Grid Architecture

Grid ArchitectureGrid Architecture

Prof. Ruay-Shiung ChangProf. Ruay-Shiung ChangMarch 2004March 2004

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Course ContentsCourse Contents Grid ArchitectureGrid Architecture Open Grid Services ArchitectureOpen Grid Services Architecture Resource and Service ManagementResource and Service Management Building Reliable Clients and ServicesBuilding Reliable Clients and Services Instrumentation and MonitoringInstrumentation and Monitoring

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Why Discuss Architecture?Why Discuss Architecture? DescriptiveDescriptive

• Provide a common vocabulary for use when Provide a common vocabulary for use when describing Grid systemsdescribing Grid systems

GuidanceGuidance• Identify key areas in which services are Identify key areas in which services are

required required PrescriptivePrescriptive

• Define standard “Intergrid” protocols and Define standard “Intergrid” protocols and APIs to facilitate creation of interoperable APIs to facilitate creation of interoperable Grid systems and portable applicationsGrid systems and portable applications

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Water Garden in EnglandWater Garden in England

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One View of RequirementsOne View of Requirements Identity & authenticationIdentity & authentication Authorization & policyAuthorization & policy Resource discoveryResource discovery Resource characterizationResource characterization Resource allocationResource allocation (Co-)reservation, workflow(Co-)reservation, workflow Distributed algorithmsDistributed algorithms Remote data accessRemote data access High-speed data transferHigh-speed data transfer Performance guaranteesPerformance guarantees MonitoringMonitoring

Adaptation Intrusion detection Resource

management Accounting &

payment Fault management System evolution etc. etc. …

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Another View: “Three ObstaclesAnother View: “Three Obstaclesto Making Grid Computing Routine”to Making Grid Computing Routine”

1)1) New approaches to problem solvingNew approaches to problem solving• Data Grids, distributed computing, peer-to-peer, Data Grids, distributed computing, peer-to-peer,

collaboration grids, …collaboration grids, …2)2) Structuring and writing programsStructuring and writing programs

• Abstractions, toolsAbstractions, tools3)3) Enabling resource sharing across distinct Enabling resource sharing across distinct

institutionsinstitutions• Resource discovery, access, reservation, Resource discovery, access, reservation,

allocation; authentication, authorization, policy; allocation; authentication, authorization, policy; communication; fault detection and notification; communication; fault detection and notification; ……

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The Systems Problem:The Systems Problem:Resource Sharing Mechanisms That …Resource Sharing Mechanisms That …

Address security and policy concerns of Address security and policy concerns of resource owners and usersresource owners and users

Are flexible enough to deal with many Are flexible enough to deal with many resource types and sharing modalitiesresource types and sharing modalities

Scale to large number of resources, many Scale to large number of resources, many participants, many program componentsparticipants, many program components

Operate efficiently when dealing with large Operate efficiently when dealing with large amounts of data & computationamounts of data & computation

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Aspects of the Systems Aspects of the Systems ProblemProblem

1)1) Need for Need for interoperabilityinteroperability when different groups when different groups want to share resourceswant to share resources• Diverse components, policies, mechanismsDiverse components, policies, mechanisms• E.g., standard notions of identity, means of E.g., standard notions of identity, means of

communication, resource descriptionscommunication, resource descriptions2)2) Need for Need for shared infrastructure servicesshared infrastructure services to to

avoid repeated development, installationavoid repeated development, installation• E.g., one port/service/protocol for remote access to E.g., one port/service/protocol for remote access to

computing, not one per tool/appcomputing, not one per tool/app• E.g., Certificate Authorities: expensive to runE.g., Certificate Authorities: expensive to run

A common need for A common need for protocols & servicesprotocols & services

15Hence, a Protocol-Oriented ViewHence, a Protocol-Oriented Viewof Grid Architecture, that Emphasizes of Grid Architecture, that Emphasizes

…… Development of Development of Grid protocols & servicesGrid protocols & services

• Protocol-mediated access to remote resourcesProtocol-mediated access to remote resources• New services: e.g., resource brokeringNew services: e.g., resource brokering• ““On the Grid” = speak Intergrid protocolsOn the Grid” = speak Intergrid protocols• Mostly (extensions to) existing protocolsMostly (extensions to) existing protocols

Development of Development of Grid APIs & SDKsGrid APIs & SDKs• Interfaces to Grid protocols & servicesInterfaces to Grid protocols & services• Facilitate application development by supplying Facilitate application development by supplying

higher-level abstractionshigher-level abstractions The (hugely successful) model is the InternetThe (hugely successful) model is the Internet

