Service-Based Service-Based ParadigmParadigm

Anchoring the Indefinable FieldAnchoring the Indefinable Field

Of Pervasive ComputingOf Pervasive Computing

Presenter:

Vijay Dheap

OutlineOutline

I.I. Pervasive ComputingPervasive ComputingII.II. The Cognitive HurdleThe Cognitive HurdleIII.III. Basic PropositionBasic PropositionIV.IV. What is a Service?What is a Service?V.V. Service-Based ParadigmService-Based ParadigmVI.VI. Mapping: SbP to Pervasive ComputingMapping: SbP to Pervasive ComputingVII.VII. Enabling TechnologiesEnabling TechnologiesVIII.VIII. Case Study: Web ServicesCase Study: Web ServicesIX.IX. Why SbP?Why SbP?X.X. New FrontiersNew Frontiers

Pervasive ComputingPervasive Computing

““Environments saturated by computing and Environments saturated by computing and communication capability, yet gracefully communication capability, yet gracefully integrated with human users” integrated with human users”

Computing and Communication - Anywhere & Computing and Communication - Anywhere & AnytimeAnytime

Smart Spaces, Self-tuning …Smart Spaces, Self-tuning …

Transparent, Proactive, Intelligent …Transparent, Proactive, Intelligent …

Context Awareness / User IntentContext Awareness / User Intent

Evolution rather than RevolutionEvolution rather than Revolution

The Cognitive HurdleThe Cognitive Hurdle

Pervasive Computing as a whole is discussed with Pervasive Computing as a whole is discussed with relation to its Vision. When attempting to relation to its Vision. When attempting to crystallize that Vision, various aspects are crystallize that Vision, various aspects are considered in terms of technologies required.considered in terms of technologies required.

A checklist of criteria that a pervasive computing A checklist of criteria that a pervasive computing environment should meet. environment should meet.

Technologies required for implementing a Technologies required for implementing a pervasive computing environment exists already, pervasive computing environment exists already, yet we must find the means of “gluing” them yet we must find the means of “gluing” them together. (Mobile Computing, Distributed together. (Mobile Computing, Distributed Computing)Computing)

The Cognitive HurdleThe Cognitive Hurdle

Research lacks a roadmap for achieving the ideal Research lacks a roadmap for achieving the ideal vision of Pervasive Computing.vision of Pervasive Computing.

A grasp of the research focus in this field has A grasp of the research focus in this field has been evasive.been evasive.

A clear, concise description or A clear, concise description or abstraction of Pervasive Computing abstraction of Pervasive Computing has so far not been presented.has so far not been presented.

Basic PropositionBasic Proposition

Resources are present in our environment.Resources are present in our environment.

Building a pervasive computing environment Building a pervasive computing environment requires that the resources available in the requires that the resources available in the environment be manipulated in a manner to environment be manipulated in a manner to assist computation anywhere at any time.assist computation anywhere at any time.

Access and utilization of resources can be termed Access and utilization of resources can be termed as a service.as a service.

Basic PropositionBasic Proposition

Services are provided when demand Services are provided when demand justifies their creation.justifies their creation.

The prevalence of diverse, yet useful The prevalence of diverse, yet useful services in a particular location would services in a particular location would enable the establishment of “smart enable the establishment of “smart spaces”. spaces”.

Increasing the number and size of smart Increasing the number and size of smart spaces will enable end users to experience spaces will enable end users to experience a pervasive computing environment. a pervasive computing environment.

What is a Service?What is a Service?

The means employed to achieve a certain task or The means employed to achieve a certain task or goal. goal.

A service would be required to expose its A service would be required to expose its functionality through interfaces. functionality through interfaces.

Functionality would be defined as the purpose for Functionality would be defined as the purpose for the establishment of a service. the establishment of a service.

What is a Service?What is a Service?

Resources are consumed or employed upon Resources are consumed or employed upon execution.execution.

The contract of the service is that given a set of The contract of the service is that given a set of pre-conditions, a certain set of post-conditions pre-conditions, a certain set of post-conditions will result through the execution of the service. will result through the execution of the service.

S ≡ PreCond ⇒I [F (IN, OUT, sS ≡ PreCond ⇒I [F (IN, OUT, sii, s, sff) ⇚R] ⇒PostCond.) ⇚R] ⇒PostCond.

