Although I can see where Mike might get these impressions, they are
not completely accurate. You can define a large number of different
entity types which are standardized. The fundamental design of DIS is
not flawed when it comes to entities describing their own behavior in
an efficient, network-friendly(i.e. scalable) way. Currently you can have
300-400 simultaneous entities moving & reporting simultaneously, which is far
more than other wide-area-network-distributed systems have been able to
accomplish (they usually top out around twenty). Although progress
continues, the true bottlenecks are just now beginning to be understood.
Mike Macedonia is finishing some important work which describes how
you can scale to thousands of interactive entities using DIS
partitioned into multicast channels. Each channel corresponds to
realistic categories such as geographic region, functional
characteristic etc. For more info see current VRAIS proceedings or
ftp://taurus.cs.nps.navy.mil/pub/NPSNET_MOSAIC/Explointing.Reality.with.Multicast.Groups.ps
DIS also has a free-format Message PDU and a free distribution library
(NPSNET).
My expectation is that VRML can get a lot of mileage out of IEEE DIS
protocol capability for interactive communication of entities. Best
approach will likely be to extend a subset of the DIS spec, as happened
with OpenInventor. Splicing DIS functionality as an optional
"behavior" is particularly appealing.
More information on DIS proper appears in a paper by John Locke at
ftp://taurus.cs.nps.navy.mil/pub/cs_dept/DISIntro.ps
all the best, Don
--
Don Brutzman Naval Postgraduate School, Code UW/Br work 408.656.2149
Monterey California 93943-5000 USA fax 408.656.3679
AUV Underwater Virtual World ftp://taurus.cs.nps.navy.mil/pub/auv/auv.html