Our work on exploiting data regions with local properties to create better software defect and effort prediction models has won the Best Paper award at the MSR’2012 conference!

Abstract – Much research energy in software engineering is focused on the creation of effort and defect prediction models. Such models are important means for practitioners to judge their current project situation, optimize the allocation of their resources, and make informed future decisions. However, soft- ware engineering data contains a large amount of variability. Recent research demonstrates that such variability leads to poor fits of machine learning models to the underlying data, and suggests splitting datasets into more fine-grained subsets with similar properties. In this paper, we present a comparison of three different approaches for creating statistical regression models to model and predict software defects and development effort. Global models are trained on the whole dataset. In contrast, local models are trained on subsets of the dataset. Last, we build a global model that takes into account local characteristics of the data. We evaluate the performance of these three approaches in a case study on two defect and two effort datasets. We find that for both types of data, local models show a significantly increased fit to the data compared to global models. The substantial improvements in both relative and absolute prediction errors demonstrate that this increased goodness of fit is valuable in practice. Finally, our experiments suggest that trends obtained from global models are too general for practical recommendations. At the same time, local models provide a multitude of trends which are only valid for specific subsets of the data. Instead, we advocate the use of trends obtained from global models that take into account local characteristics, as they combine the best of both worlds.

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Reference:

@inproceedings{bettenburg:msr2012,
 author={Nicolas Bettenburg and Meiyappan Nagappan and Ahmed E. Hassan},
 booktitle={MSR '12: Proceedings of the 9th Working Conference on Mining Software Repositories},
 title={Think Locally, Act Globally: Improving Defect and Effort Prediction Models},
 year={2012},
 pages={60-69},
 publisher={IEEE},
 location={Zürich, Switzerland}}

Our work on using clone detection methods to discover which parts of the source code of a software system developers frequently discuss has been accepted for publication at the 2012 European Conference on Software Maintenance and Reengineering (CSMR’12)!

Abstract – When discussing software, practitioners often reference parts of the project’s source code. Such references have different motivations, such as mentoring and guiding less experienced developers, pointing out code that needs changes, or proposing possible strategies for the implementation of future changes. The fact that particular parts of a source code are being discussed makes these parts of the software special. Knowing which code is being talked about the most can not only help practitioners to guide important software engineering and maintenance activities, but also act as a high-level documentation of development activities for managers. In this paper, we use clone-detection as specific instance of a code search based approach for establishing links between code fragments that are discussed by developers and the actual source code of a project. Through a case study on the Eclipse project we explore the traceability links established through this approach, both quantitatively and qualitatively, and compare fuzzy code search based traceability linking to classical approaches, in particular change log analysis and information retrieval. We demonstrate a sample application of code search based traceability links by visualizing those parts of the project that are most discussed in issue reports with a Treemap visualization. The results of our case study show that the traceability links established through fuzzy code search-based traceability linking are conceptually different than classical approaches based on change log analysis or information retrieval.

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Copyright © by ADD_PUBLISHER_HERE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author’s copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.

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Reference:

@inproceedings{bettenburg:csmr2012,
 author={Nicolas Bettenburg and Stephen W. Thomas and Ahmed E. Hassan},
 booktitle={CSMR '12: Proceedings of the 16th European Conference on Software Maintenance and Reengineering},
 title={Using Code Search to Link Code Fragments in Discussions and Source Code},
 year={2012},
 pages={319-329},
 publisher={IEEE},
 location={Szeged, Hungary}}

I am pleased to announce that I will be presenting my PhD research at the Doctoral Symposium track of the 19th ACM SIGSOFT International Symposium on Foundations of Software Engineering (FSE’2011), which will this year take place in Hungary.

Abstract – Software development is a largely collaborative effort, of which the actual encoding of program logic in source code is a relatively small part. Yet, little is known about the impact of collaboration between stakeholders on software quality. We hypothesize that the collaboration between stakeholders during software development has a non-negligible impact on the software system. Information about collaborative activities can be recovered from traces of their communication, which are recorded in the repositories used for the development of the software system. This thesis contributes the following: 1) to make this information accessible for practitioners and researchers, we present approaches to distill communication information from development repositories, and empirically validate our proposed extractors. 2) By linking back the extracted communication data to the parts of the software system under discussion, we are able to empirically study the impact of communication, as a proxy to collaboration between stakeholders, on a software system. Through case studies on a broad spectrum of open-source software projects, we demonstrate the important role of social interactions between stakeholders with respect to the evolution of a software system.

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Publisher: ACM.
Copyright © by ACM. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author’s copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.

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Reference:

@inproceedings{Bettenburg:2011:MDR:2025113.2025165,
   author = {Bettenburg, Nicolas},
   title = {Mining development repositories to study the impact of collaboration on software systems},
   booktitle = {Proceedings of the 19th ACM SIGSOFT symposium and the 13th European conference on Foundations of software engineering},
   series = {ESEC/FSE '11},
   year = {2011},
   isbn = {978-1-4503-0443-6},
   location = {Szeged, Hungary},
   pages = {376--379},
   numpages = {4},
   url = {http://doi.acm.org/10.1145/2025113.2025165},
   doi = {10.1145/2025113.2025165},
   acmid = {2025165},
   publisher = {ACM},
   address = {New York, NY, USA},
   keywords = {collaboration, empirical studies, socio-technical congruence, software repositories, unstructured data}
}

I am pleased to announce, that our paper “A Lightweight Approach To Uncover Technical Information in Unstructured Data” has been accepted for publishing at the 19th IEEE International Conference on Program Comprehension (ICPC’11), which will this year take place in lovely Kingston, Ontario, Canada.

