Self-organization of teams for free/libre open source software development

This paper provides empirical evidence about how free/libre open source software development teams self-organize their work, specifically, how tasks are assigned to project team members. Following a case study methodology, we examined developer interaction data from three active and successful FLOSS projects using qualitative research methods, specifically inductive content analysis, to identify the task-assignment mechanisms used by the participants. We found that ‘self-assignment’ was the most common mechanism across three FLOSS projects. This mechanism is consistent with expectations for distributed and largely volunteer teams. We conclude by discussing whether these emergent practices can be usefully transferred to mainstream practice and indicating directions for future research.     

Survival analysis on the duration of open source projects

ContextOpen source (FLOSS) project survivability is an important piece of information for many open source stakeholders. Coordinators of open source projects would like to know the chances for the survival of the projects they coordinate. Companies are also interested in knowing how viable a project is in order to either participate or invest in it, and volunteers want to contribute to vivid projects.ObjectiveThe purpose of this article is the application of survival analysis techniques for estimating the future development of a FLOSS project.MethodIn order to apply such approach, duration data regarding FLOSS projects from the FLOSSMETRICS (This work was partially supported by the European Community’s Sixth Framework Program under the Contract FP6-033982) database were collected. Such database contains metadata for thousands of FLOSS projects, derived from various forges. Subsequently, survival analysis methods were employed to predict the survivability of the projects, i.e. their probability of continuation in the future, by examining their duration, combined with other project characteristics such as their application domain and number of committers.ResultsIt was shown how probability of termination or continuation may be calculated and how a prediction model may be built to upraise project future. In addition, the benefit of adding more committers to FLOSS projects was quantified.ConclusionAnalysis results demonstrate the usefulness of the proposed framework for assessing the survival probability of a FLOSS project.     

Identifying exogenous drivers and evolutionary stages in FLOSS projects

The success of a Free/Libre/Open Source Software (FLOSS) project has been evaluated in the past through the number of commits made to its configuration management system, number of developers and number of users. Most studies, based on a popular FLOSS repository (SourceForge), have concluded that the vast majority of projects are failures.This study’s empirical results confirm and expand conclusions from an earlier and more limited work. Not only do projects from different repositories display different process and product characteristics, but a more general pattern can be observed. Projects may be considered as early inceptors in highly visible repositories, or as established projects within desktop-wide projects, or finally as structured parts of FLOSS distributions. These three possibilities are formalized into a framework of transitions between repositories.The framework developed here provides a wider context in which results from FLOSS repository mining can be more effectively presented. Researchers can draw different conclusions based on the overall characteristics studied about an Open Source software project’s potential for success, depending on the repository that they mine. These results also provide guidance to OSS developers when choosing where to host their project and how to distribute it to maximize its evolutionary success.     

Effort estimation of FLOSS projects: a study of the Linux kernel

Empirical research on Free/Libre/Open Source Software (FLOSS) has shown that developers tend to cluster around two main roles: “core” contributors differ from “peripheral” developers in terms of a larger number of responsibilities and a higher productivity pattern. A further, cross-cutting characterization of developers could be achieved by associating developers with “time slots”, and different patterns of activity and effort could be associated to such slots. Such analysis, if replicated, could be used not only to compare different FLOSS communities, and to evaluate their stability and maturity, but also to determine within projects, how the effort is distributed in a given period, and to estimate future needs with respect to key points in the software life-cycle (e.g., major releases). This study analyses the activity patterns within the Linux kernel project, at first focusing on the overall distribution of effort and activity within weeks and days; then, dividing each day into three 8-hour time slots, and focusing on effort and activity around major releases. Such analyses have the objective of evaluating effort, productivity and types of activity globally and around major releases. They enable a comparison of these releases and patterns of effort and activities with traditional software products and processes, and in turn, the identification of company-driven projects (i.e., working mainly during office hours) among FLOSS endeavors. The results of this research show that, overall, the effort within the Linux kernel community is constant (albeit at different levels) throughout the week, signalling the need of updated estimation models, different from those used in traditional 9am–5pm, Monday to Friday commercial companies. It also becomes evident that the activity before a release is vastly different from after a release, and that the changes show an increase in code complexity in specific time slots (notably in the late night hours), which will later require additional maintenance efforts.     

Free/libre open source software implementation in schools: Evidence from the field and implications for the future

This empirical paper shows how free/libre open source software (FLOSS) contributes to mutual and collaborative learning in an educational environment. Unlike proprietary software, FLOSS allows extensive customisation of software to support the needs of local users better. This also allows users to participate more proactively in the development and implementation process of a FLOSS-based system. In this paper, we observes how implementing FLOSS in an Italian high school challenges the conventional relationship between end users themselves (e.g. teachers and students) and that between users and developers. The findings will shed some light on the social aspects of FLOSS-based computerization – including the role of FLOSS in social and organizational change in educational environments and the ways that the social organization of FLOSS are influenced by social forces and social practices.     