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Layered Grid ArchitectureLayered Grid Architecture(By Analogy to Internet (By Analogy to Internet

Architecture)Architecture)Application

Fabric“Controlling things locally”: Access to, & control of, resources

Connectivity“Talking to things”: communication (Internet protocols) & security

Resource“Sharing single resources”: negotiating access, controlling use

Collective“Coordinating multiple resources”: ubiquitous infrastructure services, app-specific distributed services

InternetTransport

Application

Link

Internet Protocol Architecture

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Protocols, Services,Protocols, Services,and APIs Occur at Each Leveland APIs Occur at Each Level

Languages/Frameworks

Fabric Layer

Applications

Local Access APIs and Protocols

Collective Service APIs and SDKsCollective Services

Collective Service Protocols

Resource APIs and SDKsResource Services

Resource Service Protocols

Connectivity APIsConnectivity Protocols

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Important PointsImportant Points Built on Internet protocols & servicesBuilt on Internet protocols & services

• Communication, routing, name resolution, etc.Communication, routing, name resolution, etc. ““Layering” here is conceptual, does not Layering” here is conceptual, does not

imply constraints on who can call whatimply constraints on who can call what• Protocols/services/APIs/SDKs will, ideally, be Protocols/services/APIs/SDKs will, ideally, be

largely self-containedlargely self-contained• Some things are fundamental: e.g., Some things are fundamental: e.g.,

communication and securitycommunication and security• But, advantageous for higher-level functions to But, advantageous for higher-level functions to

use common lower-level functionsuse common lower-level functions

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The Hourglass ModelThe Hourglass Model

Focus on architecture issuesFocus on architecture issues• Propose set of core services Propose set of core services

as basic infrastructureas basic infrastructure• Use to construct high-level, Use to construct high-level,

domain-specific solutionsdomain-specific solutions Design principlesDesign principles

• Keep participation cost lowKeep participation cost low• Enable local controlEnable local control• Support for adaptationSupport for adaptation• ““IP hourglass” modelIP hourglass” model

Diverse global services

Coreservices

Local OS

A p p l i c a t i o n s

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HourglassHourglass

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Where Are We With Where Are We With Architecture?Architecture?

No “official” standards existNo “official” standards exist But: But:

• Globus Toolkit™ has emerged as the de facto Globus Toolkit™ has emerged as the de facto standard for several important Connectivity, standard for several important Connectivity, Resource, and Collective protocolsResource, and Collective protocols

• GGF has an architecture working groupGGF has an architecture working group• Technical specifications are being developed Technical specifications are being developed

for architecture elements: e.g., security, for architecture elements: e.g., security, data, resource management, informationdata, resource management, information

• Internet drafts submitted in security areaInternet drafts submitted in security area

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Fabric LayerFabric LayerProtocols & ServicesProtocols & Services

Just what you would expect: the diverse mix of Just what you would expect: the diverse mix of resources that may be sharedresources that may be shared• Individual computers, Condor pools, file systems, Individual computers, Condor pools, file systems,

archives, metadata catalogs, networks, sensors, archives, metadata catalogs, networks, sensors, etc., etc.etc., etc.

Few constraints on low-level technology: Few constraints on low-level technology: connectivity and resource level protocols form connectivity and resource level protocols form the “neck in the hourglass” the “neck in the hourglass”

Defined by interfaces not physical Defined by interfaces not physical characteristicscharacteristics

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Fabrics in generalFabrics in general

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Connectivity LayerConnectivity LayerProtocols & ServicesProtocols & Services

CommunicationCommunication• Internet protocols: IP, DNS, routing, etc.Internet protocols: IP, DNS, routing, etc.

Security: Grid Security Infrastructure (GSI)Security: Grid Security Infrastructure (GSI)• Uniform authentication, authorization, and Uniform authentication, authorization, and

message protection mechanisms in multi-message protection mechanisms in multi-institutional settinginstitutional setting

• Single sign-on, delegation, identity mappingSingle sign-on, delegation, identity mapping• Public key technology, SSL, X.509, GSS-APIPublic key technology, SSL, X.509, GSS-API• Supporting infrastructure: Certificate Supporting infrastructure: Certificate

Authorities, certificate & key management, …Authorities, certificate & key management, …

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Not too many connections!Not too many connections!

