M-grid

1. M-grid Using Ubiquitous Web Technologies to create a Computational Grid R J Walters and S Crouch21 January 2009

2. Before I start: • How many of you have your laptops with you? • Please open a browser and point it at:http://dawkins:8080/mgrid/JobRequest • (And press the pause button) • You will need to be connected using the ECS VPN for this to work • I’m going to try and use your machines...

3. Should look like this: http://dawkins:8080/mgrid/JobRequest

4. Contents • Background/Motivations • Computational Grids • Java Applets • M-grid • In action • Conclusions

5. Background/Motivations • Grid technologies can be used within increasing number of domains • E-business • Computer games • Military (simulations) • Drive towards a more pervasive grid • Existing grid technologies are sophisticated, and complex

6. Computational Grids Client Executor • Users supply tasks to be performed via client • Classically these tasks can be divided into may parts which can be processed in parallel • Execution nodes contribute processing power • Generally there is one Coordinatornode which distributes tasks and marshals results. Client Coordinator Executor … …

7. Computational Grids – Issues • Hard to set up • Software to install and configure • May require physical visits to each node • Administrator-level knowledge (and privilege) generally required • (Third year UG coursework defeated many students)

8. Why so hard? • “Real” GRID systems are made to do really big tasks • Need for reliability and securityAnd... • The processing nodes execute “foreign” code

9. Idea: use something everyone has already • Web browsers know how to execute foreign code without getting hurt • Java applets are executed within a ‘sandbox’ • Stringent security restrictions imposed

10. M-Grid • Jobs are submitted to a web page • Uses standard browsers at processing nodes • Only software which needs to be installed is on the co-ordinating machine (plus Tomcat) • (Students can do their coursework using M-Grid)

11. M-grid: Restrictions • Jobs have to be submitted as a Java Applet, plus a text file listing parameters for each sub-task • Access to large datasets is awkward • Jobs have to respect all the usual constraints for Applets: • Communication restricted to the supplying server • No access to local file system • In return jobs can run just about anywhere on any platform without formality

12. How to develop your applet • Just like any other applet • M-Grid implementation provides some classes to use to do some setup, get your parameters and send write the results • Two versions of these classes • One for working with during development • Output written to screen... • Other version is substituted by M-Grid when you submit your job to the server

13. Tomcat implementation • Running on Dawkins in my office • Demo... http://dawkins:8080/mgrid/JobRequest

14. Some thoughts and issues • Scalability ? – Not sure • Performance? – Surprising • We expected to executing as an applet in a browser would slow processing to a crawl • Applets can be ‘hidden’ on any web page • Could steal processing power from unwitting viewers of your page(s)

15. Conclusions • Conventional Grid software requires considerable effort to install and configure • We offer M-Grid as a lightweight alternative • Potentially interesting exploitation (of processing nodes) issue • Is being used in teaching grid basics