1. Diistributed Data Management DDM in HLA

2. 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

3. Geographic Interest Management Region 1 Region 2Region 3

4. Geographic The 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

5. Routing Spaces A routing space is defined in the FOM (spaces (space (dimension ) ) There is a default routing space provided if you don’t define one

6. Creating Regions You 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

7. Attributes An 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) )

8. Attributes and Routing The name for the routing space dimension is not tied to class attributes If 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

9. Attributes An “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

10. Subscribing Suppose you want to learn of all class attribute updates in region X Make 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

11. Management Object Model The 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

12. MOM Suppose we want to find out about the other federates The 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