Service-Based ParadigmService-Based Paradigm

It encapsulates all the high-level characteristics and It encapsulates all the high-level characteristics and concepts associated with a pervasive computing concepts associated with a pervasive computing environment. environment.

It delineates the core research segments necessary It delineates the core research segments necessary to construct a pervasive computing environment.to construct a pervasive computing environment.

Service-Based ParadigmService-Based Paradigm

Segments: Segments:

Service DescriptionService Description

Service Offering/DiscoveryService Offering/Discovery

Service/Request Matching & Service CompositionService/Request Matching & Service Composition

Service Execution & ManagementService Execution & Management

Service DescriptionService Description

A mechanism for demonstrating the functionality A mechanism for demonstrating the functionality of a Service.of a Service.

Information about a service including the inputs Information about a service including the inputs needed, outputs produced, constraints that must needed, outputs produced, constraints that must hold on these inputs and outputs, the protocols hold on these inputs and outputs, the protocols used …used …

Access to both static and dynamic attributes of Access to both static and dynamic attributes of the service.the service.

Constraints/Interrelatedness: support for Constraints/Interrelatedness: support for automation – service offering/discovery, access …automation – service offering/discovery, access …

Service Offering/DiscoveryService Offering/Discovery

Motivation: Transition away from manual Motivation: Transition away from manual configuration each time new devices or configuration each time new devices or applications are incorporated into an applications are incorporated into an environment. environment.

Mechanism employed significantly dependent on Mechanism employed significantly dependent on computing/communication infrastructure.computing/communication infrastructure.

Mechanics of this segment are well understood.Mechanics of this segment are well understood.

Constraints/Interrelatedness: problem of Constraints/Interrelatedness: problem of interoperability – service to request matching, interoperability – service to request matching, service composition…service composition…

Service/Request MatchingService/Request Matching

Gap between service availability and invocation. Gap between service availability and invocation.

Analyze services offered and provide suitable Analyze services offered and provide suitable responses for requests.responses for requests.

QOS issues: response time of the matching QOS issues: response time of the matching procedure; selection among alternativesprocedure; selection among alternatives

Constraints/Interrelatedness: Approach will depend Constraints/Interrelatedness: Approach will depend on syntactic vs. semantic debate in service on syntactic vs. semantic debate in service descriptions and standardization of mechanisms descriptions and standardization of mechanisms in service offering/discoveryin service offering/discovery

Service CompositionService Composition

Many-to-one matching of services to requests.Many-to-one matching of services to requests.Semantic interaction a necessity.Semantic interaction a necessity.Drawing knowledge from Artificial Intelligence – Drawing knowledge from Artificial Intelligence – predicate & situational calculus – required for predicate & situational calculus – required for planning.planning.Dynamic or static composition of services based Dynamic or static composition of services based on computing/communication infrastructure.on computing/communication infrastructure.Partial satisfaction of requests.Partial satisfaction of requests.

Constraints/Interrelatedness: Assigning the Constraints/Interrelatedness: Assigning the responsibility for composing services – service responsibility for composing services – service management.management.

Service ExecutionService Execution & Management & Management

Entails invoking the functionality of a service Entails invoking the functionality of a service through defined interfaces that are publicly through defined interfaces that are publicly accessible.accessible.

Insight from distributed, network-centric Insight from distributed, network-centric computation.computation.

Requires loosely-coupled systems.Requires loosely-coupled systems.

Reliability, fault tolerance achieved through Reliability, fault tolerance achieved through service execution management.service execution management.

Delegation of administrative overhead.Delegation of administrative overhead.

Multi-level managementMulti-level management

Constraints/Interrelatedness: Complexity dependent Constraints/Interrelatedness: Complexity dependent on service composition (interaction among a on service composition (interaction among a number of services), service description number of services), service description (contracts) (contracts)

Service ExecutionService Execution & Management & Management

MappingMapping

Application: A coordinating set of services.Application: A coordinating set of services.

Context Awareness/User Intent: Service offering, Context Awareness/User Intent: Service offering, service matching/composition.service matching/composition.

Self-tuning & adaptability: Service description, Self-tuning & adaptability: Service description, service management.service management.

MappingMapping

Intelligent/Proactive behavior: Service Intelligent/Proactive behavior: Service composition, service management.composition, service management.

Transparency/Invisibility: Automating the cycle - Transparency/Invisibility: Automating the cycle - service offering/discoveryservice offering/discovery→ service/request → service/request matching & service composition→ service matching & service composition→ service execution & management.execution & management.

