Grid Computing Presentation 2

Grid Computing Architectures

Noman Islam

References

•

‘The Anatomy of the Grid: Enabling Scalable

Virtual Organizations’

, I. Foster, C. Kesselman,

S. Tuecke. International J. Supercomputer

Applications

• ‘

The Physiology of the Grid: An Open Grid

Services Architecture for Distributed Systems

Integration

’, I. Foster, C. Kesselman, J. Nick, S.

Tuecke, Open Grid Service Infrastructure

•

‘The Anatomy of the Grid: Enabling

Scalable Virtual Organizations’

, I. Foster,

C. Kesselman, S. Tuecke. International J.

Supercomputer Applications

– Justifies the need for Grid Computing

Technology

– Presents an open generalized Grid

Computing Architecture

Introduction to Grid

• Coordinated resource sharing and problem

solving in dynamic, multi-institutional virtual

organizations

• Current Distributed Computing Environments

doesn’t address VO requirements well:

– Internet – addresses only communication

– EJB, CORBA – resource sharing with in single organization

Fabric Layer

• Implements the local, resource specific operations that occur on specific resource

• At a minimum enquiry and resource management mechanisms

– Computational Resources – start/stop/monitor programs, enquire about hardware /software characteristics, state information (current queue state etc.)

– Storage Resources - putting / getting files, enquire about available space et.

– Network Resources – enquire about network characteristics / load, QoS control

– Code Repositories – mechanism for managing versioned source and object code

Connectivity Layer

• Core communication and authentication

protocols required for Grid-specific

network transactions

• Communication requirements include

transport, routing, and naming

• The

Internet (IP and ICMP), transport

(TCP, UDP), and application (DNS,

Connectivity Layer – contd…

• Many of the security standards developed within the context of the Internet protocol suite are applicable

– Single sign on. Users must be able to “log on” (authenticate) just once and then have access to multiple Grid resources defined in the Fabric layer, without further user intervention

– Delegation. A user must be able to endow a program with the ability to run on that user’s behalf, so that the program is able to access the resources on which the user is authorized

– Integration with various local security solutions like Kerberos don’t ask for realistically wholesale

Resource Layer

• Define protocols for the secure negotiation,

initiation, monitoring, control, accounting, and

payment of sharing operations on individual

resources

– Information protocols - used to obtain information about the structure and state of a resource

– Management protocols - used to negotiate access to a shared resource, specifying, for example, resource requirements (including advanced reservation and quality of service) and the operations to be

Collective Layer

• Are not associated with anyone specific resource but rather are global in nature and capture interactions across collections of resources

• They can implement a wide variety of sharing behaviors without placing new requirements on the resources being shared

– Directory services

– Data replication services

– Monitoring and Diagnostics services - support the monitoring of VO resources for failure, adversarial attack

– Software Discovery Services discover and select the best

Application Layer

• Applications are constructed in terms of,

and by calling upon, services defined at

any layer

• What is labeled “applications” and show in

a single layer may in practice call upon

Perspectives on Grid

•

“The Grid is a next-generation Internet”

– “The Grid” is not an alternative to “the

Internet”: it is rather a set of additional

Perspectives on Grid

•

“The Grid is a source of free cycles”

– Grid computing does not imply unrestricted access to resources. Grid computing is about controlled sharing. Resource owners will typically want to enforce

policies that constrain access according to group membership, ability to pay, and so forth. Hence,

accounting is important, and a Grid architecture must incorporate resource and collective protocols for

Perspectives on Grid

•

“The Grid requires a distributed operating

system”

– Grid software should define the operating system

services to be installed on every participating system providing transparency However, we this perspective is inconsistent with the primary goals of broad

deployment and interoperability. We argue that the

appropriate model is rather the Internet Protocol suite. The tremendous physical and administrative

heterogeneities encountered in Grid environments means that the traditional transparencies are

Perspectives on Grid

•

The Grid requires new programming models

– Programming in Grid environments introduces

challenges that are not encountered in sequential (or parallel) computers, such as multiple administrative domains, new failure modes, and large variations in performance. Abstraction and Encapsulation can

reduce complexity and improve reliability. A developer who believes that all Grid resources should be

presented to users as objects needs simply to

Perspectives on Grid

•

The Grid makes high-performance computers

superfluous

– The hundreds, thousands, or even millions of processors that may be accessible within a VO

represent a significant source of computational power, if they can be harnessed in a useful fashion. This

does not imply, however that traditional

• ‘

The Physiology of the Grid: An Open Grid

Services Architecture for Distributed

Systems Integration

’, I. Foster, C.

