6.2 Controlling the Visibility of Data 6.2 Controlling the - PDF document

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