Transcript A Modular Service-Oriented Programming Model for Pervasive

Fasten the seat belt, here we Go
Home sweet home,
where the lights along the corridor flicker
The 3500 °F Incinerator for the Charcoal Grill
3500°F !!
The Duel Between Stew and IceCube
Hey, Who Turns
Off The Light?
Attention! Time for Roll Call!
Does Your Smart House Know Better?
A Safety-Oriented
Programming Model for
Pervasive Computing Systems
Pervasive & Mobile Computing Lab
Hen-I Yang
April 21, 2007
Characteristics of
Pervasive Computing Systems
•
•
•
•
•
•
•
•
Interaction with Physical World
Highly Personalized/Customized
Dynamicity
Open
Diversity/Heterogeneity
Complexity and Scalability Issue
Predication on Human Intention
Multiple Modalities in Interface
Safety Vs. Expressiveness
Proposed New Model
Interrupt & Exception Handling
Y = X/0
Memory
access
violation
Divided
by 0
Interrupt
Fire Alarm
Out of Op
Impermissible Range
Context
Exception
The Four Elements
Elements in
Pervasive Computing Environment
•
•
•
•
•
•
•
Sensor Devices
Actuator
Service Services
Applications
Users
User
Space Space
System Support
Element 1: Device
• Sensors, actuators and other smart appliances
are the I/O devices that serve as the bridge
between the physical world and the pervasive
computing systems.
• Source of data and/or sink of commands
• Accurate description of devices is the key, it
defines how to interact with these devices
Modeling of Device
• Service oriented architecture
• Can be interpreted on the fly, or created and
compiled prior
Type: (Sensor/Actuator/Both)
Domain of data: e.g. Temperature, Luminance, Device Internal
Data Schema: XML Document Type Declaration Including,
but not limited to maximum and minimum values, resolution of
data, unit of data
Interface Methods: Methods available to be invoked externally
Physical Medium Description: Description of the Interface/
Conduit/Channel that is to be used
Interaction Protocol Description: Support for Poll or Push
methods, maximum frequency of data exchange
Other Support Information: e.g. Vendor and other
contact/support information
Safety Measure for Device
• Automatically appended exception handling
routine
• Device Safety: Avoid conflicting directives and
unsafe/unacceptable operations, similar to
Electric Breaker
• Regulate the incoming commands and detect
abnormal command/access pattern
• Using maximum and minimum values to filter or
red-flag abnormal values
Element 2: Service
• The core active member of pervasive computing
system
• More complicated than the usual software in
desktop because of the heterogeneity and
dynamicity
• Service/Application
• Service Lifecycle management is crucial
•
•
•
•
•
•
•
•
•
Implemented
Aligned (Target Setup, possibly using user preferences)
Binded (to devices or other services)
Context input as conditions
Logics/Actions/Behaviors
Change of Preference
Change of Binding
Change of Conditions
Priority Level
Modeling of Services
Services
Services
Services
Service Registry
Programmed
Services
Services
Devices
Binded
User
Preference
User Preference Change Event
Aligned
Terminated
Service/Device Change Event
Active
Active Contexts
Impermissible Context Event
Active Context Change Event
Service
Behavior 1
Service
Behavior 2
….
Service
Behavior n
Safety Measure for Service
• Service Safety: Whenever device safety, user safety or
space safety is violated, the exception handler will
suspend or terminate all relevant services
• Services have to properly Binded and Aligned before
become eligible for execution. The existence of
Terminated state ensure each service has a Hand Break
that can be activated when needed
• Throughout execution, services subscribe to relevant
active contexts, and suspend or terminate when
impermissible contexts become active
• Service is as safe as the safety feature of the language
used to implement it, but the safety measure reduce the
risk of damage caused by services
Element 3: User
• In every single pervasive computing system,
even those aiming at automation without
human interventions, the ultimate goal: to
achieve and fulfill functionality defined by
users’ desires and intentions.
• There will be no need for the existence of
any system if there was nothing users want
to achieve.
• Integral part of pervasive computing system,
as their behaviors or mere existence
inadvertently affect the system
Modeling of User
• Digital representation: User Profile
• Static profile
•
•
•
•
Describes users’ relevant attributes and preferences
Used to setup the goal of the service and applications
Critical for customization and users’ intention prediction
E.g. special assistance needed, or the preferred room and
water temperature settings, or even users’ calendar
• Dynamic profile
•
•
•
•
Data gathered by the system about the user
Updated by the system
Treated as contexts in the system
E.g. the current location of the user, the blood pressure and
glucose level attained by medical sensors
Safety Measure for User
• 1st and 2nd Laws of Robotics
• A robot may not injure a human being or, through
inaction, allow a human being to come to harm.
