Inria Doctoral Seminar

1. Dynamic Synthesis of Mediators
in Pervasive Environments
Amel Bennaceur supervised by Valérie Issarny
ARLES
14 February 2012, Junior Seminar, INRIA

2. Dynamic Synthesis of Mediators
14 February 2012
Outline
 My team, my project, my thesis
 Interoperability through dynamic synthesis
of mediators
 Reflections
2
 My team, my project, my thesis
 Interoperability through dynamic synthesis
of mediators
 Reflections

3. Dynamic Synthesis of Mediators
14 February 2012
Middleware for pervasive, distributed computing
System Architecture
My Team: ARLES
 Software Architectures for Distributed Systems
• enabling the pervasive computing/ambient intelligence vision
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QualityofService
Interoperability
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

4. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
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Highly-dynamic and complex environments

5. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
 Discovery
5
What are the available services in vicinity?

6. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
 Discovery
6
, Interaction
How can I communicate with other peers?

7. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
 Discovery
7
What kind of data can I exchange with other peers?
, Interaction, Data

8. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
 Discovery
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What kind of application can I use?
, Interaction, Data , Application

9. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
 Discovery
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Am I allowed to forward data to other peers?
, Interaction, Data , Application, NFP heterogeneity

10. Dynamic Synthesis of Mediators
14 February 2012
Illustrating the Interoperability
Challenges
 GMES: Global Monitoring for Environment & Security
 Discovery
10
, Interaction, Data , Application, NFP heterogeneity

11. Dynamic Synthesis of Mediators
14 February 2012
Existing Approaches to
Interoperability
Changing systems
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Change the system
or attach an adaptor
Legacy systems
Code unavailable
×
System 2System1

12. Dynamic Synthesis of Mediators
14 February 2012
Existing Approaches to
Interoperability
× Changing systems
Standardization
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A chosen shared language
Tanenbaum & 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
given the heterogeneity and
complexity of pervasive
systems (and systems of
systems)
×
System 2System1

13. Dynamic Synthesis of Mediators
14 February 2012
Existing Approaches to
Interoperability
× Changing systems
× Standardization
Common Abstraction
13
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

14. Dynamic Synthesis of Mediators
14 February 2012
Babel fish
Transform 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
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
System 2System1

15. Dynamic Synthesis of Mediators
14 February 2012
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.
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16. Dynamic Synthesis of Mediators
14 February 2012
Dynamic Mediation to Support
Interoperability
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Discovery
Model
level
System
level
→ Learning → Synthesis → Concretization → Monitoring
DownloadPhoto
write PhotoFile
write PhotoMetadata
Model
Extraction
Model
Extraction
read PhotoFile
Mediator Model
downloadPhoto
read PhotoMetadata
Deployment
Monitor
Emergent
Middleware
Ontolog
yDownloadPhoto = getPhoto
Photo = PhotoMetadata + PhotoFile
PhotoMetadata = PhotoID + Location + CameraID + details …
Synthesize
write PhotoFile
write PhotoMetadata
System (NS2)
DownloadPhoto
System (NS1)

17. Dynamic Synthesis of Mediators
14 February 2012
Outline
 My team, my project, my thesis
 Interoperability through dynamic synthesis
of connectors
• Modeling
• Synthesis
• Deployment
 Reflections
17

18. Dynamic Synthesis of Mediators
14 February 2012
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
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Interface
Networked
System
Affordance Behaviour
1
0..n
1
Ontologies
<SendSOAPRequest,
DownloadPhoto,{CameraID}, >
<ReceiveSOAPResponse,
DownloadPhoto, , {Photo}>

19. Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis
Informed by Ontologies
System (NS2)Functional
Matching
System (NS1)
Ontologies
Does it make sense for NS1 and NS2
to interact?
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20. Dynamic Synthesis of Mediators
14 February 2012
Functional Matching
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System 2System1
AffC2 = <Req, PhotoSharing,
{CameraID}, {PhotoFile}>
AffDrone = <Prov, PhotoSharing,
, {Photo}>
What is the relation between a
PhotoFile and Photo ?

