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The Second International Conference on Advanced Engineering Computing and Applications in Sciences (ADVCOMP 2008) September 29 - October 4 Valencia, Spain Middleware with QoS support Middleware with QoS support to control intelligent to control intelligent systems systems José Luis Poza Luján, Juan Luis Posadas Yagüe, José E. José Luis Poza Luján, Juan Luis Posadas Yagüe, José E. Simó Ten Simó Ten Institute of Industrial Control Systems Institute of Industrial Control Systems Polytechnic University of Valencia Polytechnic University of Valencia
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Middleware with QoS support to control intelligent systems

Jun 10, 2015

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Page 1: Middleware with QoS support to control intelligent systems

The Second International Conference on Advanced Engineering Computing and Applications in Sciences (ADVCOMP 2008) September 29 - October 4Valencia, Spain

Middleware with QoS support Middleware with QoS support to control intelligent systemsto control intelligent systems

José Luis Poza Luján, Juan Luis Posadas Yagüe, José E. Simó TenJosé Luis Poza Luján, Juan Luis Posadas Yagüe, José E. Simó Ten

Institute of Industrial Control SystemsInstitute of Industrial Control Systems

Polytechnic University of ValenciaPolytechnic University of Valencia

Page 2: Middleware with QoS support to control intelligent systems

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ContentsContents IntroductionIntroduction FundamentalsFundamentals

DCPSDCPS SWESWE

ArchitectureArchitecture OverviewOverview ControlControl Formal modelFormal model

ImplementationImplementation DesignDesign ExampleExample

ConclusionsConclusions

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IntroductionIntroduction ChallengeChallenge

Management of peer-to-peer quality of service Management of peer-to-peer quality of service (QoS) for component-based distributed (QoS) for component-based distributed intelligent control systemsintelligent control systems

This aspect of distributed systems goes beyond This aspect of distributed systems goes beyond the real-time requirements because involves the real-time requirements because involves considerations such as.considerations such as.

Computational resources availabilityComputational resources availability SecuritySecurity Control algorithms cooperationControl algorithms cooperation StabilityStability Task control performanceTask control performance Redundant information management.Redundant information management.

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IntroductionIntroduction Communications in distributed Communications in distributed

systemssystems To manage complex component-based To manage complex component-based

distributed intelligent control systems, distributed intelligent control systems, much more QoS features are needed.much more QoS features are needed.

A way of getting these new features are A way of getting these new features are communications based on communications based on

Message queuing technologies Message queuing technologies Publish-subscribe paradigm Publish-subscribe paradigm Control system based on services paradigmControl system based on services paradigm

Standards are useful references to Standards are useful references to design a middlewaredesign a middleware

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IntroductionIntroduction FundamentalsFundamentals

Communications: Data Distribution Service (DDS) Communications: Data Distribution Service (DDS) provides a system based on publish-subscribe paradigm provides a system based on publish-subscribe paradigm with ability to manage a large amount of QoS policies.with ability to manage a large amount of QoS policies.

Control: Sensor Web Enablement (SWE) allows a simple Control: Sensor Web Enablement (SWE) allows a simple intelligent control model based on services capable of intelligent control model based on services capable of managing complex sensor networks.managing complex sensor networks.

ArchitectureArchitecture Joining DDS and SWE standards is interesting because it Joining DDS and SWE standards is interesting because it

provides a unique environment to implement a solution provides a unique environment to implement a solution to manage component-based distributed intelligent to manage component-based distributed intelligent control system, based on the combination of several QoS control system, based on the combination of several QoS policies.policies.

The implementation of this architecture is called Framed The implementation of this architecture is called Framed Sensor Adapter Control (FSA-Ctrl) whose communication Sensor Adapter Control (FSA-Ctrl) whose communication components are based on the DDS model and its control components are based on the DDS model and its control components are based on the SWE model. The QoS components are based on the SWE model. The QoS merges communications and control components.merges communications and control components.

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Fundamentals: DDSFundamentals: DDS Data Distribution Service (DDS) provides a Data Distribution Service (DDS) provides a

platform independent model that is aimed to real-platform independent model that is aimed to real-time distributed systems, is based on publish-time distributed systems, is based on publish-subscribe communications paradigm. subscribe communications paradigm.

