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Several new developments are brewing in the metaverse. The Massive Multiplayer Online Experiences IETF group has started to form, co-chaired by Linden Lab and IBM. Linden Lab has started publishing standards drafts for virtual world interoperability. OpenSim has started exploring linking grids together with HyperGrid. The topic of virtual world interoperability is at the forefront of many people's minds. Due in part to the success of the web model (everyone can run their own website), individuals and businesses are waiting for the opportunity to run their own virtual world simulation, content development or storage business, spatial search engines, or maybe a mashup service that twitters virtual world activity. But before this can happen, the barriers need to be broken down between the walled garden virtual worlds of today and allow virtual concepts (identity, persistence, content) to move between worlds. How we get there is the topic of a heated debate.

First, some definition of terms. When I talk about multiple virtual worlds or multiple grids, I'm referring to multiple (independent) administrative domains. Intel has a vast set of web services that they offer under a single administrative domain at intel.com. I have my own personal blog and an OpenID service at jhurliman.org, my own administrative domain. This blog links to both intel.com and jhurliman.org, creating a possible interaction for the reader with those domains. Virtual world interoperability is about exploring the possible interactions across virtual world administrative domains. Even the simple concept of linking raises questions about carrying avatar identity and appearance across domains, and the complex topic of content transfer touches on nearly every hot security issue from DRM to webs of trust.

It always helps to start with a use case to ground discussions in reality. In an interview with Reuters, David Levine from IBM coined a popular use case that has helped shaped the conversation around virtual world interoperability. “Success in this space means killing a dragon and taking its head to another grid, slapping it down in a nightclub and having a disco,” he said. To map this back to virtual world interoperability terms, the use case would be obtaining some content in one administrative domain and transferring it to another administrative domain. There is an implicit notion that you have to obtain the content in administrative domain A before "slapping it down in a nightclub" in administrative domain B. In other words, preserving the scarcity (and therefore preserving some value) of content across administrative domains.

Preserving scarcity of a virtual good across administrative domains brings up a number of issues. Why is that content scarce in domain A? Do the same reasons for scarcity exist in domain B? The content may be the result of a difficult quest in the fantasy world of A, but how do you preserve the meaning in domain B and make it more than just another disco decoration?

 

In this approach, we assume the dragon head is implicitly valuable. Possessing a dragon head has value both in world A and world B. No technical measures are used to attempt to preserve the scarcity of content. However, a set of permissions can be assigned to content, and content fingerprints and auditing trails can help track down unauthorized usage. This approach has some proven value as it's the approach taken by Second Life, one of the most successful virtual economies, along with many web content businesses such as stock photo or 3D model vendors.

Solution #2: Move the content, reference the context

This solution assumes the content itself has no value, and all of the value exists in the contextual meaning of the content. The dragon head can be moved to a domain where it's assumed everyone will make copies and those copies will proliferate to even more domains. However, those dragon heads can link back to something in domain A that proves a particular user completed a quest. An example of this solution is the Xbox Live Achievements. I can put a "gamer card" on any website that says what my current Xbox gamer score is, and I can copy that content and edit my gamer score to say whatever I want. However, the real value of the card is being able to follow a link from it to http://live.xbox.com/member/jhurliman, which exists inside the xbox.com domain and authoritatively confirms what my Xbox gamer score is (would be much better if it wasn't for all this virtual world stuff).

Another version of this solution is to use cryptographic signatures to prove that domain A stated that some identity completed the dragon head quest. In the Xbox Live Achievements example, xbox.com could vouch that the jhurliman identity has a particular gamer score on a particular date. Although the implementation is different, it's still the same solution category because it assumes the content itself has no value. Only the contextual meaning of the content is valuable. If the dragon head itself had value, there's nothing stopping anyone from separating the content from the signature and copying it from one end of the metaverse to the other.

