11

Grids: Concepts, Technologies and

ApplicationsGeoffrey Fox

Computer Science, Informatics, Physics

Pervasive Technology Laboratories

Indiana University Bloomington IN 47401

April 25 2005

gcf@indiana.edu

http://www.infomall.org

22

So what is a Grid? Supporting human decision making with a network of at least

four large computers, perhaps six or eight small computers, and a great assortment of disc files and magnetic tape units - not to mention remote consoles and teletype stations - all churning away. (Licklider 1960)

Coordinated resource sharing and problem solving in dynamic multi-institutional virtual organizations

Infrastructure that will provide us with the ability to dynamically link together resources as an ensemble to support the execution of large-scale, resource-intensive, and distributed applications.

Realizing thirty year dream of science fiction writers that have spun yarns featuring worldwide networks of interconnected computers that behave as a single entity.

33

Internet Scale Distributed Services Grids use Internet technology and are distinguished by managing

or organizing sets of network connected resources• Classic Web allows independent one-to-one access to

individual resources • Grids integrate together and manage multiple Internet-

connected resources: People, Sensors, computers, data systems

Organization can be explicit as in• TeraGrid which federates many supercomputers; • Deep Web Technologies IR Grid which federates multiple

data resources; • CrisisGrid which federates first responders, commanders,

sensors, GIS, (Tsunami) simulations, science/public data Organization can be implicit as in Internet resources such as

curated databases and simulation resources that “harmonize a community”

44

Different Visions of the Grid Grid just refers to the technologies

• Or Grids represent the full system/Applications DoD’s vision of Network Centric Computing is just a Grid

(linking sensors, warfighters, commanders, backend resources) and they are building the GIG (Global Information Grid)

Utility Computing or X-on-demand (X=data, computer ..) is major computer Industry interest in Grids

e-Science or Cyberinfrastructure are virtual organization Grids supporting global distributed science (note sensors, instruments are people are all distributed

Skype (Kazaa) VOIP system is a Peer-to-peer Grid (and VRVS/GlobalMMCS like Internet A/V conferencing are Collaboration Grids)

Commercial 3G Cell-phones and DoD ad-hoc network initiative are forming mobile Grids

55

e-moreorlessanything and the Grid e-Business captures an emerging view of corporations as

dynamic virtual organizations linking employees, customers and stakeholders across the world. • The growing use of outsourcing is one example

e-Science is the similar vision for scientific research with international participation in large accelerators, satellites or distributed gene analyses.

The Grid integrates the best of the Web, traditional enterprise software, high performance computing and Peer-to-peer systems to provide the information technology e-infrastructure for e-moreorlessanything.

A deluge of data of unprecedented and inevitable size must be managed and understood.

People, computers, data and instruments must be linked. On demand assignment of experts, computers, networks and

storage resources must be supported

66

More Broad Classes of Grid Applications Enterprise Grid supports information system for an

organization; includes “university computer center”, “(digital) library”, sales, marketing, manufacturing …

Outsourcing Grid links different parts of an enterprise together (Gridsourcing)• Manufacturing plants with designers• Animators with electronic game or film designers and

producers• Coaches with aspiring players (e-NCAA or e-NFL etc.)

Customer Grid links businesses and their customers as in many web sites such as amazon.com

e-Multimedia can use secure peer-to-peer Grids to link creators, distributors and consumers of digital music, games and films respecting rights

Distance education Grid links teacher at one place, students all over the place, mentors and graders; shared curriculum, homework, live classes …

77

e-Defense and e-Crisis Grids support Command and Control and provide

Global Situational Awareness • Link commanders and frontline troops to themselves and to

archival and real-time data; link to what-if simulations • Dynamic heterogeneous wired and wireless networks• Security and fault tolerance essential

System of Systems; Grid of Grids• The command and information infrastructure of each ship is

a Grid; each fleet is linked together by a Grid; the President is informed by and informs the national defense Grid

• Grids must be heterogeneous and federated Crisis Management and Response enabled by a Grid

linking sensors, disaster managers, and first responders with decision support

88

Types of Computing Grids Running “Pleasing Parallel Jobs” as in United Devices,

Entropia (Desktop Grid) “cycle stealing systems” Can be managed (“inside” the enterprise as in Condor)

or more informal (as in SETI@Home) Computing-on-demand in Industry where jobs spawned

are perhaps very large (SAP, Oracle …) Support distributed file systems as in Legion (Avaki),