• A robot must obey orders given it by human beings
except where such orders would conflict with the First
Law
•
Humans need to be
locked monitor
up so they users’
User Safety 1: Smart space should
commit crime
status and activate emergencycannot
measure
should
to harm other
users appear to be in danger [using
the
humans
mechanism for Space Safety]
• User Safety 2: Smart space should function to
serve users’ preference and obey users’ order
[using the mechanism for service safety]
Element 4: Space
• Most models do not consider space itself as a
critical element of pervasive computing system
• Influence the decision making (context)
• Big pictures on the effects of service and
applications
• Big pictures for user apprehension and
visualization
• Provide critical perspective when there are
resource sharing
Modeling of Space
• Independent Context Manager and Context
Graph
• Contexts defined using standardized
ontology
• Categorization of
preferred, transitional
and impermissible
contexts
• Visualization in a
summary-in-a-glance
view on overall
context of the space
Blown fuse
Murky air
Medium power
draw
Clean air
Low power
draw
Overcooked
Steak
Cooked Steak
Raw Steak
Hot Indoor
Warm Indoor
Cold Indoor
Context
Preferred Context
Impermissible Context
Potential Transitions
Safety Measure for Space
• Space Safety Monitor: Whenever
impermissible context is detected, the
space safety monitor will invoke exception
handling routine, similar to interrupt/signal
capture
• In the worst case where there is no
exception handling available, a prompt
would be send to the user or the emergency
contact person, so human actions can take
place to handle the situation
Recap
• Enforce Safety at Each h/w and s/w Entity in
the intelligent environment
• Device Safety Enforcer
• Service Signal Handling Vector
• Respect Users’ Wishes, and Constantly Look
After Them
• Look at the Big Picture, and make sure the
interactions among users and entities are not
harmful
Prior Endeavors
ATLAS Middleware
IDE: Atlas Plug-in for Eclipse
What does Atlas plug-in do?
•
•
•
•
•
Browse Available Entities and Services
Provide Information on OSGi bundles
Design by Selection
Semi-automatic Environment Setup
Integrate seamlessly with all the nice
features and assistance provided by
Eclipse
• Deploy New Bundles Back to Smart
Space
Context-Driven Model
• Reactive Programming Model
• Ontology Based context graph
• Categorize contexts into desirable,
transitional and impermissible context
• Find the actions required to take us from
currently active contexts to preferred
contexts, and activate special measures
when impermissible contexts are active
Hybrid Model
Epilogue
Past, Present and Future
• Past
• Establish safety-oriented programming model
• Implement IDE to support basic OSGi bundle
authoring
• Present
• Implementation of the new safety framework with
safety enforcer into both the ATLAS Middleware and
the IDE support
• Future
• Evaluating the safety feature of the intelligent
environment created based on this framework
Conclusion
• Pervasive Computing Systems are Intimate
• The failure and unreliability can result in strong
feeling of betrayal and frustration
• Intelligent Environment Affects Numerous
Aspects of the Daily Life
• Ensure Safety of the System by Ensuring
Safety of All Entities and the Environment as a
Whole
• Safety Enforcement is accomplished by the
collaboration at both implementation/
compilation time as well as runtime.
Thank You
Design Philosophy
• Safety Feature:
• Each individual device has a device breaker to monitor
abnormal access pattern and invalid values
• The smart space as a whole guarded by context
manager
• Orthogonal Elements:
• Simplify the design, implementation and maintenance
of the heterogeneous and dynamic system
• Dual text/object approach:
• Text based implementation allows common,
configurable services to be created without coding and
maximum portability;
• Object embodies more complicated or less-common
logic to be created for specific services
The Path Forward
• Analysis of Pervasive Computing Systems
and elements of them
• Design programming model and necessary
abstractions to simplify design and
implementation
• Focuses on safety features to protect users,
devices and the smart space as a whole
Modeling of Services
Service/Device Change Event
Programmed Service
Service Registry
Service Binded
Services
Services
Services
Binded Service
Devices
Devices
Devices
User Preference
Aligned Service
User Preference Change Event
Active Context Change Event
Active Contexts
Service
Behavior 1
Service
Behavior 2
….
Service
Behavior n
Pervasive Computing
• “The most profound technologies are those that disappear.
They weave themselves into the fabric of everyday life until
they are indistinguishable from it.”
-- Mark Weiser
• “The creation of environments saturated with computing and
communication yet gracefully integrated with human users”
-- Pervasive Magazine, Inauguration Issue
• “Embedding computation into the environment and everyday
objects to enable people to interact with informationprocessing devices more naturally and casually than they
currently do, and in whatever location or circumstance they
find themselves.”
Other alternative terms: Ubiquitous computing, calm
technology, things that think, everyware
-- Wikipedia
Goals of
Proposed Programming Model
•
•
•
•
•
•
Safe
Service Oriented Architecture (SOA)
Open
Configurable/Customizable
Orthogonal Description
Easily Programmable
Background
ATLAS Architecture
Programming Tool
Applications
Intelligent Environment
(e.g. Smart Home)
ATLAS Sensor/Actuator Technology
ATLAS Sensor Platform
• The basic building block for programmable pervasive
spaces.
• Atlas provides
• physical nodes for connecting various heterogeneous
devices,
• a system for translating those devices into software services,
• a system for maintaining a library of device services and
their interfaces, and
• a runtime environment for
accessing services and
composing applications.
Middleware
• Context Manager
• Originally designed and
implemented for ContextDriven Model
• Implemented using
ontology software and
inference engine
• Parts of implementation
concerning impermissible
contexts and their
emergency handling
routines are retained and
modified
• Visualization will be
added to provide quick
snapshot view
• Atlas Developer API
Method
Class/Interface
Description
receivedData
AtlasClient
Data handler called by service
bundle when data arrives
addProperty
AtlasService
Add a property pair (key, value)
to be associated with this
service
removeProp
erty
AtlasService
Remove a property associated
with this service
getPropertie
s
AtlasService
Get all properties associated
with this service
sendComma
nd
AtlasService
Send control commands (used
by service associated with an
actuator)
getData
AtlasService
Pull data from sensor
associated with this service
Subscribe
AtlasService
Request data stream from
sensor
Unsubscribe
AtlasService
Halt data stream from sensor
isSubscriber
AtlasService
Check if application is
receiving data stream from
particular sensor
dataHandler
AtlasService
Data handler called by middleware
when data arrives for particular
service. Must be implemented by
device service developer.