Full HTML for

Basic foilset Overview of HLA and RTI DMSO Standards

Given by Geoffrey Fox but selected by W. Furmanski from DMSO at ARL Training Session IMT Dec 4 97 on Dec 4 97. Foils prepared Nov 29 97
Outside Index Summary of Material

This selects from the major DMSO HLA Training Resource at
Core Material
and Additional Material
This selects from HLA Overview, HLA Process and Policy
RTI 1.0 Tutorial, Time Management in the HLA, HLA Object Model Template (OMT)
and HLA Interface Specification
From additional material resource, we select Object Model Development Tools (OMDT)

Table of Contents for full HTML of Overview of HLA and RTI DMSO Standards

 Denote Foils where Image Critical
Denote Foils where HTML is sufficient
1 DMSO High Level Architecture Overview
2 DoD M&S Strategy: An Analogy to City Planning
3 How Did We Get Here?
4 High-Level Architecture Definition Process
5 Some Terminology
6 Some More Terminology
7 HLA Comprises Three Components: Rules, Runtime Infrastructure, Templates
8 A Federation Must Play by the Rules
9 Each Federate Must Play By the Rules
10 HLA Object Model Template
11 OMT Components
12 Object Class Structure Table (Template)
13 Object Interaction Table (Roughly Methods in CORBA)
14 Attribute/Parameter Table
15 Architecture Splits Functions Between Simulations and Runtime Infrastructure
16 In RTI 1.0, a Federate Process Contains Federate and RTI Code
17 Some RTI Services Are Initiated by Federate, Some by RTI
18 In the Beginning, There's an RTI Executive...
19 A Federate, Acting as a Federation Execution Manager, Creates a Federation Execution
20 Other Federates Join the Federation Execution
21 Hierarchy of Simulations
22 Federation Object Model (FOM) Defines Each Federation's Realm of Discourse
23 Interactions Represent Events in Time
24 Run-Time Infrastructure Provides Six Categories of Services
25 Federation Management Services
26 Declaration Management
27 Object Management Lets Federates See Each Other's Objects
28 Object Management Services
29 Ownership Management Allows Shared Responsibility for Simulating an Object
30 Ownership May Be Pushed to Another Federate
31 Ownership May Be Pulled from Another Federate
32 Time Management
33 Challenge: Time Management Interoperability
34 Logical Time
35 Time Management Services
36 Example: Event Driven Federate
37 Data Distribution Management
38 The Role of the Federate in DDM
39 The Role of the RTI in DDM
40 Illustration of DDM services
41 HLA Object Model development process and supporting tools
42 Introduction
43 HLA FEDEP Model
44 OMDTs aka HLA ComponentWare
45 AEgis OMDT (COM Object Model)
46 TASC OMDT(Java(bean) Object Model)
47 HLA Object Model Library
48 Object Model Data Dictionary System (OMDDS)
49 Use Case: Developing a New FOM
50 Data Interchange Formats
51 HLA DIFs
52 Access to the HLA OM Tool Suite

Outside Index Summary of Material

HTML version of Basic Foils prepared Nov 29 97

Foil 1 DMSO High Level Architecture Overview

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Defense Modeling & Simulation Office
(703) 998-0660 Fax (703) 998-0667 hla@msis.dmso.mil
http://www.dmso.mil/
Comments in Green with a left vertical bar
have been added by NPAC
and are not endorsed by DMSO
Original Powerpoint at http://www.dmso.mil/hla/edu_trng/regional/core_mat/
This selection at http://www.npac.syr.edu/users/gcf/dmsohlaforarldec97/
See also http://osprey7.npac.syr.edu:1998/iwt98/projects/webhla/
HTML version of Basic Foils prepared Nov 29 97

Foil 2 DoD M&S Strategy: An Analogy to City Planning

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
HTML version of Basic Foils prepared Nov 29 97

Foil 3 How Did We Get Here?

