Javascript Cog Kit

By Zhenhua Guo

Grid Applications

• Currently, most grid related applications are written as separate software.– server side:

• Globus, UNICORE, gLite ...

– client side• Most groups write their own client-side programs to

utilize remote grid services.

Web 2.0

• Recently, web 2.0 becomes popular as a rich client technology.– Ajax– Flex– Silverlight– ...

Combination

• web-based applications vs traditional software– Platform independent– No installation (or minimum installation)

• So, why not write a web 2.0 library for gird access client.

Architecture - Job Submission

client AgentExecutor

MyProxy

Grid

Service

Account database

Authentication.

job execution

Fetch proxy certificate

job submissionrequest. job

forward

XML-RPC or JSON-RPC

By web service interface

CoG Kit

fetch Account data

certificate

Architecture – Query(1)

job queryrequest.client Agent

Executor

MyProxy

Grid

Service

Account database

Authentication.

job status check

Fetch proxy certificate

XML-RPC or JSON-RPC

By web se

rvice

interface

?

CoG Kit

fetch Account data

certificate

Status Repository

status query

status update

Architecture – Query(2)

job queryrequest.client Agent

Executor

MyProxy

Grid

Service

Account database

Authentication.

job status check

Fetch proxy certificate

XML-RPC or JSON-RPC

By web service interface

CoG Kit

fetch Account data

certificate

status query

Procedure Sample• First, user must be authenticated by username and password• User is provided a web-based text area where workflow description

can be input.

For example, a user inputs following Karajan workflow

<project> <include file="cogkit.xml"/> <execute executable="/bin/date" stdout="thedate"

host="gf1.ucs.indiana.edu" provider="GT2" redirect="false"/> <echo message="Job completed. Transferring the output"/> <transfer srchost="gf1.ucs.indiana.edu" srcfile="thedate"

desthost="localhost" provider="gridftp"/> <echo message="Transfer complete"/></project>

• The workflow is transferred to agent server.• Agent server forwards (maybe does some transformation) received request to bac

kend web service.• Backend web service fetches a proxy certificate from MyProxy server before it is a

ble to submit jobs to grid infrastructure.

Client-side Tech

• We choose Ajax because it is enabled almost on all machines.

• Users can submit workflow description by web-based interface

• Users must have accounts to submit jobs.• Javascript library is being written to make

development of client-side grid access program easier (Currently, abstraction is based on Cog kit)

Communication between client and agent

• XML vs JSON– XML

• extensible, powerful• but sometimes we don’t need all its features.

– JSON• simple, efficient• built-in support in Javascript• have limitations

– No absolutely good or bad– Our choice:

• support both of them• users can choose either one they like.• Conversion between them is supported.• XML-RPC and JSON-RPC are used to specify the detailed format.• Currently, XML-RPC is used.

Examples(1)

• XML

<project> <task execute=“/bin/ls” stdout=“list”/> <transfer src=“list” dst=“locallist”/></project>

• JSON{ project: {

task:{execute:/bin/ls,stdout:list} transfer:{src:list, dst:locallist}

}}

Example(2)• XML-RPC • JSON-RPC

{ version:1.1 method:BioCalculate params:

[

workflow1 description,

workflow2 description

]

}

<methodCall> <methodName> BioCalculate </methodName> <params> <param> <value> <string>

workflow1 description </string> </value> </param> <param> <value> <string>

workflow2 description </string> </value> </param> </params> </methodCall>

Agent

• Before users submit jobs, they must be authenticated first.

• Agent receives job submission request from client.

Executor

• CoG Kit is used to hide complexity of various grid infrastructure.

• Before submitting job to final grid infrastructure, a valid proxy certificate must be fetched from MyProxy server.

• This functionality is wrapped as web service to enhance interoperability.

• In my project, Axis2 is used to generate web service interface.

Future

• Session management– Agent audits job submission from users and

related information should be stored.

• Job management

• More sophisticated authentication mechanism.