1. Vassilis Papataxiarhis, V.Tsetsos, and S.Hadjiefthymiades vpap@di.uoa.gr Department of Informatics and Telecommunications University of Athens – Greece ICPS-2010, 13 - 15 of July 2010, Berlin A Knowledge Plane for Context-Aware Applications in Autonomic Computing

2.  Introduction to IPAC  The IPAC Knowledge Plane  Functionality and Services  Experimental Evaluation  Conclusions Outline

3. The IPAC Project  Integrated Platform for Autonomic Computing  EU-funded research project (ICT framework)  Partners with expertise in telecommunications, sensing technologies, data/knowledge management and software engineering.  Main goals Middleware for autonomic computing Application Creation Environment

4. Visual Editor Textual Editor Code Generation Emulator Debugger IPAC Applications IPAC Middleware Services OSGi Platform H/W, OS, JVM IPAC Node Developer WiseMAC WiFi Short Range Communication Interfaces Sensing Elements GPS SunSPOTs Visual Sensors The IPAC Ecosystem

5. IPAC Node Overview

6. The IPAC Knowledge Plane  Requirement for real-time self-adaptation based on Context-awareness Interoperability between nodes  It provides a cross-layer reconfiguration approach  It adopts knowledge-based technologies to model possible situations of the node store information reason over contextual data  Required expressiveness → conjunctive rules

7. Reasoner Service  The core component of the IPAC Knowledge Plane  Drives the self-adaptation process and checks for possible conflicts  Managing and reasoning over Application Profiles Node Profile Sensor Model Policies  Based on the J2ME version of the Java Internet Prolog (JIProlog) engine

8. Reconfiguration Service  Takes advantage of the Reasoner service  Supports 3 types of reconfiguration On application startup requirements matching Explicit request by application during its execution Periodical checks (through policy rules) “optimize” the node operation

9. Functionality - Workflow

10. Reconfiguration Scenario(1/2)  Node Profile supportsUI(node03,visual). supportsUI(node03,audio). hasUI(node03,visual). supportsCommInterface(node03,wisemac). supportsCommInterface(node03,802.11). hasCommInterface(node03,wisemac). numberOfNeighbors(node03,4).  1. Application startup requiresUI(app02,audio). UI switches to audio.

11. Reconfiguration Scenario(2/2)  2. Application Request event(fireAlarm) :- smoke_sensor_1>=0, temp_sensor_1>=20. According to sensor measurements, reconfiguration action may be triggered.  3. Policy checking policy(hasCommInterface,X,802.11) :- node(X), hasCommInterface(X,wisemac), numOfNeighbors(X,N), N=0. The node03 switches to IEEE 802.11 interface

12.  ASUS Eee PC 900, Intel Celeron 900MHz, 1GB  Loading time – All rules and facts are inserted into the main memory for efficient query answering – Models loaded once – Application profiles loaded/retracted on-demand Evaluation(1/3)  Linear Dependency 2 apps → 15ms 20 apps → 125ms  Real time checks do not negatively impact the overall response time of the system.

13. Evaluation(2/3)  Reconfiguration time Sensitivity of the system according to context changes Includes Update of the knowledge base Policy execution Check of the applicability of the request Execution of the reconfiguration  Linear Dependency period 1sec → 546ms period 20sec → 10425ms  Real time checks do not negatively impact the overall response time of the system.

14. Evaluation(3/3)  Memory Consumption Depends on the number of application profiles loaded Mean size per profile → 4KBs All the required middleware services are included (i.e., Reasoner, Reconfiguration and Scheduler services)  Linear Dependency 0 apps → 20623KBs 20 apps → 21214KBs  ~25KBs per profile are needed

15.  Contributions – Cross-layer reconfiguration approach (e.g., networking, operation of peripheral devices) – Extensible approach Updating policies does not require changes to the algorithms  Future Work – Optimization of policy checking mechanism – Adopt modern and more expressive knowledge representation languages Conclusion

16. Thank you! Project Website: http://ipac.di.uoa.gr