2020自由开源软件发展蓝图综述*

对开源世界论坛2008及其2020发展自由开源软件（FLOSS）发展蓝图的起源及其主要内容进行了简明扼要的述评和分析,包括七条预言、八条关键建议、五大重要事件及其2009年的工作计划。提出了应对未来挑战的八条建议,即营造FLOSS生态环境、重视FLOSS标准工作、投资FLOSS研究和开发、挖掘典型FLOSS应用、建立FLOSS公共平台、鼓励FLOSS社区、发展FLOSS教育、培训和弘扬FLOSS精神。     

How do architecture patterns and tactics interact? A model and annotation

Software architecture designers inevitably work with both architecture patterns and tactics. Architecture patterns describe the high-level structure and behavior of software systems as the solution to multiple system requirements, whereas tactics are design decisions that improve individual quality attribute concerns. Tactics that are implemented in existing architectures can have significant impact on the architecture patterns in the system. Similarly, tactics that are selected during initial architecture design significantly impact the architecture of the system to be designed: which patterns to use, and how they must be changed to accommodate the tactics. However, little is understood about how patterns and tactics interact. In this paper, we develop a model for the interaction of patterns and tactics that enables software architects to annotate architecture diagrams with information about the tactics used and their impact on the overall structure. This model is based on our in-depth analysis of the types of interactions involved, and we show several examples of how the model can be used to annotate different kinds of architecture diagrams. We illustrate the model and annotation by showing examples taken from real systems, and describe how the annotation was used in architecture reviews. Tactics and patterns are known architectural concepts; this work provides more specific and in-depth understanding of how they interact. Its other key contribution is that it explores the larger problem of understanding the relation between strategic decisions and how they need to be tailored in light of more tactical decisions.     

Assessing the health of open source communities

Before contributing to a free or open source software project, understand the developers, leaders, and active users behind it. The computing world lauds many Free/Libre and open source software offerings for both their reliability and features. Successful projects such as the Apache httpd Web server and Linux operating system kernel have made FLOSS a viable option for many commercial organizations. While FLOSS code is easy to access, understanding the communities that build and support the software can be difficult. Despite accusations from threatened proprietary vendors, few continue to believe that open source programmers are all amateur teenaged hackers working alone in their bedrooms. But neither are they all part of robust, well-known communities like those behind Apache and Linux.     

Tactics based approach for integrating non-functional requirements in object-oriented analysis and design

Non-Functional Requirements (NFRs) are rarely treated as “first-class” elements in software development as Functional Requirements (FRs) are. Often NFRs are stated informally and incorporated in the final software as an after-thought. We leverage existing research work for the treatment of NFRs to propose an approach that enables to systematically analyze and design NFRs in parallel with FRs. Our approach premises on the importance of focusing on tactics (the specific mechanisms used to fulfill NFRs) as opposed to focusing on NFRs themselves. The advantages of our approach include filling the gap between NFRs elicitation and NFRs implementation, systematically treating NFRs through grouping of tactics so that tactics in the same group can be addressed uniformly, remedying some shortcomings in existing work (by prioritizing NFRs and analyzing tradeoff among NFRs), and integration of FRs and NFRs by treating them as first-class entities.     

开源软件开发者的演化研究

开源软件的开发主要依靠开发人员的自我管理和志愿贡献。在软件开发过程中,开发人员的组成、分工、能力等会发生经常性的改变,这些改变都会通过交互行为的变化反映出来。已有研究成果表明开源软件存在核心团队,他们主导项目的开发与实施,但对开发团队随时间而发生的结构变化的研究较少。通过观测软件项目生命周期中开发者总体的变化情况,研究了开发者网络与软件的协同演化机理,以GNU/Linux公共数据集为例,讨论了开源软件开发者数量、自愿度、开发者经验与项目的协同演化现象,并给出了演化的合理解释。     

A longitudinal study of development and maintenance

ContextThe information systems we see around us today are at first sight very different from those that were developed 15 years ago and more. On the other hand, it seems that we are still struggling with many of the same problems, such as late projects and unfulfilled customer demands.ObjectiveThe paper presents finding relative to the distribution of work between maintenance and development tasks, comparing to the results reported earlier to assess the stability of important metrics within the area.MethodThis paper presents the main results of a survey-investigation performed in 2008 in 67 Norwegian organizations comparing the distribution of work to results from similar investigations performed in Norway in 1993, 1998, and 2003. Some comparisons to similar investigations performed in USA before this is also provided.ResultsThe amount of application portfolio upkeep (work made to keep up the functional coverage of the application system portfolio of the organization, including the development of replacement systems), is at the same level as reported in 1998 and 2003. The level of application maintenance is also on the same level as the similar investigations conducted in 2003 and 1998. There was a significant increase in both maintenance and application portfolio upkeep from 1993 to 1998, which could partly be attributed to be the extra maintenance and replacement-oriented work necessary to deal with the “year 2000 problem”, but this seemed to be reversed in 2003 and 2008. As for the 2003 investigation, the slow IT-market in general seemed to have influenced the results negatively seen from the point of view of application systems support efficiency in organization. No similar explanation can be used for the 2008 numbers.ConclusionBased on the last surveys it seems than a stable level of work distribution both on maintenance and application portfolio upkeep have been reached, although the underlying development technologies are still undergoing large changes. This is contrary to others claiming that the amount of maintenance is still increasing.     

