Revision as of 17:52, 16 May 2006

This is the Debug Model Sub-group

Lead: Pawel Piech (Wind River)
Members: Mikhail Khodjaiants (QNX), Freescale, Nokia

Requirements discussion

Introduction

I really don't know how it's possible to start a requirements discussion without having a specific problem or use case to be solved. What generally happens in these situations, is that a set of adjectives are listed that are so un-specific that they are impossible to take an action upton: "scalable", "flexible", "responsive", etc. On the other extreme, if everyone comes to the table and describes their specific problem that they are trying to solve, the discussion tends to drift towards completely irrelevant topics and often goes to try to solve conflicting problems that aren't even in the scope of the original architecture.

So I propose a third approach to this discussion, which I think might be a lot more fun than describing intricate details of everyone's debugger. Let's define a completely theoretical debugger problem, one that we can use to represent all of the different types of problems that we have to solve for our very different debuggers. We don't necessarily have to try to roll all of our different and sometimes divergent problems into one theoretical model, we could have many different versions of the model, and then try to apply our solution to fit these different needs. As we introduce features into this model, we could tie these into specific requirements that we already have defined for our products. Hopefully this will be a lot more fun than a traditional technical discussion.

Debugger for citizen monitoring system in George Orwell's 1984

For those unfamiliar with the book. In 1984, the citizen of Oceania live under the constant watchful eye of the Party and its leader Big Brother. The Party has mandated that all citizen have a telescreen installed in their private home, as well as in all public spaces in Oceania. The telescreens are both a camera through which a party official could be looking, and a display monitor through which messages could be sent to the individual citizen.

Designing the monitoring system was a formidable task, Oceania is a huge nation of hundreds of milions of citizen, and only 15% of this population are members of the Party, and of those 15%, only a small fraction are in the Inner Party who are trusted enough to be monitoring citizen and other Party members. So most of the work of the monitoring system falls onto the automated monitoring system, based on latest microprocessor designs no doubt, which looks at everyone through all telescreens all the time and watches for signs of thoughtcrime.

We would like to design a debugger which will help us debug the telescreen monitoring system within our Eclipse-based debugger. And based on the information so far, we can already draw up some requirements that our debug model will have to meet:

• There should be no assumptions about the number of objects that the debugger might need to track. In Oceania, there are hundreds of millions of citizen and there are just as many telescreens.
• The debugger views need to be able to rely on the external debugger process to perform filtering and sorting of the data to be presented to the user. There is a powerful database computer somewhere deep within the headquaters of Thought Police, that performs the tasks of sorting, filtering lists of citizen, there is no way that a simple PC could store this much information, much less to process all of it.