Abstract – Developer communication through email, chat, or issue report comments consists mostly of largely unstructured data, i.e., natural language text, mixed with technical artifacts such as project-specific jargon, abbreviations, source code patches, stack traces and identifiers. These technical artifacts represent a valuable source of knowledge on the technical part of the system, with a wide range of applications from establishing traceability links to creating project-specific vocabularies. However, the lack of well-defined boundaries between natural language and technical content make the automated mining of technical artifacts challenging. As a first step towards a general-purpose technique to extracting technical artifacts from unstructured data, we present a lightweight approach to untangle technical artifacts and natural language text. Our approach is based on existing spell checking tools, which are well-understood, fast, readily available across platforms and impartial to different kinds of textual data. Through a handcrafted benchmark, we demonstrate that our approach is able to successfully uncover a wide range of technical artifacts in unstructured data.

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Publisher: IEEE.
Copyright © by IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author’s copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.

[I AGREE - DOWNLOAD PDF]

Reference:

@inproceedings{DBLP:conf/iwpc/BettenburgAHS11,
  author    = {Nicolas Bettenburg and
               Bram Adams and
               Ahmed E. Hassan and
               Michel Smidt},
  title     = {A Lightweight Approach to Uncover Technical Artifacts in
               Unstructured Data},
  booktitle = {ICPC},
  year      = {2011},
  pages     = {185-188},
  ee        = {http://doi.ieeecomputersociety.org/10.1109/ICPC.2011.36},
  crossref  = {DBLP:conf/iwpc/2011},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}

@proceedings{DBLP:conf/iwpc/2011,
  title     = {The 19th IEEE International Conference on Program Comprehension,
               ICPC 2011, Kingston, ON, Canada, June 22-24, 2011},
  booktitle = {ICPC},
  publisher = {IEEE Computer Society},
  year      = {2011},
  isbn      = {978-1-61284-308-7},
  ee        = {http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=5968117},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}

Wonderful news! My application for the 2011-2012 OGS was successful! I wasn’t really counting on winning this scholarship for a second year in a row, as competition is extremely strong – especially in the category of international graduate students.

I am pleased to announce that we received notification today that the Journal of Science of Computer Programming (SCICO) has accepted our paper “An Empirical Study on Inconsistent Changes to Code Clones at Release Level” for print.

The electronic version is available under DOI:10.1016/j.scico.2010.11.010
or by following this link.

I’ll be giving a talk at the 2010 Fall Meeting of the Canadian Consortium for Software Engineering Research (CSER) on “Managing Community Contributions: Lessons Learned from a Case Study on Android and Linux”.

Abstract – Modern companies realize that collaboration with a thriving community is important for creating innovative technology driven by market demand, and have sought ways to stimulate contributions from outsiders into their development process. There are multiple contribution styles, with varying levels of community involvement, but most companies are only familiar with closed contribution (via NDAs). This paper/talk aims at supporting software companies in assessing whether integrating community contributions into their software development is worthwhile, and determining processes and practices involved. We perform an empirical study on one for-profit (Android) system and compare our findings to a non-for-profit (Linux) system. We find that Android, even though being a for-profit system with a more closed contribution style, is similarly successful as Linux in attracting a growing community that makes significant contributions to major subsystems of the software.

Parsing through the list of PostgreSQL 9.0 release notes, we counted how many contributions each developer named made to get this release up and going. Top contributor by large is Tom Lane, who we also found in previous studies to be one of the most active and central members of the project. Surprisingly, we also see this time that many contributions to the latest version have been made by developers outside the core member team – demonstrating that the project is once again successful in attracting members from the open source community.

Parsed from http://developer.postgresql.org/pgdocs/postgres/release-9-0.html

What were their contributions about?

Tom Lane:

Peter Eisentraut:

Bruce Momjian:

Who contributed the most overall?

Here is the list, ordered by most contributions:

66 Tom Lane
25 Peter Eisentraut
19 Itagaki Takahiro
16 Robert Haas
16 Bruce Momjian
9 Pavel Stehule
7 Tim Bunce
7 Teodor Sigaev
7 Boszormenyi Zoltan
5 Andrew Dunstan
4 Michael Meskes
4 Magnus Hagander
4 Heikki Linnakangas
4 Fujii Masao
4 Andrew Gierth
3 Simon Riggs
3 Petr Jelinek
3 Joachim Wieland
3 Andres Freund
2 Roger Leigh
2 Leonardo F
2 Kurt Harriman
2 KaiGai Kohei
2 John Naylor
2 Hitoshi Harada
2 Greg Stark
2 Caleb Welton
2 Bernd Helmle
2 Alvaro Herrera
2 Alex Hunsaker
1 Zdenek Kotala
1 Tsutomu Yamada
1 Tollef Fog Heen
1 Taro Minowa Higepon
1 Steve Prentice
1 Stef Walter
1 Sergey Karpov
1 Robert Fleming
1 Nobuhiro Iwamatsu
1 Michael Paquier
1 Marko Tiikkaja
1 Marko Kreen
1 Mark Cave-Ayland
1 Marcus Kempe
1 Laurenz Albe
1 Khee Chin
1 Kevin Grittner
1 Joshua Tolley
1 Jim Cox
1 Jeremy Kerr
1 Jeff Davis
1 Hiroshi Inoue
1 Hannu Valtonen
1 Guillaume Smet
1 Guillaume Lelarge
1 Greg Smith
1 Greg Sabino Mullane
1 Emmanuel Cecchet
1 Distinguished Name
1 Dean Rasheed
1 Dave Page
1 Damien Clochard
1 Craig Ringer
1 Brendan Jurd
1 Alexey Klyukin
1 Abhijit Menon-Sen