Special Course on Networked Virtual Environments February 20, 2004 Jouni Smed 1
§6.2 Controlling §6.2 Controlling the Visibility of Data the Visibility of Data
- Area
Area-
- of
- f-
- interest
interest filters filters
- each host provides explicit data filters
each host provides explicit data filters
- filters define the interest in data
filters define the interest in data
- Multicasting
Multicasting
- use existing routing protocols to restrict the flow of data
use existing routing protocols to restrict the flow of data
- divide the entities or the region into multicast groups
divide the entities or the region into multicast groups
- Subscription
Subscription-
- based aggregation
based aggregation
- group available data into fine
group available data into fine-
- grained ‘channels’
grained ‘channels’
- hosts subscribe the appropriate channels
hosts subscribe the appropriate channels
Protocol Optimizations Protocol Optimizations
M M H H B B T T P P Compression Compression M M H H B B T T P P Host Filtering Host Filtering M M H H B B T T P P Aggregation Aggregation
Why to Do Why to Do Data Flow Data Flow Restriction? Restriction?
( (x x, , y y, , z z) ) ( (∆ ∆x x, , ∆ ∆y y, , ∆ ∆z z) ) Fire Fire o
- 2
2
C r e a t e C r e a t e a n e w a n e w
- b
j e c t
- b
j e c t J
- i
n J
- i
n R e l e a s e l
- c
k R e l e a s e l
- c
k L L
7 7
Destroy object Destroy object Alive Alive o
- 26
2 6
Alive Alive o
- 3
7 3 7
Fire Fire o
- 55
55
‘ ‘ E n e m y E n e m y s i g h t e d ! ’ s i g h t e d ! ’
Awareness and the Spatial Model of Interaction Awareness and the Spatial Model of Interaction
Key concepts: Key concepts:
- medium
medium: communication type : communication type
- aura
aura: subspace in which : subspace in which interaction can occur interaction can occur
- awareness
awareness: quantifies one object’s : quantifies one object’s significance to another object (in a significance to another object (in a particular medium) particular medium)
- focus
focus: represents an observing : represents an observing
- bject’s interest
- bject’s interest
- nimbus
nimbus: represents an observed : represents an observed
- bject’s wish to be seen
- bject’s wish to be seen
- adapters
adapters: can modify an object’s : can modify an object’s auras, foci, and nimbi auras, foci, and nimbi
User’s User’s video aura video aura Television’s Television’s video aura video aura Television’s video nimbus Television’s video nimbus User’s video User’s video focus focus
Nimbus Nimbus-
- Focus Information Model
Focus Information Model
- Nimbus: entity data should only
Nimbus: entity data should only be made available to entities be made available to entities capable of perceiving that capable of perceiving that information information
- Focus: each entity is only
Focus: each entity is only interested in information from a interested in information from a subset of entities subset of entities
- Ideally, all information is
Ideally, all information is processed individually and processed individually and delivered only to entities delivered only to entities
- bserving it
- bserving it
- what about scaling up?
what about scaling up?
- processing resouces
processing resouces
- each packet has a custom set of
each packet has a custom set of destination entities destination entities ⇒ ⇒ hard to hard to utilize multicasting utilize multicasting
⇒ ⇒ Approximate the pure nimbus
Approximate the pure nimbus-
- focus model
focus model
Area Area-
- of
- f-
- Interest Filtering Subscriptions
Interest Filtering Subscriptions
- Hosts
Hosts transmit transmit information to a set of subscription managers information to a set of subscription managers (or (or area area-
- of
- f-
- interest
interest managers managers, filtering servers) , filtering servers)
- Managers receive subscription descriptions from
Managers receive subscription descriptions from the the participating participating hosts hosts
- For each piece of data, the managers determine which of the
For each piece of data, the managers determine which of the subscription subscription requests requests are satisfied and disseminate the are satisfied and disseminate the information to the corresponding subscribing hosts information to the corresponding subscribing hosts
- AOI filtering:
AOI filtering:
- restricted
restricted form of the pure nimbus form of the pure nimbus-
- focus
focus model model
- ignores nimbus specifications
ignores nimbus specifications
- subscription
subscription descriptions specify the entity’s focus descriptions specify the entity’s focus
- reduces the processing requirements of the pure model
reduces the processing requirements of the pure model