Subject: [SWMP] Kicking things off

From: "Jay C. Weber" <[email-masked]>
Date: Fri, 01 Jun 2007 09:34:03 -0700

Thanks for your interest in standardizing a Simple Wide-area 
Multiuser-3D Protocol.  So far, this list is to gauge both interest and 
consensus in the subject, and could lead to the creation of an IETF 
Working Group that would pursue an Internet standard.  I created this 
list and will moderate it at this stage.

The idea is to create a line protocol that is, in the IETF tradition, a 
simple and practical solution to the problem of synchronizing 3D scenes 
among clients, servers, and peers connected over heterogeneous wide-area 
networks.  This problem has been solved many times over, as shown by the 
panoply of Massively Multiplayer Online Games, and seemingly in similar 
ways, making it a well-understood problem.   However, there has been 
almost no effort to date to foster interoperability among those systems 
and system components.  Standardization of the line protocol should 
enable efficient development and a robust middleware ecology, thereby 
freeing up technical resources to concentrate on more advanced 
multi-user functionality.

I should note that there does exist a related IEEE standard called HLA 
(cf. https://www.dmso.mil/public/transition/hla/), but I think that not 
even its proponents would claim that it is simple and practical in the 
IETF tradition.  Please share your thoughts on this work, as well as any 
other relevant standards-based work.

My interest in this area, and that of my company, started and is still 
primarily focused on a multi-user line protocol that works well with the 
ISO-standard X3D/VRML modeling language and API, but it may be that the 
proper focus for a future working group is broader than that.  Please 
share your thoughts on other content and client technologies.

Most of all, please share what you and your companies are doing in this 
area, interested in doing in this area, and interested in contributing 
to a standardization effort.  Please invite interested colleagues to 
join the discussion as well.  I look forward to hearing from all of you!

jay
--
Jay C. Weber
CTO, Media Machines
www.mediamachines.com

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From: Alan Hudson <[email-masked]>
Date: Tue, 29 May 2007 09:49:23 -0700

> other relevant standards-based work.

HLA took the course of standardizing an API interface.  There is no 
defined wire protocol at all.  Hence its basically useless as an 
interoperability standard.

TENA(HLA Competitor) is taking a similar approach.  I think this is done 
so the vendors can lock you into their systems.  The main claim is this 
allows the software vendor to optimize the wire protocol based on the 
features requested and networks its deployed on.  Doesn't seem worth the 
tradeoff.

DIS defined a wire protocol but did not have a good extension mechanism 
for new concepts beyond "bang your dead. "

Somewhere in the middle is hopefully a useful place.

-- 
Alan Hudson

President Yumetech, Inc.                               www.yumetech.com
President Web3D Consortium                             www.web3d.org
206 340 8900

---

From: Dethe Elza <[email-masked]>
Date: Tue, 29 May 2007 10:12:06 -0700

On 29-May-07, at 9:49 AM, Alan Hudson wrote:

> TENA(HLA Competitor) is taking a similar approach.  I think this is  
> done so the vendors can lock you into their systems.  The main  
> claim is this allows the software vendor to optimize the wire  
> protocol based on the features requested and networks its deployed  
> on.  Doesn't seem worth the tradeoff.
>
> DIS defined a wire protocol but did not have a good extension  
> mechanism for new concepts beyond "bang your dead. "
>

One system I know of which is actively sharing environments via 3D  
(besides things like Quake and Halo) is the Croquet project.  Is  
their TeaTime[1] protocol/architecture of relevance to this group?   
Their goal with it is for it to be an open protocol and they have  
already been working to make it cross-language (it is already cross- 
operating system).

[1] http://www.opencroquet.org/index.php/ 
System_Overview#TeaTime_Architecture

--Dethe

"Any idea that couldn't stand a few decades of neglect is not worth  
anything." --Gabriel Garcia Marquez

---

From: Braden McDaniel <[email-masked]>
Date: Tue, 29 May 2007 13:14:14 -0400

On Tue, 2007-05-29 at 09:49 -0700, Alan Hudson wrote:

[snip]

> TENA(HLA Competitor) is taking a similar approach.

No, it isn't. TENA is built on top of CORBA and it uses IIOP.

>   I think this is done 
> so the vendors can lock you into their systems.

There is a single vendor for TENA.

(I am one of the TENA Middleware developers.)

-- 
Braden McDaniel                           e-mail: <[email-masked]>
<http://endoframe.com>                    Jabber: <[email-masked]>

---

From: Alan Hudson <[email-masked]>
Date: Tue, 29 May 2007 10:20:23 -0700

> There is a single vendor for TENA.

k.  That's one way to solve interoperability issues.

> (I am one of the TENA Middleware developers.)

Excellent.  Information from the developers.

I found a power point slide here:

http://www.google.com/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Fwww.dtic.mil%2Fndia%2F2006test%2Fhudgins.pdf&ei=tV9cRuCMPJXmgQPQ2ISRBQ&usg=AFrqEzfxshHV-vgke_DVfAbBeaMw6xzg0Q&sig2=Zv-fDXeO5Lo0s8OxcOn45Q

Slide 34(TENA Solutions to Interoperability Challenges) talks about 
On-the-wire specification and says this:

API Standard allows future technological advances for data transmission
to be much more cost-effectively incorporated

I had taken this to mean that TENA took the same approach as HLA.

Of course its just one powerpoint slide which could be wrong.  But it 
was the first I'd seen about it.
-- 
Alan Hudson

---

From: Braden McDaniel <[email-masked]>
Date: Tue, 29 May 2007 13:55:40 -0400

On Tue, 2007-05-29 at 10:20 -0700, Alan Hudson wrote:

[snip]

> I had taken this to mean that TENA took the same approach as HLA.

Heh... I don't know that that prose *means* anything. ;-)

Keep in mind that TENA is a software product whereas HLA is a spec. TENA
makes no pretense to vendor-independence.

As I mentioned, TENA is built on top of CORBA. The DMSO RTI (an HLA
implementation) was built on CORBA, too. But it was implementing a
abstraction independent of CORBA (or much else); as such, the fact that
it was using CORBA under the hood was not terribly relevant.

Since TENA is a particular implementation that implements an abstraction
*in terms of* CORBA, you can go to the (generated) CORBA IDL files for
ground truth. Though in practice, I cannot imagine someone wanting to
*talk* to TENA apps via the TENA mechanisms without themselves *being* a
TENA app.

[I don't think this is particularly topical to the SWMP list. If you'd
like to know more about TENA, we should probably continue this
off-list.]

---

From: Alan Hudson <[email-masked]>
Date: Tue, 29 May 2007 11:10:42 -0700

> like to know more about TENA, we should probably continue this

No problem.  I've just be wrestling with where to go past HLA.  Jay 
brought up HLA as a possible solution to this space.  I thought TENA was 
following the same path so I blasted both with the same barrel.  Sounds 
like TENA is not trying to solve the same standardization problem.

-- 
Alan Hudson

---

From: Braden McDaniel <[email-masked]>
Date: Tue, 29 May 2007 15:44:35 -0400

> like TENA is not trying to solve the same standardization problem.

At the protocol level, neither HLA nor TENA will be much help. Both of
these solutions include concepts that one can learn from when designing
a shared simulation. But I hope SWMP's goals are much more conservative
than specifying the scope of communications for objects in a shared
simulation.