Dynamic Synthesis of Mediators to Support Interoperability in Autonomic Systems

Dynamic Synthesis of Mediators

to Support Interoperability in

Autonomic Systems

Amel Bennaceur and Valérie Issarny

ARLES project-team

Inria Paris-Rocquencourt

NII-Shonan Workshop: Engineering Autonomic Systems (EASy)

Interoperability in Autonomic

Systems

Systems are becoming increasingly connected

• Future Internet, Cyber-Physical System, Internet of Things

• Integration becoming more difficult

Interactions among components cannot be planned

beforehand

• Increasingly dynamic

• Unanticipated components

System and its components figure out how to interact at

runtime

• Automatically ensuring interoperation at runtime

Our Research on Interoperability

Sustaining composition in highly heterogeneous

and dynamic environments

• Multi-* networking environments with heterogeneity at

all layers (application, middleware)

• Semantics of networked systems needed to reason

about and achieve on-the-fly interoperability

• Ontology for the description of functional

semantics

• LTSs for the description of behavioural semantics

3

Illustrating the Interoperability

Challenges

GMES: Global Monitoring for Environment & Security

Discovery

4

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

Existing Approaches to

Interoperability

5

Change the system

or attach an adaptor× A chosen shared

language

No one-size-fits-all

standard

Use a common abstraction

Need to be aware about all the

possible configurations beforhand

Legacy systems

No runtime support

× ×

Transform on the fly using

an intermediary system:

the mediator

Can we observe, synthesize and deploy mediators

dynamically?

Dynamic Mediation to Support

Interoperability

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.

6

Dynamic Mediation to Support

InteroperabilityDiscovery

Model

level

System

level

→ Learning → Synthesis → Concretization → Monitoring

DownloadPhotowrite PhotoFile

write PhotoMetadata

Model

Extraction

Model

Extraction

read PhotoFile

Mediator Model

downloadPhoto

read PhotoMetadata

Deployment

Monitor

Emergent

Middleware

Ontolog

yDownloadPhoto = getPhotoPhoto = PhotoMetadata + PhotoFile

PhotoMetadata = PhotoID + Location + CameraID + details …

write PhotoFile

write PhotoMetadata

System (NS2)

DownloadPhoto

System (NS1)

Synthesis

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

8

Interface

Networked

System

Affordance Behaviour1

0..n

1

Ontologies

<SendSOAPRequest,

DownloadPhoto,{CameraID}, >

<ReceiveSOAPResponse,

DownloadPhoto, , {Photo}>

Functional

Matching

Emergent Middleware Synthesis

Informed by Ontologies

Affordance

Behaviour

NS2 Model

<Prov, B, IB,OB>

Interface

?δ2!ρ2

!δ1?ρ1

?λ1

t3

t4

!δ1

δ1 = <SOAPCall, d, id, od>

λ1 = <SOAPCall, l, il, ol>

ρ1 = <SOAPCall, r, ir, or>

Affordance

Behaviour

Model

<Req, A, IA,OA>

Interface

NS1

α1 = <rd, a, ia, oa>

β1 = <out, b, ib, ob>

?β1!α1

?α2 !β2

t1

t2

ia

a Thing

Nothing

Ontologies

dir AB

Does it make sense for NS1 and NS2

to interact?

Middleware

Abstraction

Emergent Middleware Synthesis

Informed by Ontologies

Affordance

Behaviour

NS2 Model

<Prov, B, IB,OB>

Interface

?δ2!ρ2

!δ1?ρ1

?λ1

t3

t4

!δ1

δ1 = <SOAPCall, d, id, od>

λ1 = <SOAPCall, l, il, ol>

ρ1 = <SOAPCall, r, ir, or>

Affordance

Behaviour

Model

<Req, A, IA,OA>

Interface

NS1

α1 = <rd, a, ia, oa>

β1 = <out, b, ib, ob>

?β1!α1

?α2 !β2

t1

t2

ia

a Thing

Nothing

Ontologies

dir AB

Abstract from the communication

protocol details and concentrate on

application semantics

Emergent Middleware Synthesis

Informed by Ontologies

Affordance

Behaviour

NS2 Model

<Prov, B, IB,OB>

δ

δλ

ρ

ρ

δ = <d, id, od>

λ = <l, il, ol>

ρ = <r, ir, or>

Interface

Affordance

Behaviour

Model

<Req, A, IA,OA>

Interface

NS1

α β

α

α = <a, ia, oa>

β = <b, ib, ob> Ontology-based

Action Mapping

α' = < α , <δ, λ> >

β' = < β , <ρ> >

….

ia

a Thing

Nothing

Ontologies

dir AB

What are the translations that need to

be performed?

