Slides for Grid Computing: Techniques and Applications by Barry Wilkinson, Chapman & Hall/CRC press, © 2009.Chapter 1, pp 19-28. For educational use only. All rights reserved. Aug 24, 2009 1-2.1

Grid Computing Software Interface

•Brief introduction to Globus

•Executing a simple job on command line

•Executing program through a Grid portal

Grid computing infrastructure (middleware) software

Primary objective:

To make seamless environment for users to access distributed resources.

1-2.2

Grid computing infrastructure software

Key aspects include:

• Secure envelop over all transactions

• Single sign-on - being able to access all available resources and run jobs without having to supply additional passwords or account information.

• Data management tools

• Information services providing characteristics of resources and their status (including dynamic load)

• APIs and services that enable applications themselves to take advantage of Grid platform

• Convenient user interface1-2.3

1-2.4

Globus Project• Open source software toolkit developed for

Grid computing.

• One of the most influential projects

• Roots in I-way experiment.

• Work started in 1996.

• Four versions developed to present time.

• Reference implementations of Grid computing standards.

• Defacto standard for Grid computing.

1-2.5

Globus• A “toolkit” of services and packages for

creating the basic grid computing infrastructure

• Higher level tools added to this infrastructure

• Version 4 is web-services based

• Some non-web services code exists from earlier versions (legacy) or where not appropriate (for efficiency, etc.).

1-2.6

Some Globus toolkit versions(approximate time line)

Fig. 1.5

Globus ToolkitFive major parts:

• Common run time- Libraries and services

• Security- Components to provide secure access

• Execution management- Executing, monitoring and management of jobs

• Data Management- Discovery access and transfer of data

• Information- Discovery and monitoring of resources and services

1-2.7

Some basic Globus components

• GSI Grid Security Infrastructure– Provides for security envelop around Grid resources– Uses public key cryptography

• GRAM (Globus/Grid Resource Allocation Management)– Globus’ basic execution management component – Used to issue and manage jobs

• MDS (Monitoring and Discovery Service)– To discover resources and their status

• GridFTP– For transferring files between resources

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1-2.9

Security

• Has to cross administrative domains.

• Need agreed mechanisms and standards.

• Focus on Internet security mechanisms, modified to handle the special needs of Grid computing.

Security• Distributed resources must be protected from unauthorized

access.• GSI (Grid Security Infrastructure) -- Globus components for

creating security envelop. • Requires each user to be authenticated (their identity

proved). • Uses public key cryptography (basis of Internet security)• Each user must possess a so-called (digital) certificate,

signed by a trusted certificate authority. • Users will also need to be able to give their authority to Grid

components to act on their behalf.• Users generally will also need accounts of resources they

intend to use (authorization).

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1a.11

Resource Discovery

• Still primitive and in research but ideal is to be able to submit a job and the system find the best grid resources for that job across the whole grid

Resource Discovery

• Basic Globus component called MDS (Monitoring and Discovery System).

• Users might access MDS to discover status of compute resources. In practice, users often know what resources are there but not dynamic load.

• MDS might be used by other Grid components such as schedulers.

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Executing a Job

• Next user typically would want to submit a job.

• Basic Globus component for running a job is GRAM (Globus or Grid Resource Allocation Management).

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Command-line interfaceGrid computing environments mostly Linux-based and originally accessed through a command line.

Once you have established your security credentials, to run a simple job you might issue GRAM command:

globusrun-ws -submit -c prog1

where prog1 is executable of job.

Executable needs to be present on compute resource that is to execute it.

Above command does not specify compute resource and hence computer executing globusrun-ws command will execute prog1.

Executing a Job (continued)

• May be necessary beforehand to transfer files to resources and afterwards to transfer files to other locations including back to user.

• User might use data management component called GridFTP for that.

1-2.15

GridFTP command to transfer files

globus-url-copy \

gsiftp://www.coitgrid02.uncc.edu/~abw/prog1out \

file:///home/abw/

First argument is source location and second argument is destination location.

In the above case, the file:

www.coit-grid02.uncc.edu/~abw/prog1out

transferred to

home/abw/

on the local computer.

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User employing Globus services and facilities

Fig. 1.6

Grid PortalCommand-line interface a very primitive way of interacting with Grid resources. Web-based interface called a Grid portal more desirable. UNC–Charlotte Grid portal course based upon GridSphere Grid portal toolkit.

Fig. 1.7

Before users can log on, they need a user name and password for portal.

They must have user “credentials” and accounts on the resources they wish to access.

In UNC–Charlotte course portal, PURSe (Portal-based User Registration Service) portlet used to facilitate setup procedures.

Reached by selecting “Register” tab.

User enters required information (name, email address, institution, etc.) which is forwarded to Grid system administrator to set up accounts and credentials.

1-2.19

PURSe registration portlet

Fig. 1.8

Registration activities

Fig. 1.9 1-2.21

Once logged into Grid portal, user will see a number of tabs across top, which enable user to perform many basic tasks.

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Grid information tab

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Proxies

To use many services, you are required to have a proxy certificate (a proxy).

Proxies are part of Grid security infrastructure, discussed later in course.

Proxy is an electronic document that enables resources to be accessed on user’s behalf.

Very convenient to use credential management service called myProxy to hold proxies

Usually, Gridsphere automatically obtains a proxy from the myProxy server for you when you log in.

1-2.25

Proxy management tab

1-2.26

File management tab

Batch job submission tab

1a.28

Questions

Quiz

Question: What is meant by "single sign-on"?

(a) Allowing only one person to sign onto a computer

(b) Not allowing a person to log onto a computer more than once in any one period

(c) A mechanism in which a user does not need to sign again to acquire additional resources.

(b) None of the other answers

1a-2.29

Question: Which of the following is not provided for directly in the Globus version 4 software?

(a) Execution management

(b) Accounting

(c) Network security

(d) Resource discovery

(e) File transfers

1a-2.30

Discussion Question

Is it possible to use the tradition security

method of username/password on a grid?

What problems exist for this method?

1a-2.31