middleware platform for sentient computing applications
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Project IST-2000-26031
Middleware Platform for Sentient Computing Applications
Computing Department, Lancaster University, UK
Thirunavukkarasu Sivaharan, Maomao Wu, Gordon Blair, Adrian Friday, Paul Okanda.
2nd MiNEMA Closed Workshop@ Lancaster, 1st Dec 2004
Lancaster University2
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Overview of Presentation IntroductionSentient ObjectsResearch Challenges &
Component Frameworks Middleware ArchitectureSentient Vehicle DemonstratorConclusions
Lancaster University3
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Introduction(2)
EU FET Project : CORTEX– Universidade de Lisboa (Portugal)– Lancaster University (United Kingdom)– Trinity College (Ireland)– Universität Ulm (Germany)
Aims– Middleware support for constructing distributed mobile
proactive applications based on real-time sentient objects– Proposes sentient object model to support the construction
of mobile, context aware, decentralised ,autonomus ,proactive and collaborative applications such as intelligent vehicles and smart buildings.
– A middleware for networked embedded systems
Lancaster University4
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Sentient Object Model(1) Sentient Object Model
– System consists of environment and a set of sentient objects
– Sentient objects are capable of independently sensing the environment, derive context and infer autonomous actions
– Sentinet objects communicate using event channels to establish higher level context and thus cooperate with each other
SentientObjectC P
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Lancaster University5
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Sentient Object(2)
Consume Produce
Sensory Capture
and Fusion
Context Representation
Inference Engine
Sensor
Sensor
Actuator
Actuator
Sentient Object
Event
Lancaster University6
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Autonomous sentient vehicle application in MANET
Autonomous navigation of vehicles from a source to destinations
Cooperating vehicles in MANETContext aware vehicles
Lancaster University7
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Some of the research challenges addressed
Suitable Communication Model for MANETRouting in mobile ad-hoc environmentContext-awareness End-to-End QoS and Fail safetyRun time and deployment time reconfigurations
Lancaster University8
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Component Framework based Reflective Middleware
Publish-Subscribe Component framework (CF)Multicast CFContext CFResource Management CF
Lancaster University9
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Why Component Framework based Middleware Platform?Middleware is engineered as family of Component
frameworks (CF) using Reflection and component technology
Each CF addresses specific research areasComponent Frameworks are highly configurable and
dynamically reconfigurable (with the granularity of a component)
Clear separation of concernsAdaptable to diversity of CORTEX applicationsReduction of memory footprint CFs are implemented using Lancaster’s OpenCOM
reflective component technology
Lancaster University10
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Middleware Architecture
WLAN 802.11b (ad-hoc), Windows CE
Payload Channel TCB control channel
Group Communication CF-( Ad-hoc Multicast )
Publish-Subscribe CF- (for MANET)
Programming InterfacesMIDDLEWARE
SentientObjects
SentientObjects
Context CF-Sensor Fusion
Inference Engine
Timely Computing Base
Middleware Configuration for MANET
Lancaster University11
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Publish-Subscribe CF(1)Communication model inspired by STEAM Implicit event modelSender & receiver based event filteringSubscription Language supports subject, content &
context based event filteringSupports distance based context filtering & extensible to
other contextsXML based generic eventsEvents transported via selectable Multicast protocol
Lancaster University12
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Publish-Subscribe CF(2)
Subscriber
SOAP Messaging
Filter
SOAPtoMulticast
Multicast
IFilter
IMulticast
ISOAPMessaging
ISubscribe
ISOAPTransport
Publisher Notifier
IApplicationNotify
Filter
IFilter
Receptacle
Interface
IPublish
Dispatcher
IDispatch
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Multicast CF
Underlying event Routing Protocol is based on multicast
The multicast protocol for ad-hoc networks is a probabilistic, stateless and multi-hop protocol
We offer this service in the form of a component framework.
Shared memory based IP
MulticastProbabilistic Multicast
Lancaster University14
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Context CF (1)Sensor capture and fusion
– Multivariate Gaussian modelling– Bayesian networks– Dead-reckoning
Inference engine– A program that reasons about a set of rules (a knowledge base)
in order to derive an output.– The knowledge is encoded as a set of production rules, contexts
are represented as “fact”.– CLIPS – C Language Integrated Production System, its internal
implementation is based on RETE net.
