15/09/2015Semantic Week - 2009Page 1 Enhancing Service Selection by Semantic QoS Henar Muñoz Frutos...

19/04/23 Semantic Week - 2009

Enhancing Service Selection by Semantic

QoSHenar Muñoz FrutosTelefónica I+D


Introduction

Conclusions and Future Directions

Proposed Approach

Implementation


Context

• Marketplace model: customers and providers interact for trading services– Introduction of Grid and Cloud technologies – New services included: infrastructure services

• Services: Storage, computing, infrastructure, software as a Service

• Provided by Amazon, Google, HP…– Services encapsulate resources

• Resources: machines, hard disk, applications, licenses• Key element: Service Selection based on QoS metrics

– Due to the increase of functionally similar services – Due to the importance of non-functional properties: QoS metrics

availability, performance, price, reliability, infrastructure properties– To find the best service to meet user requirements and assure

QoS


Context

• Important is to have a contract between the involved entities (customer-providers)– Need Service Level Agreement

• terms for the provision of the service (service description),

• Quality of service (QoS) level to be maintain, • Information about resources to be provided, • the liability to compensation if SLAs are not met.

• SLA templates used for achieving an agreement between customers and provider specifying the terms under the provision of the service

• SLA templates can be used as input for the service selection based on QoS metrics


Problem statement

• Main SLA specifications– WS-Agreement (OGF-GRAAP)-WSLA (IBM)– They covers the syntactic aspects in the description of SLA:

• a schema for specifying an agreement and an agreement template,

• no focus on vocabulary domain– WS-Agreement non-goals: Defining Specification of metrics

associated with agreement parameters i.e., how and where these are measured

• Specification assumes that other complimentary specifications will address these requirements

• Current SLA specifications lack in interoperability:– Open marketplace: Providers and consumers are collaborating on a

global scale competing for offering and consuming services – Different terminologies to describe the vocabulary domain

(performance vs. response time)– Different language (performance vs. rendimiento)


Example

ANSYS request

•CPUName: IntelCore Duo•CPU Speed: 2 GHz•Capacity: 400 MB•Price: 27 euros per day•DiskSpace: 250GB

-RAMMemory: 7.5 GB-ComputeUnit: 4 ECU-Storage: 850GB-Platform: 64 bit-Price: $0.4 per instance hour

CUSTOMER

AMAZON

Software engineering company

-MemoryPerTask: 7.5 GB-ClockCPUSpeed: 100 MHz / process-StorageCapability: 850GB-Cost: 5 euros/task/hour

BSC

PROVIDERSCloud and Grid providers


Objectives

• Improve interoperability between service providers and clients– Providing semantic interoperability by the introduction of semantic

annotations– Beyond syntax to semantics, mapping of data exchanged between the involved

parties

• Be backwards compatible – Compatible with current SLA specification e.g. WS-Agreement, WSLA– Compatible with current components (which do not understand the

specification…)• If specification is used, then extra reasoning is feasible• If NOT then the process continues normal operation

• A lightweight approach, so that, a easy way for providers to introduce these annotations.

• Increase automation in the selection process to reduce human intervention



Related Work

Implementation

Introduction

Proposed Approach


Proposed ApproachSpecification for semantic Annotations (SA-SLA)

- Backwards compatible

- Lightweight approach

Conceptual model - QoS ontology

Implementation

- Semantic Enhanced service Selection (SESS)

Selection algorithm- ranking services- taken from [Wang2006]


SA-SLA• Introduction of semantic annotations in current SLA

template files– Based on SA-WSDL– WS-Agreement + WSLA compatible

• Allow for annotating SLA description with pointers to semantic concepts

• Annotation of: SLA Parameters. Metrics

Metric Parameter SLO

modelReferences SchemaMappings

Non-semantic descriptions

Semantic descriptions

RDF, OWL, WSML

SA-SLA

SLA template

QoS metrics SLA terms


SA-SLA


Conceptual Model

• Framework capturing the QoS provided by the suppliers and required by the customer to match between the two