Globus with (web-enhanced) UNIX programming paradigm• Particle Physics will run some 30,000 simultaneous jobs

Linking Supercomputers as in TeraGrid Pipelined applications linking data/instruments,

compute, visualization Seamless Access where Grid portals allow one to choose

one of multiple resources with a common interfaces

99

Utility and Service Computing An important business application of Grids is believed to be

utility computing Namely support a pool of computers to be assigned as needed to

take-up extra demand• Pool shared between multiple applications

Natural architecture is not a cluster of computers connected to each other but rather a “Farm of Grid Services” connected to Internet and supporting services such as• Web Servers• Financial Modeling • Run SAP • Data-mining• Simulation response to crisis like forest fire or earthquake• Media Servers for Video-over-IP

Note classic Supercomputer use is to allow full access to do “anything” via ssh etc.• In service model, one pre-configures services for all programs

and you access portal to run job with less security issues

1010

Some Important Styles of Grids Computational Grids were origin of concepts and link

computers across the globe – high latency stops this from being used as parallel machine

Knowledge and Information Grids link sensors and information repositories as in Virtual Observatories or BioInformatics

• More detail on next slide Education Grids link teachers, learners, parents as a VO with

learning tools, distant lectures etc. e-Science Grids link multidisciplinary researchers across

laboratories and universities Community Grids focus on Grids involving large numbers of

peers rather than focusing on linking major resources – links Grid and Peer-to-peer network concepts

Semantic Grid links Grid, and AI community with Semantic web (ontology/meta-data enriched resources) and Agent concepts

1111

Information/Knowledge Grids Distributed (10’s to 1000’s) of data sources (instruments,

file systems, curated databases …) Data Deluge: 1 (now) to 100’s petabytes/year (2012)

• Moore’s law for Sensors Possible filters assigned dynamically (on-demand)

• Run image processing algorithm on telescope image• Run Gene sequencing algorithm on compiled data

Needs decision support front end with “what-if” simulations

Metadata (provenance) critical to annotate data

Integrate across experiments as in multi-wavelength astronomy

Data Deluge comes from pixels/year available

1212

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 ComputerFarmGrid of Grids: Research Grid and Education Grid

GISGrid

Sensor GridDatabase Grid

Compute Grid

1313

iSERVO in a nutshelliSERVO in a nutshell Designed to link Designed to link data-setsdata-sets (repositories and real time), (repositories and real time),

computationscomputations and and earthquake scientistsearthquake scientists in ACES (Asia in ACES (Asia Pacific) CooperationPacific) Cooperation• Australia China Japan USAAustralia China Japan USA

Exemplified by Exemplified by SERVOGrid SERVOGrid in USA led by in USA led by JPLJPL Supports Supports simulationsimulation and and datamining datamining as servicesas services Adopts conservative Adopts conservative WS-I+ Web Service InteroperabilityWS-I+ Web Service Interoperability

standardsstandards Builds full “Grid” in a library fashion as a Builds full “Grid” in a library fashion as a Grid of GridsGrid of Grids

• GISGIS (Geographic Information System) (Geographic Information System) GridGrid built as a set of built as a set of OGCOGC compatible Web Services “talking” compatible Web Services “talking” GMLGML

• iSERVO federatesiSERVO federates separate Grids in each separate Grids in each country/organization/functioncountry/organization/function

• A Grid is A Grid is “just” a collection of Services“just” a collection of Services aka distributed programs aka distributed programs Multi-scaleMulti-scale simulations supported by simulations supported by Grid workflowGrid workflow Portals Portals based on NSF Middleware Initiative NMI based on NSF Middleware Initiative NMI Open Open