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
88 89 90 91 92 93 94 95 96
Technical
Management
Limited scope simulations, little interoperability prior to 1988
DSB: Computer Applications
to Training & Wargaming
DIS Standards begun
ALSP- linking of Service wargames
DEPSECDEF Memo
EXCIMS and DMSO established
SIMNET
HLA Baseline approved
HLA begun
Service M&S Offices established
DoDD 5000.59
HTML version of Basic Foils prepared Nov 29 97

Foil 4 High-Level Architecture Definition Process

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
DARPA's Program Evaluation Team
Mar 95
Initial
definition
of HLA
Aug 96
Baseline
definition
of HLA
Evolution
DoD-wide Architecture Management Group
( STOW, CCTT(CATT), JTCTS, BDS-D, BFTT/NSS, WARSIM 2000, NASM, JSIMS, JWARS, T&E, DIS, IADS, JMASS, SBD, DISA/D8)
Prototypes
Frequent Reviews Throughout
DoD Policy Issued
10 Sept 1996
HTML version of Basic Foils prepared Nov 29 97

Foil 5 Some Terminology

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Federation: a set of simulations, a common federation object model, and supporting RTI, that are used together to form a larger model or simulation
Federate: a member of a federation; one simulation
  • Could represent one platform, like a cockpit simulator
  • Could represent an aggregate, like an entire national simulation of air traffic flow
A federate could be large or small grain -- for initial activity of integrating existing pre HLA simulations, a federate is typically large grain size
However HLA is a "complete" model and one could build simulations where a federate is finr grain object and federation is simulation of these interacting objects
Federation Execution: a session of a federation executing together
HTML version of Basic Foils prepared Nov 29 97

Foil 6 Some More Terminology

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Object: An entity in the domain being simulated by a federation that
  • Is of interest to more than one federate (if internal to an existing non HLA compliant simulation, then this is an object but not an HLA object)
  • Is handled by the Runtime Infrastructure (RTI)
Interaction: a non-persistent, time-tagged event generated by one federate and received by others (through RTI)
Attribute: A named datum (defined in Federation Object Model) associated with each instance of a class of objects
Parameter: A named datum (defined in Federation Object Model) associated with each instance of a class of interactions
HTML version of Basic Foils prepared Nov 29 97

Foil 7 HLA Comprises Three Components: Rules, Runtime Infrastructure, Templates

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
HLA Rules: A set of rules which must be followed to achieve proper interaction of federates during a federation execution. These describe the responsibilities of federates and of the runtime infrastructure in HLA federations
  • HLA Rules correspond roughly to a CORBA vertical facility
Interface Specification: Definition of the interface services between the runtime infrastructure and the federates subject to the HLA
  • In CORBA, this would correspond to services
Object Model Templates: The prescribed common method for recording the information contained in the required HLA Object Model for each federation and federate
  • In CORBA, this would correspond to the IDL specification of objects but in HLA, objects are specified as tables of properties which are linked by interactions whereas in CORBA, one uses methods of objects.
HTML version of Basic Foils prepared Nov 29 97

Foil 8 A Federation Must Play by the Rules

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
1. Federations shall have an HLA Federation Object Model (FOM), documented in accordance with the HLA Object Model Template (OMT)
A FOM is like a particular facility in CORBA
2. In a federation, all representation of objects in the FOM shall be in the federates, not in the runtime infrastructure (RTI)
3. During a federation execution, all exchange of FOM data among federates shall occur via the RTI
4. During a federation execution, federates shall interact with the runtime infrastructure (RTI) in accordance with the HLA interface specification
5. During a federation execution, an attribute of an instance of an object shall be owned by only one federate at any given time
HTML version of Basic Foils prepared Nov 29 97

Foil 9 Each Federate Must Play By the Rules

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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6. Federates shall have an HLA Simulation Object Model (SOM), documented in accordance with the HLA Object Model Template (OMT)
7. Federates shall be able to update and/or reflect any attributes of objects in their SOM and send and/or receive SOM object interactions externally, as specified in their SOM
8. Federates shall be able to transfer and/or accept ownership of attributes dynamically during a federation execution, as specified in their SOM
9. Federates shall be able to vary the conditions (e.g., thresholds) under which they provide updates of attributes of objects, as specified in their SOM
10. Federates shall be able to manage local time in a way which will allow them to coordinate data exchange with other members of a federation
HTML version of Basic Foils prepared Nov 29 97

Foil 10 HLA Object Model Template

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
The HLA OMT is a standardized presentation format for describing HLA object models
Sort of like Design Rules or Frameworks in ComponentWare
Rationale:
  • Facilitates FOM development coordination
  • Provides a common means of describing potential federation members
  • Facilitates the design and development of common FOM development toolsets
HTML version of Basic Foils prepared Nov 29 97

