Grids Web ServicesThe Global Operating system

of the WorldIts Killer Applications

February 28 2005Geoffrey Fox

Community Grids LabIndiana Universitygcf@indiana.edu

e-Infrastructure e-Infrastructure builds on the inevitable increasing performance

of networks and computers linking them together to support new flexible linkages between computers, data systems and people• Grids and peer-to-peer networks are the technologies that

build e-Infrastructure• e-Infrastructure called CyberInfrastructure in USA

We imagine a sea of conventional local or global connections supported by the “ordinary Internet”• Phones, web page accesses, plane trips, hallway conversations• Conventional Internet technology manages billions of

broadcast or low (one client to Server) or broadcast links On this we superimpose high value multi-way organizations

(linkages) supported by Grids with optimized resources and system support and supporting virtual (electronic) enterprises• Low multiplicity fully interactive real-time sessions• Resources such as databases supporting (larger) communities

A typical Web Service In principle, services can be in any language (Fortran .. Java ..

Perl .. Python) and the interfaces can be method calls, Java RMI Messages, CGI Web invocations, totally compiled away (inlining)

The simplest implementations involve XML messages (SOAP) and programs written in net friendly languages like Java and Python

PaymentCredit Card

WarehouseShippingcontrol

WSDL interfaces

WSDL interfaces

Security CatalogPortalService

Web Services

Web Services

Services and Distributed Objects A web service is a computer program running on either the local

or remote machine with a set of well defined interfaces (ports) specified in XML (WSDL)

Web Services (WS) have many similarities with Distributed Object (DO) technology but there are some (important) technical and religious points (not easy to distinguish)• CORBA Java COM are typical DO technologies• Agents are typically SOA (Service Oriented Architecture)

Both involve distributed entities but Web Services are more loosely coupled• WS interact with messages; DO with RPC (Remote Procedure Call)• DO have “factories”; WS manage instances internally and interaction-

specific state not exposed and hence need not be managed• DO have explicit state (statefull services); WS use context in the messages

to link interactions (statefull interactions) Claim: DO’s do NOT scale; WS build on experience (with

CORBA) and do scale

Philosophy of Web Service Grids• Much of Distributed Computing was built by natural

extensions of computing models developed for sequential machines

• This leads to the distributed object (DO) model represented by Java and CORBA– RPC (Remote Procedure Call) or RMI (Remote Method

Invocation) for Java• Key people think this is not a good idea as it scales badly

and ties distributed entities together too tightly– Distributed Objects Replaced by Services

• Note CORBA was considered too complicated in both organization and proposed infrastructure– and Java was considered as “tightly coupled to Sun”– So there were other reasons to discard

• Thus replace distributed objects by services connected by “one-way” messages and not by request-response messages

Web services• Web Services build

loosely-coupled, distributed applications, (wrapping existing codes and databases) based on the SOA (service oriented architecture) principles.

• Web Services interact by exchanging messages in SOAP format

• The contracts for the message exchanges that implement those interactions are described via WSDL interfaces.

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What is a Grid?• You won’t find a clear description of what is Grid and how

does differ from a collection of Web Services– I see no essential reason that Grid Services have different

requirements than Web Services– Geoffrey Fox, David Walker, e-Science Gap Analysis, June 30

2003. Report UKeS-2003-01, http://www.nesc.ac.uk/technical_papers/UKeS-2003-01/index.html.

– Notice “service-building model” is like programming language – very personal!

• Grids were once defined as “Internet Scale Distributed Computing” but this isn’t good as Grids depend as much if not more on data as well as simulations

• So Grids can be termed “Internet Scale Distributed Services” and represent a way of collecting services together to solve problems where special features and quality of service needed.

Community Resources Grid Community databases have analogy to Television and the News Web that allow individuals

to communicate instantly with each other via Web Pages and Headline News acting as proxies N resources deposit information and N can view – Complexity O(N)

Large and Small Grids N resources in a community (N is billions for the world

and 1000-10000 for many scientific fields) Communities are arranged hierarchically with real work

being done in “groups” of M resources – M could be 10-100 in e-Science

Metcalfe’s law: value of network grows like square of number of nodes M – we call Grids where this true Metcalfe or M2 Grids

Nature of Interaction depends on size of M or N• Shared Information O(N) Complexity Grids for largish N

• Complexity M2 Metcalfe Grids for smaller M < N Grids must merge with peer-to-peer networks to support

both Complexity O(N) and M2 Systems

M2 Interactions• Superimpose M2

“Grids” on the sea (heatbath) of O(N) “ordinary” interactions

Architecture of (Web Service) Grids Grids built from Web Services communicating through

an overlay network built in SOFTWARE on the “ordinary internet” at the application level

