WSOL & WSOI - Web Service Offerings Language and

Infrastructure

Vladimir Tosic, Bernard Pagurek, Kruti Patel, Babak Esfandiari, Wei Ma

Network Management & Artificial Intelligence Lab Department of Systems & Computer

EngineeringCarleton University, Ottawa, Canada

vladimir@sce.carleton.cahttp://www.sce.carleton.ca/~vladimir/

WSOLpublications.html

Outline

=> Introduction: definition of terminology, problem statement

Web Service Offerings Language (WSOL)

Web Service Offerings Infrastructure (WSOI)

Conclusions and future work

Definition of Terminology

Web Service (WS) - software application Identified by URIs Using XML messaging (SOAP), description

(WSDL), and discovery (UDDI) Web Service composition

(orchestration, choreography, flow, network)

Consumer(Requester)

WS

Provider(Supplier)

WS

AnotherWS

Problem Statement

WSDL does not formally describe important management information classes of service, SLAs, constraints, prices,

penalties, management parties, policies, … => Our solution: WSOL

How to implement management of WSOL-enabled Web Service and their compositions

=> Our solution: WSOI

=> WSOL

Introduction

=> Web Service Offerings Language (WSOL): language constructs, WSDL and WSOL, support for management applications, comparisons with related work

Web Service Offerings Infrastructure (WSOI) Conclusions and future work

WSOL Language Constructs

Service Offering (SO) - class of service constraints (functional, QoS, access rights)

expressions (Boolean, arithmetic, …)

statements (prices/penalties, management responsibility)

reusability constructs (extension, constraint groups, inclusion, instantiation of constraint group templates, …)

Service Offerings Dynamic Relationships (SODRs) - can change during run-time

WSDL and WSOL: Example

buyStock Web Service

buyStockPortType buySingleStockOperation buySingleStockRequest symbol quantity buySingleStockResponse totalStockBuyingCost … buyStockBindingbuyStockPort

buyStock.wsdl ServiceOffering1

accounting party: provider Constraint1: preCondition domain: buyStockOperation quantity > 0 Constraint2: QoSConstraint domain: buyStockOperation ResponseTime < 0.5 s Price: 0.5 $ServiceOffering2 …

buyStock.wsol

Applications of WSOL

Web Service Management (WSM) Measurement and calculation of QoS metrics,

evaluation of constraints, accounting and billing, control of the behavior of the Web Service

WS Composition Management (WSCM) Which WS co-operate in a composition What contracts are used => dynamic

manipulation of WSOL service offerings Dynamic selection and negotiation of

Web Services and classes of service

WSOL Support for WSM

Service offerings - a lightweight alternative to SLAs, contracts, profiles

Constraints and statements - policies QoS constraints - performance mgmt.Price/penalty statements - accounting mg. Functional constraints - fault managementManagement responsibility statements -

configuration management (part.)Access rights - security management (part.)

WSOL Support for WSCM

Service offerings dynamic relationships (SODRs) for switching, deactivation, and reactivation

of service offerings

Reusability constructs (static relationships between service offerings) mainly for creation of service offerings

WSOL - Some Related Work

Differentiated services (e.g., in telecom) Formal specification of various constraints Specification and management of

custom-made SLAs for Web Services: WSLA (Web Service Level Agreement) - IBM WSML (… Management ...) - HP SLAng - University College London

WS-Policy - IBM/Microsoft/BEA/SAP DAML-S - the Semantic Web community

Distinctive Characteristics of WSOL

Classes of service (service offerings) Various types of constraint Management statements Broad set of reusability constructs SO dynamic relationships (SODRS)Management third parties, accounting

parties Relative simplicity Features with lower run-time overhead Support for WSM and WSCM

=> WSOI

IntroductionWeb Service Offerings Language (WSOL)

=> Web Service Offerings Infrastructure (WSOI): support for monitoring of Web Services, mechanisms for manipulation of service offerings

and WSOI support for these mechanisms, comparisons with related work

Conclusions and future work

WSOI Support for WSMWSM - monitoring of WSOL service offerings:

Measurement and calculation of QoS metrics Evaluation of constraints Accounting

Modules for WSM: Based on open-source Apache Axis SOAP engine WSOI-specific handlers and chains Timer module Data structures Modules for SO Management (SOM) port types

WSOI-specific Handlers and Chains: Example

req.

res.

op. call

WSOI (Extends Axis SOAP Engine)

Pr

…SH

SH

SOI

SOO…

WSOIChain

RTB

RTS

AI

AO QCE

WSCM - Dynamic Manipulation of WSOL SOs

Switching between service offerings Provider- or consumer-initiated

Deactivation and reactivation of SOs With accommodation of affected consumers

Deletion of deactivated SOs Creation of new SOs (same WSDL files)

Provider decides when it is possible and allowed

Deactivation, reactivation, deletion, and creation of SODRs

Benefits of Manipulation of Service Offerings

Comparison methodology: Analytical studies and experiments with WSOI

=> Simpler, faster, and incurs less overhead than re-negotiation of SLAs and switching or re-composition of Web Services

Provides additional flexibility Enhances robustness of WS compositions Not a complete replacement for alternatives Can be their lightweight complement

WSOI Support for WSCM

Implementation of algorithms and protocols for the manipulation of SOs

Modules for WSCM (not based on Axis): SOMgmtDecisions module - operations

with decisions about applying manipulation of SOs

Modules for SO Management (SOM) port types

Data structures (same as for WSM)

SOM Port Types

SessionMgmt

SONotification

SOComparisons

SOM-Prov

SODRMgmt

SOM-Cons

SOM-AccP

SOSecurity

SOM-MgmtPSOInfo

Monitoring of SOs: Manipulation of SOs:

WSOI - Comparison with Related Work

Related work: Management infrastructure for WSLA Management infrastructure for WSML A number of WSM papers and products (often

based on JMX or gateways/hubs/proxies) Several WSCM papers and products Management of Grid Computing

The main distinctive characteristic of WSOI: Monitoring and dynamic manipulation of

classes of service for Web Services

=> Conclusions and Future Work

Introduction Web Service Offerings Language

(WSOL) Web Service Offerings Infrastructure

(WSOI)

=> Conclusions and future work

Conclusions

WSOL and WSOI support WSM and WSCMWSOL support for management

applications: classes of service (service offerings), various types of constraint and statement, relationships between classes of service, …

WSOI support for management applications: WSOI-specific handlers and chains for Axis, algorithms and protocols for manipulation of

WSOL service offerings, modules, data structures, SOM port types, …

Current and Future WorkFull prototype implementation of the Web

Service Offerings Infrastructure (WSOI) Further experiments with the manipulation

of service offerings and alternatives Minor improvements of WSOL Full implementation of a prototype WSOL

compiler Integration of WSOL with UDDI …

Questions, please ...

http://www.sce.carleton.ca/~vladimir/WSOLpublications.html

vladimir@sce.carleton.ca