Distributed Simulation Processes and Tools DSPT

1
Distributed Simulation Processes and Tools (DSPT)

• From HLA to MMOG and Back Again Charles J. Cohen,
  Ph.D.
• Rob C. Buse
• Douglas Haanpaa
• Charles J. Jacobus, Ph.D.

2
Outline

• Background
• Bridging the Divide
• An MMOG 1516 Compliant RTI
• The Game Developer Friendly API
• Retrofitting Games that have Multiplay
• Conclusions

3
Background

• HLA Middleware between simulation application
  and network/operating system infrastructure
• HLA Allows developer to generate messages about
  objects, interactions, and component parts
• HLA SISO/IEEE 1.3 and 1516 specifications for
  standardizing RTI implementations

4
HLA RTI Capabilities

• Object Management
• Federation Management
• Time Management
• Data Distribution Management (DDM)
• Management Object Model (MOM)
• Ownership Management

5
Cybernets First Game Oriented HLA

• Created our own mini-RTI
• Not required
• Time management
• DDM
• Save/Restore
• MoM (implemented our own Lobby Management)
• Created ImportExportTable interface

6
Cybernets First Game Oriented HLA

• Needed for game development, but not in HLA
• Play Time Billing
• Web site support
• Player authentication
• Persistent database (world)
• Patching and database updates
• Massive Multiplay (gt100,000)

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Advantage of HLA

• Defines a shared distributed object definition
  set
• Standardizes all communications within a shared
  distributed interactive simulation (DIS)
• Multiple independently created simulation
• Can interact within this shared standardized
  object framework
• Each simulation participant only needs awareness
  of relevant objects/definitions
• Each simulation independently developed and tested

8
Typical Game Messaging

• HLA and DIS are peer-to-peer nxn communications
• HLA not easily scalable
• Games use Client-Server Model
• Communications order n

9
Unreal Network Architecture

• Variable
• Object
• Actor
• Level
• Tick
• Game State of Level
• Instance of Unreal Engine
• Game Serve

10
DirectPlay Network Architecture

• DirectPlay is network component of DirectX
• Not object oriented (like Unreal)
• Socket-like connection functions
• Includes
• Lobby Management
• Sending messages
• Receiving messages
• Implementing callbacks
• Does not define an sharable object
  orientedstructure between clients and servers

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Bridging the Divide

• Allow commercial and military to use their own
  API
• Implement a scheme to translate between them
• Use alternative RTIs
• Require easy to use development tools
• Government would rather have standardization
• HLA is more complex than game developer wants

12
Security

• Cheating / Security / Authentication is a huge
  issue in the gaming community
• Military, though, can use Peer-to-Peer.
  Training, not gaming, and are supervised
• Authentication important to both
• Military assessing access rights based on
  national security policies
• Commercial support correct billing and
  maintenance of personal information privacy

13
An MMOG 1516 Compliant RTI

• 1516 API for Windows, WinCE, and Linux/Unix users
• Includes lobby management, DDM, time management,
  MOM, object, ownership, and federation management
• For game development, includes
• Distributed fault tolerant dynamically scalable
  Federation management and message routing fabric
  
• Attached message filters, allowing control of
  update and message flow

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An MMOG 1516 Compliant RTI (cont)

• For game development, includes (cont)
• Developer interface over HLA, called
  Point-to-Point Switch, and simplified
  Import/Export Table
• Shared persistent SQL database function for game
  state
• Web site template
• Authentication/billing function

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Implementation

• Place Lobby Manager on a broker server to manage
  a large network of federations
• FedHost process launches upon user request
• FedHost process are spawned on each repeater
  server (through Lobby Manager)
• Clients do not communicate with each other
• Network traffic reduced to order n into the
  FedHost cloud
• FedHosts perform culling rules

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Culling Rules

• Reside on the repeater server
• Defined as member functions for the attribute
  sets in the FOM file
• Can use default culling modules
• Can develop game-specific culling routines in
  DLLs
• Can be used to implement security or quality of
  service algorithms
• Can be turned on and off at run-time

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More Game Implementations

• Can shift clients from failed FedHosts to new
  ones without stopping the game (dynamic
  rebalancing)
• Clients/Federates run by game user (residing on
  Win CE, Windows, or Linux/Unix machines)
• Federation created by first Host Federate request
  to the Lobby Manager
• Game Server Federate(s) used to control aspects
  of game not implement in client (such as score
  book keeping, persistent elements, etc.)
• Database/Authentication Server can be encrypted

18
The Game Developer Friendly API

• Need to hide HLA complexity from game developers.
  Two interfaces created
• Import/Export Table (IET) object based
• Point-to-Point Switch (P2PS) message based

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IET Interface

• Use to network the information so other
  applications can see the object
• Graphical configuration tool
• User enters information needed for networked
  objects
• Configure program automatically generate the
  configuration and source files for multiplayer
  applications
• Federation Execution Detail
• Includes object fields that are sent over network
  at every update
• IET entities map directly to FOM objects and
  attributes described in the Federation Execution
  Detail
• Import/Export Tables
• C class is created, mapping variables to
  attributes

20
P2PS

• Provides ability to send messages to named
  objects that might not even exist yet
• Currently not in HLA specification
• Was required for at least one game development we
  performed.

21
Retrofitting Multiplay Games

• Military simulation can easily go from multiplay
  to MMP using Cybernets OpenSkies implementation
  of DMSO HLA
• Versions 1.3 or 1516 are transparently
  interoperable together within the same federation
• HLA to game world is more difficult
• No automatic game independent way to achieve an
  HLA FOM to commercial game mapping I.e.
  automatic network message interoperability
• Easy to substitute the IET, P2PS and other HLA
  APIs for commercial game code when source code is
  available.

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Conclusions

• Tools available to use game and military features
  in both spaces
• HLA compliant system available with interfaces
  for commercial gaming space
• Required commercial game features added to HLA
  compliant system
• Implementation is possible on variety of
  platforms (including non-standard ones such as
  tablets, tough books, PDAs, etc.)