Amel Bouzeghoub
Serge Garlatti
Context Modeling&Adaptation
Mobile Learning Summer School - Brest 4th-9th july 2009Page 2
Outline
Context & Context-Awareness General Model of Context-Awareness Context Modeling Applications Context-Aware Learning Systems Adaptation: Main issues Adaptation Process and Principles Mobilearn Project P-LearNet Project Conclusion
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Defining Context
Location, identities of nearby people and objects [Schilit and Theimer]
Location, identities of the people around the user, the time of day, season, temperature, etc. [Brown et al.]
The user’s location, environment, identity and time [Ryan et al.]
The user’s emotional state, focus of attention, location and orientation, date and time, objects, and people in the user’s environment [Dey]
The elements of the user’s environment that the user’s computer knows about [Brown]
The situation of the user [Franklin & Flaschbart]Is all this information necessary?
Is all this inform
ation measurable?
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Defining Context (cont’d)
Dey defines the context as “any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves.”
Schilit et al. claim that the important aspects of context are: where you are, who you are with, and what resources are nearby. They define context to be the constantly changing execution environment• Computing environment available processors, devices
accessible for user input and display, network capacity, connectivity, and costs of computing
• User environment location, collection of nearby people, and social situation
• Physical environment lighting and noise level
Which aspects of all situations are im
portant ?
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Defining Context (cont’d)
Context is the set of environmental states and settings that either determines an application’s behavior or in which an application event occurs and is interesting to the user [Chen]:
• Active context: influences the behavior of the application - an application automatically adapts its behavior to
discovered context• Passive context: context that is relevant but
not critical - an application presents the new or updated context to
an interested user or makes the context persistent for the user to retrieve later
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Defining Context (cont’d)
Other classifications of context:• Low-level vs High-level context
• External (physical)- Context that can be measured
by hardware sensors– location, light, sound,
movement, touch, temperature, air pressure, etc.
• Internal (logical)- Mostly specified by the user or
captured monitoring the user’s interaction
– the user’s goal, tasks, work context, business processes, the use’s emotional state, etc.
social
temporal
motivational
location
user
Sensor data
computing
Low-levelcontext
Context processing
high-levelcontext
Context-aware application
activecontext
passivecontext
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Defining Context (cont’d)
3 entities• Places (rooms, buildings, etc.)• People (individuals, groups)• Things (physical objects, computer components, etc.)
Attributes• Identity (each entity has an unique identifier)• Location (an entity’s position, co-location, proximity, etc.)• Status (or activity)• Time (used for timestamps to accurately define situation,
ordering events, etc.)• …
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Challenges
Context is most useful in dynamic, mobile environments. But what is the relevant information in various situations?
Mobility results in continuous updates of context information. How can we efficiently manage this?
How can we share context? How do we handle uncertainty of context
information? How do we ensure privacy control and
management of context information? How do we reach a common understanding of
implications and semantics of (shared) context information?
Resource restrictions
[Roy Campbell]
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Context-Awareness
“A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task.” [Dey’s definition]
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General Model of Context-Awareness
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Abstract Layer Architecture
Generation
Usage
Sensing: numeric observables
Perception: symbolic observables
Situation and context
Applications Privacy/Security/Trust
History Discovery/Recovery
[J. Coutaz, et al.]
