funded by national science foundation grants: eia-9973465 and iis-0312746
DESCRIPTION
Managing Real-Time Transactions in Mobile Ad-Hoc Network Databases Le Gruenwald The University of Oklahoma School of Computer Science Norman, Oklahoma, U.S.A. http://www.cs.ou.edu/~database [email protected]. Funded by National Science Foundation Grants: EIA-9973465 and IIS-0312746. - PowerPoint PPT PresentationTRANSCRIPT
Managing Real-Time Managing Real-Time Transactions in Mobile Transactions in Mobile
Ad-Hoc Network Ad-Hoc Network DatabasesDatabases
Le GruenwaldLe GruenwaldThe University of OklahomaThe University of OklahomaSchool of Computer ScienceSchool of Computer ScienceNorman, Oklahoma, U.S.A.Norman, Oklahoma, U.S.A.
http://www.cs.ou.edu/~databasehttp://www.cs.ou.edu/[email protected]@ou.edu
Funded by National Science FoundationFunded by National Science Foundation
Grants: EIA-9973465Grants: EIA-9973465 andand IIS-0312746IIS-0312746
IntroductionIntroductiono GoalGoal
• To develop and prototype a real-time database transaction management model for Mobile Ad-Hoc Network (MANET).
o MANETMANET::• Collection of wireless mobile nodesCollection of wireless mobile nodes• No fixed infrastructureNo fixed infrastructure• Frequent occurrence of Network PartitionsFrequent occurrence of Network Partitions• Server and Client Power restrictionServer and Client Power restriction• Time-critical applicationsTime-critical applications
o Used in Battlefield, Disaster Recovery, etc.Used in Battlefield, Disaster Recovery, etc.
System ArchitectureSystem Architecture
o Servers (Large Mobile Host LMH)Servers (Large Mobile Host LMH)• Classical workstations with high memory, power and computing Classical workstations with high memory, power and computing
capabilitiescapabilities• Contains the complete DBMSContains the complete DBMS
o Clients (Small Mobile Host SMH)Clients (Small Mobile Host SMH)• Computers with reduced memory, power and computing Computers with reduced memory, power and computing
capabilitiescapabilities• Clients contain the Query Processing Module of the DBMSClients contain the Query Processing Module of the DBMS
Client1
Server1
Server2
Client2
Client3
Client4Client5
Client6
Server3Server4
Research IssuesResearch Issueso Transaction ManagementTransaction Management
o Data CachingData Caching
o Data ReplicationData Replication
o Concurrency ControlConcurrency Control
o Commit ProtocolCommit Protocol
o Recovery Recovery
Transaction Transaction ManagementManagement
o Incorporated three energy modes: active, doze and sleep.
o Designed a Client Transaction Submission Protocol: LEQ (Location-Energy-Queue)
o Firm Transactions
• Time is the most important factor => sent to the least workload and nearest server for transaction processing.
o Soft Transaction
• Energy is the most important factor => sent to the least workload and highest energy server for transaction processing.
Transaction Transaction ManagementManagemento Designed a Real Time Transaction Scheduling
algorithm.
s = d - (t + c + Pd * Td)
o Designed a Server Transaction Processing protocol making use of servers’ energy modes (active vs. doze) to reduce the number of firm transaction aborts while conserving energy.
o Designed a Server Transaction Result Delivery protocol making use of clients’ energy modes (active vs. doze) to reduce the number of firm transaction aborts while conserving energy.
s – Slack Timed – Deadlinet – Transaction Execution Timec – Current TimePd – Probability of DisconnectionTd – Average Disconnection Time
Simulation Results Simulation Results (Transaction Management)(Transaction Management)
Figure 4.1 Effect of Firm Ratio on % Missed Deadlines
01020304050607080
0 0.25 0.5 0.75 1Firm Ratio
% M
issed D
eadlin
e
SSR SMR Caching
Figure 4.2 Effect of Firm Ratio on Overall Energy Consumption
20
30
40
50
60
70
0 0.25 0.5 0.75 1Firm Ratio
Tota
l Energ
y
consum
ptio
n (
kW)
SSR SMR Caching
Figure 4.8 Effect of Disconnection Probability on % Missed Deadlines
0
20
40
60
80
0 0.1 0.2 0.3 0.4 0.5Disconnection Probability
% M
issed
Deadlin
e
SSR SMR Caching
Figure 4.9 Effect of Disconnection Probability on Overall Energy Consumption
20
30
40
50
60
70
0 0.1 0.2 0.3 0.4 0.5Disconnection Probability
Tota
l Energ
y
consum
ptio
n (
kW)
SSR SMR Caching
GMANET (Group based GMANET (Group based MANET) Caching ModelMANET) Caching Model
o Group leader movement vector: GM
o Group member movement vector: RM + GM
GMANET Caching ModelGMANET Caching Modelo Cache AssignmentCache Assignment
o Selective caching: only data with access frequency Selective caching: only data with access frequency higher than some threshold is cached.higher than some threshold is cached.