Solution #3: Digital Rights Management

In theory, DRM will allow content to carry an inseparable list of rights that governs usage. This is the content publisher's utopia, as content can transfer between any administrative domains and be copied any number of times, but the original publisher has full control over when, where, and how content can be used. An example of this is Apple's encrypted songs purchased from their iTunes store. It also means that no effort has to be spent developing virtual world interoperability standards that protect content, because the content can protect itself. The only problem is that it doesn't work. However, a reasonable approach is to stay open to the possibility that some domains will want to implement DRM regardless of technical feasibility, or that the technology landscape may shift in the future to a scenario where it is possible.

Solution #4: Trust maps

This category of solutions supports situations where the content itself may or may not have value. The general idea is to setup virtual world grids that have trust agreements and create a list of policies for content transfer. Domain A can say "I trust that domain B will take reasonable measures (such as solutions #1 or #3) to prevent users from making unauthorized copies of the content, therefore I will allow the dragon head to transfer to domain B". These policies are really just the technical implementation of a data sharing partnership. If Blizzard and Linden Lab want to allow content to transfer between the World of Warcraft and Second Life worlds, there is nothing standing in the way aside from a Simple Matter of Programming. Standards make the programming well defined, but selling this as virtual world interoperability is disingenuous. The other solutions attempt to solve the problem of content transfer between untrusted domains, while this solution dodges the question by growing administrative domains with explicit trust maps. Once you have have a million fantasy quest worlds and half a million casual social worlds all wanting to transfer content between each other, the N by N trust mapping fails to scale. Linden Lab's Agent Domain and OpenSim's current HyperGrid implementation fall into this same solution space on opposite sides of the spectrum (agent domain blacklists by default and hypergrid whitelists by default).

In Summary

None of these solutions preclude the others. In fact, solutions #1, #2, #3, and #4 can all be used in conjunction. Heated debate usually arises when one of these solutions is presented as "the" solution for virtual worlds, and a model for interoperability is presented that requires a particular solution or precludes other solutions. Whatever interoperability model finally emerges, it seems reasonable that it will support all of these possibilities and require none of them. That's part of what makes the web so successful today.

February 19, 2009 9:35 PM PST Gigs

http://amandafrench.net/2009/02/16/facebook-terms-of-service-compared/

February 20, 2009 1:13 AM PST thay SinghT

I really believe it is far too early for the IETF to look at standardizing interoperability between MMOPWs. This is at least because there is really only one of them, SecondLife. OpenSim and HyperGrid are entirely derivative of SL's technology base. I've been a long-time user of SecondLife, and also have something of a hard-core technical background in server-side networking and million-user-scale systems, and frankly SL *still* doesn't scale the way it should. This comment isn't the place to begin delineating the technical errors that are deeply embedded in SL's infrastructure, but even at the point of 'standardizing' virtual goods, SL is a dead-end. Their object modelling is woefully behind the technology curve. Their avatar/texture mapping is also fundamentally limited. Bringing all of these technologies up to scratch would be merely a first step towards a useful, standardised infrastructure. The great problem, of course, is that competition in this domain is nearly impossible, but it will happen as long as premature standardization does not create a lock-in for LindenLab's inferior technologies.

February 20, 2009 9:30 AM PST John Hurliman

thay: Excellent points, I agree across the board. However, I think if we get to the point where we are standardizing on specific technicals in the Second Life world we're on a doomed path anyways. A successful virtual world standardization will not tell you how simulators partition up virtual space, or how in-world scripting works. Even assuming that two worlds both have a scripting language, or have gravity at all is going to be an unreasonable limitation. From the discussion on the MMOX list so far, it seems reasonable to assume that all virtual worlds interested in interoperability have concepts of identity, presence, and one form or another of an avatar. Just getting that part working across worlds will keep the stakeholders busy for a while.

March 1, 2009 1:29 PM PST Virtual

The success of the Metaverse doesn't rely so much on the entire linking aspect. The linking or hypergrid teleports will be a part of it. I think it will still take many years before it even becomes important since virtual worlds are still so young. They will get adapted and people will find use for them but I don't see the need of spending so much attention just on the linking part or how they connect with each other. Instead of placing the focus on how can avatar teleport from world A to world B and keep his stuff with him one should put attention to the fact what on earth is the reason that avatar will use a virtual world?