Publish-subscribe components connect Publish-subscribe components connect information producers (publishers) and information producers (publishers) and consumers (subscribers) and isolate publishers consumers (subscribers) and isolate publishers and subscribers in time, space and message flow.and subscribers in time, space and message flow.

To configure the communications, DDS uses QoS To configure the communications, DDS uses QoS policies.policies. A QoS policy describes the service behavior according to A QoS policy describes the service behavior according to

a set of parameters defined by the system a set of parameters defined by the system characteristics or by the administrator user.characteristics or by the administrator user.

DDS specifies two areas: Data-Centric Publish-DDS specifies two areas: Data-Centric Publish-Subscribe (DCPS) witch is responsible for data Subscribe (DCPS) witch is responsible for data distribution and DLRL which is responsible for the distribution and DLRL which is responsible for the data adaptation.data adaptation.

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Fundamentals: DDS & DCPSFundamentals: DDS & DCPS When an producer (component, agent or application) When an producer (component, agent or application)

wants to publish some information, should write it in a wants to publish some information, should write it in a TopicTopic by means of an component called by means of an component called DataWriterDataWriter witch is managed by another component called witch is managed by another component called PublisherPublisher. Both components, . Both components, DataWriterDataWriter and and PublisherPublisher, are included in another component called , are included in another component called DomainParticipantDomainParticipant..

On the other side ofOn the other side ofthe communication,the communication,a Topic can bea Topic can bereceived by tworeceived by twokinds of components:kinds of components:DataReadersDataReadersand and ListenersListeners by by means a means a SubscriberSubscriber..

A A DataReaderDataReader provides the messages to application. A provides the messages to application. A ListenedListened sends the messages to the application. sends the messages to the application.

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Fundamentals: DCPS & QoSFundamentals: DCPS & QoS QoS is a concept that defines a set of parameters QoS is a concept that defines a set of parameters

by which to evaluate a service offered. by which to evaluate a service offered. In the field of control architectures, there are In the field of control architectures, there are

many definitions of quality of service. many definitions of quality of service. Processing viewpoint: QoS represents the set of both: Processing viewpoint: QoS represents the set of both:

quantitative and qualitative characteristics of a quantitative and qualitative characteristics of a distributed system needed to achieve the functionality distributed system needed to achieve the functionality required by an application.required by an application.

Communications viewpoint: QoS is defined as all the Communications viewpoint: QoS is defined as all the requirements that a network must meet to message flow requirements that a network must meet to message flow transport.transport.

DCPS specification defines 22 different QoS DCPS specification defines 22 different QoS policies that can be classified into four areaspolicies that can be classified into four areas

All components of a DCPS based communication, All components of a DCPS based communication, can establish a set of QoS policies into them can establish a set of QoS policies into them independently the others components.independently the others components.

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Fundamentals: SWEFundamentals: SWE The main objective of Sensor Web Enablement (SWE) The main objective of Sensor Web Enablement (SWE)

is to provide a new and unique framework of open is to provide a new and unique framework of open standards for exploiting Web-connected sensors and standards for exploiting Web-connected sensors and sensor systems of all types.sensor systems of all types.

The components of SWE are divided into two groups:The components of SWE are divided into two groups: Information models: standard specifications in XML and processes Information models: standard specifications in XML and processes

interchange messages.interchange messages. Services: control components that process the information models. Services: control components that process the information models.

Control processes are based on interconnected Control processes are based on interconnected components. components. These components receive information models from other These components receive information models from other

components and send the process results to other connected components and send the process results to other connected components.components.

A component is a particular process that transforms A component is a particular process that transforms information. information. Simple examples of SWE components are sensors, effectors or Simple examples of SWE components are sensors, effectors or

physical process filters. physical process filters. Complex examples of SWE components are control kernels or Complex examples of SWE components are control kernels or

sensor data fusion algorithms.sensor data fusion algorithms.

