context-awareness and heterogeneity in pervasive computing environments

40
Context-awareness and Heterogeneity in Pervasive Computing Environments Kashif Imran Ravi Tiwari

Upload: barnabas-sean

Post on 03-Jan-2016

59 views

Category:

Documents


5 download

DESCRIPTION

Context-awareness and Heterogeneity in Pervasive Computing Environments. Kashif Imran Ravi Tiwari. Overview. Pervasive computing Requirements for ubiquitous and adaptive collaboration Middleware to provide heterogeneity and context-awareness in pervasive computing environments - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Context-awareness and Heterogeneity in Pervasive Computing Environments

Context-awareness and Heterogeneity in Pervasive Computing Environments

Kashif Imran

Ravi Tiwari

Page 2: Context-awareness and Heterogeneity in Pervasive Computing Environments

Overview

Pervasive computing Requirements for ubiquitous and adaptive

collaboration Middleware to provide heterogeneity and

context-awareness in pervasive computing environments Model for adaptive collaborative mechanisms

in heterogeneous environments A generic framework for context-awareness Middleware providing network heterogeneity

Page 3: Context-awareness and Heterogeneity in Pervasive Computing Environments

Pervasive Computing

Computing appliances seemly integrated into our lives, providing any time anywhere information.

Vision of digital life style Early work at Palo Alto Research Center Intelligent doorknobs to toilet-paper holders

Page 4: Context-awareness and Heterogeneity in Pervasive Computing Environments

Pervasive Computing Environments

Handheld Devices

Pervasive computing devices communicate and take actions.

Laptops

Atlas nodes

Network camera

Page 5: Context-awareness and Heterogeneity in Pervasive Computing Environments

Requirements for ubiquitous and adaptive collaboration Dynamic application adaptation to contextual

changes, such as changes in users’ interest, location, communication bandwidth etc

Platform-independent application descriptions to support multiple platform deployment

Heterogeneous service and device discovery Support of heterogeneous data formats e.g.

by not sending a high quality video stream to a low resolution screen

Page 6: Context-awareness and Heterogeneity in Pervasive Computing Environments

Role of Middleware

To analyze the role of middleware in context-aware application development for heterogeneous pervasive environments.

Application adaptation to multiple platforms Networked, heterogeneous devices Interoperability among heterogeneous networks

Page 7: Context-awareness and Heterogeneity in Pervasive Computing Environments

Middleware for heterogeneous context-aware applications

Kernel Runner, KR Application Package, AP Application Repository, AR Configuration Repository, CR Resource Repository, RR Context sensor, CS Mobility and Configuration Manager, MCM Context Manager, CM

Page 8: Context-awareness and Heterogeneity in Pervasive Computing Environments

Kernel Runner

Responsible for mobility and adaptation of apps Enables loading, execution, updating and stopping of

the applications or components Composed of three elements

The Interface Application Cache

ExistApp, UploadApp Execution Engine

StartExecution, StopExecution, CheckRunning and OnlineReloadParameters

Page 9: Context-awareness and Heterogeneity in Pervasive Computing Environments

Application Package

Facilitates the distribution of the applications through the different nodes

The AP is an XML file with two kinds of information Configuration parameters Application executables

Separates the application files from the execution parameters achieving platform independent description of application

Able to send all the running files needed in an XML formatted file, to extract and launch them in the different KRs

Page 10: Context-awareness and Heterogeneity in Pervasive Computing Environments

Application Package

Page 11: Context-awareness and Heterogeneity in Pervasive Computing Environments

Other Components

Application repository, AR An application repository on the network Stores each application developed as XML file SearchApp, DownloadApp, UploadAdd There can be many AR in a network

Configuration repository, CR Similar to the AR, the CR holds information in XML file

format related with the application configurations Resource repository, RR

Holds information in XML file format on music, photos, videos, etc. and information can be served online to an external component.

Page 12: Context-awareness and Heterogeneity in Pervasive Computing Environments

Other Components

Context sensor, CS components that inform of the state of the environment

and any changes to the same Mobility and configuration manager, MCM

responsible for the discovery and control of the different KRs on the network

has the ability to move, launch, or stop the applications in the different KRs

moves the correct version of application from the AR to the KR along with required configuration file with the

application’s last execution parameters from the CR Context Manager, CM

On context change the CM uses its inference system to decide what action it must perform.

Page 13: Context-awareness and Heterogeneity in Pervasive Computing Environments

Comparison with OSGi

Intermediary between different bundles Bundles provide service to other bundles OSGi limitation: Interoperability is ensured in

the same machine between different bundles. It does not ensure correct running of different bundles in an open, distributed system using different devices such as PC, PDA, smartphones etc.

AP can be launched without partner AP.

Page 14: Context-awareness and Heterogeneity in Pervasive Computing Environments

WILDCAT

Generic framework to ease the development of context-aware applications

Provides dynamic model to represent application’s execution context

Facilitates the acquisition and aggregation of contextual data to create reusable objects to represent aspects of execution context relevant to many applications

Page 15: Context-awareness and Heterogeneity in Pervasive Computing Environments

Logical Data Model

Context class Facade of whole system from client’s view One instance per application Context is made of several domains

Sys: local hardware, net: topology, geo: geophysical info (location, temperature..), user: preference (activity, mood..)