sensors
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Abstract Layer Architecture (cont’d)
The sensing layer generates numeric observables to determine meaning from numeric observables, the system must perform transformations
• Physical sensors- RFID, camera, microphone, accelerometer, GPS, thermometer
• Virtual sensors- From software: browsing an electronic calendar, a travel booking system,
emails, mouse movements, keyboard input• Logical sensors
- Combination of physical and virtual sensors
The perception layer is independent of the sensing technology and provides symbolic observables at the appropriate level of abstraction
Changes of Context !! Most of contextual information changes as time goes on Context changes can be sensed by, periodic polling, advertising, selective polling
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Abstract Layer Architecture (cont’d)
The situation and context layer identifies the current situation and context from observables
The exploitation layer acts as an adapter between the application and the infrastructure. This is where applications express their requests for context services at a high level of abstraction
At every level of abstraction, one must incorporate mechanisms and facilities to support privacy, trust, and security as well as history management and discovery/recovery
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Context Modeling
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Motivations
Context modeling requirements:
• Formality
• Support for efficient reasoning
• Support for imperfect context information (imprecise, ambiguous, incomplete information)
• Appropriate abstractions to support requirements analysis, design and programming tasks
• Support for interoperability
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Context Modeling
Context Model• Define and store context data in a machine
processable form Context Modeling Approaches
• Key-Value Models• Markup Scheme Models• Graphical Models• Object Oriented Models• Logic Based Models• Ontology Based Models
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Context Modeling Approaches Key-Value-Pairs Models [Context Toolkit]
• Most simple category of models• Not very efficient for more sophisticated structuring
purposes• Only exact matching (set loc=room_134)• No inheritance Standard Retrieval Method: Linear Search
Markup Scheme Models [Stick-e]• XML-based models • Composite Capabilities/Preference Profile (CC/PP),
[W3C, 2004], User Agent Profile (UAProf) encoded in RDF/S [Wapforum, 2001]
Standard Retrieval Method: Markup Query Language
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Context Modeling Approaches (cont’d)
Graphical Models [ORM]• UML-like languages (CML)
• Particularly useful for structuring, but usually not used on instance level
Standard Retrieval Method: Transformation
Object Oriented Models [Hydrogen]• Intention behind object orientation is (as always)
encapsulation and reusability• Standard Retrieval Method: Algorithm
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Context Modeling Approaches (cont’d)
Logic Based Models [eWallet – myCampus]• Logic defines conditions on which a concluding expression or fact
may be derived from a set of other expressions or facts (reasoning)
→ context is defined as facts, expressions and rules• High degree of formality• Cannot inherently deal with uncertain or conflicting information• Suit better in cases, where we are certain about the quality of the
collected data Standard Retrieval Method: Inference
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Context Modeling Approaches (cont’d)
Ontology Based Models [SOCAM, CoBrA, Context Managing Framework]• Ontology used as explicit specification of a
shared conceptualization • Context is modeled as concept and facts• Advantages:
- formal models that can be– shared– reused,– extended– combined
Standard Retrieval Method: Reasoning
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Summary
Approach Requirements
dc pv qua inc for app
Key-value models - - - - - +
Markup scheme models
+ ++ - - + ++
Graphical models - - + - + +
OO models ++ + + + + +
Logic based models ++ - - - ++ -
Ontology based models
++ ++ + + ++ +
dc: distributed compositionpv: partial validation
qua: quality of informationInc: incompleteness and ambiguity
app: applicability to existing env. for: level of formality
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Applications
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Applications - Efficient UI
More efficient UI as context changes• Brighter display in dark place• Simplified text when I am moving
normal dark place & user is moving
[Team Edward : Hee-Jung Yang and Hyeong-Ho Yoo (2005)]
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Applications - Efficient UI (cont’d)
Show only important part of clip for poor network bandwidth or small display
Different menu for different place Sort people list by distance or show on a map
big display small display
Depend on user’s preference
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Applications - Reconfiguration
Optimize internal components• Choose the fastest connection to server• Print with the closest printer
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Applications - Triggering
Trigger useful information relevant to current context• Car navigation system• Explanation about the place where user travels• Show cooking guide in kitchen, show work files in office
Reminder for specified context• When I next meet Serge, tell him ...• When next at a market, buy ...
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Applications – Memory Retrieval
Save contexts of each event and retrieve them later• Who were the girls with Serge at the last meeting in
Paris?
• What was the note I made at a meeting last June in this conference room? I remember Bill and John were there.