Abstract CONNECTor Model

α

δλ

β

ρ

Success

α' = < α , <δ, λ> >

β' = < β , <ρ> >

….

Behavioral

Matching & Synthesis

Emergent Middleware Synthesis

Informed by Ontologies

Affordance

Behaviour

NS2 Model

<Prov, B, IB,OB>

δ

δλ

ρ

ρ

δ = <d, id, od>

λ = <l, il, ol>

ρ = <r, ir, or>

Interface

Affordance

Behaviour

Model

<Req, A, IA,OA>

Interface

NS1

α β

α

α = <a, ia, oa>

β = <b, ib, ob>

Select the appropriate mapping processes

and compose them such that both

systems reach their final states

Abstract CONNECTor Model

α

δλ

β

ρ

Concretization

Concrete CONNECTor Model

?β1!ρ1

?ρ2 !β2?δ2

!α2

!δ1?α1

?λ1

t1

t2 t3

t4

Emergent Middleware Synthesis

Informed by Ontologies

Affordance

Behaviour

NS2 Model

<Prov, B, IB,OB>

δ

δλ

ρ

ρ

δ = <d, id, od>

λ = <l, il, ol>

ρ = <r, ir, or>

Interface

Affordance

Behaviour

Model

<Req, A, IA,OA>

Interface

NS1

α β

α

α = <a, ia, oa>

β = <b, ib, ob>

ia

a Thing

Nothing

Ontologies

dir AB

Refines the mediator model into a

concrete software artifact:

an emergent middleware

Approach In Action:Domain-specific Ontology

14

PhotoSharingProducer PhotoSharingServer PhotoSharingConsumer

PhotoMetadata PhotoFile

Photo

SearchPhoto DownloadPhoto UploadPhoto

PhotoSharing

PhotoSharingProducer PhotoSharingServer PhotoSharingConsumer

PhotoMetadata PhotoFile

Photo

SearchPhoto DownloadPhoto UploadPhoto

PhotoSharing

Subsumption (is-a)

PhotoID: stringCameraID: stringLongitude: doubleLatitude: doubleResolution: integerInformation:string

Approach In Action:Functional Matching

15

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)

Approach In Action:Middleware Ontology

16

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

Approach In Action:

Middleware Abstraction

17

<SendSOAPRequest,

DownloadPhoto,{CameraID}, >

<ReceiveSOAPResponse,

DownloadPhoto,{Photo} >

<DownloadPhoto,{CameraID}, {Photo}>

C2 BehaviorC2 Middleware-agnostic

Behavior

Approach In Action:Middleware Abstraction

18

Drone BehaviorDroneMiddleware-agnostic

Behavior

<write, PhotoMetaData, ,

{photometadata}>

<write,

PhotoFile, , {photofile}>

<PhotoMetaData, , {photometadata}>

<PhotoFile, , {photofile}>

Approach In Action:Generating Mapping Processes

19

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

Approach In Action:Behavioral Matching

20

PhotoMetaData

PhotoFile

PhotoMetaData

PhotoFile

DownloadPhoto

DownloadPhoto

Drone BehaviorC2 Behavior Mediator Behavior

Approach In Action:Deployment

Refine the mapping

processes using

middleware semantics

21

<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

Approach In Action:Deployment

Composer 2

Parser 2

Parser 1Composer

1

Emergent Middleware

Mediator

System 2System1

Open Issues

Learning is (almost) always partial

Evolution and incremental synthesis

23

Monitoring

Evolution of the

NS Model

Discovery

Learning

Synthesis

New NSs

(re)Synthesis

Open Issues In CONNECT

Enforcing the goal instead of achieving it

Ontologies

• Processing overhead, fuzziness, learning,

heterogeneity in ontologies, alignment

Summary

Interoperability remains a fundamental

problem in today’s complex systems

Dynamic synthesis of mediators promises

to address interoperability in a future-proof

manner

Still..

Need to make complete the NS model and

re(synthesize) mediators incrementally

25

Thank you

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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