Grid Computing EnvironmentGrid Computing Environment OGCE OGCE

1414

In flight data

Airline

Maintenance Centre

Ground Station

Global NetworkSuch as SITA

Internet, e-mail, pager

Engine Health (Data) Center

DAME

Rolls Royce and UK e-Science ProgramDistributed Aircraft Maintenance Environment

~ Gigabyte per aircraft perEngine per transatlantic flight

~5000 engines

1515

NASA Aerospace Engineering Grid

•Lift Capabilities•Drag Capabilities•Responsiveness

•Deflection capabilities•Responsiveness

•Thrust performance•Reverse Thrust performance•Responsiveness•Fuel Consumption

•Braking performance•Steering capabilities•Traction•Dampening capabilities

Crew Capabilities- accuracy- perception- stamina- re-action times- SOP’s

Engine Models

Airframe Models

Wing Models

Landing Gear Models

Stabilizer Models

Human Models

Whole system simulations are produced by couplingall of the sub-system simulations

It takes a distributed virtual organization to design, simulate and build a complex system like an aircraft

16

Virtual Observatory Astronomy GridIntegrate Experiments

Radio Far-Infrared Visible

Visible + X-ray

Dust Map

Galaxy Density Map

1717

e-Chemistry LaboratoryExperiments-on-demand

X-Raye-Lab

Analysis

Properties

Propertiese-Lab

SimulationVideo

Diffr

acto

mete

r

Globus

StructuresDatabase

Grid Resources

Grid-enabled Output Streams

1818

CERN LHC Data Analysis Grid

1919

HPCSimulation

DataFilter

Data FilterD

ata

Filt

er

Data

Filter

Data

Filter

Distributed Filters massage dataFor simulation

Other

Grid

and W

eb

Servi

ces

AnalysisControl

Visualize

SERVOGrid (Complexity) Computing Model

Grid

OGSA-DAIGrid Services

This Type of Gridintegrates with

Parallel computingMultiple HPC

facilities but only use one at a time

Many simultaneous data sources and

sinks

Grid Data Assimilation

2020

Sources of Grid Technology Grids support distributed collaboratories or virtual

organizations integrating concepts from The Web Agents Distributed Objects (CORBA Java/Jini COM) Globus, Legion, Condor, NetSolve, Ninf and other High

Performance Computing activities Peer-to-peer Networks With perhaps the Web and P2P networks being the most

important for “Information Grids” and Globus for “Compute Grids”

2121

The Essence of Grid Technology? We will start from the Web view and assert that basic

paradigm is Meta-data rich Web Services communicating via

messages These have some basic support from some runtime

such as .NET, Jini (pure Java), Apache Tomcat+Axis (Web Service toolkit), Enterprise JavaBeans, WebSphere (IBM) or GT3/4 (Globus Toolkit 3/4)• These are the distributed equivalent of operating system

functions as in UNIX Shell

• Called Hosting Environment or platform W3C standard WSDL defines IDL (Interface

standard) for Web Services

2222

Meta-data Meta-data is usually thought of as “data about data” The Semantic Web is at its simplest considered as

adding meta-data to web pages For example, the hospital web-page has meta-data

telling you its location, phone-number, specialties which can be used to automate Google-style searches to allow planning of disease/accident treatment from web

Modern trend (Semantic Grid) is meta-data about web-services e.g. specify details of interface and useage• Such as that a bioinformatics service is free or bandwidth

input is of limited amount Provenance – history and ownership – of data very

important

2323

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

2424

Raw (HPC) Resources

Middleware

Database

PortalServices

SystemServices

SystemServices

SystemServices

Application Service

SystemServices

SystemServices

UserServices

“Core”Grid

Typical Grid Architecture

Each Blob is a Computer Program!

2525

Classic Grid Architecture

Database Database

Netsolve

Computing

SecurityCollaboration

CompositionContent Access

Resources

Clients Users and Devices

Middle TierBrokers Service Providers

Middle Tier becomes Web Services

2626

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

2727

What is Happening? Grid ideas are being developed in (at least) four communities

• Web Service – W3C, OASIS, (DMTF)• Grid Forum (High Performance Computing, e-Science)• Enterprise Grid Alliance (Commercial “Grid Forum” with a

near term focus) Service Standards are being debated Grid Operational Infrastructure is being deployed Grid Architecture and core software being developed

• Apache has several important projects as do academia; large and small companies

Particular System Services are being developed “centrally” – OGSA framework for this in GGF; WS-* for OASIS/W3C/Microsoft-IBM

Lots of fields are setting domain specific standards and building domain specific services

USA started but now Europe is probably in the lead and Asia will soon catch USA if momentum (roughly zero for USA) continues

2828

Technical Activities of Note Look at different styles of Grids such as Autonomic (Robust

Reliable Resilient) New Grid architectures hard due to investment required Program the Grid – Workflow Access the Grid – Portals, Grid Computing Environments Critical Services Such as

• Security – build message based not connection based

• Notification – event services

• Metadata – Use Semantic Web, provenance

• Fabric and Service Management

• Databases and repositories – instruments, sensors

• Computing – Submit job, scheduling, distributed file systems

• Visualization, Computational Steering

• Network performance

LowLevelWS-*

High Levele.g. OGSA

29

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.