Enabling TechnologiesEnabling Technologies

Computing Infrastructure: Embedded, Mobile, Computing Infrastructure: Embedded, Mobile, Fixed.Fixed.

Networking Technologies: Mobile Wireless Networking Technologies: Mobile Wireless Communications.Communications.

Distributed Computing (P2P)Distributed Computing (P2P)

Enabling TechnologiesEnabling Technologies

Service-Oriented Software DesignService-Oriented Software Design

Power ManagementPower Management

Security: Trust, Privacy, Secure Systems.Security: Trust, Privacy, Secure Systems.

Sensor networksSensor networks

Web ServicesWeb Services

Web services are one specific type of service that Web services are one specific type of service that can be offered. At present it can be can be offered. At present it can be conceptualized as a limited deployment of a conceptualized as a limited deployment of a virtual pervasive computing environment.virtual pervasive computing environment.

Service Description: Web Services Description Service Description: Web Services Description Language (WSDL).Language (WSDL).Service Offering/Discovery: Universal Description, Service Offering/Discovery: Universal Description, Discovery, and Integration (UDDI).Discovery, and Integration (UDDI).Service/Request Matching & Service Composition: Service/Request Matching & Service Composition: UDDI.UDDI.Service Execution & Management: Web server Service Execution & Management: Web server and client.and client.

Web Service DescriptionWeb Service Description

XML is the standard meta language to describe XML is the standard meta language to describe the services offered.the services offered.

WSDL is an XML based specification that provides WSDL is an XML based specification that provides for syntactic description of Web Services.for syntactic description of Web Services.

Web Service DescriptionWeb Service Description

Darpa Agent Markup Language for Web Services Darpa Agent Markup Language for Web Services (DAML-S) is also an XML based specification but is (DAML-S) is also an XML based specification but is being promoted for semantic description of Web being promoted for semantic description of Web Services.Services.

Semantic descriptions make use of ontologies Semantic descriptions make use of ontologies which are shared vocabularies and can be used to which are shared vocabularies and can be used to reason about service functionality. reason about service functionality.

UDDIUDDI

The mechanism used for offering and discovering The mechanism used for offering and discovering web services – Directory Service.web services – Directory Service.

Service providers register with the directory Service providers register with the directory service.service.

Service users query the directory for services.Service users query the directory for services.

UDDIUDDI

The directory service provides service users with The directory service provides service users with necessary information (URL) about the requested necessary information (URL) about the requested services to invoke them. – syntactic matching.services to invoke them. – syntactic matching.

Subsequently the service provider and the service Subsequently the service provider and the service user interact directly.user interact directly.

Web Services Execution Web Services Execution

The web server and the client are only entities The web server and the client are only entities involved once a web service is invoked.involved once a web service is invoked.

Fault-tolerance is the responsibility of the client.Fault-tolerance is the responsibility of the client.

Satisfies the loosely-coupled requirement.Satisfies the loosely-coupled requirement.

QOS management is managed by the web server.QOS management is managed by the web server.

Composition of web services is possible but has to Composition of web services is possible but has to be done explicitly or statically. be done explicitly or statically.

Why SbP?Why SbP?

Clear, concise and extendable abstraction of Clear, concise and extendable abstraction of Pervasive Computing.Pervasive Computing.

Bottom-Up approach free of proprietary Bottom-Up approach free of proprietary methodology.methodology.

Facilitates the recognition, integration and Facilitates the recognition, integration and coordination among research projects.coordination among research projects.

Enables identification of points where Enables identification of points where standardization is required.standardization is required.

New FrontiersNew Frontiers

Power to explain the growth of interest in Grid Power to explain the growth of interest in Grid Computing and Autonomic Computing.Computing and Autonomic Computing.

Computing power is the primary service of Computing power is the primary service of interest in grid computing.interest in grid computing.

A hierarchical structure of the management A hierarchical structure of the management services is the basis of Autonomic Computing. services is the basis of Autonomic Computing.

Questions??Questions??Comments…Comments…

““If the facts don’t fit the theory, If the facts don’t fit the theory, change the facts” – Albert Einsteinchange the facts” – Albert Einstein

““If you can’t convince them, confuse If you can’t convince them, confuse them” – Chinese Proverbthem” – Chinese Proverb