Designing,visualizing, and discussing algorithms within a CS 1 studio experience: An empirical study

Within the context of an introductory CS1 unit on algorithmic problem-solving, we are exploring the pedagogical value of a novel active learning activity—the “studio experience”—that actively engages learners with algorithm visualization technology. In a studio experience, student pairs are tasked with (a) developing a solution to an algorithm design problem, (b) constructing an accompanying visualization with a storyline, and finally (c) presenting that visualization for feedback and discussion in a session modeled after an architectural “design crit.” Is a studio experience educationally valuable? What kind of technology can best support it? To explore these questions, we conducted an empirical study of two alternative CS1 studio experiences in which students used one of two different kinds of algorithm development and visualization technology: (a) a text editor coupled with art supplies, or (b) ALVIS Live!, a computer-based algorithm development and visualization tool. We found that the students who used ALVIS Live! developed algorithms with significantly fewer semantic errors. Moreover, discussions mediated by ALVIS Live! had significantly more student audience contributions, and retained a sharper focus on the specific details of algorithm behavior, leading to the collaborative identification and repair of semantic errors. In addition, discussions mediated by both ALVIS Live! and art supplies contained substantial evidence of higher order thinking. Based on our results, we make recommendations for educators interested in exploring studio-based approaches, and we propose an agenda for future research into studio-based learning in computer science education.     

Automatic recommendation to appropriate log levels

A log statement is one of the key tactics for a developer to record and monitor important run-time behaviors of our system in a development phase and a maintenance phase. It composes of a message for stating log contents, and a log level (eg, debug or warn) to denote the severity of a message and controlling its visibility at run time. In spite of its usefulness, a developer does not tend to deeply consider which log level is appropriate in writing source code, which causes the system to be unmaintainable. To address this issue, this paper proposes an automatic approach to validating the appropriateness of the log level in consideration of the semantic and syntactic features and recommending a proper alternative log level. We first build the semantic feature vector to quantify the semantic similarity among application log messages using the word vector space, and the syntactic feature vector to capture the application context that surrounds the log statement. Based on the feature vectors and machine learning techniques, the log level is automatically validated, and an alternative log level is recommended if the log level is invalid. For the evaluation, we collected 22 open-source projects from three application domains, and obtained the 77% of precision and 75% of recall in validating the log levels. Also, our approach showed 6% higher accuracy than that of the developer group who has 7 to 8 years of work experience, and 72% of the developers accepted our recommendation.     

面向零售业的精准营销与维系系统

针对零售业的特点, 在国内某零售商集团公司的需求基础上提炼总结出一套精准营销与维系系统的解决方案, 在构建数据集市的基础上实现了整套方案, 经过实践后取得了较好的效果, 设计的基于业务组件的可插拔式开发架构在其他的项目中得到广泛的使用, 即节省了大量的人力物力, 也加快了开发速度.     

Organizing Projects Around the Mitigation of Risks Arising from System Dynamic Behavior

Many of the key products and services used by modern societies are the result of large-scale engineering projects. Despite decades of theoretical and practical work in the art of systems engineering and project management, project execution results remain somewhat inconsistent, in the sense that many projects fail to produce a product that meets the original specifications, and many more projects achieve some measure of technical success only after taking significantly more time and/or money than originally expected. One source of such failures is the occurrence of unplanned and adverse dynamic behavior in the resulting system. This paper summarizes research being conducted to look at the potential of design-phase actions that centralize control of the eventual system''s dynamic behavior as a potential solution to some instances of this problem. This approach could lead to increased chances of success on future major system development projects, through a new method for instituting better control of the dynamic behavior of such a system.     

An extension of secure group communication using key graph

With the continuously emerging of Internet applications based on secure group communication, the design of secure group communication becomes an important Internet design topic. Group key management is important for secure group communication. Previous work focuses on key tree, which is an important type of key graphs. In this paper, we first propose another type of key graph—key link-tree, which shows better performance than key tree in single rekeying. Considering that the adoption of key link-tree results in worse than key tree in batch rekey, we propose two transform algorithms between key tree and key link-tree, which can get better rekey performance.     

