University of Southampton Electronics and Computer Science M-grid: Using Ubiquitous Web Technologies to create a Computational Grid Robert John Walters Stephen Crouch 14 / 02 / 2005

University of Southampton Electronics and Computer Science Contents Background/Motivations Computational Grids Java Applets M-grid Limitations, Future Work Conclusions

University of Southampton Electronics and Computer Science 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 -> significant complexity –To what extent can this be reduced?

University of Southampton Electronics and Computer Science Computational Grids - in General Users supply tasks to be performed via client Execution nodes contribute processing power Coordinator node sends tasks to execution nodes, ensuring results returned CoordinatorExecutor Client … …

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science M-grid: Overview Implemented on Microsoft’s 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

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science Client 2: Collecting Results Client directs browser to jobCollectsResults page Selects job’s output by job id Output sent to user

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science Limitations Preliminary work! Scalability? Performance? Control, flexibility Constrained to Java –Jobs currently need applet wrapper code No user authorisation

University of Southampton Electronics and Computer Science 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

University of Southampton Electronics and Computer Science Conclusions Grid software often requires considerable effort to install and configure T&M security for free Exploitation issue Application in teaching grid basics