1. M-grid Using Ubiquitous Web Technologies to create a Computational Grid R J Walters and S Crouch 21 January 2009

2. 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... Before I start:

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 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 Coordinator node which distributes tasks and marshals results. CoordinatorExecutor Client … …

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

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. 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) 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. 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 How to develop your applet

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

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