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Applications – Memory Retrieval (cont’d)
Object is defined by relative context• Filename is the context in which it is made
- We don’t have to remember the filename
• Interrupted task is resumed if the context revived
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Applications – Sharing Experience
Refer other people's contexts• Travelers download my contexts of my trip
Broadcast my context• I send to neighbors the information about cheap
theatres
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Context-Aware Learning Systems
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Other definitions…
Ogata, & Yano : “ Ubiquitous learning is characterized by providing intuitive ways for identifying right collaborators, right contents and right services in the right place at the right time based on learners surrouding context »
Derntl & Hummel: « learning context is used to describe the current situation of a person related to a learning activity. In addition to attributes relying on the physical world model »
A. Kurti & M. Milrad: « information and content in use to support a specific activity (being individual or collaborative) in a particular physical environment ».
Adaptation • Learner-centered + • Environmental factors (e.g. location, time of the day, delivery media)
Goal: capturing and usage of contextual information in context-aware learning environments
Mobile Learning Summer School - Brest 4th-9th july 2009Page 32
How to model mobile learning context considering individual tasks, community activities, and current environment?
How to use context in a particular mobile learning scenario in order to provide adaptation to users?
How to develop a flexible system architecture for adaptive activity-based vs situation-based learning?
Research Questions
Mobile Learning Summer School - Brest 4th-9th july 2009Page 33
Adaptation
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Context-Awareness and Adaptation• At different levels in the global architecture
- HCI components- Educational and semantic components- Middleware components- Network components
page 34
Main Issues
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Main Issues
Context properties• Dynamic • “Context-as-construct”. • Context settings could be “unpredictable”
because it is dynamically created and modified through continual interactions with users and environment.
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Main issues
Context-Awareness and Adaptation• Select dynamically the relevant resources
- Teachers, Learners, Communities, - HCI components, - Scenarios, activities, multimedia documents- Middleware components, web services- Network components, etc.
• According to the current situation - As a subset of the context model
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Adaptation Process and Principles
On Mobile Learningpage 37
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Adaptation Process and Principles
Context-Awareness and Adaptation• Context model assumptions: a set of structured
features- scenario, activity, - Learner, teacher, Community, - Location, time, network, - Device, - Tools, etc.
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Adaptation Process and Principles
page 39
Context and Adaptation Mangement Process
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Adaptation Process and Principles
1) Resource Retrieval• Resources
- Multimedia documents: images, movies, texts, sounds, etc.
- Activities, scenarios, Web services, Web page patterns, - HCI components, middleware components, etc.
• Query - Result: a set of resources
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Adaptation Process and Principles
2) Resource retrieval refinement• Filtering process • Matching context model against resource metadata
or indexing• Outcome, at least, two classes: « Good » and
« Bad » Or up to 5 classes (ressource clustering)- Mutually exclusive equivalence classes!!!!!!!
3) Applying and adaptation method• Annotation, hiding, sorting or ranking, etc.
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according to resource category!
page 42
Input content:
Resources
Metadata Features
Context Features
Clustering Filtering
Relevant content
{«Good» «Bad»}
Ranking/Annotation
Situation
Adaptation process
«Average»
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Adaptation Process and Principles
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Adaptation Process and Principles
Unfortunately• Context settings could be “unpredictable”
- Not really possible to deal with!
• Consequences - Membership rules combine contextual and metadata
properties to classify resources– What happens when some properties are not
available?
– Impossible to compute membership?
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Adaptation Process and Principles
How to manage context features to have flexibility as much as possible?
Two Case Studies• Mobilearn• P-LearNet
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Mobilearn Project
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Mobilearn Project
Goals• Produce an integrated architecture for learners
with mobile devices• Support for collaborative learning• Adaptive human interface• Context-aware presentation of content, options
and services to support learning activities
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Context Hierarchy• Scenarios
- Determine the relevant context elements
- To match the context-awareness of the learner’s needs
Mobilearn Project
page 47
Context
What's going over time
Context State
Elements (currently present) from the Learning and Setting at one particular point in time, space, or goal sequence
Context Substate
Elements from the Learner and Setting that are relevant to the current focus of learning and desired level of context awareness
Context Feature
Context Feature
Context Feature
Context Feature
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Mobilearn Project
Context awareness architecture
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Mobilearn Project
Basis Cycle of operation• 1) Gathering and input of context metadata• 2) Construction of context substate• 3) Exclusion of unsuitable content• 4) Ranking of remaining content• 5) Output of ranked list of content
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Mobilearn Project
Context feature belong to two types• Excluders
- Items of content, deemed entirely inapropriate for the current context are excluded
– Belong to class « Bad » and are hidden
• Or Rankers- Increments the score of each content item that has
metadata matching the value of any particular context feature
- The size of increment depends on the salience value associated to the considered context feature
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Mobilearn Project
On Mobile LearningPage 51
Resources
Metadata / indexing
Context Substate
Excluders Filtering
Classified content Relevant content
{«Good» - «Bad»}
Rankers
Context substate
Adaptation process
Mobile Learning Summer School - Brest
Mobilearn Project
Context awareness and adaptation• As the adaptation process is dedicated to a
single feature, it is possible to deal with almost « unpredictable » context settings.
