A Context-Aware Middleware for Applications in Mobile Ad Hoc Environments

1. A Context-Aware Middleware for Applications in Mobile AdHoc Environments Sørensen. C.F ,Sivaharan. T, Blair. G.S, Friday. A, Wu. M, Duran-Limon. H, Okanda. P,. Computing Department, Lancaster University, UK MPAC Workshop @Middleware 2004 ,Toronto ,18th October 2004

2. Overview of Presentation • Introduction • Cooperating Sentient Vehicle Application Scenario • Challenges • Middleware Architecture • Sentient Vehicle Test Bed • Demo • Conclusions Lancaster University

3. Introduction(2) • EU FET Project : CORTEX • Universidade de Lisboa (Portugal) • Lancaster University (United Kingdom) • Trinity College (Ireland) • Universität Ulm (Germany) • 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. • ‘Cooperating sentient vehicles’ is a key demonstrator of the project Lancaster University

4. Introduction(3) • 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 Lancaster University

5. Cooperating Sentient Vehicle Application Scenario • Two Sub problems • Cooperative behaviour without human control • Autonomous vehicle navigation from a given source to pre-determined destination • Vehicles 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 University

6. Research Challenges • Communication Model • Routing Protocol • Context Awareness • End-to-End QoS and Fail safety Lancaster University

7. Component Framework based Middleware Platform • Middleware is engineered as family of Component frameworks (CF) using Reflection and component technology • Each CF addresses specific research areas • Component Frameworks are highly configurable and dynamically reconfigurable (with the granularity of a component) • Clear separation of concerns • Adaptable to diversity of CORTEX applications • CFs are implemented using Lancaster’s OpenCOM reflective component technology Lancaster University

8. Middleware Architecture Sentient Objects Sentient Objects Context CF- Sensor Fusion Inference Engine M I D D L E W A R E Programming Interfaces Publish-Subscribe CF- (for MANET) Timely Computing Base Group Communication CF-( Ad-hoc Multicast ) Payload Channel TCB control channel WLAN 802.11b (ad-hoc), Windows CE Middleware Configuration for MANET Lancaster University

9. Communication model-Publish-Subscribe CF(1) • Implicit event model • Sender & receiver based event filtering • Subscription Language supports subject, content & context based event filtering • Supports distance based context filtering & extensible to other contexts • XML based generic events • Events transported via selectable Multicast protocol Lancaster University

10. ISubscribe IDispatch IPublish Subscriber Dispatcher Publisher Notifier ISOAPMessaging IFilter IApplicationNotify SOAP Messaging IFilter Filter Filter ISOAPTransport Receptacle SOAPtoMulticast Interface IMulticast Multicast Publish-Subscribe CF(3) Lancaster University

11. Shared memory based IP Multicast Probabilistic Multicast Routing Protocol-Multicast CF • A Multicast service is of vital importance to the CORTEX environment. Sentient objects need m-to-n event communication in a reliable manner. • We offer this service in the form of a component framework. Lancaster University

12. Context Awareness-Context Component Framework (CF) • The Sentient Vehicles require higher level context information such as relative location, orientation, status , event channel QoS etc w.r.t entities in its proximity in real time to autonomously decide its speed and steer control actuations. • Fundamental challenge is constructing exact ‘image’ (perception) of the surrounding environments in real time Lancaster University

13. 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 University

14. Non event publishing obstacle Ultrasonic sensors Ultra sound waves Context Component Framework (CF)(1) • 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. Lancaster University

15. Cooperating Sentient Vehicles location Satellites Car publishes on Carcontrol channel: Event Packet: <car status, Location> Car publishes on Carcontrol channel: Event Packet: <car status, Location> Car subscribes to: CarControlChannel & Receives events from other cars Car subscribes to: CarControlChannel & Receives events from other cars IEEE 802.11b(ad-hoc) ---Event Channel---CarControlChannel Car A Car B 4m OC BEHIND OC CLOSE( 4m) OC FAR(4- 10m) OC VERY FAR OC BEHIND OC CLOSE Other Car’s location context w.r.t Car B Other car’s location context w.r.t car A OC – Other car Lancaster University

16. Inference Service Obstacle Sensing Service Location Sensing Service Direction Sensing Service GPS Fusion 2 Component Ultrasonic Fusion 2 Component GPS Fusion 1 Ultrasonic Fusion 1 Compass Fusion 1 CLIPS Inference Engine Speed Actuator Ultrasonic sensor Car Sentient Object and Context CF Steer Actuator GPS sensor Consume Produce Sentient object Sentient object Digital Compass sensor Interface receptacle Lancaster University

17. End-to-End QoS Management and Fail Safety- Timeliness requirement • Sentient Vehicles must take action based on up-to-date representations of the environment • 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-vehicle 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 University

18. 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 the vehicles to fail-safe state as soon as QoS specifications are violated. Lancaster University

19. Sentient Vehicle Test Bed Lancaster University

20. Cont’d Lancaster University

21. Cont’d Lancaster University

22. Demo Settings Lancaster University

23. Waypoint 3 Waypoint 2 Traffic Light Waypoint 4 Waypoint 1 Virtual Circuit Lancaster University

24. Demo Video Lancaster University

25. Concluding Remarks • The sentient object model • has proved to be an excellent 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. Lancaster University

26. Thank You Questions Lancaster University