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Fundamentals: SWEFundamentals: SWE A A Process ModelProcess Model is a single component, is a single component,

used within a more complex structure, used within a more complex structure, called a called a Process ChainProcess Chain. Moreover, a . Moreover, a Process Process ModelModel is based on a is based on a Process MethodProcess Method witch witch acts as a acts as a Process ModelProcess Model template. template.

A A Process MethodProcess Method specifies both thespecifies both theinterface and howinterface and howto implement theto implement theProcess ModelProcess Model. . It also defines It also defines inputs, outputs andinputs, outputs andthe operating the operating parameters.parameters.

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Architecture: overviewArchitecture: overview Frame Sensor Adapter to Control (FSA-Ctrl) is an Frame Sensor Adapter to Control (FSA-Ctrl) is an

architecture inspired by DDS and SWE models and architecture inspired by DDS and SWE models and is an evolution of an architecture developed by is an evolution of an architecture developed by the research group called Frame Sensor Adapter the research group called Frame Sensor Adapter (FSA)(FSA)

The architecture has two The architecture has two distinct areas: communications distinct areas: communications and control. QoS Policiesand control. QoS Policiesconnects both areas. connects both areas.

The communication layerThe communication layerorganizes the organizes the LogicalDataLogicalDatain a symbolic hierarchical treein a symbolic hierarchical treestructure called Logical structure called Logical Namespace Tree (LNT)Namespace Tree (LNT)

Control layer organizes theControl layer organizes theSensorsSensors on a graph, called on a graph, calledLogical Sensor Graph (LSG)Logical Sensor Graph (LSG)

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Architecture: system controlArchitecture: system control

Components witch implements the control system Components witch implements the control system are named Logical Sensors (LS) and contains the are named Logical Sensors (LS) and contains the control algorithms.control algorithms. Logical Sensors may include others Logical Sensors to Logical Sensors may include others Logical Sensors to

create complexes Logical Sensors than gives more create complexes Logical Sensors than gives more complex algorithmscomplex algorithms

Communication Communication into Logical Sensors into Logical Sensors can be of two kinds can be of two kinds (depending on (depending on location in the location in the distributed distributed system)system) Internal: LSGInternal: LSG External: LNTExternal: LNT

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Architecture: formal modelArchitecture: formal model

FSA-Ctrl FSA-Ctrl Architecture model Architecture model implements implements communications communications and control by and control by means a group of means a group of classes.classes.

A group of QoS A group of QoS classes can be classes can be associated to every associated to every class.class.

DCPS and SWE DCPS and SWE components can be components can be implemented with implemented with a set of QoS a set of QoS associatedassociated

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Implementation: designImplementation: design

Application to design an specific LNT Application to design an specific LNT and LSG for a control system.and LSG for a control system.

LNT LNT desigdesig

n n panepane

Logical Logical Sensor Sensor implementatiimplementationon

LSG LSG desigdesign n panepane

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Robot ControlRobot ControlNavigationNavigation

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ConclusionsConclusions FSA-Ctrl is a component-based distributed FSA-Ctrl is a component-based distributed

intelligent control architecture with QoS support. intelligent control architecture with QoS support. Communications based on publish-subscribe paradigm Communications based on publish-subscribe paradigm

and the DCPS standard endorsed by OMG allows to and the DCPS standard endorsed by OMG allows to convert easily the system into another. convert easily the system into another.

Control based on SWE standard endorsed by OGC allows Control based on SWE standard endorsed by OGC allows the high-distributed control algorithms. the high-distributed control algorithms.

The FSA-Ctrl architecture especially focuses on The FSA-Ctrl architecture especially focuses on setting QoS management policies. setting QoS management policies. With these policies, the system can make decisions about With these policies, the system can make decisions about

questions like the discrimination of redundant information.questions like the discrimination of redundant information. The architecture can be applied to evaluate the The architecture can be applied to evaluate the

proper location for the components. proper location for the components. Since certain control components with a set of QoS Since certain control components with a set of QoS

restrictions for each, the architecture could distribute restrictions for each, the architecture could distribute automatically the agents’ control processes according to automatically the agents’ control processes according to the restrictions. the restrictions.