Foil 11 OMT Components

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Object Class Structure Table
Object Interaction Table
  • Equivalent to methods in CORBA
Attribute/Parameter Table
  • Enumerated Datatype Table
  • Complex Datatype Table
  • Equivalent to properties in CORBA
FOM/SOM Lexicon
  • Remember FOM is the federation object model and SOM the internal simulation object model for a given member federate of the federation
HTML version of Basic Foils prepared Nov 29 97

Foil 12 Object Class Structure Table (Template)

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
General Case
Example
P=Publish and S=Subscribe
HTML version of Basic Foils prepared Nov 29 97

Foil 13 Object Interaction Table (Roughly Methods in CORBA)

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
General Case
Example
HTML version of Basic Foils prepared Nov 29 97

Foil 14 Attribute/Parameter Table

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
The Columns define characteristic properties of an HLA simulation object which would be defined by IDL in
CORBA and Java Class definition in RMI/Javabean Approach
HTML version of Basic Foils prepared Nov 29 97

Foil 15 Architecture Splits Functions Between Simulations and Runtime Infrastructure

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Live
Participants
Interface
Runtime Infrastructure
Data Collector/
Passive Viewer
Federation Management Declaration Management
Object Management Ownership Management
Time Management Data Distribution Management
RTI is a bit like IIOP with critical addition of time
management services
HTML version of Basic Foils prepared Nov 29 97

Foil 16 In RTI 1.0, a Federate Process Contains Federate and RTI Code

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Network
Ambassadors hold equivalent of stubs and skeletons in CORBA/RMI/COM distributed object models.
These are proxies for remote objects
HTML version of Basic Foils prepared Nov 29 97

Foil 17 Some RTI Services Are Initiated by Federate, Some by RTI

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Federate
Ambassador
RTI Ambassador
Interfaces are method calls on objects (C++, Ada-95, Java)
Federate-initiated serves are invoked on an instance of RTI Ambassador
RTI-initiated services are invoked on an instance of Federate Ambassador
HTML version of Basic Foils prepared Nov 29 97

Foil 18 In the Beginning, There's an RTI Executive...

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
RTI Executive is a 1.0-supplied server started by hand
It's an artifact of 1.0 design, not inherent in RTIs
There is usually 1 Executive per LAN
RTI Executive is a naming service for federation executions
RTI Executive
This is by hand start up process with naming server etc.
HTML version of Basic Foils prepared Nov 29 97

Foil 19 A Federate, Acting as a Federation Execution Manager, Creates a Federation Execution

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
RTI
Executive
FedEx
Federate invokes createFederationExecution on its RTI Ambassador
RTI Ambassador reserves name with RTI Executive
RTI Ambassador spawns FedEx process
FedEx registers its communication address with RTI Executive
"Host" for a Federation
Top level
Super "Host"
HTML version of Basic Foils prepared Nov 29 97

Foil 20 Other Federates Join the Federation Execution

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
RTI
Executive
FedEx
Another federate invokes joinFederationExecution on its RTI Ambassador
RTI Ambassador consults RTI Executive for address of FedEx
RTI Ambassador invokes joinFederationExecution on FedEx
This arrangement of separate processes for RTIexec and FedEx is an RTI 1.0 artifact
HTML version of Basic Foils prepared Nov 29 97

Foil 21 Hierarchy of Simulations

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
RTI Executive, FEDEX's and Federates are arranged hierarchically where you can think of a federate as a single process (as far as HLA is concerned) running in a single computer.
  • This would not be true for linking complex legacy systems where a federate is itself a distributed simulation
RTI Executive
Fedex Executive
.........
Fedex Executive
Federates
HTML version of Basic Foils prepared Nov 29 97

Foil 22 Federation Object Model (FOM) Defines Each Federation's Realm of Discourse

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Data passed between federates by the RTI is entirely parametric to the RTI (i.e. RTI does not Interpret it -- the FOM explains it)
This contrasts with DIS, where a new data item means a new PDU and changes to DIS infrastructure
  • DIS is the real time platform FOM
FOM describes the kinds of things federates will talk about in a federation including: objects and interactions
FOM (object attributes and their interaction) is agreed by federation designers before execution
Parts of the FOM are supplied, at execution time, as data to the RTI
  • In 1.0, the FOM data takes the form of <fedexname>.fed (equivalent of IDL file in CORBA) , for "federation execution data"
  • File must be stored in a place accessible to each federate; where federate looks is a configuration item
HTML version of Basic Foils prepared Nov 29 97