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P-LearNet Project
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P-LearNet and e-retail requirements
How can I get supports or helps?
What activities I can do in the selling situation?
How can I realize an activity when the working situation changes?What and how
can I learn during working activities?
Need to model activities (scenario)Need to model activities (scenario)
Need to achieve an activity in different contexts, across different contexts
Need to achieve an activity in different contexts, across different contexts
-Need to integrate learning and working activities-Continuous professional learning at the workplace or elsewhere
-Need to integrate learning and working activities-Continuous professional learning at the workplace or elsewhere
SellerSeller
Increasing the system capability to get information about physical Increasing the system capability to get information about physical and social selling environment to enrich learning at the workplace to and social selling environment to enrich learning at the workplace to improve the marketimprove the market
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Context modeling
A context management model • A context model, • A context metadata schema• A set of situations
- A situation: a partial instantiation of the context model consisting of the available features
- Organized in historical dependencies
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Goals
Designing a context-aware and adaptive mechanism to select relevant resources to achieve activities• Finding relevant resources according to the
current situation• Modeling integrated context-aware learning and
working scenarios in the workplace
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Two Adaptation Strategies
Situation-based Learning • Passive Adaptation • Proactive Adaptation
- Recommendation system
- Depending on learner situation
- proposes right contents, right services, right activities, right collaborators in the right place at the right time
Activity-based Learning• Task/method paradigm
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Mobile Learning Summer School - Brest
Situation-based Learning
59Location
Activity Device Environment
User Time
innearBy
usesdo(role)
User current situation
in
at
collaboratenearBy
hasSituation
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Situation-based Learning
Passive adaptation - Reduces the number of resources according to user current situation- Uses filters: user knowledge, profile and preferences
Proactive adaptation • Allows an active recommendation of resources without user
intervention simply by detecting predefined events or system events - Uses ECA rules (Event/Condition/Action). - Authors describe resource behaviour depending on events that occur during the
situation
• Prototypical situations, hierarchical organization- Authors have to provide pedagogical rules for the course or to precise which rules to
use among the set of existing rules. - Example: in such situation, (situation in which the learner encounters difficulties and
needs help), the author may indicate which action is needed to help the learner: provide an easier or more detailed resource
On Mobile Learning
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Situation-based Learning: Passive Adaptation
Input
content:
Resources
Context Metadata
Current situation
EvaluationFilteringKnowledgePreferences
Relevant content
Ranking/
Annotation
Current Situation
Passive Adaptation
User Queries
Weighted content
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Resource Retrieval and Adaptation
Mobile Learning Summer School - BrestPage 62
Situation-based Learning: Proactive Adaptation
Events: Matching
Prototypical situations
Evaluation Filtering RankingAnnotation
Matched
situations
Current situation Current situation
Context Metadata
Weighted
content Relevant
content
Current situation
,
,
Passive Adaptation
Proactive Adaptation
ECA / Situational rulesPedagogical rules
Searching Resource
Resources
On Mobile Learning
Provides the relevant esources according to current situation
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Activity-based Learning
Working and learning activities are intertwined in the workplace• How to model integrated learning and working activities in
workplace – e-retail system?
Seamless Learning and Working • Achieve activities according to the current situation• New situation New way to achieve an activity?
