a middleware service for coordinated adaptation of communication services in groups of devices
DESCRIPTION
Fakultät Informatik, Institut für Systemarchitektur, Professeur Rechnernetze. A Middleware Service for Coordinated Adaptation of Communication Services in Groups of Devices. Mobilis Project. Jordan Janeiro [email protected]. Agenda. Motivation Goals Moratus SACS Evaluation - PowerPoint PPT PresentationTRANSCRIPT
A Middleware Service for Coordinated Adaptation of Communication Servicesin Groups of Devices
Fakultät Informatik, Institut für Systemarchitektur, Professeur Rechnernetze
Jordan [email protected]
Mobilis Project
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Agenda
• Motivation• Goals• Moratus• SACS• Evaluation• Future Work
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Motivation
• In ubiquitous computing, context information is important to execute dynamic adaptations• Bandwidth rate is considered as context (local
context)• Low transmission rates -> Better message
compression service• A device adaptation is based on ist context
• In a group communication, to assume the overall group context may be suitable• Collaborative applications
• Co-edition of Presentations
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Goals
• Determination of the overall group context• Global Context
• Adaptation of communication services in all group members
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Related Work
• Graceful Adaptation Protocol• Does not tolerante disconnection
• Ensemble• Not transparent adaptation
• NeCoMan• Does not tolerante disconnection• Pair-to-Pair Adaptation
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Moratus
• Protocol for coordinated service adaptation, among mobile group members, based on global context
• Communication services are called Message Transformation Services (MTS)• Optimize wireless group communication• Compression and segmentation• Divided in 2 modules:
• Encoder and Decoder
• Assumes a reliable group communication service• Jgroups
• Divide in 2 steps:• Global context election• Coordinated adaptation
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Global Context Election
• Any context variable might be used• RSSI in this case
• Starts upon a significant context variation• RSSI value ranges
• Different global context calculations might be implemented• Mean, lower value and highest value
• Handle device disconnection• Context of device is not considered
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Global Context Election
Variação significativa do contexto detectada !
Global
Context
Calculated
Global
Context
Calculated
Global
Context
Calculated
Global
Context
Calculated
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Global Context Election - Disconnection
Variação significativa do contexto detectada !
Global
Context
Calculated
Global
Context
Calculated
Global
Context
Calculated
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Coordinated Adaptation
• Divided in 4 steps to allow transparent adaptation:• Service installation• Activation of new decoder• Activation of new encoder• Deactivation of the old decoder
• One of the group devices coordinates the process
• Handle device disconnection
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Coordinated Adaptation
Group is
ready to
start the
adaptation
Install Service
Service
Instaled
Service
Instaled
Service
Instaled
Activate New
Decoder
New
Decoder
Activated
New
Decoder
Activated
New
Decoder
Activated
Coordinator
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Service for Coordinated Service Adaptation
• Used by distributed applications• Transparent communication
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Communication Service
• The use of Jgroups middleware• Proposes a protocol stack
• Allows reliable group communication• NACKACK protocol
• Disconnection handling• FAILURE_DETECTOR protocol
• Heartbeat message• Helps to refreshs list of group members
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Evaluation
• Scalability tests• Executed in a cluster with 30 machines• Groups of 5, 10, 15, 20, 25 and 30
elements
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Evaluation
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Conclusion
• Development of Moratus protocol• Adaptation based on the group context• Execution of coodinated adaptation
• Implementation of Moratus as a middleware service• Applications use the middleware transparently
• Limitations using Jgroups in wireless networks• Constant delays for protocol convergence
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Future Work
• Detect the consumption of all messages before concluding the coordinated adaptation
• Try to avoid consecutive and unnecessary adaptations
• Calculate global context considering multiple variables• Battery, bandwidth and processing