A Unified Framework for Instruction Scheduling and Mapping for Function Units with Structural Hazards

Software pipelining methods based on an ILP (integer linear programming) framework have been successfully applied to derive rate-optimal schedules under resource constraints. However, like many other previous works on software pipelining, ILP-based work has focused on resource constraints of simple function units, e.g., “clean pipelines”—pipelines without structural hazards. The problem for architectures beyond such clean pipelines remains open. One challenge is how to represent such resource constraints for unclean pipelines, i.e., pipelined function units, but having structural hazards.In this paper, we propose a method to constructrate-optimalsoftware pipelined schedules for pipelined architectures with structural hazards. A distinct feature of this work is that it provides a unified ILP framework for two challenging and interrelated aspects of software pipelining—the scheduling of instructions at particular times and the mapping of those instructions to specific function units. Solving both of these aspects is essential to finding schedules which will work both on VLIW machines which map instructions to fixed function units and on dynamic out-of-order superscalars. We propose two ILP formulations to solve the integrated scheduling and mapping problem. Both adopt principles of graph coloring in an ILP framework, and one usesforbidden latenciesin an elegant extension of classical hardware pipeline control theory.We have run experiments on four variations of our proposed formulations. As input we used a set of 415 “unique” loops taken from several benchmark suites, and we targeted an architecture whose function units contain many structural hazards. All four of our variations did well, with the best finding a rate-optimal schedule for 65% of the loops. This compares favorably with a leading heuristic, Huff'sSlack Scheduling—the ILP approaches found a schedule with smaller initiation interval for over 50% of the loops, with a mean improvement of almost 30%. Finally, we have found that reusing pipeline stages—and thus adding hazards—results in only a 10% drop in performance, while permitting significant savings in area.     

Specifying redundancy tactics as crosscutting concerns using aspect-oriented modeling

Various redundancy tactics can be modeled at the design stage of safety-critical systems thereby providing a set of fault-tolerance guidelines for subsequent development activities. However, existing approaches usually interweave redundancy tactics into the functional models making them complex and cluttered; the maintenance of such models is time-consuming and error-prone. To address this problem, we provide a modeling approach to separate the redundancy tactics from the base functional models using aspect-oriented modeling. More specifically, the conceptual models of the redundancy tactics and their semantic constraints are first defined for deriving the relevant aspects. Subsequently, a UML profile is proposed to specify the tactic aspects followed by mapping these concepts to the corresponding concepts of aspect-oriented modeling based on pre-defined principles. In accordance with our proposed profile, reuse directives are applied to handle the overlap of structural features between redundancy tactics and other kinds of tactic. Based on our tactic aspects and their configured attributes, a weaving algorithm is proposed to associate the tactic aspects with the base functional models. The proposed approach is compared with a traditional tactic modeling approach using two safety-critical systems, revealing that: 1) our approach significantly reduces the number of extra model elements needed in the tactic design stage; 2) our approach can largely avoid the impact of changing of the base functional model as the model evolves.     

Program tactics and logic tactics

In this paper we present a first order classical metatheory, called MT, with the following properties: (1) tactics are terms of the language of MT (we call these tactics,Logic Tactics); (2) there exists a mapping between Logic Tactics and the tactics developed as programs within the GETFOL theorem prover (we call these tactics,Program Tactics). MT is expressive enough to represent the most interesting tacticals, i.e.,then, orelse, try, progress andrepeat. repeat allows us to express Logic Tactics which correspond to Program Tactics which may not terminate. This work is part of a larger project which aims at the development and mechanization of a metatheory which can be used to reason about, extend and, possibly, modify the code implementing Program Tactics and the GETFOL basic inference rules.Some parts of this paper were preliminarily discussed in a paper that appeared inProceedings of the Fifth International Conference on Logic Programming and Automated Reasoning (LPAR '94).     

Using knowledge-based systems for estimating risks inherent in a proposed KBS project

Abstract: This article describes the development of a knowledge-based system (KBS) for guiding both technical and non-technical managers in estimating the risks inherent in proposed KBS development projects. The work described here is part of an ongoing research project studying the use of KBS both to teach and to do KBS development. So far, as part of this research project, over the past two years close to 150 non-technical and technical full-time business managers have developed some 75 KBS prototypes in conjunction with an MBA course in strategic planning. Based on replies to a survey of this test group, 17% of the KBS developed were reportedly used at work, 14% led to promotions, pay raises, or new jobs, and 14% led to participation in other KBS development projects at work. All but two of the survey respondents reported that their work on the KBS development project led to a substantial increase in their job knowledge or performance. The KBS work described here extends research work described by Cullen and Bryman [1988], Slagle and Wick [1988], Cohen and Howe [1988], Dologite [1988, 1989], and Mockler [1989(A) and (B)].