That's roughly accurate, and DIS doesn't really stand alone. The basic
model is as follows:
- DIS is used to support real-time simulation, most commonly of a
battlespace
- each simulator (e.g., a tank, an F16) maintains a local "world model"
(geodata, imagery) and it's own behavioral/physics model (be it
automated or driven by a person-in-the-driver's seat)
- each simulator broadcasts updates to its motion vector, as well as
things like weapons fire and damage events (usually over IP multicast)
- each simulator updates it's local model of all the other objects in
the battlespace - using the incoming messages, as well as performing
dead reckoning between updates
- yup, lots of opportunities to broadcast fallacious information -
generally these simulations are run on private networks, validated and
trusted to operate properly
HLA is a little more robust in terms of controlling who can do what -
it's a middleware layer that essentially behaves as a replicated object
store. You still distribute the initial state-of-the-world (geodata,
imagery, list of players) through out-of-band means. When a simulator
comes on-line, it publishes an object into the local datastore, and
copies of that object pop up in everyone else's datastores (actually
RTI, "run time interface"). When the "owner" updates it's local copy,
the changes propagate to all other copies.
I find both to be fascinating models of how to keep replicated world
models synchronized. DDS (Data Distribution Service) is similar in
approach, but a bit more general in application. For some reason, I
kind of think of all of them as akin to NNTP (massive replication of
identical objects).
John Carlson wrote:
Ah, I thought DIS only sent id, position, orientation, velocity and
acceleration. Do objects own their properties, or can anyone on the
network provide them?
I've heard of people mixing X3D with DIS. I thought that X3D provided
all the modelling and visualization, and DIS provided the above. X3D
is a textual language. When asked about security on the X3D-public
list, the suggestion was to use session ids....yeah, right, one key
for the whole browser.
On Wed, Feb 13, 2013 at 8:58 PM, Miles Fidelman
<mfidel...@meetinghouse.net <mailto:mfidel...@meetinghouse.net>> wrote:
John Carlson wrote:
Miles wrote:
> There's a pretty good argument to be made that what "works"
are powerful building blocks that can be combined in lots of
different ways;
So the next big thing will be some version of minecraft? Or
perhaps the older toontalk? Agentcubes? What is the right 3D
metaphor? Does anyone have a comfortable metaphor? It would
seem like if there was an open, federated MMO system that
supported object lifecycles, we would have something. Do we
have an "object web" yet, or are we stuck with text forever,
with all the nasty security vunerabilities involved? Yes I
agree that we lost something when we moved to the web.
Perhaps we need to step away from the document model purely
for security reasons.
DIS (Distributed Internet Simulation) or HLA (High Level
Architecture) - both are distributed, real-time object protocols
for managing very complex virtual worlds (specifically, military
simulations and wargames).
--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
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In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
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