• Conceptual model in QoS which is shared by customers and providers and formalized as OWL– It can be extended by domain requirements (domain

specific)

• QoS ontology: specify SLA parameters and metrics for infrastructure services and their relationships– Based on [Wang2006], [Lee2003], [Tsesmetzis2006],

[Ren2007]

• QoS categorization: infrastructure, system, network, and security and cost


QoS ontology


Conceptual Model

• To solve the terminology problem (different terms for the same concept)– Simple Knowledge Organization System (SKOS)– Standard way to represent knowledge organization using

RDF

• SKOS is used for solving terminology problem

<rdf:Description rdf:about="http:// brein.com/ontology/Upper/QoS#ResponseTime">

<skos:inScheme rdf:resource="http://eu-brein.com/thesaurus/QoSmetrics"/> <rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#Concept"/> <skos:prefLabel xml:lang="en">Response Time</skos:prefLabel> <skos:altLabel xml:lang="es">Tiempo de Respuesta</skos:altLabel></rdf:Description>



Proposed Approach

Introduction

Implementation


Architecture

Comon conceptual

model

SESS SESS

SLA framework SLA framework

SA-SLA(WS-Agreement

WSLA)

Local domain

knowledge

Local domain

knowledge


Ontology Manager

Local domain

ontologySKOS representation

SKOS Manager

SA-SLA

TSLA Parser

Customer Request

TSLASelector

SLA template scores

SA-SLA

Provides Offers

Architecture

Semantic Enhanced Service Selector


Implementation

• Ontologies– Common conceptual model: OWL– Local knowledge: OWL + RDF (SKOS)

• Local knowledge repository– Query engine: Jena– Query language: SPARQL– Reasoner: Pellet

• Semantic Enhanced Service Selector– Parse the SLA templates files (JAXB and XPATH) and– match providers offers with customers’ requirements

(selection algorithm taken from [Wang2006])– Interact with local domain repository for semantic

support (create SLA instances, obtain local metrics)


Proposed Approach

Introduction

Implementation

Conclusions


Conclusions

• The increasing number of functionally similar services requires non-functional selecting process

• Non-functional properties as QoS which are described as part of the SLA templates files

• The introduction of semantic annotations in current SLA specifications allows solving the QoS metric definition problem

• Using semantic technologies in a non-intrusive way addresses the issue of backwards compatibility and eases development of tools

• Our proposal is based on existing specifications (WS-Agreement, SAWSDL)


References

• [Wang2006] Wang, X, Vitvar, T., Kerrigan, M., and Toma, I.; A QoS-aware selection model for semantic Web Services. In 4th International Conference on Service Oriented Computing (ICSOC 2006), Chicago, USA, Dec. 2006.

• [Lee2003] Lee, K, Jeon, J, Lee, W, Jeong, S., and Park, S., QoS for Web Services: Requirements and Possible Approaches, W3C Working Group Note 25, 2003. http://www.w3c.or.kr/kroffice/TR/2003/ws-qos/

• [Tsesmetzis2006] Tsesmetzis, D. T., Roussaki, I. G., Papaioannou, I. V., and Anagnostou, M. E. 2006. QoS awareness support in Web-Service semantics. AICT-ICIW. IEEE Computer Society, Washington, 128.

• [Ren2007] Ren, K.; Jinjun Chen; Tao Chen; Junqiang Song; Nong Xiao; Grid-Based Semantic Web Service Discovery Model with QoS Constraints, Semantics, Knowledge and Grid, Third International Conference on 29-31 Oct. 2007 Page(s):479 – 482


Thank you for listening Any questions?

15/09/2015Semantic Week - 2009Page 1 Enhancing Service Selection by Semantic QoS Henar Muñoz Frutos...

Documents

Transcript of 15/09/2015Semantic Week - 2009Page 1 Enhancing Service Selection by Semantic QoS Henar Muñoz Frutos...