Foil 23 Interactions Represent Events in Time

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
An interaction represents an event in time that has no continuing state, e.g. a change in an ATC clearance or the firing of a weapon
An interaction, unlike an object does not persist; it occurs at a specified time
Federations subscribe to classes of interactions. They are then notified when another federate sends an interaction of that class
Each interaction class specifies the set of parameters for each instance of that class
Like object classes, one interaction class can inherit from another
An interaction is instantiated by messages which are essentially sent and received by methods of objects
HTML version of Basic Foils prepared Nov 29 97

Foil 24 Run-Time Infrastructure Provides Six Categories of Services

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Category
Functionality
Federation Management
Create and delete federation executions
Join and resign federation executions
Control checkpoint, pause, resume,
restart
Declaration Management
Establish intent to publish and subscribe
to object attributes and interactions
Object Management
Create and delete object instances
Control attribute and interaction
publication
Create and delete object reflections
Ownership Management
Transfer ownership of objects/attributes
Time Management
Coordinate the advance of logical time
and its relationship to real time
Data Distribution
Management
Controls the efficient routing of
information between federates
CORBA has services and horizontal facilities
HTML version of Basic Foils prepared Nov 29 97

Foil 25 Federation Management Services

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
2.1 Create Federation Execution
2.2 Destroy Federation Execution
2.3 Join Federation Execution
2.4 Resign Federation Execution
2.5 Request Pause
2.6 Initiate Pause †
2.7 Pause Achieved
2.8 Request Resume
2.9 Initiate Resume †
2.10 Resume Achieved
2.11 Request Federation Save
2.12 Initiate Federate Save †
2.13 Federate Save Begun
2.14 Federate Save Achieved
2.15 Request Restore
2.16 Initiate Restore †
2.17 Restore Achieved
Services are generic
capabilities needed
by all objects and
federations
HTML version of Basic Foils prepared Nov 29 97

Foil 26 Declaration Management

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Allow federates to specify the types of data they will send or from the FOM
Interface receive by object class and attribute name and by interaction class functions include specification of:
  • Data to be sent:
    • Object classes and attributes and interaction classes that the federate is able to update or send
  • Data to be received:
    • Object classes and attributes and interaction classes that the federate is interested to receive
  • Controls on data to be sent:
    • Feedback to the federates from the RTI when attribute updates and interactions should be sent given the interest in those by other federates
This is roughly structure of object classes as opposed to particular instance of objects -- the latter is handled by object management service
HTML version of Basic Foils prepared Nov 29 97

Foil 27 Object Management Lets Federates See Each Other's Objects

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
RTI
This is a publish-and-subscribe service
  • It's parameterized by FED at execution time,
  • Adjusted by each federate dynamically,
  • It's subject to time management (about which more later).
Federate A creates obj 1 reflects 2, 3
Federate B creates obj 2, 3 reflects 1
Federate C reflects 1, 2, 3
HTML version of Basic Foils prepared Nov 29 97

Foil 28 Object Management Services

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
4.1 Request Id
4.2 Register Object
4.3 Update Attribute Values
4.4 Discover Object †
4.5 Reflect Attribute Values †
4.6 Send Interaction
4.7 Receive Interaction †
4.8 Delete Object
4.9 Remove Object †
4.10 Change Attribute Transportation Type
4.11 Change Attribute Order Type
4.12 Change Interaction Transportation Type
4.13 Change Interaction Order Type
4.14 Request Attribute Value Update
4.15 Provide Attribute Value Update †
4.16 Retract
4.17 Reflect Retraction †
These are services
needed to manipulate
particular instances
of objects
HTML version of Basic Foils prepared Nov 29 97

Foil 29 Ownership Management Allows Shared Responsibility for Simulating an Object