Grids provide the special quality of service (security, performance, fault-tolerance) and customized services needed for “distributed complex enterprises”

We need to work with Web Service community as they debate the 60 or so proposed Web Service specifications• Use Web Service Interoperability WS-I as “best practice”• Must add further specifications to support high performance• Database “Grid Services” for O(N) Community case• Streaming support for M2 case

Web Services WS-*• Java is very powerful partly due to its many “frameworks” that

generalize libraries e.g.– Java Media Framework– Java Database Connectivity JDBC

• Web Services have a correspondingly collections of specifications that represent critical features of the distributed operating systems for “Grids of Simple Services”– Some 60 active WS-* specifications for areas such as– a. Core Infrastructure Specifications– b. Service Discovery– c. Security– d. Messaging– e. Notification– f. Workflow and Coordination– g. Characteristics– h. Metadata and State– i. User Interfaces

A List of Web Services I• a) Core Service Architecture• XSD XML Schema (W3C Recommendation) V1.0 February 1998,

V1.1 February 2004 • WSDL 1.1 Web Services Description Language Version 1.1, (W3C

note) March 2001 • WSDL 2.0 Web Services Description Language Version 2.0, (W3C

under development) March 2004 • SOAP 1.1 (W3C Note) V1.1 Note May 2000• SOAP 1.2 (W3C Recommendation) June 24 2003 • b) Service Discovery• UDDI (Broadly Supported OASIS Standard) V3 August 2003 • WS-Discovery Web services Dynamic Discovery (Microsoft, BEA,

Intel …) February 2004 • WS-IL Web Services Inspection Language, (IBM, Microsoft)

November 2001

A List of Web Services II• c) Security• SAML Security Assertion Markup Language (OASIS) V1.1 May

2004 • XACML eXtensible Access Control Markup Language (OASIS)

V1.0 February 2003 • WS-Security 2004 Web Services Security: SOAP Message

Security (OASIS) Standard March 2004• WS-SecurityPolicy Web Services Security Policy (IBM,

Microsoft, RSA, Verisign) Draft December 2002• WS-Trust Web Services Trust Language (BEA, IBM, Microsoft,

RSA, Verisign …) May 2004• WS-SecureConversation Web Services Secure Conversation

Language (BEA, IBM, Microsoft, RSA, Verisign …) May 2004 • WS-Federation Web Services Federation Language (BEA, IBM,

Microsoft, RSA, Verisign) July 2003

A List of Web Services III• d) Messaging• WS-Addressing Web Services Addressing (BEA, IBM, Microsoft)

March 2004 • WS-MessageDelivery Web Services Message Delivery (W3C

Submission by Oracle, Sun ..) April 2004 • WS-Routing and Referral SOAP Routing Protocol (Microsoft) October 2001• WS-RM Web Services Reliable Messaging (BEA, IBM, Microsoft,

Tibco) v0.992 March 2004 • WS-Reliability Web Services Reliable Messaging (OASIS Web Services

Reliable Messaging TC) March 2004• SOAP MOTM SOAP Message Transmission Optimization Mechanism

(W3C) June 2004 • e) Notification• WS-Eventing Web Services Eventing (BEA, Microsoft, TIBCO) January

2004 • WS-Notification Framework for Web Services Notification with WS-

Topics, WS-BaseNotification, and WS-BrokeredNotification (OASIS) OASIS Web Services Notification TC Set up March 2004

• JMS Java Message Service V1.1 March 2002

A List of Web Services IV• f) Coordination and Workflow, Transactions and Contextualization• WS-CAF Web Services Composite Application Framework including WS-CTX,

WS-CF and WS-TXM below (OASIS Web Services Composite Application Framework TC) July 2003

• WS-CTX Web Services Context (OASIS Web Services Composite Application Framework TC) V1.0 July 2003

• WS-CF Web Services Coordination Framework (OASIS Web Services Composite Application Framework TC) V1.0 July 2003

• WS-TXM Web Services Transaction Management (OASIS Web Services Composite Application Framework TC) V1.0 July 2003

• WS-Coordination Web Services Coordination (BEA, IBM, Microsoft) September 2003

• WS-AtomicTransaction Web Services Atomic Transaction (BEA, IBM, Microsoft) September 2003

• WS-BusinessActivity Web Services Business Activity Framework (BEA, IBM, Microsoft) January 2004

• BTP Business Transaction Protocol (OASIS) May 2002 with V1.0.9.1 May 2004• BPEL Business Process Execution Language for Web Services (OASIS) V1.1 May

2003 • WS-Choreography (W3C) V1.0 Working Draft April 2004 • WSCI (W3C) Web Service Choreography Interface V1.0 (W3C Note from BEA,