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Resource LayerResource LayerProtocols & ServicesProtocols & Services

Grid Resource Allocation Management (GRAM) Grid Resource Allocation Management (GRAM) • Remote allocation, reservation, monitoring, control Remote allocation, reservation, monitoring, control

of compute resourcesof compute resources GridFTP protocol (FTP extensions)GridFTP protocol (FTP extensions)

• High-performance data access & transportHigh-performance data access & transport Grid Resource Information Service (GRIS)Grid Resource Information Service (GRIS)

• Access to structure & state informationAccess to structure & state information Others emerging: Catalog access, code Others emerging: Catalog access, code

repository access, accounting, etc.repository access, accounting, etc. All built on connectivity layer: GSI & IPAll built on connectivity layer: GSI & IP

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Collective LayerCollective LayerProtocols & ServicesProtocols & Services

Index servers aka metadirectory servicesIndex servers aka metadirectory services• Custom views on dynamic resource collections assembleCustom views on dynamic resource collections assembled by a community d by a community

Resource brokers (e.g., Condor Matchmaker)Resource brokers (e.g., Condor Matchmaker)• Resource discovery and allocationResource discovery and allocation

Replica catalogsReplica catalogs Replication servicesReplication services Co-reservation and co-allocation servicesCo-reservation and co-allocation services Workflow management servicesWorkflow management services etc.etc.

Condor: www.cs.wisc.edu/condor

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Collectives: The BorgsCollectives: The Borgs

Resistance is futile. You will be assimilated.

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ComputeResource

SDKAPI

AccessProtocol

CheckpointRepository

SDKAPI

C-pointProtocol

Example: High-Throughput Computing Example: High-Throughput Computing SystemSystem

High Throughput Computing System

Dynamic checkpoint, job management, failover, staging

Brokering, certificate authorities

Access to data, access to computers, access to network performance data

Communication, service discovery (DNS), authentication, authorization, delegation

Storage systems, schedulers

Collective(App)

App

Collective(Generic)

Resource

Connect

Fabric

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Example:Example:Data Grid ArchitectureData Grid Architecture

Discipline-Specific Data Grid Application

Coherency control, replica selection, task management, virtual data catalog, virtual data code catalog, …

Replica catalog, replica management, co-allocation, certificate authorities, metadata catalogs,

Access to data, access to computers, access to network performance data, …

Communication, service discovery (DNS), authentication, authorization, delegation

Storage systems, clusters, networks, network caches, …

Collective(App)

App

Collective(Generic)

Resource

Connect

Fabric

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CERN’s Data Grid ApplicationCERN’s Data Grid Application

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The Compact Muon Solenoid

OpenOpen Grid Service Grid Service ArchitectureArchitecture

Minds are like parachutes, they Minds are like parachutes, they only function when they are only function when they are openopen. .

– Thomas Robert Dewar– Thomas Robert Dewar

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Service-Oriented ArchitectureService-Oriented Architecture Service: an entity that provides some Service: an entity that provides some

capability to its clients by capability to its clients by exchanging messagesexchanging messages

Service: defined by identifying Service: defined by identifying sequences of specific message sequences of specific message exchanges that cause the service to exchanges that cause the service to perform some operationsperform some operations

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Service-oriented ArchitectureService-oriented Architecture Great flexibiliGreat flexibility in implemty in implemen-tation anen-tation and location: bd location: because all opecause all operations are erations are defined in terdefined in terms of messams of message exchangesge exchanges

SOAP: Simple Object Access Protocol

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Service-oriented ArchitectureService-oriented Architecture Definition: a service-oriented architecture Definition: a service-oriented architecture

is one in which all entities are services, and is one in which all entities are services, and thus any operation visible to the thus any operation visible to the architecture is the result of message architecture is the result of message exchangeexchange

Underlyinginfrastructure

Message exchanges services

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Service-oriented architectureService-oriented architecture Examples:Examples:

• A storage serviceA storage service• A data transfer serviceA data transfer service• A troubleshooting serviceA troubleshooting service

Two important themesTwo important themes

low-level service

high-level service

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But, first four personality typesBut, first four personality types

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Service-oriented architectureService-oriented architecture Common behaviors can reoccur in Common behaviors can reoccur in

different contextsdifferent contexts• A goal of OGSA design is to allow these A goal of OGSA design is to allow these

behaviors to be expressed in standard behaviors to be expressed in standard ways regardless of contexts, so as to ways regardless of contexts, so as to simplify application design and simplify application design and encourage code reuseencourage code reuse

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Service-oriented architectureService-oriented architecture A higher-level service behavior (data A higher-level service behavior (data

transfer) can be implemented via the transfer) can be implemented via the composition of simpler behaviors composition of simpler behaviors (storage service)(storage service)• Ease of composition is a second major Ease of composition is a second major

design goal for OGSAdesign goal for OGSA

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Service-oriented architectureService-oriented architecture Similarity in Similarity in

protocolsprotocols

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Service-oriented architectureService-oriented architecture By encapsulating service operations By encapsulating service operations

behind a common message-oriented behind a common message-oriented service interface, service-oriented service interface, service-oriented architecture encourages architecture encourages service service virtualizationvirtualization, isolating users from , isolating users from details of service implantation and details of service implantation and locationlocation