o Data accessed by UD (Up-to-Date) type transactions are Data accessed by UD (Up-to-Date) type transactions are cached at group server leaders LMHg.cached at group server leaders LMHg.
o Data accessed by OU (Outdated Data) type transactions Data accessed by OU (Outdated Data) type transactions are cached at clients (LMHs and SMHs)are cached at clients (LMHs and SMHs)..
o Cache ConsistencyCache Consistency• Caches on clients are maintained at the weak Caches on clients are maintained at the weak
consistency level => calculate refresh time estimate for consistency level => calculate refresh time estimate for randomly/periodically updated data.randomly/periodically updated data.
• Caches on group leaders are maintained at the strong Caches on group leaders are maintained at the strong consistency level => invalidation method.consistency level => invalidation method.
o Cache Replacement• Based on access frequency and transaction type (firm
vs. soft)
GMANET Caching ModelGMANET Caching Model
o All write transactions are sent to LMHgs.All write transactions are sent to LMHgs.
o UD type read-only transactions can access UD type read-only transactions can access cached data on LMHgscached data on LMHgs• Cache on LMHgs is always fresh by the strong Cache on LMHgs is always fresh by the strong
consistency protocol.consistency protocol.
o OD type read-only transactions can access OD type read-only transactions can access cached data on clients and LMHgscached data on clients and LMHgs• They accept stale cached data in return for They accept stale cached data in return for
fast retrieval.fast retrieval.
Simulation Results Simulation Results (Caching)(Caching)
Figure 5.2 Effect of Firm Ratio on Total Energy Consumption of LMHs
10
20
30
40
50
60
0 0.25 0.5 0.75 1Firm Ratio
Tota
l Energ
y
Consum
ptio
n o
f All
LM
Hs (
KW
)
NO Caching MANET CachingCHAN Caching GMANET Caching
Figure 5.13 Effect of MH Disconnection Probability on % Missed Deadlines
0
10
20
30
40
50
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7MH Disconnection Probability
% M
issed D
eadlin
es
NO Caching MANET CachingCHAN Caching GMANET Caching
Figure 5.14 Effect of MH Disconnection Probability on Total Energy Consumption of All LMHs
5
15
25
35
45
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7MH Disconnection Probability
Tota
l Energ
y
Consum
ptio
n o
f All
LM
Hs (
kw
)
NO Caching MANET CachingCHAN Caching GMANET Caching
Data ReplicationData ReplicationContacted the Norman Fire department and OU Military department for data and transaction model requirements.
Data Items
Read-Only Data ItemsTemporal Data Items Persistent Data Items
Periodic Update Periodic UpdateAperiodic Update Aperiodic Update
Transactions
Read Transactions Write Transactions
MRV MRVP OD Insert/Delete Use Previous
Value
Overwrite Previous
ValueMRV – Most Recent ValueMRVP – Most Recent Value in a PartitionOD – Outdated Data
Replication StrategyReplication Strategy
o Real Time Aware: data items accessed by firm transactions are replicated before those accessed by soft transactions.
o Partition Aware: the decision to replicate is based on:• Current network topology • Remaining power of servers• MRVP transactions are used to address network
partitioning.
o Power Aware: Servers with higher power hold the data items that are most frequently accessed.
Data Replication Data Replication StrategyStrategy
o Access frequencies of data items are computed based on:• Data Types• Transaction Types
o Hot data items are replicated before cold data items.
o Data accessibility is improved by reducing replica duplication between servers.
PrototypePrototype
o HardwareHardware• Laptop (Servers)Laptop (Servers)• PDA (Clients)PDA (Clients)• Global Positioning System (GPS)Global Positioning System (GPS)• Wireless LAN CardWireless LAN Card
o SoftwareSoftware• Servers: MySQL, Linux, C, C++Servers: MySQL, Linux, C, C++• Clients: DALP, Win CE, Embedded Visual C++ Clients: DALP, Win CE, Embedded Visual C++ • Routing ProtocolRouting Protocol
Future Research Future Research DirectionsDirections
o Develop a Real-Time Commit Protocol for MANET databases.
o Develop a Real-Time Concurrency Control Protocol for MANET databases.
o Evaluate the performance of the proposed techniques using the developed prototype for
Fire Department and Military applications.
Thanks!Thanks!