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Dynamic Synthesis of Mediators
in Pervasive EnvironmentsAmel Bennaceur supervised by Valérie Issarny
ARLES
14 February 2012, Junior Seminar, INRIA
Dynamic Synthesis of Mediators
14 February 20122
Outline
My team, my project, my thesis
Interoperability through dynamic synthesis of mediators
Reflections
My team, my project, my thesis
Interoperability through dynamic synthesis of mediators
Reflections
Dynamic Synthesis of Mediators
14 February 20123
Middleware for pervasive, distributed computing
System Architecture
My Team: ARLES
Software Architectures for Distributed Systems• enabling the pervasive computing/ambient intelligence vision
Qu
ality o
f Se
rvice
Intero
pera
bility
CONNECT Project
Multi-radio
Abstracting pervasive networks and resources
Leveraging highly dynamic and heterogeneous networking environments
System Models
Access and Interaction
Runtime Composition, Reconfiguration, and Adaptation
Discovery
Multi-device Multi-platform
Dynamic Synthesis of Mediators
14 February 20124
Illustrating the Interoperability Challenge
GMES: Global Monitoring for Environment & Security Discovery
What are the available services in vicinity?How can I communicate with other peers?What kind of data can I exchange with other peers?What kind of application can I use?Am I allowed to forward data to other peers?
, Interaction, Data , Application, NFP heterogeneity
Highly-dynamic and complex environments
Dynamic Synthesis of Mediators
14 February 20125
Existing Approaches to Interoperability
Changing systems
Change the system or attach an adaptor
Legacy systemsCode unavailable
×
System 2System1
Dynamic Synthesis of Mediators
14 February 20126
Existing Approaches to Interoperability
× Changing systems
Standardization
A chosen shared languageTanenbaum & Van Steen:
“the extent by which two implementations of systems from different manufacturers can co-exist and work together by merely relying on each other’s services as specified by a
common standard”
No one-size-fits all standard giventhe heterogeneity and complexity
of pervasive systems (and systems of systems)
×
System 2System1
Dynamic Synthesis of Mediators
14 February 20127
Existing Approaches to Interoperability
× Changing systems
× Standardization
Common Abstraction
One speaker talks the other’s language
Use an abstraction to design the component
Need to be aware a priori about all the possible configurations
×
System 2System1
Dynamic Synthesis of Mediators
14 February 20128
Babel fishTransform on the fly
using an intermediary system: the mediator
Can we observe, synthesize and deploy mediators dynamically?
Approaches to Interoperability
× Changing systems
× Standardization
× Common Abstraction
Mediation
System 2System1
Dynamic Synthesis of Mediators
14 February 20129
Thesis Statement
Systems with compatible functionalities should be able to interact despite heterogeneities in
their data and behavioral models.
Mediators that seamlessly overcome these heterogeneities should be dynamically
synthesized and deployed in their environment.
Dynamic Synthesis of Mediators
14 February 201210
Dynamic Mediation to Support Interoperability
Discovery
Modellevel
Systemlevel
→ Learning → Synthesis → Concretization → Monitoring
DownloadPhoto write PhotoFile
write PhotoMetadata
Model Extraction
Model Extraction
read PhotoFile
Mediator Model
downloadPhoto
read PhotoMetadata
Deployment
Monitor
Emergent Middleware
OntologyDownloadPhoto = getPhoto
Photo = PhotoMetadata + PhotoFilePhotoMetadata = PhotoID + Location + CameraID + details …
SynthesizeModeling
Synthesis
Deployment
write PhotoFile
write PhotoMetadata
System (NS2)
DownloadPhoto
System (NS1)
Dynamic Synthesis of Mediators
14 February 201211
Outline
My team, my project, my thesis Interoperability through dynamic synthesis
of connectors• Modeling• Synthesis• Deployment
Reflections
Dynamic Synthesis of Mediators
14 February 201212
Ontology-based Networked System Model
Ontology-based Functional Semantics• Affordance
• The high-level functionality of a system• e.g., <Req, PhotoSharing, Preferences, Photo>
• Interface• A set of observable actions• e.g., <SendSOAPRequest, DownloadPhoto,
{CameraID}, >
LTS-based Behavioural semantics• The way the observable actions are coordinated• At both application and middleware layers
• Application → Business logic• Middleware → Communication & coordination protocol
Interface
Networked System
Affordance Behaviour1
0..n
1
Ontologies
<SendSOAPRequest, DownloadPhoto,{CameraID}, >
<ReceiveSOAPResponse, DownloadPhoto, , {Photo}>
Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis Informed by Ontologies
System (NS2)FunctionalMatchingSystem (NS1)
Ontologies
Does it make sense for NS1 and NS2 to interact?
13
Dynamic Synthesis of Mediators
14 February 201214
Functional Matching
System 2System1
AffC2 = <Req, PhotoSharing, {CameraID}, {PhotoFile}>
AffDrone = <Prov, PhotoSharing, , {Photo}>
What is the relation between a PhotoFile and Photo ?