Kesselman, J. Nick, S. Tuecke, Open Grid

Service Infrastructure Working Group,

Global Grid Forum, June 22, 2002

Introduction to OGSA

• OGSA is a SOA architecture for Grid and is the

creation of the GlobusAlliance (

http://

www.globus.org/

), a community of organizations

and individuals dedicated to advancing grid

technologies

Introduction to Web Services

• In its simplest definition, Web services is an

instantiation of a Service-Oriented Architecture

(SOA) where all of the following apply:

– Service interfaces are described using Web Services Description Language WSDL).

– Payload is transmitted using Simple Object Access Control over HTTP (Hypertext Transfer Protocol). – Universal Description Discovery and Integration

Introduction to WebServices

• The growing success of Web services is due to a number of factors, including those below

– Systems can interact with one another dynamically via standard Internet technologies.

– Services are built once and reused many times.

– Services can be implemented in any programming language.

– Service consumers do not need to worry about firewalls because communication is carried over HTTP.

Introduction to WSDL

• Web Services Description Language is the

standard format for describing a web service. A

WSDL definition describes how to access a web

service and what operations it will perform.

• WSDL document describes a web service using

these major elements

– <portType> The operations performed by the web service

– <message> The messages used by the web service – <types> The data types used by the web service

WSDL Example

<message name="getTermRequest"> <part name="term" type="xs:string"/> </message>

<message name="getTermResponse"> <part name="value" type="xs:string"/> </message>

<portType name="glossaryTerms"> <operation name="getTerm">

<input message="getTermRequest"/> <output message="getTermResponse"/> </operation>

</portType>

Introduction to SOAP

• The Simple Object Access Protocol

(SOAP)

– is a simple enveloping mechanism for XML

payloads that defines a remote procedure call

(RPC)

– SOAP is independent of the underlying

Introduction to SOAP contd…

• A SOAP message is an ordinary XML document

containing the following elements:

– A required Envelope element that identifies the XML document as a SOAP message

– An optional Header element that contains header information

– A required Body element that contains call and response information

– An optional Fault element that provides information about errors that occurred while processing the

An Example SOAP Message

<?xml version="1.0"?> <soap:Envelope

xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">

<soap:Body>

<m:GetPrice xmlns:m="http://www.w3schools.com/prices"> <m:Item>Apples</m:Item>

</m:GetPrice> </soap:Body>

UDDI

• UDDI (Universal Description, Discovery

and Integration Service) is an XML-based

distributed directory that enables

businesses to list themselves, as well as

dynamically discover each other

Other Standards

• The WS-Inspection specification provides

an XML format for assisting in the

inspection of a site for available services

and a set of rules for how inspection

related information should be made

available for consumption

OGSA

• The Open Grid Services Architecture

(OGSA) describes an architecture for a

service-oriented grid computing

environment for business and scientific

use

OGSA

• OGSA defines the mechanisms for creating, managing, and exchanging information among entities, called Grid Services

• The Globus Toolkit 4.0 is an open source project that can be downloaded from the Globus Alliance Web site • It provides a set of OGSA capabilities based on WSRF

(WS-Resource Framework)

• The WSRF is a set of Web Service specifications being developed by the OASIS organization that, taken

OGSA contd…

• OGSA represents everything as a Grid

Service

• Grid Services are stateful transient Web

Service instances that are discovered and

created dynamically to form larger

OGSA – contd…

• A Grid Service conforms to a set of conventions, expressed as WSDL (Web Service Description

Language) interfaces, extensions, and behaviors, for such purposes as:

– Discovery: mechanisms for discovering available services and for determining the characteristics of those services so that they can be invoked appropriately

• Registery interface

• GridService interface’s FindServiceData

– Dynamic service creation: mechanisms for dynamically creating and managing new service instances – Factory Interface’s

OGSA contd…

– Lifetime management: mechanisms for

reclaiming services and state in the case of

failed operations

• SoftState approach

– Notification: mechanisms for asynchronously

notifying Grid Service clients of changes in

state