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Service-oriented architectureService-oriented architecture

Virtualization

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Service-oriented architectureService-oriented architecture VirtualizationVirtualization

• Everything is becoming virtual: virtual Everything is becoming virtual: virtual stores, virtual workspace, virtual stores, virtual workspace, virtual organization, virtual networks, …organization, virtual networks, …

• More than 60 million US workers work More than 60 million US workers work remotelyremotely

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Service-oriented architectureService-oriented architecture Interaction with a given service is Interaction with a given service is

facilitated by using a standard facilitated by using a standard interface definition languageinterface definition language ( (IDLIDL), ), such as WSDL, to describe the such as WSDL, to describe the service’s interfaces.service’s interfaces.

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Service-oriented architectureService-oriented architecture Web service description languageWeb service description language

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Service-oriented architectureService-oriented architecture IDL: a cornerstone of interoperability IDL: a cornerstone of interoperability

and transparencyand transparency

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Service-oriented architectureService-oriented architecture An IDL defines the operations An IDL defines the operations

supported by a service, by specifying supported by a service, by specifying the messages that a service the messages that a service consumes and producesconsumes and produces

An interface specification describes An interface specification describes the messages the service expects the messages the service expects but does not define what the service but does not define what the service does in response to those messages does in response to those messages (i.e., its behavior)(i.e., its behavior)

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Service-oriented architectureService-oriented architecture A well-defined interface definition A well-defined interface definition

language and a separation of language and a separation of concerns between service interface concerns between service interface and implementation simplify the and implementation simplify the manipulation and management of manipulation and management of services in four important respects: services in four important respects: service discovery, composition, service discovery, composition, specialization, and interface specialization, and interface extensionextension..

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Service-oriented architectureService-oriented architecture Service discoveryService discovery

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Service-oriented architectureService-oriented architecture Service discovery Service discovery

• Service Location Protocol (SLP)Service Location Protocol (SLP)• Jini: A service discovery architecture based Jini: A service discovery architecture based on Javaon Java• Universal Plug and Play (UPnP): Microsoft's Universal Plug and Play (UPnP): Microsoft's solution to service discoverysolution to service discovery• Salutation: A light weight network protocol iSalutation: A light weight network protocol independent service discovery protocol ndependent service discovery protocol

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Service-oriented architectureService-oriented architecture Service compositionService composition

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Service-oriented architectureService-oriented architecture Service specialization: use of Service specialization: use of

different implementations of a different implementations of a service interface on different service interface on different platformsplatforms

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Service-oriented architectureService-oriented architecture Interface extension: Interface extension:

allow for specialized allow for specialized implementations to implementations to add additional, add additional, implementation-implementation-specific specific functionality, while functionality, while still supporting the still supporting the common interfacecommon interface A value-added extension

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Open Grid Service ArchitectureOpen Grid Service Architecture Objectives of OGSAObjectives of OGSA

• Manage resources across distributed Manage resources across distributed heterogeneous platforms heterogeneous platforms

• Deliver seamless quality of service Deliver seamless quality of service • Provide a common base for autonomic Provide a common base for autonomic

management solutions management solutions • Define open, published interfaces Define open, published interfaces • Exploit industry standard integration Exploit industry standard integration

technologies technologies

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Open Grid Service ArchitectureOpen Grid Service Architecture Three principal elements of OGSA: OGSI, Three principal elements of OGSA: OGSI,

OGSA services, OGSA applicationsOGSA services, OGSA applicationsOGSA main architecture

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Open Grid Service InfrastructureOpen Grid Service Infrastructure OGSI: OGSI: provides a uniform way for provides a uniform way for

software developers to model and interact software developers to model and interact with grid services by providing interfaces with grid services by providing interfaces for discovery, life cycle, state for discovery, life cycle, state management, creation and destruction, management, creation and destruction, event notification, and reference event notification, and reference management. management.

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Requesting a serviceRequesting a service

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Important OGSI concepts and Important OGSI concepts and interactionsinteractions

service data, keep-alive,notifications,

service invocation

create service

grid service handleservice requester

servicediscovery

serviceregistry

registerservice

resourceallocation

service factory

serviceinstances

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Open Grid Service InfrastructureOpen Grid Service Infrastructure OGSI and web services: OGSA architecture OGSI and web services: OGSA architecture

enhances Web services to accommodate enhances Web services to accommodate requirements of the grid. These enhancements requirements of the grid. These enhancements are specified in OGSI. Over time, it's expected are specified in OGSI. Over time, it's expected that much of the OGSI functionality will be that much of the OGSI functionality will be incorporated in Web services standards. incorporated in Web services standards.