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Each attribute of each object has an owner: the owner is the federate responsible for updating that attribute
  • Called "owner-computes rule"! Any object must be updated by a particular federate
Different attributes of the same object may have different owners. One federate is updating an aircraft's position; another federate, subscribing to the position, is updating icing
"Privilege to delete" an object is an attribute owned by some federate
Ownership can change: responsibility for updating an attribute can pass from one federate to another. E.g., an aircraft modeled in an aggregate simulation could transfer ownership of the position attribute to a cockpit
Ownership exchange may be pushed or pulled
HTML version of Basic Foils prepared Nov 29 97

Foil 30 Ownership May Be Pushed to Another Federate

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Federate wishing to give up ownership
Federate accepting ownership
step 1 Request
Attribute
Ownership
Divestiture
(service 5.1)
step 2 Request
Attribute
Ownership
Assumption
(service 5.2)
step 3 Attribute
Ownership
Divestiture
Notification
(service 5.3)
step 3 Attribute
Ownership
Acquisition
Notification
(service 5.4)
HLA Runtime Infrastructure
HTML version of Basic Foils prepared Nov 29 97

Foil 31 Ownership May Be Pulled from Another Federate

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Federate wishing to take ownership
Federate releasing ownership
step 1 Request
Attribute
Ownership
Acquisition
(service 5.5)
step 2 Request
Attribute
Ownership
Release
(service 5.6)
step 3 Attribute
Ownership
Acquisition
Notification
(service 5.4)
HLA Runtime Infrastructure
HTML version of Basic Foils prepared Nov 29 97

Foil 32 Time Management

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Control advancement of federates along with federation time
  • Coordinated with object management services to support causal behavior across the federation
  • Designed to support federates with different ordering and delivery requirements
Interface functions include
  • Request current values of time
    • Federation time, federate's logical time (LT), lower bound time stamp (LBTS), minimum next event time
  • Set and request lookahead
  • Time advance request, next event and flush queue request, and grant
Time Management is critical difficulty in simulations as hard to make efficient -- subject of much research!
HTML version of Basic Foils prepared Nov 29 97

Foil 33 Challenge: Time Management Interoperability

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Goal: provide services to support interoperability among federates with different local time management schemes in a single federation execution.
Observation: RTI by itself cannot guarantee interoperability.
Run Time Infrastructure (RTI)
training federate:
real-time execution
constructive federate:
time-stepped execution
Run Time Infrastructure (RTI)
constructive federate:
event driven execution
Run Time Infrastructure (RTI)
live component:
real-time execution
w/ hard deadlines
Run Time Infrastructure (RTI)
multiprocessor
parallel simulation federate:
optimistic Time Warp execution
Run Time Infrastructure (RTI)
HTML version of Basic Foils prepared Nov 29 97

Foil 34 Logical Time

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Classical discrete event simulation programs process all events in time stamp order
A mechanism is required to enable federates to interleave processing of local events with those received from other federates
Logical time (applicable to coordinated time advance federates):
  • If the logical time of a federate is T, the RTI guarantees no more TSO messages will be passed to the federate with time stamp < T
  • Local events with time stamp < T can be "safely" processed
  • Logical time in a federate only advances when that federate explicitly requests an advance:
    • Time Advance Request (T): requests advance to time T
    • Next Event Request (T): requests advance to time stamp of next TSO message, or T, which ever is smaller
    • RTI issues Time Advance Grant (T') when logical time advanced to T'
  • Federates responsible for pacing logical time advances with wallclock time in (scaled) real-time executions
HTML version of Basic Foils prepared Nov 29 97

Foil 35 Time Management Services

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
federate
local time and event management
mechanism to pace execution with wallclock time (if necessary)
federate specific techniques (e.g., compensation for message latencies)
wallclock time
(synchronized with other processors)
logical time
FIFO
queue
time
stamp
ordered
queue
Runtime
Infrastructure
(RTI)
state updates
and interactions
logical time advance
requests and grants
receive
order
messages
time stamp
order
messages
HTML version of Basic Foils prepared Nov 29 97

Foil 36 Example: Event Driven Federate

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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while (simulation still in progress)
invoke Next Event Request (Tlocal = time stamp of next local event)
RTI delivers next TSO event w/ time stamp Š Tlocal if any exist (+ others w/ same time stamp)
RTI advances federate's logical time, invokes Time Advance Grant
if (TSO message(s) delivered in above Next Event Request service call)
process the remote event(s) delivered to the federate
else process next local event
Goal: merge TSO messages (events from other federates) with local events so all events are processed in time stamp order
RTI
federate
TSO
messages
local
events
logical
time
current
time
next
local
event
next
remote
event
Tlocal
HTML version of Basic Foils prepared Nov 29 97

