Mgrid: Using Ubiquitous Web Technologies to create a Computational Grid

1
M-grid Using Ubiquitous Web Technologies to
create a Computational Grid

• Robert John Walters
• Stephen Crouch
• 14 / 02 / 2005

2
Contents

• Background/Motivations
• Computational Grids
• Java Applets
• M-grid
• Limitations, Future Work
• Conclusions

3
Background/Motivations

• Realisation that grid tech. can be used within
  increasing number of domains
• E-business
• Computer games industry (Butterfly.net)
• Military (simulations)
• Drive towards a more pervasive grid
• Existing grid tech. sophisticated -gt significant
  complexity
• To what extent can this be reduced?

4
Computational Grids - in General
Executor
Client
Coordinator
Executor
Client

• Users supply tasks to be performed via client
• Execution nodes contribute processing power
• Coordinator node sends tasks to execution nodes,
  ensuring results returned

5
Computational Grids Issues

• Require proprietary software installed
• For coordinator, execution client(?) nodes
• Administrator-level knowledge (and privilege)
  required
• Of system environment
• Of the grid system
• Security executing foreign code
• Trust issues between client, coordinator and
  execution nodes
• Far more of an issue with wide-area grids

6
Java Applets

• But web browsers execute foreign code
• Java applets executed within a sandbox virtual
  machine
• Stringent security restrictions imposed
• In-built security configuration in browsers
• Applet can only contact originating server
• Risk significantly reduced

7
M-grid A Lightweight Grid I

• M-grid
• Execution node Java-applet enabled browser
• Client browser
• Coordinator web server
• Tasks distributed as Applets in web pages
• Execution node browser opens web page on server
• Runs task applet
• Uploads results to server

8
M-grid A Lightweight Grid II

• Eliminates need for
• Communications infrastructure
• Trust relationships
• Installation on the execution and client nodes
• Works inherently over the web
• Domains can contribute processing power to
  another
• Jobs can be submitted from outside the domain web
  server firewall permitting
• Get encryption for free
• Configure web server to use HTTPs
• Multi-platform
• Execution nodes tested on Linux, Windows
• Tradeoffs flexibility, overall control,
  efficiency

9
M-grid Overview

• Implemented on Microsofts IIS (internet
  Information Server) using ASP
• Could also be done on Apache Tomcat
• Client
• 1. Submits job as applet to web server via
  jobSubmit page
• 2. Eventually collects results using
  jobCollectResults page
• Execution node
• 3. Requests a job via jobRequest page
• 4. Applet submits results from job using
  jobSubmitResults page

10
Client 1 Submitting a Job

• Client directs browser to jobSubmit page
• Insert jobs details into form
• Including location of applet class file
• Submit form, job class and details uploaded to
  server
• Job stored in collection of tasks awaiting
  processing, job id returned to user

11
Client 2 Collecting Results

• Client directs browser to jobCollectsResults page
• Selects jobs output by job id
• Output sent to user

12
Executor Requesting a Job

• Client directs browser to jobRequest page, which
  continually refreshes
• When job is available
• Applet task moved to working dir., job id prefix
• Applet is packaged in web page and delivered
• When job is finished, waits as before

13
Executor Returning Results

• Once applet has completed, uploads results to
  jobSubmitResults on server
• Applet removed from working directory
• Results placed into complete directory with job
  id prefix

14
Exploitation Issue

• Applets can be hidden on any web page
• Use technology to steal processor cycles from
  visiting machines browser
• Attach to popular web pages
• Cycleware

15
Limitations

• Preliminary work!
• Scalability?
• Performance?
• Control, flexibility
• Constrained to Java
• Jobs currently need applet wrapper code
• No user authorisation

16
Further Future Work

• Load balancing between multiple servers
• Execution nodes get passed around servers until
  job received
• Busy servers redirect job submissions to less
  busy servers

17
Conclusions

• Grid software often requires considerable effort
  to install and configure
• TM security for free
• Exploitation issue
• Application in teaching grid basics