1. 1 VPC: Multilayered View HBN S1S1 S2S2 S3S3 S4S4 S5S5 VPC = {SPC}  {MPC} SPC - Primary copy on a stationary node MPC - Primary copy on a mobile host... Zone of Influence SPC 1 SPC 2 MPC 1 MPC 2

2. 2 VPC: Simulation  Primary Copy Method vs. VPC  Transaction processing system with read-only, write-only, write-read requests  Assumptions  Simulation parameters  number of hosts (both stationary & mobile)  number of data objects  transaction events, etc  Transaction behaviour  Simulation outputs  VPC outperforms PC for applications  write- dominated  fixed set of transactions  Tx - connection/disconnection ratio increases

3. 3 VPC: Performance Comparison Cost ratio 1:2:20, Transaction to connection/disconnection ratio 1:1 % of writes Cost per committed transaction ( Cost -Tx ) 0 50 100 150 200 250 300 020406080100 0 10 20 30 40 50 60 70 80 90 100 Total number of committed transactions ( Com - Tx ) COST- Tx-PC COST- Tx- VPC COM- Tx-PC COM- Tx- VPC