Information Technology Reference
In-Depth Information
18.4.5
Object and Ownership Management Service
The OOMS is a combined grid service related to the HLA object manage-
ment and ownership management service groups. The OOMFS dei nes a
createResource operation invoked by the FMRI to create an OOMRI for a
new federation. The OOMIS dei nes some operations corresponding to
the HLA object management and ownership management service groups
such as registerObjectInstance and attributeOwnershipAcquisition. It also
dei nes operations for fetching some information kept in OOMRIs. The
OOMRI keeps all object instances in the federation and their handles. It
also keeps the attribute ownership information for each object instance.
Since the attribute ownership information is specii ed per object instance,
it is convenient to include both the HLA object management and owner-
ship management service groups in the OOMS.
18.4.6
Time Management Service
The TMS is a grid service related to the HLA TMS group. The TMFS
dei nes a createResource operation invoked by the FMRI to create a TMRI
for a new federation. The TMIS dei nes some operations corresponding
to the HLA TMS group. The TMRI keeps relevant information for time
management in the federation. The operations dei ned by the TMIS and
data kept in the TMRI depend on the time-advancing algorithm used in
our SOHR framework.
If a centralized algorithm is used, the TMS does the major processing of
time management, such as the recalculation of lower bound time stamp
(LBTS) in HLA 1.3 or greatest available logical time (GALT) in HLA 1516
for each constrained federate based on time information of regulating
federates. Since time information is frequently exchanged, the TMS may
be easily overloaded with increasing federation size. So a distributed
time-advancing algorithm is more attractive to SOHR.
A distributed algorithm, such as the one in RTI version F.0 [31], can be
easily adapted to our SOHR framework. The TMIS dei nes operations for
changing of a federate's regulating or constrained status such as enable-
TimeRegulating and disableTimeConstrained. The TMRI keeps the regu-
lating and constrained status of all federates in the federation. When a
federate enables/disables its constrained status, the TMRI notii es all reg-
ulating federates' LRIs to update their TM modules. In this way, a list of
constrained federates in the TM module of each regulating federate's LRI
is always kept updated. With the always updated list of constrained feder-
ates, a regulating federate's LRI directly sends its time information to each
of the constrained federates' LRIs. The TM module of a constrained feder-
ate's LRI may recalculate the constrained federate's LBTS (or GALT in
HLA 1516) when time information of a regulating federate is received. In
this way, the major processing of time management is done by the TM
module of each federate's LRI, which makes SOHR more scalable.
 
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