Foil 37 Data Distribution Management

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Allow federates to specify the distribution conditions for the specific data they send or expect to receive
  • RTI uses this information to route data as specified in declaration management services
  • Not bound by FOM, data distribution can be managed based on other characteristics of objects important to particular federation execution
  • Federation design creates `routing spaces' for use during runtime; these are specified at federation creation time
Interface functions include
  • Create and modify `update' and `subscription' regions to bound routing space
  • Associate update regions with specific object instances
  • Change thresholds for changing regions
Critical for efficient implementations -- SIMNET broadcast updates to every process and this does not scale
HTML version of Basic Foils prepared Nov 29 97

Foil 38 The Role of the Federate in DDM

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Create Subscription Region
  • Specify conditions under which they expect to receive the object state data and interactions they specified using declaration management services (Subscribe Object Class Attribute and Subscribe Interaction Class) and
Create Update Region
Associate Update Region (with an object instance or interaction)
  • Specify conditions under which they are providing data (characteristics of object or interaction which map to dimension of routing space fall with region bounds)
Modify Region or Associate Update Region
  • As the state of the objects change, the federate may need to either adjust the bounds on the associated regions or change the association to another region
HTML version of Basic Foils prepared Nov 29 97

Foil 39 The Role of the RTI in DDM

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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The routing space, regions, and association data is used by the RTI to distribute data
When an update region and subscription regions of different federates overlap
  • The RTI ensures that the attribute updates and interactions associated with that update region are routed to federates with subscription regions which overlap the sender's update region
Change Thresholds
  • The RTI provides feedback to federate on the amount of change in extents which will lead to data distribution changes
In Javabeans, we would set this up as "listeners" which are associated with observers (receivers of events) and which are notified when changes made
HTML version of Basic Foils prepared Nov 29 97

Foil 40 Illustration of DDM services

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Two Dimensional Interest Space
Update Region
Subscription Region
Overlap Region - Published Data Sent to Subscribing Federate
HTML version of Basic Foils prepared Nov 29 97

Foil 41 HLA Object Model development process and supporting tools

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Defense Modeling & Simulation Office
(703) 998-0660 Fax (703) 998-0667 hla@msis.dmso.mil
http://www.dmso.mil/
Current as of 25 Sept 97
Tools to support construction of HLA Compliant Simulations
HTML version of Basic Foils prepared Nov 29 97

Foil 42 Introduction

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
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Feedback from HLA protofederations emphasized need for process descriptions for HLA federation and object model development
HLA Federation Development and Execution Process (FEDEP) model developed through cooperative effort between HLA protofederations and HLA TSTCore
Sharing of OM development concepts among HLA protofederations (via the OMT Working Group) provided the foundation of the HLA Object Model Development Process
HLA protofederation feedback also emphasized need for automated tools to support development processes
  • Led to development of the HLA Tool Architecture
HTML version of Basic Foils prepared Nov 29 97

Foil 43 HLA FEDEP Model

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Fed Object Model
Library of
SOMs
of FOMs
Sponsor
Scenario
Development
Management
Requirements
Common Fed Functionality
Execution
Environment
Federation Execution Data
Results
Objects,
Attributes,
Interactions
Determine
suitability of
Develop
Identifies
Guides
Defines
Drives
Record
Feeds
Provides
input to
Derives
Inputs to
Provides
input to
Provides
input to
Provides
input to
Feedback
Defines/Refines
Drives
Design
Provides
input to
Generates
FRED
Scenario Instances
-- Where
-- Who
-- Details
Feeds
Fed Commonality
Object Model
ED
Fed Development
Products
Modeling and Simulation Resource Repository
Federation
Library
Federation
Federation
Test
Federation
Execution
Conceptual
Analysis
Other Resources
HLA FOM
Scenario Data
HTML version of Basic Foils prepared Nov 29 97

