Design and Performance Evaluation of a Service-Oriented HLA RTI on the Grid - Grid Computing: Infrastructure, Service, and Applications - page 461

(step 15). The LIS1 asks the RTI index service for the FMRI EPR of the
federation (step 16) and invokes a joinFederationExecution service invoca-
tion of the corresponding FMIS (step 17). The DMRI EPR of the federation
is fetched and stored in LRI1's DM module (step 18). Similarly, the OOMRI
EPR and TMRI EPR of the federation are fetched and, stored, respectively,
in LRI1's OOM module and TM module. Next, Federate1 requests to sub-
scribe to interactions of Class2 (step 19) and publish interactions of Class1
(step 22). Each of the two requests is forwarded to LIS1 by LRC1 (steps 20
and 23) and further forwarded to DMIS (steps 21 and 24). The getSuper-
ClassesOf InteractionClass service invocation of DMIS (step 25) is to deal
with an interaction class hierarchy dei ned in the FOM. Since no interac-
tion class hierarchy exists in this ping-pong experiment, it simply returns
an empty list. After Federate1 i nishes its initialization, Federate2 joins the
created federation, subscribes to interactions of Class1, and publishes inter-
actions of Class2 in a similar way.
After the initialization stage, interactions are exchanged between
Federate1 and Federate2 as shown in Figure 18.4. Federate1 keeps calling
RTIambassador.tick until an interaction is received from Federate2 (step
29). Federate2 requests to send an interaction of Class2 (step 26) and LRC2
translates this request to a sendInteractionOut service invocation of LIS2
(step 27). The LRI2's DM module keeps the list of subscribers and their
LRI EPRs. Because Federate1 is subscribing to interactions of Class2 (step
19), it should be included in the list. This causes a sendInteraction service
invocation of LIS1 by LIS2 (step 28). Then LRC1 receives this interaction
(step 30) when Federate1 calls an RTIambassador.tick (step 29) and deliv-
ers this interaction to Federate1 (step 31). After Federate1 receives the
interaction, it requests to send an interaction of Class1 and this interaction
is received by Federate2 in the reverse way (steps 32, 33, 34, 35, 36, and 37).

Federate1 LRC1 LIS1 LIS2 LRC2 Federate2

26. sendInteraction Class 2

27. sendInteractionOut Cl a ss 2

28. sendInteraction Class 2

29. tick

30. getCallbacks

31. receiveInteraction C lass 2
32. sendI nteraction Class 1

33. s endInteractionOut Cl ass 1

34. sendInteraction Class 1

35. tick

36. getCallbacks

37. recei veInteracti on Class 1

FIGURE 18.4 Interaction trace of the ping-pong experiment on SOHR.