21. Dynamic Synthesis of Mediators
14 February 2012
Domain-specific Ontology
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PhotoSharingProducer PhotoSharingServer PhotoSharingConsumer
PhotoMetadata PhotoFile
Photo
SearchPhoto DownloadPhoto UploadPhoto
PhotoSharing
PhotoSharingProducer PhotoSharingServer PhotoSharingConsumer
PhotoMetadata PhotoFile
Photo
SearchPhoto DownloadPhoto UploadPhoto
PhotoSharing
Subsumption (is-a)
PhotoID: string
CameraID: string
Longitude: double
Latitude: double
Resolution: integer
Information:string

22. Dynamic Synthesis of Mediators
14 February 2012
Functional Matching
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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)

23. Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis
Informed by Ontologies
Middleware Abstraction Middleware Abstraction
System (NS2)Functional
Matching
Yes
System (NS1)
Middleware-agnostic
Networked System (NS2)
Middleware-agnostic
System (NS1)
Ontologies
Abstract from the communication
protocol details and concentrate on
application semantics
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24. Dynamic Synthesis of Mediators
14 February 2012
Middleware Ontology
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RemoteProcedureCallAPI
MethodName Arguments ReturnValue
0..1 + follows {some} 0..1 + follows {some}
RemoteProcedureCallAPI
ReceveReply ReceiveCall Reply
MethodName Arguments ReturnValue
0..1 + follows {some}
+hasInput {some}
+hasOutput {some}
+hasOutput {some}
+hasInput {some}
+hasOutput {some}
Call
0..1 + follows {some}
+hasInput {some}
+hasInput {some}
Call
RemoteProcedureCallAPI
ReceveReply ReceiveCall Reply
MethodName Arguments ReturnValue
0..1 + follows {some}
+hasInput {some}
+hasOutput {some}
+hasOutput {some}
+hasInput {some}
+hasOutput {some}
SendSOAPRespReceiveSOAPResp ReceiveSOAPRqt
SOAPRequest SOAPResponse
SendSOAPRqt
Call
0..1 + follows {some}
+hasInput {some}
ReceiveReply ReceiveCall ReplyCall

25. Dynamic Synthesis of Mediators
14 February 2012
Middleware Abstraction
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<SendSOAPRequest,
DownloadPhoto,{CameraID}, >
<ReceiveSOAPResponse,
DownloadPhoto,{Photo} >
<DownloadPhoto,{CameraID}, {Photo}>
C2 Behavior
C2 Middleware-agnostic
Behavior

26. Dynamic Synthesis of Mediators
14 February 2012
Middleware Abstraction
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Drone Behavior
DroneMiddleware-agnostic
Behavior
<write, PhotoMetaData, ,
{photometadata}>
<write,
PhotoFile, , {photofile}>
<PhotoMetaData, , {photometadata}>
<PhotoFile, , {photofile}>

27. Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis
Informed by Ontologies
Middleware Abstraction Middleware Abstraction
System (NS2)Functional
Matching
Yes
System (NS1)
Middleware-agnostic
Networked System (NS2)
Middleware-agnostic
System (NS1)
Ontologies
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Generate Mapping Processes
Mapping Processes
What are the translations that need to
be performed?

28. Dynamic Synthesis of Mediators
14 February 2012
Generating Mapping Processes
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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

29. Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis
Informed by Ontologies
Middleware Abstraction Middleware Abstraction
Compatible
Partially compatible
Not compatible
Behavioral
Matching
System (NS2)Functional
Matching
Yes
System (NS1)
Middleware-agnostic
Networked System (NS2)
Middleware-agnostic
System (NS1)
Ontologies
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Generate Mapping Processes
Mapping Processes
Relies on ontology-based model
checking to verify the correctness of
the mapping processes

30. Dynamic Synthesis of Mediators
14 February 2012
Behavioral Matching
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PhotoMetaData
PhotoFile
PhotoMetaData
PhotoFile
DownloadPhoto
DownloadPhoto
Drone BehaviorC2 Behavior Mediator Behavior

31. Dynamic Synthesis of Mediators
14 February 2012
Emergent Middleware Synthesis
Informed by Ontologies
Middleware Abstraction Middleware Abstraction
CompatibleNot compatible
Behavioral
Matching
System (NS2)Functional
Matching
Yes
System (NS1)
Middleware-agnostic
Networked System (NS2)
Middleware-agnostic
System (NS1)
Ontologies
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Generate Mapping Processes
Mapping Processes
Deployment
Emergent
Middleware
Refines the mediator model into a
concrete software artifact:
an emergent middleware
Failure

32. Dynamic Synthesis of Mediators
14 February 2012
Deployment (1)
 Refine the mapping
processes using
middleware semantics
32
<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

33. Dynamic Synthesis of Mediators
14 February 2012
Deployment (2)
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Composer 2
Parser 2
Parser 1
Composer
1
Emergent Middleware
Mediator
System 2System1

34. Dynamic Synthesis of Mediators
14 February 2012
Reflections (1)
 Interoperability remains a fundamental
problem in today’s complex distributed
systems
 Dynamic synthesis of mediators promises
to address interoperability in a future-proof
manner
 Ontologies have a key role to play in
supporting synthesis at both application
and middleware layers
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35. Dynamic Synthesis of Mediators
14 February 2012
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
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36. Dynamic Synthesis of Mediators
14 February 2012
Thank you

37. Dynamic Synthesis of Mediators
14 February 2012
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
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