Diistributed Data Management DDM in HLA. Distributed Data Management HLA by default does one sort of interest management: functional. Your federate can.

Diistributed Data Management

DDM in HLA

Distributed Data Management

HLA by default does one sort of interest management: functional. Your federate can express interest (subscribe to) instances of particular classes and their attributes

Only those class attributes will be sent to you when they are updated

This is actually somewhat sophisticated, or can be, depending on the (black box) RTI implementation

Just as with DIS we may want to limit distribution of object information to a specific area

Geographic Interest Management

Region 1

Region 2 Region 3

GeographicThe overall space is divided up into smaller

regions, and individual federates can listen to a subset of the total geographic space

This is called a “routing space”. A routing space is simply a list of attributes along with minimum and maximum values

Normally the attributes define an area or volume, but this isn’t a restriction on the concept. You can use any bounded variable

Routing SpacesA routing space is defined in the FOM(spaces (space <name> (dimension <name>) (dimension <name>))There is a default routing space provided

if you don’t define one

Creating RegionsYou can dynamically create regions in the

routing space with a call to the RTIAmbassador createRegion(). You get back a handle for that newly created region, and can set the extent of the region with setLowerBound(), etc.

Each federate knows only of the regions it creates; there is no way to share regions between federates. Regions are not globally known to the federation execution

AttributesAn object attribute is tied to a routing

space in the fed file(spaces (space TestSpace (dimension TestDimension) ))…(class A (attribute aa reliable timestamp TestSpace) (attribute ab reliable timestamp TestSpace))

Attributes and RoutingThe name for the routing space dimension

is not tied to class attributesIf you have a tank with attributes (lat, lon)

defined in the FOM, this does not necessarily have any link to the routing space dimensions of (lat, lon)

The producing federate must associate object updates with regions

AttributesAn “attribute instance” is one attribute of

one object instance (vs. the class attributes)

You can tie attribute instances to a region with associateRegionForUpdates() on particular object instances

Attribute instances can be associated with only one region at a time

SubscribingSuppose you want to learn of all class

attribute updates in region XMake call to

subscribeObjectClassAttributesWithRegion()

Associates the given attributes from the given class with a region, so any updates to attributes in other federates will result in a notification to your federate

Similar mechanism for interactions

Management Object ModelThe MOM refers to metainformation about

HLA itself--the federates, the RTI, the federation execution, etc

We want to learn about what is going on in the simulation at runtime

HLA uses HLA to find out about itself at runtime

MOMSuppose we want to find out about the

other federatesThe RTI can maintain information about

this in an object, and if that is the case, why not make it an HLA object?

That is the basic insight of MOM--HLA objects are used to describe the state of the simulation