Conference Presentation, SIMULTECH 2010

1. A Model Transformation Approach for
the Development of HLA-based
Distributed Simulation Systems
1st International Conference on Simulation and Modelling Methodologies,
Technologies, and Applications (Simultech), July, 2011
Andrea D'Ambrogio, Giuseppe Iazeolla, Alessandra Pieroni
University of Rome TorVergata
dambro@uniroma2.it
Daniele Gianni
European Space Agency
daniele.gianni@esa.int

2. 2
Distributed Simulation and HLA
 Simulation partitioned on two or more processors
connected by a communication network
 Some benefits
• Geographical distribution
• Increased performance (speed-up, fault tolerance, etc.)
• Enhanced reusability of HW and SW resources
 Distributed simulators are more complex than local
ones (inherent parallelism, synchronization, etc.)
 HLA is a IEEE standard (4 docs) aiming to increase DS
simulation SW reusability and interoperability

3. 3
HLA Main Components
 Federate: a remotely-
accessible simulation sub-
system
 Federation: the overall DS
system, composed of a set
of Federates
 RTI: provides
communication and
coordination services to the
Federates that join into a
Federation
 Data exchange: HLA Object
for persistent entities, HLA
Interactions for temporary
entities
Federate
RTI Ambassador
Federate Ambassador
Runtime Infrastructure (RTI)

4. 4
Outline
 Motivation
 Problem statement
 Model Transformation Approach
 Example Application

5. 5
Motivation
HLA is technically complex and involves:
 Acquiring knowledge of HLA concepts (steep learning
curve)
 Making design choices, which can in turn affect the
simulation model
 Developing federates, either from scratch or by
reusing already available federates
There is room for:
 Reducing development effort and time
 Better support for managing increasingly complex
software
 Enhancing the reuse of software products

6. 6
Problem Statement
 How can we improve the development of
HLA-based distributed simulation systems?
 By applying a Model-driven engineering
(MDE) approach that automates the
production of a HLA simulators from a UML
model of the system to be simulated
 By using standards methodologies (e.g. MDA)
and technologies for general-purpose SW

7. 7
MDA development lifecycle
source: OMG’s MDA Guide v1.0.1
Platform
Independent
Model
Platform
Specific
Model
This paper contributionExample Application
UML
HLA UML Profile

8. 8
Quick notes on UML constructs
 Actor-Boundary Class: interface with the outside
world
 Control Class: execution flow in a use case
 Entity Class: persistent data exchanged between
actors
 Associated Entity Class: aggregation of entity
classes
 Actor-Boundary Messages: temporary data
 Boundary-Control messages: temporary data

9. 9
HLA UML Profile

10. 10
PIM-PSM Transformation Rules
 Rule 1 “Actor-Boundary to Federate”
• Federate: the smallest independent unit (by definition)
 Rule 2 “Control to Federate”
• Use case flow  federate implementing the respective flow
 Rule 3 “Entity to Object Class”
• HLA Object (by definition)
 Rule 4 “Associated Entities to Federate”
• Federate: group of entities encapsulating behaviour
 Rule 5 “Actor-Boundary Messages to Self-Messages”
• Sequence interactions between federates
 Rule 6 “Boundary-Control messages to RTI messages”
• Sequence interactions between federate and RTI

11. 11
PSM-Code Transformation Rules
 Rule 1 “PSM Federate to Java Federate and Federate
Ambassador Classes”
 Rule 2 “PSM Object Class to FOM Object Class*”
*(HLA persistent –and shared– data in a HLA federation)
 Rule 3 “PSM Interaction Class to FOM Interaction Class*”
*(HLA temporary data exchanged in a HLA federation)

12. 12
Example Application

13. 13
Entity Classes

14. 14
Derived UML HLA Federates

15. 15
Derived UML HLA Object Classes

16. 16
HLA Code Generation

17. 17
Conclusions
 HLA presents several shortcomings (specialised know-
how, development effort, limited reusability, etc.)
 A model-driven approach can contribute to overcome
these shortcomings by raising the design from a
programming to a model level
 We have implemented a MDA-based approach for the
automatic derivation of HLA simulators
• UML profile for HLA
• PIM to PSM QVT transformation
• PSM to Java Code QVT transformation
 We have shown an example application to the
derivation of a HLA simulator for a Phone SIM card
system

18. 18
We would like to thank Simone Loprieno and Giacomo
Tiberia for the transformation implementation and
example validation.
Acknowledgements

19. 19
Extra Slides

20. 20
Applying MDA to HLA
 Definition of UML profile for HLA (HLA UML)
 Definition of PIM to PSM transformation,
using QVT
• relationships between UML concepts with HLA
UML concepts
 Definition of PSM to code transformation,
using QVT
• relationships between HLA UML concepts and
Java coding for the HLA simulator

21. 21
Model-Driven Architecture
 The OMG (Object Management Group) addresses MDE with
MDA, the Model Driven Architecture
 MDA Motivation: transfer the focus of work from coding
(“everything is an object”) to modeling (“everything is a
model”)
 MDA provides a set of guidelines for structuring specifications
expressed as models and the transformations between such
models
 The transformations map the elements of a source model that
conforms to a specific metamodel to the elements of another
model, the target model, that conforms to the same or to a
different metamodel

22. 22
Traditional non-MDE development lifecycle
source: OMG’s MDA Guide v1.0.1

23. 23
Model Transformation
(marking approach)
source: OMG’s MDA Guide v1.0.1
Transformations are
defined as set of
relationship between a
source metamodel and a
target metamodel

24. 24
Associated standards
Model definition
 UML Profiles: language for the specialization of UML
metamodel.
 Meta Object Facility (MOF): language for the definition of
metamodels
 XML Metadata Interchange (XMI): XML coding format for
MOF metamodels
Model transformation
 MOF 2.0 Query/View/Transformation (QVT): a standard
language for specifying transformations.

25. 25
OMT Kernel Package

26. 26
Rule 3 Graphical Representation
name = n
«Entity»
self : Class
Entity to ObjectClass
destination : UMLsource : UML
C E
name = n
«ObjectClass»
result : Class
self.isStereotypeApplied(self.getAppliedStereotype(“MVC::Entity”)
when

27. 27
Rule 1 Textual Representation
«DEFINE javaClass FOR Federate»
package nome_federato */
«FILE './'+name+'/'+name+".java"»
package «name»;
import hla.rti1516.RTIambassador;
public class «name» {
private «"HLA1516FederateAmbassador"+name» fedamb;
private RTIambassador rtiamb;
public void log(String s){
System.out.println("«name» "+s);}
«FOREACH features AS f»
private «f.type.name» «f.name»;
public void «f.setter()»(«f.type.name» «f.name»){
this.«f.name» = «f.name»;}
public «f.type.name» «f.getter()»(){
return «f.name»;}
«ENDFOREACH»
public void run(){}
}
«ENDFILE»

28. 28
Transformation Tool