HIGH LEVEL ARCHITECTURE

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1 ARCHITEC Department of Electrical and Computer Engineering University of Arizona November 13, 2008

2 The High Level (HLA) is an architecture for reuse and interoperation of simulations. Tools may include: MATLAB/Simulink OMNeT++ CPNTools DEVSJAVA Delta3D

3 Definitions: Federation: A named set of federate applications and a common Federation Object Model that are used as a whole to achieve some specific objective. Runtime Infrastructure (RTI): The software that provides common interface services during a High Level (HLA) federation execution for synchronization and data exchange. Federate: An application that may be or is currently coupled with other software applications under a Federation Object Model Document Data (FDD) and a runtime infrastructure (RTI).

4 Some easier interpretation of these concepts: Federation: A composable set of interacting simulations. Runtime Infrastructure (RTI): The software managing the interaction among federates. Federate: An elementary HLA-compliant program, e.g. a specific simulation.

5 Figure: Functional View of an HLA Federation

6 Major functional components: Simulations; Data Collector and Viewer; Interface to Live Participants; These three components are, in general, the federates. All object representation is in the federates. Federates allow the objects in one simulation to interact with objects in other simulations through the exchange of data supported by services implemented in RTI. RTI; Interface to RTI.

7 The HLA interface specification describes the runtime services provided to the federates by the RTI, and by the federates to the RTI. There are six classes of services: Federation management service; Declaration management service; Object management service; Ownership management service; Time management service; Data distribution management service;

8 HLA object models are description of the essential sharable elements of the simulation or federation in object terms and each federate and federation document its object model using a standard object model template. The HLA specifies two types of object models: Federation Object Model (FOM) describes the set of objects, attributes and interactions, which are shared across a federation; Simulation Object Model (SOM) describes the simulation (federate) in terms of the types of objects, attributes and interactions it can offer to future federations. Both the HLA FOM and SOM are documented using the standard Medel Template (OMT).

9 HLA rules summarize the key principles behind the HLA. The rules for federations are: Federations shall have an HLA FOM, documented in accordance with the HLA OMT. In a federation, all simulation-associated object instance representation shall be in the federates, not in the RTI. During a federation execution, all exchange of FOM data among joined federates shall occur via the RTI. During a federation execution, joined federates shall interact with the RTI in accordance with the HLA interface specification. During a federation execution, an instance attribute shall be owned by at most one joined federate at any given time.

10 The rules for federates are: Federates shall have an HLA SOM, documented in accordance with the HLA OMT Federates shall be able to update and/or reflect any instance attributes and send and/or receive interactions, as specified in their SOMs. Federates shall be able to transfer and/or accept ownership of instance attributes dynamically during a federation execution, as specified in their SOMs. Federates shall be able to vary the conditions (e.g., thresholds) under which they provide updates of instance attributes, as specified in their SOMs. Federates shall be able to manage local time in a way that will allow them to coordinate data exchange with other members of a federation.

11 The HLA Federation Deelopment and Execution (FEDEP) has been developed and is being evolved based on user experience with the application of HLA. The process covers five basic steps: Concept development; Federation design; Federation execution implementation; Testing; Operations.

12 Examples of HLA support software include: RTI ; Object Model Tools; Object Model Development Tool; Object Model Library; Object Model Data Dictionary; Federation Executing Planning and Runtime Support Tools;

13 The DoD High Level : An Update http: //portal.acm.org/citation.cfm?id= Creating Computer Simulation Systems An to the High Level Creating-Computer-Simulation-Systems- dp/ /ref=pd_bbs_sr_1?ie=utf8&s= books&qid= &sr=8-1