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

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

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 3 Middleware for pervasive, distributed computing Quality of Service Interoperability C ONNECT 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 2012 Illustrating the Interoperability Challenge  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

Dynamic Synthesis of Mediators 14 February 2012 Existing Approaches to Interoperability Changing systems 5 Change the system or attach an adaptor Legacy systems Code unavailable Legacy systems Code unavailable × System 2 System1

Dynamic Synthesis of Mediators 14 February 2012 Existing Approaches to Interoperability × Changing systems Standardization 6 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) No one-size-fits all standard given the heterogeneity and complexity of pervasive systems (and systems of systems) × System 2 System1

Dynamic Synthesis of Mediators 14 February 2012 Existing Approaches to Interoperability × Changing systems × Standardization Common Abstraction 7 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 2 System1

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 8 System 2 System1

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. 9

Dynamic Synthesis of Mediators 14 February 2012 Dynamic Mediation to Support Interoperability 10 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 y DownloadPhoto = getPhoto Photo = PhotoMetadata + PhotoFile PhotoMetadata = PhotoID + Location + CameraID + details … Synthesize Modeling Synthesis Deployment write PhotoFile write PhotoMetadata System (NS2) DownloadPhoto System (NS1)

Dynamic Synthesis of Mediators 14 February 2012 Outline  My team, my project, my thesis  Interoperability through dynamic synthesis of connectors Modeling Synthesis Deployment  Reflections 11

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., 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 12 Interface Networked System AffordanceBehaviour 1 0..n 1 Ontologies

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? 13

Dynamic Synthesis of Mediators 14 February 2012 Functional Matching 14 System 2 System1 Aff C2 = Aff Drone = <Prov, PhotoSharing, , {Photo}> What is the relation between a PhotoFile and Photo ?

Dynamic Synthesis of Mediators 14 February 2012 Domain-specific Ontology 15 Subsumption (is-a)

Dynamic Synthesis of Mediators 14 February 2012 Functional Matching 16 System 2 System1 Aff C2 = Aff Drone = <Prov, PhotoSharing, , {Photo}> There is a functional matching between Aff C2 and Aff Drone 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 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 17

Dynamic Synthesis of Mediators 14 February 2012 Middleware Ontology 18

Dynamic Synthesis of Mediators 14 February 2012 Middleware Abstraction 19 C2 Behavior C2 Middleware-agnostic Behavior C2 Middleware-agnostic Behavior

Dynamic Synthesis of Mediators 14 February 2012 Middleware Abstraction 20 Drone Behavior DroneMiddleware-agnostic Behavior DroneMiddleware-agnostic Behavior <write, PhotoFile, , {photofile}>

Dynamic Synthesis of Mediators 14 February 2012 Emergent Middleware Synthesis Informed by Ontologies Middleware Abstraction System (NS2) Functional Matching 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 2012 Generating Mapping Processes 22 Drone Interface C2 Interface DownloadPhoto PhotoMetaDataPhotoFile 1 - Define the constraints that need to hold between compatible actions 2- Use constraint programming to find possible mapping between interfaces, > 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 Compatible Partially compatible Not compatible Behavioral Matching System (NS2) Functional Matching 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 2012 Behavioral Matching 24 PhotoMetaData PhotoFile PhotoMetaData PhotoFile DownloadPhoto Drone Behavior C2 Behavior Mediator Behavior

Dynamic Synthesis of Mediators 14 February 2012 Emergent Middleware Synthesis Informed by Ontologies 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 25 Generate Mapping Processes Mapping Processes Deployment Refines the mediator model into a concrete software artifact: an emergent middleware Refines the mediator model into a concrete software artifact: an emergent middleware Failure

Dynamic Synthesis of Mediators 14 February 2012 Deployment (1)  Refine the mapping processes using middleware semantics 26 <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 Middleware & Domain-specific Ontologies

Dynamic Synthesis of Mediators 14 February 2012 Deployment (2) 27 Listener 2 Actuator 2 Listener 1 Actuator 1 Emergent Middleware Mediator System 2 System1

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 2012 Further Information  Home page: www-rocq.inria.fr/~bennaceu  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