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Technical Relationship betweenWSMX & Globus Toolkit

Matthew Moran, Kashif Iqbal

Digital Enterprise Research Institute, Galway{Matthew.moran, Kashif.Iqbal}@deri.org

14 Jan 2005

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Agenda

• Setting the scene– Introduction & motivation– Distributed computing– Framework for comparison

• Semantic Web Services– Rationale and research focus– WSMX

• Grid Computing– Rationale and research focus– Globus Toolkit

• WSMX and Globus Toolkit• Conclusions

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Introduction

• Two distinct research communities– Semantic Web Services– Grid Computing– Domain of both is distributed computing systems

• General – do Grid and SWS fit together?– SWS on Grid – or – Grid on SWS

• Specific – WSMX and Globus Toolkit– What is the relationship?– Complementary or competing architectures?– If complementary, how do they fit?

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Distributed Computing Systems

• Motivation– The need for system and data integration across

heterogeneous and autonomous systems

• Many previous efforts (more that are not listed)– TP Monitors – CICS,

• Excellent for transaction processing; tight code coupling– Client Server and RPC

• More flexible, still tight code coupling– Corba and DCOM

• Object oriented rather than business process or document integration

• UML a suitable modelling paradigm– Web Services

• Great potential but where are the semantics?• BPM a suitable modelling paradigm

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Distributed Computing Systems

• Functional requirements– Synchronous and asynchronous message exchange– Heterogeneous and autonomous system integration– Publish and deploy services– Discover and invoke services – Data and process mediation

• Non functional requirements– Transparency– Availability– Maximise resource usage– Throughput– Security– Transaction processing – Reliability

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Framework for Comparison

• Agree on terminology– Service– Resource– Publish and deploy– Discovery– Service level agreements (SLA)– Negotiation

• Functional and non-func requirements• Architecture • Messaging• Domain of interest

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Semantic Web Services

• What is the application area for SWS?– Application and process integration– Inter- and intra- business– Focus on business documents and processes– WS not an artificial homogeneity– SWS addresses service discovery, composition

• Problems with WS do they address?– Absence of formal semantics

• Focus for the SWS research community?– Description, discovery, composition, invocation,

mediation

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WSMX

• Mission – To develop an execution environment for dynamic

discovery, selection, mediation and invocation of Semantic Web Services

– To be the middleware for Semantic Web Services

• Conceptual model provided by WSMO– Ontology, Goal, Service, Mediator– Describe concepts from perspectives of both the

requester and provider

• Multiple execution semantics possible– For example, discovery or mediation only.

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WSM* Family

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

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WSM* Family

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

Ontology

Syntax & semantics

CompositionEvent-basedFramework

Discovery

Invocation Mediation

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WSMX

• Available functionality– Backend adaptors– Accept and parse WSML messages– Store services, goals, mediators, ontologies– Simple discovery– Data mediation– Simple invocation

• Functionality in development– Choreography component– WSMO Editor

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Grid Overview

• What is the application area for Grid?– Traditionally: computational grids– Potential: for business processes and SOA– IBM dream of computing on demand

• WS and Grid– Globus toolkit takes advantage of widely accepted

WS standards to implements its services– WS Addressing to make stateful services

• Research community focus for Grid?– Resource management, security, high throughput,

managed availability amongst others

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What is a Grid? Evolving definition …

• ’98: hardware and software infrastructure that provides dependable, consistent and pervasive access to high-end computational capabilities

• ’00: coordinated resource sharing and problem solving in dynamic, multi-institutional organizations

• ’02 checklist. A grid:– Coordinates resources that are not subject to

centralized control, …– … using standard, open, general-purpose

protocols and interfaces, …– … to deliver non-trivial qualities of service.

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What Kinds of Applications?

• Computation intensive– Interactive simulation (climate modeling)– Very large-scale simulation and analysis (galaxy formation,

gravity waves, battlefield simulation)– Engineering (parameter studies, linked component models)

• Data intensive– Experimental data analysis (high-energy physics)– Image and sensor analysis (astronomy, climate study, etc.)

• Distributed collaboration– Online instrumentation (microscopes, x-ray devices, etc.)– Remote visualization (biology)– Engineering (large-scale structural testing, chemical

engineering)

• Business grids

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What Types of Problems?

• Security: – Hard to keep track of authentication data across institutions

• Monitoring/discovery: – Hard to monitor system and app. status across institutions

• Accessing computing/processing power– Too many ways to submit jobs

• Moving data– Too many ways to store & access files and data

• Managing data– Too many ways to keep track of data

• Managing systems• System packaging/distribution

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Grid and Web Services Convergence

The definition of WSRF means that the Grid and Web services communities can move forward on a common base.

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What Is the Globus Toolkit?

