Tegawendé F. Bissyandé

Empirical Evaluation of Bug Linking

To collect software bugs found by users, development teams often set up bug trackers using systems such as Bugzilla. Developers would then fix some of the bugs and commit corresponding code changes into version control systems such as svn or git. Unfortunately, the links between bug reports and code changes are missing for many software projects as the bug tracking and version control systems are often maintained separately. Yet, linking bug reports to fix commits is important as it could shed light into the nature of bug fixing processes and expose patterns in software management. Bug linking solutions, such as ReLink, have been proposed. The demonstration of their effectiveness however faces a number of issues, including a reliability issue with their ground truth datasets as well as the extent of their measurements. We propose in this study a benchmark for evaluating bug linking solutions. This benchmark includes a dataset of about 12,000 bug links from 10 programs. These true links between bug reports and their fixes have been provided during bug fixing processes. We designed a number of research questions, to assess both quantitatively and qualitatively the effectiveness of a bug linking tool. Finally, we apply this benchmark on ReLink to report the strengths and limitations of this bug linking tool.

Bridging the gap between legacy services and web services

Web Services is an increasingly used instantiation of Service-Oriented Architectures (SOA) that relies on standard Internet protocols to produce services that are highly interoperable. Other types of services, relying on legacy application layer protocols, however, cannot be composed directly. A promising solution is to implement wrappers to translate between the application layer protocols and the WS protocol. Doing so manually, however, requires a high level of expertise, in the relevant application layer protocols, in low-level network and system programming, and in the Web Service paradigm itself. In this paper, we introduce a generative language based approach for constructing wrappers to facilitate the migration of legacy service functionalities to Web Services. To this end, we have designed the Janus domain-specific language, which provides developers with a high-level way to describe the operations that are required to encapsulate legacy service functionalities. We have successfully used Janus to develop a number of wrappers, including wrappers for IMAP and SMTP servers, for a RTSP-compliant media server and for UPnP service discovery. Preliminary experiments show that Janus-based WS wrappers have performance comparable to manually written wrappers.

Adoption of Software Testing in Open Source Projects--A Preliminary Study on 50,000 Projects

In software engineering, testing is a crucial activity that is designed to ensure the quality of program code. For this activity, development teams spend substantial resources constructing test cases to thoroughly assess the correctness of software functionality. What is however the proportion of open source projects that include test cases? What kind of projects are more likely to include test cases? In this study, we explore 50,000 projects and investigate the correlation between the presence of test cases and various project development characteristics, including the lines of code and the size of development teams.

Leveraging the Cultural Model for Opportunistic Networking in Sub-Saharan Africa

The immense potential of ICT for improving users’ livelihood has been discussed in a large body of literature and many instantiations in our daily life demonstrate this reality. In developing areas, such as Sub-Saharan Africa, ICT for development has become the frontrunner initiative that decision makers are pushing to bring millions of people out of poverty. Unfortunately, the majority of Africans, who live in rural areas, fail to identify with the existing various solutions.

Diagnosys: automatic generation of a debugging interface to the Linux kernel

The Linux kernel does not export a stable, well-defined kernel interface, complicating the development of kernel-level services, such as device drivers and file systems. While there does exist a set of functions that are exported to external modules, this set of functions frequently changes, and the functions have implicit, ill-documented preconditions. No specific debugging support is provided. We present Diagnosys, an approach to automatically constructing a debugging interface for the Linux kernel. First, a designated kernel maintainer uses Diagnosys to identify constraints on the use of the exported functions. Based on this information, developers of kernel services can then use Diagnosys to generate a debugging interface specialized to their code. When a service including this interface is tested, it records information about potential problems. This information is preserved following a kernel crash or hang. Our experiments show that the generated debugging interface provides useful log information and incurs a low performance penalty.

Typhoon: a middleware for epidemic propagation of software updates

Applications for mobiles devices are subject to very frequent updates for fixing security vulnerabilities, ensuring compatibility with new hardware and APIs or enhancing functionalities. Getting the new version of an application involves the download of a significant amount of data, which is not practical through low-bandwidth/high-cost links. As a consequence, mobile device users often fail to update their applications. This paper introduces a collaborative and epidemic updating scheme to improve software updates distribution. In our approach, updates are distributed by the surrounding devices, eliminating the need for costly resources. Moreover, the packaging of these updates, which consists in delivering binary patches of the difference with a previous version, dramatically reduces the amount of data to download. Preliminary experimental results based on real contact traces show that our approach offers an efficient selection and recovery of patches, ensuring a fast update for each participating device.

UbiGate: a gateway to transform discovery information into presence information

Pervasive computing involves various entities which need to coordinate tasks and share resources through different service discovery protocols. However, the multiplicity and the incompatibility of those protocols have made interconnectivity problematic. Moreover, most service discovery protocols require a strong participation of users to genuinely play their part. Consequently, service discovery in a pervasive environment has become a challenge that researchers as well as practitioners have tried to overcome through various approaches. Nevertheless, existing solutions mostly consist of designing new protocols which usually address specific application needs while participating in the increase of heterogeneity. To address these problems, we present a new paradigm for service discovery involving the use of a gateway, called UbiGate, and relying on SIP, a widespread signaling protocol. Centered around the notion of presence, UbiGate enables real time availability of service information while hiding the heterogeneity of underlying protocols. We have developed a prototype of UbiGate supporting service discovery protocols such as the protocol used in Bluetooth service discovery mechanism and a protocol enabling the detection mechanism of RFID. Preliminary results show that UbiGate enables new service discovery protocols, either IP or non-IP based, to be seamlessly supported with no significant overhead in discovery latency.

Improving the performance of message parsers for embedded systems

Supporting standard text-based protocols in embedded systems is challenging because of the often limited computational resources that embedded systems provide. To overcome this issue, a promising approach is to build parsers directly in hardware. Unfortunately, developing such parsers is a daunting task for most developers as it is at the cross-roads of several areas of expertise, such as low-level network programming, or hardware design. In this paper, we propose Zebra, a generative approach to drastically ease the development of hardware parsers and their use in network applications. To validate our approach, we have used Zebra to generate hardware parsers for widely used protocols, namely HTTP, SMTP, SIP, and RTSP. Our experiments show that Zebra-based parsers systematically outperform software-based parsers.