Simple Broker Example

The SimpleBroker application is a complete VR-Exchange broker.

It demonstrates how to build a broker class as well as a broker application. The SimpleBroker receives and transmits DIS PDUs as part of the example. It does not do translations in any meaningful way, and is completely non functional as a DIS broker.

Three significant classes are created in this example. DtSimpleBroker, which subclasses DtBroker, connects to the Portal via DtBroker, and registers for callbacks for broker exit. It also processes the configuration file simpleBroker.xml. Two helper classes, DtEntityTranslator and DtFireTranslator, simulate translation of Entity State PDUs and Weapon Fire PDU's. These classes were designed to show how new objects can be created and updates can be processed for both objects and interactions.

• simple.cxx
• simpleBroker.cxx
• sFireTrans.cxx
• sEntityTrans.cxx

---

simple.cxx

/****************************************************************************
 * Copyright (c) 2012 VT MAK
 * All rights reserved.
 ****************************************************************************/


#include <simpleBroker.h>
#include <broker/brokerInitializer.h>
#include <vlutil/vlExceptions.h>
#include <iostream>

using namespace MAKVrExchange;

int main( int argc, char* argv[] )
{
   try
   {
      const std::string version = "1.0";

      // Load the configuration options
      DtBrokerInitializer* init =
         new DtBrokerInitializer( argc, argv, DtPortalConnection::version().c_str() );
      init->parseCmdLine();

      // There are no connection options for this simple broker, so just return
      // without doing anything.
      if ( init->showConnectionInfoDialog() )
      {
         return 0;
      }
      
      // Create a broker instance
      DtSimpleBroker sb( init );

      // Tick the broker until we get the exit message
      while ( ! sb.isTimeToQuit() )
      {
         DtSleep( sb.pollingInterval() );
         sb.processEvents();
      }

   }
   DtCATCH_AND_WARN( std::cout );

   return 0;
}

---

simpleBroker.cxx

/*********************************************************************
 ** Copyright (c) 2005 VT MAK
 *********************************************************************/

#include "simpleBroker.h"

// VR-Link Includes for DIS 
#include <vl/exerciseConn.h>
#include <vl/exConnInit.h>

using MAKVrExchange::DtBrokerInitializer;

DtSimpleBroker::DtSimpleBroker(DtBrokerInitializer* init):
   DtBroker(init),
   myDisExConn(0),
   myFireTranslator(0),
   myEntityTranslator(0)
{
   // Create a connection to the DIS Exercise with some default parameters
   DtExerciseConnInitializer dInit;
   dInit.setPort(3005);
   dInit.setSiteId(1);
   dInit.setApplicationNumber(23);
   myDisExConn = new DtExerciseConn(dInit);

   // Create a translator for all Fire Interactions
   myFireTranslator = new DtFireTranslator(*myDisExConn, *portalConnection());

   myEntityTranslator = new DtEntityTranslator(*myDisExConn, *portalConnection());
}

DtSimpleBroker::~DtSimpleBroker()
{
   // Clean up resources
   DtDELETE( myFireTranslator );
   DtDELETE( myDisExConn );
}

DtExerciseConn *DtSimpleBroker::disExConn()
{
   return myDisExConn;
}

void DtSimpleBroker::tick()
{
   myEntityTranslator->tick();
   myDisExConn->clock()->setSimTime( simTime() );
   myDisExConn->drainInput();
}

void DtSimpleBroker::launchGui()
{
}

---

sFireTrans.cxx

/*********************************************************************
 ** Copyright (c) 2005 VT MAK
 *********************************************************************/
#include "sFireTrans.h"

// VR-Link DIS Includes
#include <matrix/vlVector.h>
#include <vl/exerciseConn.h>
#include <vlpi/entityIdentifier.h>

// Portal Includes
#include <portal/pConnection.h>
using namespace MAKVrExchange;

DtFireTranslator::DtFireTranslator(DtExerciseConn& disConn, DtPortalConnection &pConn):
   myDisConn(disConn),
   myPortalConn(pConn)
{
   DtFireInteraction::addCallback(
      &myDisConn, receiveDisInteraction, this);

   DtPortalFireInteraction::addCallback(
      &myPortalConn, receivePortalInteraction, this);

}

DtFireTranslator::~DtFireTranslator()
{
   DtFireInteraction::removeCallback(
      &myDisConn, receiveDisInteraction, this);

   DtPortalFireInteraction::removeCallback(
      &myPortalConn, receivePortalInteraction, this);
}

// -------------------------------------------------------------------
// -------- Translation Methods
// -------------------------------------------------------------------

void DtFireTranslator::createDisInteraction(const DtPortalFireInteraction& in)
{
   DtFireInteraction out;