March 19, 2009 2:28 PM PDT Dez

Virtual makes a good point; the reason that many people are interested in linking virtual worlds together is that there isnt any real content in any of the worlds that makes it desirable to stay in (or return to) one location. Like the real web (and TV) people are always channel/site hopping, looking for something interesting to watch/do. VR technology has been around for nearly 20 years now, and its still a solution in search of a problem - some companies have made a good living out of producing very bespoke VR applications which solve very specific user problems, but scaling this up to MMOG levels is going to take some time yet, mainly because many many thousands of users require many many thousands of activities to keep them occupied, and that in turn requires a lot of content developers to create the experiences. My hope for MMOX is that they stop worrying about teleporting avatars and assets between worlds, and look at the problem from another direction, e.g. they think about how to support a more federated model where individual (or composite) objects are responsible for their own presence within the virtual environment, and the infrastructure takes care of routing the inputs to these objects (inputs from users, e.g. a user touching something), and distributing the (visual) results to the viewers. Developers can then create and manage their own solutions to their problems using whatever core technology they feel fit, and then and share the results by inserting the simulation within the 3D world. The world doesn need to know how the simulation data got there, just needs to know how to distribute the info to the users. This would, IMHO, lead to much richer virtual worlds being developed.

June 1, 2009 8:53 PM PDT Danny Stefanic

Why not leverage all the existing web standards. Thats what we did with ExitReality. You can interoperate with ANY web based platform through our 3D browser. I'd love to take this discussion further, so please contact me. Kind regards, Danny Stefanic Founder & CEO ExitReality.com

October 25, 2009 12:23 AM PDT Prokofy Neva

No, John. Walled gardens do NOT "need" to be broken down just so that your large IT corporation and others' consulting companies can dig and scrape and copybot them. (Remember, you are the maker and seller of copybot in Second Life as Eddy Stryker). This interoperability you are flogging isn't a consumer-driven demand, nor is it any really promoted goal of virtual worlds themselves -- Second Life's top management has only been lukewarm in supporting all your frantic activities, and There.com seems to have pulled out -- and others are completely missing from the discussions even if lurking (Metaplace). No, this is something evidently *you personally* or perhaps even *your company* needs because you are working on a virtual world type of platform or operation yourselves and want everybody else hooked up and piped into your world and sucking the content out of other worlds. That's wrong. In the interoperability group, you and other extremists from LL and the SL resident population are completely denying the importance of taking any approach that would secure IP and metadata in various ways, constantly saying it is "technically impossible" or that it will hamper development or progress. And yet, private property forms the basis of civilization; technocommunism of the sort you are promoting (as an advantage to large companies) is decivilization. What really gives away the store here is your constant referencing to really harsh ideological norms drawn from Marxism or worse, like "This solution assumes the content itself has no value, and all of the value exists in the contextual meaning of the content" -- and pretending that these are mere "technical" matters. The other posters here are saying the obvious: interoperability is merely premature now because there's only SL and its reverse-engineered clones, and yes, they are indeed from the libsl library and are indeed reverse engineered in the grand sense of the word as you well know. The idea that somebody "needs" to hop from world to world because content is quickly 'burned through' or "valueless" or "meaningless" belongs to the mindset of aggresive gamers in MMORPGs who "burn through" content put forward to them by devs and get bored if they aren't on a quest or in a fight. Second Life is a place where people build persistence and aren't bored by content left in place even five years, just as they aren't bored in real life by having a persistent house or furniture or vehicles, not to mention friends and pets! You have a lot to learn about what virtual worlds mean to people, and it is the populations of these worlds, as they acquire the freedom of governance to roll back the authortiarian of game and world companies, that should set the program for interoperability, not tiny cabals of devs with hidden agendas.

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