Dynamic Synthesis of Mediators
14 February 201215
Domain-specific Ontology
Subsumption (is-a)
Dynamic Synthesis of Mediators
14 February 201216
Functional Matching
System 2System1
AffC2 = <Req, PhotoSharing, {CameraID}, {PhotoFile}>
AffDrone = <Prov, PhotoSharing, , {Photo}>
There is a functional matching between AffC2 and AffDrone
CameraID subsumes (co-variant) Photo subsumes a PhotoFile (contra-variant)
Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis Informed by Ontologies
Middleware Abstraction Middleware Abstraction
System (NS2)FunctionalMatching
Yes
System (NS1)
Middleware-agnostic Networked System (NS2)
Middleware-agnostic System (NS1)
Ontologies
Abstract from the communication protocol details and concentrate on
application semantics
17
Dynamic Synthesis of Mediators
14 February 2012
Middleware Ontology
18
Dynamic Synthesis of Mediators
14 February 201219
Middleware Abstraction
<SendSOAPRequest, DownloadPhoto,{CameraID}, >
<ReceiveSOAPResponse, DownloadPhoto,{Photo} >
<DownloadPhoto,{CameraID}, {Photo}>
C2 BehaviorC2 Middleware-agnostic
Behavior
Dynamic Synthesis of Mediators
14 February 201220
Middleware Abstraction
Drone BehaviorDroneMiddleware-agnostic
Behavior
<write, PhotoMetaData, , {photometadata}>
<write, PhotoFile, , {photofile}>
<PhotoMetaData, , {photometadata}>
<PhotoFile, , {photofile}>
Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis Informed by Ontologies
Middleware Abstraction Middleware Abstraction
System (NS2)FunctionalMatching
Yes
System (NS1)
Middleware-agnostic Networked System (NS2)
Middleware-agnostic System (NS1)
Ontologies
21
Generate Mapping Processes
Mapping Processes
What are the translations that need to be performed?
Dynamic Synthesis of Mediators
14 February 201222
Generating Mapping Processes
Drone InterfaceC2 Interface
<DownloadPhoto,{CameraID}, {Photo}> <PhotoMetaData, , {photometadata}><PhotoFile, , {photofile}>
DownloadPhotoPhotoMetaData PhotoFile
1 - Define the constraints that need to hold between compatible actions
2- Use constraint programming to find possible mapping between interfaces<DownloadPhoto,{CameraID}, {Photo}>⟼<<PhotoMetaData, , {photometadata}>, <PhotoFile, , {photofile}>>
e.g., photo sumsumed by photometadata union photofile
3- Generate the corresponding mapping process
Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis Informed by Ontologies
Middleware Abstraction Middleware Abstraction
CompatiblePartially compatible
Not compatible
Behavioral Matching
System (NS2)FunctionalMatching
Yes
System (NS1)
Middleware-agnostic Networked System (NS2)
Middleware-agnostic System (NS1)
Ontologies
23
Generate Mapping Processes
Mapping Processes
Relies on ontology-based model checking to generate the model of the mediator that ensures their behavioral
interoperability
Dynamic Synthesis of Mediators
14 February 201224
Behavioral Matching
PhotoMetaData
PhotoFile
PhotoMetaData
PhotoFile
DownloadPhoto
DownloadPhoto
Drone BehaviorC2 Behavior Mediator Behavior
Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis Informed by Ontologies
Middleware Abstraction Middleware Abstraction
CompatiblePartially compatible
Not compatible
Behavioral Matching
System (NS2)FunctionalMatching
Yes
System (NS1)
Middleware-agnostic Networked System (NS2)
Middleware-agnostic System (NS1)
Ontologies
25
Generate Mapping Processes
Mapping Processes
DeploymentEmergent
Middleware
Refines the mediator model into a concrete software artifact: an emergent middleware
Failure
Dynamic Synthesis of Mediators
14 February 201226
Deployment (1)
Refine the mapping processes using middleware semantics
<ReceiveCall, DownloadPhoto, {cameraID}, >
<Read, PhotoMetadata,{cameraID}, {photometadata}>
<Reply, DownloadPhoto, , {photoFile}>
<Read, PhotoFile,{photoID}, {photoFile}>
PhotoMetaData
PhotoFile
DownloadPhoto
Get photoID from photoMetadata
Middleware& Domain-specific
Ontologies
Dynamic Synthesis of Mediators
14 February 201227
Deployment (2)
Listener 2
Actuator 2
Listener 1
Actuator 1
Emergent Middleware
Mediator
System 2System1
Dynamic Synthesis of Mediators
14 February 2012
Overall Reflections (1)
Interoperability remains a fundamental problem in the complex distributed systems of today
Dynamic synthesis of mediators offers promise in addressing interoperability in a future-proof manner
Ontologies have a key role to play in supporting synthesis: both application and middleware
28
Dynamic Synthesis of Mediators
14 February 2012
Overall Reflections (2)
Ontologies• Availability, characteristics, fuzziness• Heterogeneity in ontologies, alignment
Emergent middleware• Learning, dependability, exception handling• Evolution and incremental synthesis
User in the loop• The role of end users and experts in adaptation
29
Dynamic Synthesis of Mediators
14 February 2012
Thank you
Dynamic Synthesis of Mediators
14 February 201231
Further Information
Home page: www-rocq.inria.fr/~bennaceu ARLES: www.rocq.inria.fr/arles/ Connect: connect-forever.eu/
The Role of Ontologies in Emergent Middleware: Supporting Interoperability in Complex Distributed Systems, In Proc. Middleware 2011
Middleware-layer Connector Synthesis: Beyond State of the Art in Middleware Interoperability, In SFM 2011
Towards an architecture for runtime interoperability, In Proc. ISoLA 2010