Lancaster University15
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Context CF (2)
CLIPS rule sample
The paradigm facilitates uniform treatment of both context and QoS– Rules to trigger adaptations and actuations based on changes in
measure of QoS data
CLIPS DLL and OpenCOM component for WinXP and WinCE
(defrule rule-obstacle-near "CLIPS rule for obstacle near" (car-id (id ?id)) ?f1 <- (obstacle (distance near)) => (retract ?f1) (publish ?id stop))
Lancaster University16
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
End-to-End QoS Management and Fail Safety- Timeliness requirement
How can this be achieved?– Enforcing timely perceptions of the environment and
timely actuations on it.– Which means timely event delivery and awareness of
QoS of the event channels used for inter-sentient object communication
The key issue in uncertain and highly dynamic environments is that timing bounds for distributed actions may be violated because of timing failure
Lancaster University17
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
End-to-End QoS Management and Fail Safety-Timeliness Requirements We model the uncertainty of timely event dissemination via event
channels using a dependable timing failure detection service. This service is provided by University of Lisboa’s Timely Computing
Base (TCB) TCB facilitates to construct distributed event channels with timing
bound specification This enables publisher or subscriber to be aware of the timing
failures of event channels Thus providing awareness of timing failure probability for a given
required coverage Fail safety is achieved by switching to fail-safe state as soon as QoS
specifications are violated.
Lancaster University18
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Autonomous Sentient Vehicles Demonstrator
Two Sub problems– Cooperative behaviour without human control– Autonomous vehicle navigation from a given source to
pre-determined destinationVehicles Objectives
– Travel along a given path( virtual circuit-VC) defined by set of GPS waypoints and bearings.
– Every vehicle that travels on the VC cooperate with other vehicles to avoid collisions and travel safely
– Obey external roadside traffic lights.– Give way to pedestrians who cross the road.
Lancaster University19
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
OC CLOSE( 4m)OC BEHIND OC FAR(4- 10m)
Location aware Cooperating Sentient Vehicles
Car publishes
on Carcontrol
channel: Event
Packet: <car
status,
Location>Car
subscribes to:
CarControlC
hannel &
Receives
events from
other cars
Car
subscribes to:
CarControlC
hannel &Receives
events from
other cars
Car publishes on Carcontrol
channel: Event Packet: <car
status, Location>
IEEE 802.11b(ad-hoc)---Event Channel---CarControlChannel
Satellites
Car A Car B
OC – Other car
OC VERY FAR
Other car’s location context w.r.t car A
OC BEHIND
Other Car’s location context w.r.t Car B
4m
OC CLOSE
Lancaster University20
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Pedestrian detection
Obstacle Sensing Service: Consumes raw ultrasonic sensor data and fuses using a suitable algorithm (reliable, timely-unreliable, Gaussian, …) to derive higher level obstacle distance context such as NEAR , FAR , NOOBJECT.
Ultra sound waves
Ultrasonic sensors
Non event publishing obstacle
Lancaster University21
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Component
Example: The Car Sentient Object & Context CF
Component
Location Sensing Service
GPS Fusion 1
GPS Fusion 2
Obstacle Sensing Service
Ultrasonic Fusion 1 Ultrasoni
c Fusion 2
Direction Sensing Service
Compass Fusion 1
Inference Service
CLIPS Inference Engine
Ultrasonic sensor
GPS sensor
Sentient object
Digital Compass sensor
Consume Produce
SpeedActuator
SteerActuator
Sentient object
receptacle
Interface
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Sentient Vehicle Test Bed
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Cont’d
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Cont’d
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Demo Settings
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Waypoint 1
Waypoint 2 Waypoint 3
Waypoint 4
Traffic Light
Virtual Circuit
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CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Demo Video
Lancaster University28
CO-operating Real-time senTient objects:architecture and EXperimental evaluation
Concluding Remarks The sentient object model
– has proved to be valuable programming abstraction for the development of real-time, cooperative, context-aware applications.
The component-Framework based Middleware approach– offers benefits of flexible configuration and reconfiguration of the
middleware components The middleware architecture
– also provides the management of non-functional concerns such as timeliness and reliability properties.
Our middleware is reusable– we are keen to investigate the generality of our approach by applying our
middleware to other application domains involving embedded autonomous components.
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