Intalio, SAP, Sun, Yahoo) • WSCL Web Services Conversation Language (W3C Note) HP March 2002

A List of Web Services V• h) Metadata and State• RDF Resource Description Framework (W3C) Set of recommendations expanded

from original February 1999 standard • DAML+OIL combining DAML (Darpa Agent Markup Language) and OIL

(Ontology Inference Layer) (W3C) Note December 2001 • OWL Web Ontology Language (W3C) Recommendation February 2004 • WS-DistributedManagement Web Services Distributed Management Framework

with MUWS and MOWS below (OASIS) • WSDM-MUWS Web Services Distributed Management: Management Using Web

Services (OASIS) V0.5 Committee Draft April 2004 • WSDM-MOWS Web Services Distributed Management: Management of Web

Services (OASIS) V0.5 Committee Draft April 2004 • WS-MetadataExchange Web Services Metadata Exchange (BEA,IBM,

Microsoft, SAP) March 2004 • WS-RF Web Services Resource Framework including WS-ResourceProperties,

WS-ResourceLifetime, WS-RenewableReferences, WS-ServiceGroup, and WS-BaseFaults (OASIS) Oasis TC set up April 2004 and V1.1 Framework March 2004

• ASAP Asynchronous Service Access Protocol (OASIS) with V1.0 working draft G June 2004

• WS-GAF Web Service Grid Application Framework (Arjuna, Newcastle University) August 2003

A List of Web Services VI• g) General Service Characteristics• WS-Policy Web Services Policy Framework (BEA, IBM,

Microsoft, SAP) May 2003• WS-PolicyAssertions Web Services Policy Assertions

Language (BEA, IBM, Microsoft, SAP) May 2003 • WS-Agreement Web Services Agreement Specification

(GGF under development) May 2004• i) User Interfaces• WSRP Web Services for Remote Portlets (OASIS)

OASIS Standard August 2003 • JSR168: JSR-000168 Portlet Specification for Java

binding (Java Community Process) October 2003

A List of Web Services VII• j) Recent Updates ………………… • WS-Eventing important update of this notification specification

with IBM, Sun and others joining Microsoft et al. as authors• WS-Enumeration supporting the splitting of a single entity (file

or stream) into multiple messages• WS-Transfer supporting the creation, update (by get or put) or

deletion of a resource• WS-Management competes with WS-DM to provide a Web

Service to manage resources• WS-PolicyAttachment describes how to associate policies with

UDDI and Endpoints and how to integrate with WSDL• WS-DAI is a Web Service of the OGSA-DAI Grid linkage with

databases• WS-CIM is a Web Service rendering from DMTF (Distributed

Management Task Force) of the industry standard CIM (Common Information Model) of metadata for computer devices

• The WS-* implicitly define an architecture

Peer to Peer Grid

DatabaseDatabase

Peers

Peers

Peer to Peer GridA democratic organization

User FacingWeb Service Interfaces

Service FacingWeb Service Interfaces

Event/MessageBrokers

Event/MessageBrokers

Event/MessageBrokers

Importance of SOAP• SOAP defines a very obvious message structure with a

header and a body• The header contains information used by the “Internet

operating system”– Destination, Source, Routing, Context, Sequence

Number …• The message body is partly further information used by the

operating system and partly information for application when it is not looked at by “operating system” except to encrypt, compress it etc.– Note WS-Security supports separate encryption for

different parts of a document• Much discussion in field revolves around what is referenced

in header!– e.g. WSRF adds a lot to header

Deployment Issues for “System Services”• “System Services” are ones that act before the real

application logic of a service• They gobble up part of the SOAP header identified

by the namespace they care about and possibly part or all of the SOAP body– e.g. the XML elements in header from the WS-RM

namespace

• They return a modified SOAP header and body to next handler in chain

WS-RMHandler

WS-……..Handler

Header

Body

e.g. ……. Could be WS-Eventing WS-Transfer ….

Messaging Structure• Communication Services are messaging

(transport protocol, routing) using SOAP protocol

Invoke Other Servicesfrom Header or Body

Messaging

Process SOAPHeader Body

Process SOAPBody Header

Customizable HandlerChain processesSOAP Header

Serviceitself

Service itself

Bit levelInternet

(OSI Stack)

Layered Architecture for Web Services and Grids

Base Hosting EnvironmentProtocol HTTP FTP DNS …

Presentation XDR …Session SSH …

Transport TCP UDP …Network IP …

Data Link / Physical

ServiceInternet

Application Specific GridsGenerally Useful Services and Grids

Workflow WSFL/BPELService Management (“Context etc.”)