Scenarios for modeling activities in context and across contexts
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Activity-based Learning
Context-aware scenarios• Context-aware learning scenarios at workplace
is represented by a hierarchical task model• The task/method paradigm
- Tasks:– Represent activities and sub-activities
– An abstract task is composed of sub-tasks
– An atomic task can be achieved by a simple procedure and can not be composed of sub-tasks
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Activity-based Learning
Context-aware scenarios- Methods: represent a way to achieve a given task
according to a context-
Task
Method1
Method2
Method3
realized by
Method4
Resource requirement
(Web) Service requirement
function specification
Control structure
Retrieval-MatchingRetrieval-Matching
Methods described by contextual features (Web) Services/ resources
described by metadata
SubTask1
SubTask2Define a decomposition of a task into subtasks
On Mobile Learningpage 65
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Learning task
Professional task
Mixed task
Legend: S.1.3Sale assistance in situation
M13
Context descriptor:-Role = {Saleman}-Location = {Shop}
S.3_T.1Preparing for the sale
S.3_T.2Finalizing the sale
M132
Context descriptor: (the sale with customers)-Role = {Saleman}-CollaboratorRole = {Customer}-DeviceType ={PTA, Smartphone}-NetworkType = {Wifi, Bluetooth}
M131
Context descriptor: (a saleman without customer)-Role = {Saleman}
-DeviceType = {PTA, Smartphone}-NetworkType = {Wifi, Bluetooth, GMS
Location = {Shelve}}
M133
Context descriptor: (customers are detected nearly a LCD screen)-Role = {Saleman}-CollaboratorDeviceType = {LCD Screen}-CollaboratorRole = {Customer}-DeviceType ={PTA, Smartphone}-NetworkType = {Wifi, Bluetooth}
S.3_T.1.3Identify the
client
M1321
S.3_T.1.4Search and
deliver information of products to the client
M1322
S.3_T.1.8Switch to the supervisory mode (join PTA with
LCD)
S.3_T.1.9Visualize the
summarization table of selected products
S.3_T.1.10Dialog with client on a
screen LCD
S.3_T.1.1Verify the
information about the labeling of products
S.3_T.1.5Get helps
form colleagues or experts
M1323
M1311
{SEQ(S.3_T.1, S.3_T.2)}
{SEQ(S.3_T.1.3, PAR(S.3_T.1.4, S.3_T.1.2, S.3_T.1.6, OPT(S.3_T.1.5)))}
Method
{PAR(S.3_T.1.1, S.3_T.1.2)}
{SEQ(S.3_T.1.3, PAR(S.3_T.1.4, S.3_T.1.2, S.3_T.1.6, OPT(S.3_T.1.5)),SEQ(S.3_T.1.7, SEQ(S.3_T8, PAR(S.3_T.1.9, S.3_T.1.10))))}
M1332
M1333M1334
S.3_T.1.2Revise the
knowledge of products
M1312
S.3_T.1.7Ask for an
interaction of the screen
LCD
M1331
S.3_T.1.6Consult to
FAQ
M1324
Activity-based Learning
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Select the relevant methods to achieve a given task according to the current situation
Input content:
(Methods)
Metadata/ indexing(Context descriptor/Service description)
Situation(with transitory features)
EvaluationClassification Filtering
Classified content Relevant content
{«Good» - «Bad»}
Ranking/Annotation
Situation(with permanent features)
Adaptation process
Activity-based Learning
On Mobile Learning
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Activity-based Learning
Service requirement specification
Matching
Metadata/Service description
Evaluation/Classification Filtering Ranking
Matchedservices
Domain ontology Current situation
Metadata/Service descriptionClassified
services Relevantservices
Current situation(permanent
features)
Service Invocation, Orchestration, Choreography
and Execution Subsystem
Adaptation
Service retrieval and adaptation
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Conclusion
Some Open Issues• How to manage context features and
adaptation process• How to manage adaptation at all levels?
- HCI components- Educational and semantic components- Middleware components- Network components
page 69 On Mobile Learning
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