If you instead clear out the address so that you’re just entering a blank address, the KAT will start a router for each of the predefined worlds on your local machine, and you will just connect to yourself. A few of the worlds will be empty. Some run scripts that create the worlds with some demo content. Congratulations, you’ve just set up your machine as a “host”. If that box happens to be at a fixed IP address, you can tell other people to enter that address when prompted, and they will connect to you. (They have to be able to reach port 5910 on your machine.) Of course, you can get this all fired up non-interactively — this is what the machine at does. But that’s a more detailed (and more boring) discussion. We want to make things so that you can do this and have people find you even without knowing your IP address. Next version of the software…
  • Note that when you run your own router and such, you’re taking out all the WAN network delays. We’re working on ways to reduce or eliminate these for WAN usage, too. The KAT code already does some of this and these changes are not in the other demos yet.
  • Even though the KAT is very oriented towards building things interactively while you are using them, creating your own application is certainly going to involve programming at this point. See the guide to Squeak tutorials for Croquet. But note this: you may be changing stuff so that you’ll work with other folks who are using the same Squeak image, but your changes might not work with the Collaborative.
  • When you’re ready to get into the guts of discovery and world building (current state of code), see connecting and populating developers’ wiki pages.
  • In addition to the social/user-interface properties of 3D collaboration, and the programming environment of Squeak, there is also a unique internal conceptual model in Croquet. See the model “Cliff notes” for an overview, and then, of course, the programmers guide.
  • There’s a lot of different discussions about issues on the user lists. Here and here, for example. See Nabble or your favorite forum browser.

About Stearns

Howard Stearns works at High Fidelity, Inc., creating the metaverse. Mr. Stearns has a quarter century experience in systems engineering, applications consulting, and management of advanced software technologies. He was the technical lead of University of Wisconsin's Croquet project, an ambitious project convened by computing pioneer Alan Kay to transform collaboration through 3D graphics and real-time, persistent shared spaces. The CAD integration products Mr. Stearns created for expert system pioneer ICAD set the market standard through IPO and acquisition by Oracle. The embedded systems he wrote helped transform the industrial diamond market. In the early 2000s, Mr. Stearns was named Technology Strategist for Curl, the only startup founded by WWW pioneer Tim Berners-Lee. An expert on programming languages and operating systems, Mr. Stearns created the Eclipse commercial Common Lisp programming implementation. Mr. Stearns has two degrees from M.I.T., and has directed family businesses in early childhood education and publishing.


  1. might post a date so I can tell if I am looking at yesterday or last year.

  2. Hmmm, in my browser it’s immediately above the “comments” titlebar, and says “posted at 16:460:00 on 04/15/07 by Stearns – Category: KAT”.

    Kind of small and light, though. Easy to miss…

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