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An Intelligent Broker Architecture for Context-Aware Systems

An Intelligent Broker Architecture for Context-Aware Systems. Harry Chen Dept. of CSEE, UMBC PhD Dissertation Proposal Defense. January 2003. Outline. Introduction Research Review Context Broker Architecture Research Plan & Summary. Part I. Introduction.

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An Intelligent Broker Architecture for Context-Aware Systems

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  1. An Intelligent Broker Architecture for Context-Aware Systems Harry Chen Dept. of CSEE, UMBC PhD Dissertation Proposal Defense January 2003

  2. Outline • Introduction • Research Review • Context Broker Architecture • Research Plan & Summary

  3. Part I. Introduction

  4. Too bad they can’t talk to each other… Cool toys… Yesterday: Gadgets are Everything

  5. Configuration? Too much work… Sync. Download. Done. Today: Communication is Everything

  6. Tomorrow: Service is Everything Thank God! Everything is done for me!

  7. One Step Towards Tomorrow • Context-aware Computing • Brings us one step closer to the Pervasive Computing vision • Enables computer systems to anticipate users’ needs and to act in advance • An emerging paradigm to free everyday users from manually configuring and instructing computer systems

  8. Life is Not Perfect • Building context-aware systems for Pervasive Computing is often difficult and costly: • User privacy issues when sharing personal information • Supporting resource-poor mobile devices • How to reason about sophisticated contexts in a dynamic environment • Inconsistent and ambiguous contextual knowledge • Security, trust, ... (goes on and on)

  9. My Research Objective • To develop and prototypea broker-centric agent architecture to support context-aware systems • To demonstrate this architecture can be used to reduce the difficulty and cost of building context-aware systems in an Intelligent Meeting Room environment

  10. Context Broker Architecture • The “broker” of this architecture will • Sense and reason about contexts on the behalf of capability-limited agents • Enable agents to share contextual knowledge • Protect the privacy of users • Maintain consistent contextual knowledge

  11. Let’s talk about … • Agent • Broker • Context • Context-aware systems

  12. About “Agent” • Study context-aware systems using intelligent agents (context-aware agents) • Autonomous and Proactive • Can communicate, not just connect • Have beliefs about the World • Have desires and intentions

  13. About “Broker” • Broker, an overloaded term for agents with a specialized role: • Mediator: mediate communication messages in a Multi-agent system (MAS) • Facilitator: facilitate task execution between agents to achieve cooperation • Match-maker: match/recommend service advertisements

  14. “Broker” in My Architecture • Broker is a server agent that controls and manages the contextual knowledge of a Pervasive Computing environment: • Enables agents to contribute to and access a shared model of context • Allows users to control the access of their personal information in a context-aware environment B

  15. About “Context” • In Merriam-Webster Dictionary • [1] the parts of a discourse that surround a word or passage and can throw light on its meaning • [2] the interrelated condition in which something exists or occurs We are interested in [2]

  16. Definitions of Context • In context-aware computing • No unified definition of context • Most of the definitions agree that context has something to do with the interactions between the users and the computing systems

  17. My Definition of Context • Context is information that can be used to characterize the situation of a person or an object in a Pervasive Computing environment. • The identities and attributes of people and devices • The locations of people and devices • The activities that people are participating in • The roles and intentions of people when participating in the activities

  18. The system detects his current location The phone rings in his office A user has left his office The system forwards the call to a nearby phone The system detects the user is in an meeting Calls are forwarded to his voice mailbox Context-Aware Systems (1 of 2) A Call-forwarding System

  19. The system detects his current location The system detects the user is in an meeting Context-Aware Systems (1 of 2) • Two types of contexts are used: Location Context Activity Context

  20. PDA displays the info of a store item A user enters a store Turns on his PDA + + = PDA analyzes user’s personal profile PDA recommends store items to the user As the user wonders around in the store Context-Aware Systems (2 of 2) Shopping Assistant

  21. PDA displays info of the store items + + = PDA analyzes user’s personal profile Context-Aware Systems (2 of 2) • Three types of contexts are used: Location Context Identity Context & Attribute Context

  22. System Characteristics • Context-aware agents often run on mobile devices • For agents to become context-aware, context sensing and contextreasoning mechanisms are required • Context-aware systems often exploit user information (e.g. personal profile, user location & social activity)

  23. Research Problem • Building context-aware systems can be difficult and costly because • (1) limited resources in mobile devices • (2) lack of reusable context-aware mechanisms • (3) privacy issues in accessing user information

  24. Limited Resources in Mobile Devices • Battery Power Constraint • Small devices => limited built-in sensors • Big devices => too many external sensors can be awkward • Information Storage Constraint • Historic knowledge saves computation • Limited storage => must intelligently choose what to save and delete (hard problem!)