Foil 44 OMDTs aka HLA ComponentWare

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Purpose:
  • Reduce manpower associated with FOM/SOM development
  • Provide integrated access to supporting resources
  • Automated production of Federation Execution Data (FED)
  • Maintain lowest possible learning curve
    • Intuitive user-interface
    • Help system and documentation
Common Features:
  • Data entry/modification
  • Syntax/consistency checking
  • Automated OML(library)/OMDDS(Web based resource of existing objects) access
  • FED generation
  • On-line help/documentation
HTML version of Basic Foils prepared Nov 29 97

Foil 45 AEgis OMDT (COM Object Model)

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Windows 95/Windows NT application
Developed in Visual C++ using the Microsoft Foundation Classes
Interface designed around HLA OMT tabular views
  • Supports in-place editing within cells and Win95 property sheet interfaces
  • Includes OMT extension tables
"Smart" copy/paste maintains object model relationships
Multiple Document Interface allows copy/paste between object models
Interface for editing FED data (message order, delivery category)
User's Guide and Reference Manual integrated in Windows Help
CDIF(Data Interchange Format) interface to COTS CASE tools
HTML version of Basic Foils prepared Nov 29 97

Foil 46 TASC OMDT(Java(bean) Object Model)

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Standalone Java application
  • Requires Java Development Kit to run
Multiple platforms
  • Unix, PC, Mac, ...
Easy to use interface
  • Tabs to navigate to each table in the OMT
OM Development Wizard
  • Guides the user through the OM development process
HTML version of Basic Foils prepared Nov 29 97

Foil 47 HLA Object Model Library

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Need to re-use objects between simulations
This is part of function of CORBA trader service and similar in goals to RIB project of NHSE (National High Performance Software Exchange)
Provides a central repository (currently in Texas) for HLA Federation Object Models (FOMs) and Simulation Object Models (SOMs)
Supports the Federation Execution Development Process (FEDEP) by
  • Making FOMs and SOMs accessible to anyone
    • FOMs and SOMs for specific applications
    • Reference FOMs
  • Supporting the reuse FOMs and SOMs
  • Providing pieces and parts for the creation of new FOMs and SOMs
  • Providing a basis for the comparison of semantic differences between/among multiple FOMs and SOMs
HTML version of Basic Foils prepared Nov 29 97

Foil 48 Object Model Data Dictionary System (OMDDS)

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
A web-accessible repository containing:
  • OMDD contents
  • Mappings between OMDD contents and external data standards
  • Mappings between OMDD contents and object models
The OMDDS supports:
  • Searching and browsing the OMDD contents
  • Exporting a portion of the OMDD contents (for use with Object Model Development Tools)
  • Establishing new OMDD contents
  • Mapping OMDD contents to external standards and object models (FOMs and SOMs in the OML)
HTML version of Basic Foils prepared Nov 29 97

Foil 49 Use Case: Developing a New FOM

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Define Federation
Scenario
Requirements
Search/Reuse
Existing FOMs
Identify Candidate
Simulations and
SOMs
Check/Update
Consistency with
OMDD Contents
Complete FOM,
building with
OMDD Contents
Add FOM and
SOMs to OML
Propose new
OMDD Contents
HTML version of Basic Foils prepared Nov 29 97

Foil 50 Data Interchange Formats

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
A DIF is a specification of the semantics and structure of data to be interchanged between multiple data producers and multiple data consumers
HLA DIFs are Backus Naur Form (BNF) descriptions of delimited ASCII text
HLA DIFs support the interchange of object model information among HLA tools
HLA DIFs provide an open specification for development of new object model tools which will integrate with the existing tool set
HTML version of Basic Foils prepared Nov 29 97

Foil 51 HLA DIFs

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
Object Model
Library
Object Model
Data Dictionary
System
Object Model
Development
Tools
RTIs
DoD
Data Dictionary
System
OMT
DIF
OMDD
DIF
OMT
DIF
FED
DIF
DDDS Batch Formats
HTML version of Basic Foils prepared Nov 29 97

Foil 52 Access to the HLA OM Tool Suite

From Overview of HLA and RTI DMSO Standards ARL Training Session IMT Dec 4 97 -- Dec 4 97. *
Full HTML Index
AEgis OMDT and OML will be made publicly available in late October
TASC OMDT and OMDDS will be made publicly available later this year, following further testing
To find out more on release information:
  • watch the DMSO Home Page (http://hla.dmso.mil/) for release
  • subscribe to HLA_Online through listproc@msis.dmso.mil
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