An Introduction To OpenSim: the "Apache of Virtual Worlds"

by Ostatic Staff - Aug. 18, 2008

By Wagner James Au

You've probably read a bit about OpenSim, the BSD-licensed virtual world server, and recent news that IBM and Linden Lab are working to make Second Life and OpenSim interoperable. Besides that project, what's OpenSim about, who's working on it, what are they doing with it, and how do you get involved as a developer and participant? Here's a starter's guide, created with the help of Tish Shute, whose virtual world blog UgoTrade is an indispensable resource on the latest in OpenSim news.

What's OpenSim's Relationship To Second Life?

Coded in C# and developed to operate under Mono or Microsoft .NET runtimes, OpenSim was created with libsecondlife, an open source library derived from the source code to the Second Life's viewer (which Linden Lab released in January 2007.) The code that operates SL's server grid remains closed source, however, so OpenSim is a fully open alternative.

As leading OpenSim developer Adam Frisby once told Shute: "We used the term 're-engineered'-- it was re-implemented from standards, but on the backend it's a very, very different beast. As best as we can tell (without seeing the source to the Linden Lab server), the structure internally is radically different partly due to our desire to keep things usable for non-SL style worlds."

Related to that, Frisby clarifies that OpenSim is not itself a virtual world, but code designed to run virtual worlds. By his analogy, OpenSim is to virtual worlds what Apache is to websites. "The Apache webserver is not a website," as he writes on his blog, "but ~50% of the websites online are running Apache."

What are the server grids running OpenSim?

Over two dozen on the OpenSim group's Grid List, many designed to serve specific groups and activities, such as non-English users or adult content.

What viewer software is compatible with OpenSim?

Many, including: - realXtend, a virtual world platform with impressive graphics and physics. - The Hippo OpenSim viewer, a modified version of the SL viewer. - The Opensim Kid Browser, a simplified virtual world for minors. - Xenki, an open source XBAP app that runs Second Life and OpenSim in a web browser. Of course, a release candidate of the official Second Life viewer can also access OpenSim; the company is currently taking applications for SL "gridnauts" willing to test interoperability between the two worlds.

What companies and/or organizations are most important to OpenSim development?

Tish estimates that IBM now has three or four staffers working fulltime on OpenSim, recently joined by developers with Intel. "[The] Microsoft Developer community should get a mention as being the newcomers of note," she tells me. "They have been contributing code and have set up their own grid, The Manhattan Project." In addition, there's a number of start-ups working with OpenSim, including 3Di and Genkii of Japan, and Tribal Media of Sweden, Frisby's Deep Think in Australia, and the aforementioned realXtend of Finland.

What Interesting Practical Applications Are Being Developed on OpenSim?

Shute cites the 3D virtual machines project from Michael Osias of IBM; that's an operations center for managing server networks in OpenSim. There's also the n-body simulation work by MICA and Princeton astrophysicist Piet Hut, and a fashion design prototyping lab created in OpenSim by The Fashion Research Institute.

These are promising early examples, but, Shute believes, "soon everything from energy management to product life cycle management, and city planning will occur in collaborative, programmable 3D space… The power of OpenSim is that its open source, modular design allows it to be used in a lot of different applications. Open and distributed will win."

What Are The Biggest Challenges With Interoperability Between OpenSim And Second Life?

Right now, it's only possible to move avatars between SL and OpenSim; the far greater challenge is trust management-- creating a workable, agreed-upon system for moving virtual objects, currency, and other valuable items in between worlds. For Linden Lab the company, says Shute, the biggest concern is how quickly OpenSim has grown apart from their own efforts a year after they released the source code. "OpenSim is moving very, very fast," she tells me. "Linden Lab has to invest an enormous amount of energy into maintaining their current grid and this could be an obstacle re: keeping up with the future they have seeded."

How Can Open Source Developers Get Involved in OpenSim?

The blogs OpenSim User and Virtual White are good places for interested OpenSim developers/users to get started. The heart of the OpenSim development community happens on IRC, at the channels "#opensim" and "#opensim-dev". The OpenSim Wiki is also an essential resource.