Service Discovery (UDDI) / InformationService Internet Transport Protocol

Service Interfaces WSDL

ServiceContext

HigherLevelServices

Working up from the Bottom We have the classic (CISCO, Juniper ….) Internet routing the

flood of ordinary packets in OSI stack architecture Web Services build the “Service Internet” or IOI (Internet on

Internet) with• Routing via WS-Addressing not IP header• Fault Tolerance (WS-RM not TCP)• Security (WS-Security/SecureConversation not IPSec/SSL)• Data Transmission by WS-Transfer not HTTP• Information Services (UDDI/WS-Context not

DNS/Configuration files)• At message/web service level and not packet/IP address level

Software-based Service Internet possible as computers “fast” Familiar from Peer-to-peer networks and built as a software

overlay network defining Grid (analogy is VPN) SOAP Header contains all information needed for the “Service

Internet” (Grid Operating System) with SOAP Body containing information for Grid application service

Consequences of Rule of the Millisecond• Useful to remember critical time scales

– 1) 0.000001 ms – CPU does a calculation– 2a) 0.001 to 0.01 ms – Parallel Computing MPI latency– 2b) 0.001 to 0.01 ms – Overhead of a Method Call– 3) 1 ms – wake-up a thread or process – 4) 10 to 1000 ms – Internet delay

• 2a), 4) implies geographically distributed metacomputing can’t in general compete with parallel systems

• 3) << 4) implies a software overlay network is possible without significant overhead– We need to explain why it adds value of course!

• 2b) versus 3) and 4) describes regions where method and message based programming paradigms important

Linking Modules

From method based to RPC to message based to event-based publish-subscribe Message Oriented Middleware

Module A

Module B

Method Calls.001 to 1 millisecond

Service A

Service B

Messages

0.1 to 1000 millisecond latency

Coarse Grain Service ModelClosely coupled Java/Python …

Service B Service A

PublisherPost Events

“Listener”Subscribe to Events

Message Queue in the Sky

What is a Simple Service?• Take any system – it has multiple functionalities

– We can implement each functionality as an independent distributed service

– Or we can bundle multiple functionalities in a single service• Whether functionality is an independent service or one of many

method calls into a “glob of software”, we can always make them as Web services by converting interface to WSDL

• Simple services are gotten by taking functionalities and making as small as possible subject to “rule of millisecond”– Distributed services incur messaging overhead of one (local) to

100’s (far apart) of milliseconds to use message rather than method call

– Use scripting or compiled integration of functionalities ONLY when require <1 millisecond interaction latency

• Apache web site has many projects that are multiple functionalities presented as (Java) globs and NOT (Java) Simple Services– Makes it hard to integrate sharing common security, user profile,

file access .. services

Grids of Grids of Simple Services• Link via methods messages streams• Services and Grids are linked by messages• Internally to service, functionalities are linked by methods• A simple service is the smallest Grid• We are familiar with method-linked hierarchy

Lines of Code Methods Objects Programs Packages

Overlayand ComposeGrids of Grids

Methods Services Component Grids

CPUs Clusters ComputeResource Grids

MPPs

DatabasesFederatedDatabases

Sensor Sensor Nets

DataResource Grids

Component Grids?

• So we build collections of Web Services which we package as component Grids– Visualization Grid– Sensor Grid– Utility Computing Grid– Person (Community) Grid– Earthquake Simulation Grid– Control Room Grid– Crisis Management Grid

• We build bigger Grids by composing component Grids using the Service Internet

Critical Infrastructure (CI) Grids built as Grids of Grids

Gas Servicesand Filters

Physical Network

Registry Metadata

Flood Servicesand Filters

Flood CIGrid Gas CIGrid… Electricity CIGrid …

Data Access/Storage

Security WorkflowNotification Messaging

Portals Visualization GridCollaboration Grid

Sensor Grid Compute GridGIS Grid

Core Grid Services

USArray

Seismic

Sensors

a

Topography1 km

Stress Change

Earthquakes

PBO

Site-specific IrregularScalar Measurements Constellations for Plate

Boundary-Scale Vector Measurements

aaIce Sheets

Volcanoes

Long Valley, CA

Northridge, CA

Hector Mine, CA

Greenland

Database Database

Analysis and VisualizationPortal

RepositoriesFederated Databases

Data Filter

Services

Field Trip DataStreaming Data

Sensors

?DiscoveryServices

SERVOGrid

ResearchSimulations

Research Education

CustomizationServices

From Research

to Education

EducationGrid ComputerFarmGeoscience Research and Education Grids

GISGrid

Sensor GridDatabase Grid

Compute Grid

CERN LHC Data Analysis Grid