FederateLevel Reusability: Joining a Federation with SOM Document Data

1
Federate-Level ReusabilityJoining a Federation
with SOM Document Data

• KAIST
• Jae-Hyun Kim and Tag Gon Kim

2
Software vs. Federation
Software
Federation
Interface

• Software Components
• Binary Form (Interface)
• Unit of Reusability
• Java Bins, COM/DCOM

• Federate
• Binary Form
• Unit of Reusability

Interface?
3
Simulation Object Model

• Simulation Object Model
• One per federate
• Object Model Template
• Define Objects/Interactions to be exchanged via
  HLA/RTI

Interface of a federate
4
Current HLA Standard

• Semantics used to create, join a federation
• Federation Object Model (FOM) based approach
• Requires Federation Execution Data (FED) file
  (HLA v1.3) or FOM Document Data (FDD) file (IEEE
  1516)
• FED,FDD Text file containing FOM

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HLA v1.3 Joining Process
(6) RTI-specific Join Processing
RTI process

• Connect
• Request Join

(3) FED file name
Joining Federate
(4) Search FED file in local computer (5)
Initialization Using FED
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IEEE 1516 Joining Process
(4) RTI-specific Join Processing
RTI process

• Connect
• Request Join

(3) FOM with RTI-specific data
Joining Federate
(4) Initialization
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Issues (1)

• Maintenance Problem ? Less Reusable
• All federates keep same copies of FED/FDD
• HLA v1.3 Join Federation Execution Service
  requires FED
• Accompanied Create/Join Federation Execution
  Service
• Modifications to all copies of FED/FDD
• Join new federation - new FED/FDD

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Issues (2)

• Information Hiding Problem
• Two or more federations form a bigger federation
• New FOM contains all sub FOMs
• Interoperation is the matter of Policy

9
Proposed SOM-based Semantics

• FED/FDD
• Not required or used to specify data common to
  all federates (i.e. MOM)
• SOM Document Data (SDD)
• Same format as FDD
• Contain SOM info
• Modified Join Federation Execution

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Join Federation Execution

• Supplied arguments
• Federate type(name), Federation name, SOM
  document designator
• Exceptions
• Could not locate SOM document
• Invalid SOM document
• Inconsistent Object Model

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Runtime FOM Construction

• FOM
• Mandatory Information to manage federation
• Not from FED/FDD
• Merge joining SDD to get FOM info
• For RTI internal use only

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Proposed Joining Process
(2) Merge SDD to update FOM (3) RTI-specific
Processing ex) Global Handle Assignment
RTI process
(4) SDD with RTI data
No Data flow To already joined federates
(1) SDD
Already Joined Federate
Joining Federate
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Merging Example Hall Federate Object Class
Table
(number) Globally Unique Handle
Examples are taken from IEEE Std 1516 Document
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Kitchen Object Class Table
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Merged Object Class Table
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Hall Attribute Table
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Kitchen Attribute Table
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Merged Attribute Table
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Resign

• Resign Federation Execution
• Extracting process is required?
• Additional Resource
• Simple data structure
• Possible further use

Extracting is not Required
VS.
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Comparison
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Conclusion

• Proposed SOM-based Join Semantics
• No Information Hiding Problem
• Possible to join any federation with SDD without
  modification
• No influence of object model change in other
  federates Easy maintenance

Federate-Level Reusability