   // In a real broker, some translation would need to happen here. 
   // The entity ID would need to be mapped from some string value. If there
   // was no valid conversion a unique entity Id would need to be created. 
   out.setAttackerId(DtEntityIdentifier(1,3,4));
   out.setTargetId(DtEntityIdentifier(2,4,2));
   out.setMunitionId(DtEntityIdentifier(3,4,2));
   out.setWarheadType((DtWarheadType)in.warheadType());

   myDisConn.send(out);
}

void DtFireTranslator::createPortalInteraction( const DtFireInteraction& in )
{
   DtPortalFireInteraction out;

   // The Portal uses Strings for Ids. One translation scheme 
   // would be to use the DIS ID as a string. The decision regarding
   // translation is significantly more complicated. 
   out.setAttackerId( in.attackerId().string() );
   out.setTargetId( in.targetId().string() );
   out.setMunitionId( in.munitionId().string() );
   out.setWarheadType( (DtWarheadType)in.warheadType() );

   myPortalConn.send(out);
}


// -------------------------------------------------------------------
// -------- Static Methods
// -------------------------------------------------------------------
void DtFireTranslator::receiveDisInteraction(DtFireInteraction *fire, void *usr)
{
   DtFireTranslator *trans = (DtFireTranslator*)usr;
   trans->createPortalInteraction( *fire );
}

void DtFireTranslator::receivePortalInteraction(
   const DtPortalFireInteraction &fire, void *usr)
{
   DtFireTranslator *trans = (DtFireTranslator*)usr;
   trans->createDisInteraction(fire);
}

---

sEntityTrans.cxx

/*********************************************************************
 ** Copyright (c) 2005 MaK Technologies, Inc.
 ** All rights reserved.
 *********************************************************************/
/*********************************************************************
** $RCSfile: sEntityTrans.cxx,v $ $Revision: 1.5 $ $State: Exp $
*********************************************************************/
#include "sEntityTrans.h"

// VR-Link DIS Includes
#include <matrix/vlVector.h>
#include <vl/exerciseConn.h>
#include <vl/reflEntList.h>
#include <vl/entityPub.h>
#include <vl/baseEntitySR.h>

// Portal Includes
#include <portal/pConnection.h>
#include <portal/pObjectPublisher.h>
#include <portal/pEntity.h>
using namespace MAKVrExchange;

DtEntityTranslator::DtEntityTranslator(DtExerciseConn& disConn, DtPortalConnection &pConn):
   myDisConn(disConn),
   myPortalConn(pConn),
   myDisReflectedList(0),
   myPortalReflectedManager(0),
   myDisEntityPublisher(0),
   myPortalEntityPublisher(0)
{
   // Create Reflected Lists to handle DIS Updates -- This is VR-Link DIS Code
   myDisReflectedList = new DtReflectedEntityList(&disConn);
   myDisReflectedList->addEntityRemovalCallback(DtEntityTranslator::disObjectDeletedCb, this);
   myDisReflectedList->addEntityAdditionCallback(DtEntityTranslator::disObjectAddedCb, this);

   // Create Reflected Manager for Portal Updates -- This is Portal Specific
   myPortalReflectedManager = new DtPortalReflectedEntityManager(&pConn);
   myPortalReflectedManager->addRemovalCallback(DtEntityTranslator::portalObjectDeletedCb, this);
   myPortalReflectedManager->addAdditionCallback(DtEntityTranslator::portalObjectAddedCb, this);

   myDisReflectedList->setDiscoveryCondition(disDiscoveryCriteria, this);
   myPortalReflectedManager->setDiscoveryCondition(DtEntityTranslator::portalDiscoveryCriteria, this);
}

DtEntityTranslator::~DtEntityTranslator()
{
   if (myDisEntityPublisher)
   {
      DtDELETE( myDisEntityPublisher );
   }

   if (myPortalEntityPublisher)
   {
      DtDELETE( myPortalEntityPublisher );
   }

   DtDELETE( myDisReflectedList );
   DtDELETE( myPortalReflectedManager );
}

void DtEntityTranslator::tick()
{
}
// -------------------------------------------------------------------
// -------- Translation Methods
// -------------------------------------------------------------------

void DtEntityTranslator::discoverDisObject(const DtReflectedEntity &reflectedObj)
{
   if (!myPortalEntityPublisher)
   {
      myPortalEntityPublisher = 
         new DtPortalEntityPublisher(&myPortalConn);

      // Call to update attributes - In DIS all attributes are available at discovery
      receiveDisUpdate(reflectedObj);

   }
}

void DtEntityTranslator::discoverPortalObject(const DtPortalReflectedEntity &reflectedObj)
{
   // This example only translates the first entity
   if (!myDisEntityPublisher)
   {
      // Create a DIS Publisher for this object. Most of the values for this
      // publisher are bogus. Translation of a real object is beyond the scope of 
      // this example. 
      myDisEntityPublisher = 
         new DtEntityPublisher( DtEntityType(1,2,3,4,5,6,7),
                                &myDisConn,
                                DtEntityIdentifier(1,2,3));