Databases

Humans

ProgramsComputational resources

Devices

reso

urce

s

BP

EL,

Jav

a, .N

ET

serv

ice

logi

c

<env:Envelope> <env:Header> ... </env:header> <env:Body> ... </env:Body></env:Envelope> m

essa

ge p

roce

ssin

g

SO

AP

and

WS

DL

SOAP messages

30

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

31

Plethora of Standards• 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”

– About 60 WS-* specifications introduced in last 2-3 years– These are low level with higher level standards such as access

database (OGSA-DAI) or “Submit a job” built on top of these• Many battles both between standard bodies and between companies as each tries to

set standards they consider best; thus there are multiple standards for many of key Web Service functionalities

• Microsoft a key player and stands to benefit as Web Services open up enterprise software space to all participants

– e.g. MQSeries (IBM) and Tibco have to change their messaging systems to support new open standards

32

WS-I Interoperability• Critical underpinning of Grids and Web Services is the

gradually growing set of specifications in the Web Service Interoperability Profiles

• Web Services Interoperability (WS-I) Interoperability Profile 1.0a." http://www.ws-i.org. gives us XSD, WSDL1.1, SOAP1.1, UDDI in basic profile and parts of WS-Security in their first security profile.

• We imagine the “60 Specifications” being checked out and evolved in the cauldron of the real world and occasionally best practice identifies a new specification to be added to WS-I which gradually increases in scope– Note only 4.5 out of 60 specifications have “made it” in this

definition

33

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

WS-* implies the The Service Internet 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

35

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

3636

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

3737

What is a High Performance Computer? We might wish to consider three classes of multi-node computers 1) Classic MPP with microsecond latency and scalable internode

bandwidth (tcomm/tcalc ~ 10 or so) 2) Classic Cluster which can vary from configurations like 1) to 3)

but typically have millisecond latency and modest bandwidth 3) Classic Grid or distributed systems of computers around the

network• Latencies of inter-node communication – 100’s of milliseconds

but can have good bandwidth All have same peak CPU performance but synchronization costs

increase as one goes from 1) to 3) Cost of system (dollars per gigaflop) decreases by factors of 2 at

each step from 1) to 2) to 3) One should NOT use classic MPP if class 2) or 3) suffices unless

some security or data issues dominates over cost-performance One should not use a Grid as a true parallel computer – it can

link parallel computers together for convenient access etc.

38

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

39

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

40

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

41Critical 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

4242

Two-level Programming I The paradigm implicitly assumes a two-level

Programming Model We make a Service (same as a “distributed object” or

“computer program” running on a remote computer) using conventional technologies• C++ Java or Fortran Monte Carlo module• Data streaming from a sensor or Satellite• Specialized (JDBC) database access

Such services accept and produce data from users files and databases

The Grid is built by coordinating such services assuming we have solved problem of programming the service

Service Data

4343

Two-level Programming II The Grid is discussing the composition of distributed

services with the runtime interfaces to Grid as opposed to UNIX pipes/data streams

Familiar from use of UNIX Shell, PERL or Python scripts to produce real applications from core programs

Such interpretative environments are the single processor analog of Grid Programming

Some projects like GrADS from Rice University are looking at integration between service and composition levels but dominant effort looks at each level separately

Service1 Service2

Service3 Service4

4444

What Should One Do? Grids and Service Oriented Architectures will

• Change landscape in mature areas like enterprise software

• Support new distributed applications in Science, Government, Education, Business and Community areas

• Encourage trends like outsourcing and globalization in all activities

Web Service/Grid standards and infrastructure are still in their infancy but broad principles reasonably clear

Many large scale software development activities are inconsistent with modern architectures

Development of Application specific (XML-based) standards is an important “safe” area