  25. Limited Resources in Mobile Devices • Computing Power Constraint • To process contexts needs CPU power • Limited CPU power => primitive contexts ONLY (limited intelligence)! • Communication Constraint • Contexts are “hidden” heterogeneous sources • Not knowing where are the sources and how to communicate => limited context-awareness

  26. Lack of Reusable Context-Aware Mechanisms • 2 Essential Mechanisms: • Context Sensing: acquiring information from the physical environment • Context Reasoning: interpreting the information that have been acquired • In the existing systems, both are built from the scratch every time => no reuse!

  27. Privacy Issues in Accessing User Information • Privacy is about control of information • In context-aware systems, users may not have full control of their information • Sensors are hidden in the environment • Information are collected without explicit consent from the users

  28. Privacy Issues in Accessing User Information • What about sharing of information? • You tell an agent something about you because you want its service, and later it tells someone else... (you are in trouble!) • The downstream consequences of information areunknown or unspecified.

  29. Proposed Solution • Context Broker Architecture • Philosophy: agents can’t do “everything” by themselves, let’s provide a powerful server entity to help them • Rationale: the Moore’s Law for mobile computing is likely to hold; developing a centralized solution is much easier than any P2P solutions.

  30. Context Broker Architecture • The key features: • Sense and reason about contexts on the behalf of capability-limited agents • Enable agents to share contextual knowledge • Protect the privacy of users • Maintain consistent contextual knowledge

  31. Part II. Research Review

  32. The Purpose of Research Review • (1) To argue building context-aware systems can be difficult and costly using the existing architecture • (2) To put Context Broker Architecture research into perspective (so that we can compare and contrast it with the existing systems)

  33. Look From Two Different Angles Types of Context-Aware Research Approaches to Support Context-Aware Systems

  34. Types of Context-Aware Research

  35. Enhancing User Interfaces (1 of 2) • Problem: the user interface of the existing mobile devices demand too much user attentions (i.e. cognitive and visual). • Solution: to replace the traditional user interface by enabling devices to become context-aware.

  36. Enhancing User Interfaces (2 of 2) • Microsoft research has developed a Cassiopeia E-105 that can • Active voice recording application when detects the user is holding the device like a cell phone or microphone • Automatically reformat the screen display (landscape portrait) depending how the user holds the device

  37. Guiding the Adaptation of System Behavior (1 of 2) • Problem: Environment changes can affect the performance of applications (e.g. using wireless PDA while walking on the street) • Solution: enabling applications to adapt their behavior in according to condition changes

  38. Guiding the Adaptation of System Behavior (2 of 2) • A video streaming application can dynamically adjust the streaming quality of video without interrupting the viewer’s attention (Odyssey) • Widely used contexts: network bandwidth,error rate, connection setup time, and usage costs • XeroxPARC Active Badge and PARC Tabs Applications (the 1st context-aware system)

  39. Building Pervasive Computing Services (1 of 3) • Problem: Complex computer systems are drawing humans into the world of computing • Think Oxygen & Mark Weiser’s vision • Solution: enabling computers to reason and act in according to the situation of users as they carry out their every activities

  40. Building Pervasive Computing Services (2 of 3) • In MIT’s Intelligent Room, the open/close of window curtains are automated by detecting the body position of a user in a couch

  41. Building Pervasive Computing Services (3 of 3) • In HP’s Cooltown museum, the visits of Cooltown users are automatically documented based on what they have seen.

  42. Different Types of Context-Aware Research

  43. Approaches to Supports Context-Aware Systems

  44. Acquiring Context Directly from Sensors Host Device Host Device Agent Agent Context Reasoning Context Reasoning Sensor Sensor Sensor Sensor Sensor Sensor Contexts in the Environment

  45. Agent Agent Agent Agent Facilitated by a Middle-ware Infrastructure Host Device Host Device Middle-ware Middle-ware Context Reasoning Context Reasoning Sensor Sensor Sensor Sensor Sensor Sensor Contexts in the Environment

  46. Different Approaches to Support Context-Aware Systems

  47. The Result of Research Review • Conclusion: building context-aware systems can be difficult and costly using the existing architecture • No or very minimal information sharing • No or limited reuse of context reasoning • No explicit support for privacy protection • Context Broker Architecture belongs to • Building Pervasive Computing Services • Neither “direct sensors access” or “facilitated by middle-ware”

  48. Part III. Context Broker Architecture

  49. Research Problems (again) • (1) Limited resources in mobile devices • (2) Lack of reusable context-aware mechanisms • (3) Privacy issues in accessing user information

  50. What’s the Implication? • A single agent has limited capability to acquire contexts • Building context sensing and reasoning mechanisms from the scratch can be expensive • Protecting user privacy in a context-aware environment is critical

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