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Open Grid Service InfrastructureOpen Grid Service Infrastructure Implementation of OGSI: Implementation of OGSI: The Globus TooThe Globus Toolkit 3 (GT3) is the first full-scale implementatilkit 3 (GT3) is the first full-scale implementation of the OGSI standard. on of the OGSI standard.

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OGSA Architected ServicesOGSA Architected Services OGSA architected servicesOGSA architected services

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OGSA Architected ServicesOGSA Architected Services Grid core servicesGrid core services

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OGSA Architected ServicesOGSA Architected Services Grid program execution and data Grid program execution and data

servicesservices

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OGSA Architected ServicesOGSA Architected Services Grid program execution and data services Grid program execution and data services

hostinghosting

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NamingNaming Because Grid services are dynamic and sBecause Grid services are dynamic and stateful, we need a way to distinguish ontateful, we need a way to distinguish one dynamically created service instance fre dynamically created service instance from another.om another. Thus, we need a naming scheme for Grid Thus, we need a naming scheme for Grid service instances.service instances.

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NamingNaming

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NamingNaming

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NamingNaming

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NamingNaming

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NamingNaming

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NamingNaming OGSI defines a two-level naming OGSI defines a two-level naming

scheme for Grid service instances scheme for Grid service instances based on simple, abstract, long-lived based on simple, abstract, long-lived Grid service handles (GSH).Grid service handles (GSH).

GSH can be mapped by handle GSH can be mapped by handle resolution services to concrete but resolution services to concrete but potentially short-lived Grid service potentially short-lived Grid service references (GSR).references (GSR).

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NamingNaming A GSH is a globally unique name that A GSH is a globally unique name that

distinguishes that specific Grid distinguishes that specific Grid service instance from all other Grid service instance from all other Grid service instances that have existed, service instances that have existed, exist now, or will exist in the future.exist now, or will exist in the future.

A GSH is represented using a A GSH is represented using a Uniform Resource Identifier.Uniform Resource Identifier.

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NamingNaming A GSH carries no protocol- or A GSH carries no protocol- or

instance-specific information such as instance-specific information such as network address or supported network address or supported protocol bindings.protocol bindings.

All other instance-specific All other instance-specific information is encapsulated into a information is encapsulated into a single abstraction called a Grid single abstraction called a Grid service reference (GSR).service reference (GSR).

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NamingNaming

client handleresolver

GSR1 GSR2

serviceinstance

serviceinstance

Resolve (GSH)

time>Ttime<T

migrateat time T

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Service lifetime managementService lifetime management The introduction of transient service The introduction of transient service

instances raises the issue of instances raises the issue of determining the service’s lifetimedetermining the service’s lifetime, , that is, determining when a service that is, determining when a service can or should be terminated so that can or should be terminated so that associated resources can be associated resources can be recovered.recovered.

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Happiness for a lifetimeHappiness for a lifetime

If you want happiness for an hour -- If you want happiness for an hour -- take a nap. If you want happiness for take a nap. If you want happiness for a day -- go fishing. If you want a day -- go fishing. If you want happiness for a month -- get married. happiness for a month -- get married. If you want happiness for a year -- If you want happiness for a year -- inherit a fortune. inherit a fortune. If you want If you want happiness for a lifetime -- help happiness for a lifetime -- help someone elsesomeone else. - Chinese Proverb . - Chinese Proverb

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Service lifetime managementService lifetime management OGSA addresses this problem OGSA addresses this problem

through a soft-state approach in through a soft-state approach in which Grid service instances are which Grid service instances are created with a specified lifetime.created with a specified lifetime.

Three steps:Three steps:• Negotiating an initial lifetimeNegotiating an initial lifetime• Explicit terminatingExplicit terminating• Requesting a lifetime modificationRequesting a lifetime modification

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Soft-state used in RSVPSoft-state used in RSVP What is RSVP? (What is RSVP? (Resource reSerVation Protocol)

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Soft-state used in RSVPSoft-state used in RSVP

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Path message

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Resv message

Merge the reservation

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OGSA ImplementationsOGSA Implementations

demarshaling/decodin

g

Grid serviceimplementation



protocoltermination

protocoltermination

protocoltermination

Container (good for code reuse)

Grid service

invocation

adaptationlayer

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Future DirectionsFuture Directions Service and toolsService and tools ImplementationImplementation SemanticsSemantics ScalabilityScalability ……

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