• A Grid development environment– Develop new OGSA-compliant Web Services– Develop applications using Java or C/C++ Grid APIs– Secure applications using basic security mechanisms

• A set of basic Grid services– Job submission/management– File transfer (individual, queued)– Database access– Data management (replication, metadata)– Monitoring/Indexing system information

• Tools and Examples• The prerequisites for many Grid community tools

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Globus Toolkit and Web Services

• Web services have major advantages for Grids– Standard interface definition– Good commercial tooling (eventually)

• However, not a silver bullet or complete solution …• Globus Alliance working to advance specs …

– OGSI/WSRF, OGSA-DAI, WS-Agreement, etc.– WSDL 2.0, WSDM, WS-Security, etc.

• … and implementation– Implementations of low-level specifications– WS-based interface to existing services– New WS-based services

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Components in Globus Toolkit 3.2

GSI

WS-Security

CAS(OGSI)

SimpleCA

Data Managemen

tSecurity

WSCore

Resource Managemen

t

Information Services

RFT(OGSI)

RLS

OGSI-DAI

WU GridFTP

XIO

JAVAWS Core(OGSI)

OGSI C Bindings

MDS2

WS-Index(OGSI)

Pre-WSGRAM

WS GRAM(OGSI)

OGSI Python Bindings

(contributed)

pyGlobus(contributed)

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Deployment View

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Theory -> Practice

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GT3

Security Infrastructure (GSI)

OGSI/WSRF

MJFS

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Network

RRR

A

ServiceLevel

Bringing it All TogetherScenario: Resource management & scheduling

Storage

RRRIBM

IBM

Blades

RRR

Notification

GridScheduler

WS-Resource used to “model” physical

processor resources

WS-Resource Properties “project” processor status (like utilization)

Local processor manageris “front-ended” with A Web service interface

Other kinds of resources are also“modeled” as WS-Resources

JJ

J

WS-Notification can be used to “inform” the

scheduler when processor utilization

changes

Grid “Jobs” and “tasks” are also modeled using

WS-Resources and Resource Properties

Grid Scheduleris a

Web Service

Service Level Agreement

is modeled as a WS-Resource

Lifetime of SLA Resource tied to the duration

of the agreement

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WSMX and Globus – Common

• Both distributed computing systems• Both use WS standards as foundation technology

– WSDL– SOAP

• Both provide approaches to B2B integration• Despite current differences in focus, both face the

same kind of problems– Semantics – service discovery– Service availability management– Security– Service Level Agreements (SLA)

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WSMX and Globus – Differences

• Different research communities• Different functionalities offered right now• WSMX provides SOA event driven framework• Globus is a loose toolkit• WSMX addresses service description, discovery,

invocation and mediation at data and process• Globus provides resource life-cycle mgt, soft-state,

real-time service information, service notification interface, security including delegated security, access to system data and files

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WSM* Family

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

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WSM* Family

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

Ontology

Syntax & semantics

CompositionEvent-basedFramework

Discovery

Invocation Mediation

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WSM* and Globus

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

Globus

Ontologies

Syntax

CompositionEvent-basedFramework

Discovery

Invocation Mediation

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WSM* and Globus

WSMO: Conceptual Model

WSML: Language

WSMX: Architecture & Ref. Implementation

SemanticWeb Services

Globus

Ontologies

Syntax

MonitoringSoft-state

mgt

WSRF

WS-Addressing

CompositionEvent-basedFramework

Discovery

Invocation MediationResource

MgtSecurity

ServiceFactory

SLA Mgt

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WSMX and Globus – Do the fit?

• Complementary or competitive– complementary

• WSMX in Globus – or – Globus in WSMX– Neither – they address different functionalities– GT3 is implemented as a set of WS– For GT3 services to be available to WSMX, they

need to be described in terms of WSMO– A GT3 client could choose to use WSMX as its

discovery and execution engine while using the GT3 core services for resource mgt, security etc.

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Convergence ofGrid and Web Services

Grid

Web

WSRF

Started far apart in apps & tech

OGSI

GT2GT1

HTTPWSDL,

WS-*

WSDL 2,

WSDM

Have beenconverging

• The definition of WSRF means that Grid and Web communities can move forward on a common base• Support from major WS vendors, especially in management space: e.g. HP, IBM

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Scenarios

• Stock exchange statistics example• Scenario 1– WSMX only for discovery

• Scenario 2– WSMX for discovery choreography and invocation

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Conclusion

• WSMX is an execution environment for SWS has a particular focus– Description, discovery, mediation, invocation, etc.

• Globus is a toolkit providing various services that have immediate relevance for computational grids but growing relevance for business process integration

• Both technologies are based on WS standards facilitates interoperability

• Little overlap between service offered