Summer Scholarship Programme Project Proposal

About 4 years ago SELLIC, in a previous incarnation, wrote an applet for EPCC. This demonstrated MPI blocking point-to-point communications. A simple user interface allows three processes to be programmed and the resulting program animated. This could and was used in a teaching environment. As a follow-up to this in a 1998 SSP project Tom Doel extended the existing applet to include a subset of MPI collective communications. He also simplified the process programming, see [1] for the details. However there are still some difficulties. A followup SSP project [2] in 2000 by Derrick Pisani attempted to put some of these things right but the progress made was somewhat limited. The main achievement of this visit was extensive JavaDoc documentation of the code. Some more problems with the existing code were noted and the code was tidied up somewhat.

In this 2001 project proposal we hope to remedy some of the perceived problems with the existing applet and go on, if time allows, to further improve and extend the code. The planned extension to the existing applet should allow the student to familiarise themselves with the Java application. As all the components are constructed as Java Beans it should be possible to extend this framework without too much difficulty.

[1] Tom's project summary can be found at: 1998/ProjectSummary/doel.html.

[2] Derrick's project summary can be found at: 2000/ProjectSummary/pisani.html

To start off with we would like the following modified within the existing applet:

• The Sellic applet visualises message exchanges in point-to-point communications by using an envelope representation that travels from the sending to the receiving process. Tom added collective communications. He added a buffer to the process bean and used this to visualise the collective operation process. Thus the collective operation is represented by a data exchange (without any envelopes). In the original sellic representation there is no data exchange so exchanging message does not modify the buffers. This to say the least is confusing. The first task would be to modify both mechanisms to be consistent.
• The visual design of the GUI could be changed. At present AWT classes are used - incorporating the Java foundation classes may clean the GUI and enable it to be generalised.
• Find some way of making the programming easier - it is not intuitive what has to be done. Also coming up with a `work' representation to establish the fact that the processor is doing work would make it clearer to establish non-blocking communications. A gear wheel moving round might do this job. Also adding a collective operation on one process has to be repeated across all process. This is potentially misleading, never mind tedious.

This should be enough to give us a better applet to use in the future. It should also hopefully give the student a good idea of how the underlying applet works. All of the components in this applet are based on Java beans so there is no reason as to why this should not be generalisable. The possibility we see is the following:

create a drag and drop interface using the Java f
• create a drag and drop interface using the Java foundation classes.
• on the left frame MPI programming elements will be found. These can be picked up and dragged to the canvas on the right. The first component you would pick up would be an MPI_Init block. When this is dropped on the canvas a pop up will ask how many processors. The user will select an appropriate number and then these will be set up on the canvas.
• subsequent programming will take place by grabbing other MPI blocks from the left pane and dropping these on top of each of the processes (a representation for viewing the programming flow would have to be found). Work blocks could also be added. Each time a block is dropped an appropriate dialogue will ask the student for the appropriate information.
• The number of MPI blocks produced will depend on the time remaining.

As the existing applets have been constructed using Java beans it should not be overly difficult to implement this framework using the existing beans. It is felt that this might present a much more intuitive (and easier) approach to programming the applet for the user.

Timetable:
Week 1: Meet everyone / Courses
Week 2: Courses / Evaluate applet
Weeks 3-4: Make communication exchange representations consistent
Weeks 5-9: Implement some of the recommendations
Week 10: Write up report, produce poster

Essential: Java

Preferred: JavaBeans, MPI, Swing, AWT

Essential: Introduction to High Performance Computing
Writing Message Passing Programs with MPI
Preferred: Practical Software Development (Day 1, tools) MPI-2: New Developments in MPI

Essential: Java SDK

Preferred: Access to range of browsers/machines to test applet

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