1. MARTIN P. ROBILLARD, McGill University, Canada ACM Transactions on Software Engineering and Methodology (TOSEM), vol. 17, no. 4, August 2008 Presented by Celal Ziftci, University of California San Diego CSE-294@UCSD-Spring’10 May 21 2010

2.  Part of this presentation explains the journal paper as it stands, however I have added model-driven-development as a motivation and suggestions to make use of the paper’s approach in a model-driven-development context.

3.  Motivation ◦ w.r.t. MDD ◦ Example  Approach ◦ Heuristics ◦ Definitions ◦ Sample run on our example ◦ Case-study results  Why do we care?

4.  Hopefully, a system has proper models that represent it in a true sense for round-trip engineering ◦ We can associate models to code ◦ We can associate code to models  But reality is not always so in many real-life projects… ◦ Many legacy systems have code, but no models  If MDD was used up-start, this would not happen, but here we are now…  So, what do we do, if we need to make changes to/understand the system ◦ Fixing a bug ◦ Adding new functionality ◦ New programmer in the team

5.  Big systems have so many lines of code ◦ Software running in a car  10 million lines of code  10 ECUs communicating with each other  For our use-case, let us pick a simplified car ◦ Our focus: Understanding acceleration & braking

9.  Note that, in our case, we start from source code…  We would like to explore parts of code that lead to the part we are interested in step-by-step: in waves  Can’t we do this in tools like Eclipse IDE already? ◦ Yes and No… ◦ Yes:  Eclipse can show all code paths leading to a method/field ◦ No:  No ranking in the relevancy of results  No extra custom dependencies (for eg. who writes to a field?)

10. Adapted from [1]

11.  Specificity  Reinforcement 6 is more specific 2 is more specific 6 is reinforced 2 is reinforced [1]

13.  Consider a specific relation: called-by called-by called-by T = called

14.   A: S forward ={c,d,e} ◦ c: S backward ={A} ◦ d: S backward ={A} ◦ e: S backward ={A, B, f}  B: S forward ={e} ◦ e: S backward ={A, B, f}  degree c = 0.76 * 0.75 = 0.57  degree d = 0.76 * 0.75 = 0.57  degree e = max(0.69 * 0.75, 0.9 * 0.25) = 0.52  [1]

15.  We did the sample run for called-by dependency.  Same calculations done for other dependencies as well (for eg accessed-by for fields)  All the suggestion sets are combined using fuzzy sets (similar to what we did in our example)

16.  And more similar results… [1]

17.  This tool (and other similar ones) makes it easier to follow the approach effective developers were observed to follow [2]. ◦ As the developer uses this tool in waves, the tool can record which elements were chosen to be worthy of interest and further investigation. ◦ Then, the tool can generate models out of the relationships between those elements automatically ◦ The developer already investigated and marked what is relevant, and the tool saves him from the burden of creating a model that explains what he did already.  Using this approach, we can do round-trip engineering. ◦ Even if we go the forward direction (models to code), we can use this approach to check if what we believe to exist in code is the reality

18.  Thank you! Now any further questions?

19.  [1] Robillard, M. P. 2008. Topology analysis of software dependencies. ACM Trans. Softw. Eng. Methodol. 17, 4 (Aug. 2008), 1-36. DOI=http://doi.acm.org/10.1145/13487689. 13487691  [2] Robillard,M. P.,Coelho,W., Andmurphy,G. C. 2004. How effective developers investigate sourcecode: An exploratory study. IEEE Trans. Softw. Engin. 30, 12, 889–903.