ContextDomain Object representing each domain of context Tree of named resources each being described by

attributes (simple key/value pair) Separates different aspects of execution context and

allow custom implementation

Page 16: Context-awareness and Heterogeneity in Pervasive Computing Environments

Logical Data Model

Page 17: Context-awareness and Heterogeneity in Pervasive Computing Environments

Logical Data Model

Events Each change occurring in the context model is

represented by an event RESOURCE_ADDED RESOURCE_REMOVED ATTRIBUTE_ADDED ATTRIBUTE_REMOVED ATTRIBUTE_CHANGED EXPRESSION_CHANGED CONDITION_OCCURED

Page 18: Context-awareness and Heterogeneity in Pervasive Computing Environments

Logical Data Model

Addressing URI inspired syntax to denote elements A resource

sys://storage/memory An attribute

sys://storage/disks/hda#removable Input devices

Sys://devices/input/* Mouse attributes

sys://devices/input/mouse#*

Page 19: Context-awareness and Heterogeneity in Pervasive Computing Environments

External Interfaces

Context class offers two interfaces Synchronous requests (pull mode) Asynchronous notification (push mode)

Page 20: Context-awareness and Heterogeneity in Pervasive Computing Environments

Synchronous requests (pull mode)

public class Context {String[] getDomains();Path[] getChildren(Path res);Path[] getAttributes(Path res);boolean exists(Path path);Object resolve(Path attr);

}

//Returns the list of all disk drives currently knowncontext.getChildren(new Path("sys://storage/disks"));

//Returns the amount of memory currently availablecontext.resolve(new Path("sys://storage/memory#free"));

Page 21: Context-awareness and Heterogeneity in Pervasive Computing Environments

Asynchronous notification (push mode)public class Context {long register(ContextListener listener,int eventKinds, Path pp);long registerExpression(ContextListener listener,int eventKinds, String expr);void unregister(long regId);}

//Get notified each time a new input device is plugged or unpluggedcontext.register(myListener,RESOURCE_ADDED | RESOURCE_REMOVED,new Path("sys://devices/input/*"));

//Get notified when the room temperature goes beyond 30 Ccontext.registerExpression(aListener, CONDITION_OCCURED,"geo://location/room#temperature > 30");

Page 22: Context-awareness and Heterogeneity in Pervasive Computing Environments

Internal Design

Page 23: Context-awareness and Heterogeneity in Pervasive Computing Environments

The ContextDomain interface

public interface ContextDomain {void initialize(Context ctx);String getName();boolean exists(Path path);Object resolve(Path attr);Path[] getAttributes(Path res);Path[] getChildren(Path res);void register(ContextListener listener,int eventKinds, Path path);void unregister(ContextListener listener,int eventKinds, Path path);void update(Path path, Path cause);}

Page 24: Context-awareness and Heterogeneity in Pervasive Computing Environments

Sensor Management

SensorManager class organizes all the sensors

Active sensors implement directly the Sensor interface and run in their

own threadpublic interface Sensor {

String getName();void setListener(SamplesListener listener);void start();void stop();boolean isStarted();}

Page 25: Context-awareness and Heterogeneity in Pervasive Computing Environments

Sensor Management

Passive sensors created by associating a Sampler and a Schedule to

create a SamplingSensor

public interface Sampler { SampleSet sample();

}

XMLCommandSensor class Make it easier to integrate WildCAT with existing

systems

Page 26: Context-awareness and Heterogeneity in Pervasive Computing Environments

Example Application

Page 27: Context-awareness and Heterogeneity in Pervasive Computing Environments

Network Heterogeneity in Pervasive App Environments Involvement of heterogeneous networks in

pervasive computing environments Infrastructure network, Ad-hoc network,

Sensor network

Page 28: Context-awareness and Heterogeneity in Pervasive Computing Environments

Example Scenarios

Forest Firefighting Group communication service Publish-subscribed service

Page 29: Context-awareness and Heterogeneity in Pervasive Computing Environments

Example Scenarios

Environmental informatics Data retrieval service Event service

Page 30: Context-awareness and Heterogeneity in Pervasive Computing Environments

Limitations of current middleware solutions Network-style centric Support individual network dependent

services (RPC, publish-subscribe etc) Static middleware services

Page 31: Context-awareness and Heterogeneity in Pervasive Computing Environments

Gridkit Middleware

Addresses two key requirements within the pervasive application domain Service deployment

Suitable middleware service for developers Dynamic reconfiguration

Adapt to changing network heterogeneity

Page 32: Context-awareness and Heterogeneity in Pervasive Computing Environments

Gridkit Architecture

Extensive services on top of overlay networks Overlay of overlays

Page 33: Context-awareness and Heterogeneity in Pervasive Computing Environments

Gridkit Architecture

Page 34: Context-awareness and Heterogeneity in Pervasive Computing Environments

Structure of Overlay Plug-in

Page 35: Context-awareness and Heterogeneity in Pervasive Computing Environments

Deployment and Reconfiguration of Middleware Services Policy-based deployment of middleware

services Appropriate stack of software on each node Roles of a node: Participant or Facilitator

Page 36: Context-awareness and Heterogeneity in Pervasive Computing Environments

Leveraging Facilitators

Deployment configurator Work for the nodes in the same overlay

Page 37: Context-awareness and Heterogeneity in Pervasive Computing Environments

Gridkit Deployment Service

Page 38: Context-awareness and Heterogeneity in Pervasive Computing Environments

Bridging Overlays

Page 39: Context-awareness and Heterogeneity in Pervasive Computing Environments

Conclusion

Middleware can ease the development of context-aware applications and provide transparency in heterogeneous pervasive computing environments

Page 40: Context-awareness and Heterogeneity in Pervasive Computing Environments

Qustions…

???