      // Call to update attributes - The Data Exchange makes all attributes 
      // available at discovery
      receivePortalUpdate(reflectedObj);
   }
}

void DtEntityTranslator::receiveDisUpdate(const DtReflectedEntity &reflectedObj)
{
   if (myPortalEntityPublisher)
   {
      DtPortalEntity *newSr = myPortalEntityPublisher->sr();
      const DtEntityStateRepository *sr = reflectedObj.esr();

      // Copy all values and do any translation required. In this case all DIS 
      // coords are the same as portal coords (Geocentric)
      newSr->setLocation(sr->location());
      newSr->setVelocity(sr->velocity());
      newSr->setAcceleration(sr->acceleration());
      newSr->setOrientation(sr->orientation());
      newSr->setRotationalVelocity(sr->rotationalVelocity());
      newSr->setRelativeLocation(sr->relativeLocation());
      newSr->setRelativeVelocity(sr->relativeVelocity());
      newSr->setRelativeAcceleration(sr->relativeAcceleration());
      newSr->setRelativeOrientation(sr->relativeOrientation());
      newSr->setRelativeRotationalVelocity(sr->relativeRotationalVelocity());

   }
}

void DtEntityTranslator::receivePortalUpdate(const DtPortalReflectedEntity &reflectedObj)
{
   if (myDisEntityPublisher)
   {
      const DtPortalEntity *sr = reflectedObj.sr();
      DtEntityStateRepository *newSr = myDisEntityPublisher->esr();

      // Copy all values and do any translation required. In this case all DIS 
      // coords are the same as portal coords (Geocentric)
      newSr->setLocation(sr->location());
      newSr->setVelocity(sr->velocity());
      newSr->setAcceleration(sr->acceleration());
      newSr->setOrientation(sr->orientation());
      newSr->setRotationalVelocity(sr->rotationalVelocity());
      newSr->setRelativeLocation(sr->relativeLocation());
      newSr->setRelativeVelocity(sr->relativeVelocity());
      newSr->setRelativeAcceleration(sr->relativeAcceleration());
      newSr->setRelativeOrientation(sr->relativeOrientation());
      newSr->setRelativeRotationalVelocity(sr->relativeRotationalVelocity());
   }
}

void DtEntityTranslator::processDisRemoval(const DtReflectedEntity &reflectedObj)
{
   if (myPortalEntityPublisher)
   {
      DtDELETE( myPortalEntityPublisher );
   }
}

void DtEntityTranslator::processProtalRemoval(const DtPortalReflectedEntity &obj)
{
   // Any object removal will delete this entity publisher. It means this 
   // example will appear to work only when there is one entity available. 
   if (myDisEntityPublisher)
   {
      DtDELETE( myDisEntityPublisher );
   }
}

// -------------------------------------------------------------------
// -------- Static Methods
// -------------------------------------------------------------------

void DtEntityTranslator::disObjectAddedCb(
                                          DtReflectedEntity *reflectedObj, void *userData)
{
   DtEntityTranslator *et = static_cast<DtEntityTranslator*>(userData);
   et->discoverDisObject(*reflectedObj);

   // Register for updates on this object
   reflectedObj->addPostUpdateCallback(DtEntityTranslator::disObjectUpdatedCb, userData);
}

void DtEntityTranslator::disObjectUpdatedCb(
   DtReflectedEntity *reflectedObj, void *userData)
{
   DtEntityTranslator *et = static_cast<DtEntityTranslator*>(userData);
   et->receiveDisUpdate(*reflectedObj);
}

void DtEntityTranslator::disObjectDeletedCb(
   DtReflectedEntity *reflectedObj, void *userData)
{
   DtEntityTranslator *et = static_cast<DtEntityTranslator*>(userData);
   et->processDisRemoval(*reflectedObj);
}

void DtEntityTranslator::portalObjectAddedCb(
   const DtPortalReflectedEntity& reflectedObj, void *userData)
{
   DtEntityTranslator *et = static_cast<DtEntityTranslator*>(userData);
   et->discoverPortalObject(reflectedObj);

   // Register for updates on this object
   reflectedObj.addUpdateCallback(DtEntityTranslator::portalObjectUpdatedCb, userData);
}

void DtEntityTranslator::portalObjectUpdatedCb(
   const DtPortalReflectedEntity& reflectedObj, void *userData)
{
   DtEntityTranslator *et = static_cast<DtEntityTranslator*>(userData);
   et->receivePortalUpdate(reflectedObj);
}

void DtEntityTranslator::portalObjectDeletedCb(
   const DtPortalReflectedEntity& reflectedObj, void *userData)
{
   DtEntityTranslator *et = static_cast<DtEntityTranslator*>(userData);
   et->processProtalRemoval(reflectedObj);
}


bool DtEntityTranslator::disDiscoveryCriteria(
   DtReflectedObject* ro, void *object)
{
   // HLA Object is always discoverable for this example
   return true;
}

bool DtEntityTranslator::portalDiscoveryCriteria(
   const DtPortalReflectedObject *ro, void *object)
{
   // Portal Object is always discoverable for this example
   return true;
}