Supporting End-User Development through a New Composition Model: An Empirical Study

End-user development (EUD) is much hyped, and its impact has outstripped even the most optimistic forecasts. Even so, the vision of end users programming their own solutions has not yet materialized. This will continue to be so unless we in both industry and the research community set ourselves the ambitious challenge of devising end to end an end-user application development model for developing a new age of EUD tools. We have embarked on this venture, and this paper presents the main insights and outcomes of our research and development efforts as part of a number of successful EU research projects. Our proposal not only aims to reshape software engineering to meet the needs of EUD but also to refashion its components as solution building blocks instead of programs and software developments. This way, end users will really be empowered to build solutions based on artefacts akin to their expertise and understanding of ideal solution

Spreadsheet Error Correction Using an Activity Framework and a Cognitive Fit Perspective

Errors in a spreadsheet constitute a serious reason for concern among organizations as well as academics. There are ongoing efforts toward finding ways to reduce errors, designing and developing visualization tools to support error correction activities being one of them. In this paper, we propose a framework for classifying activities associated with spreadsheet error correction. The purpose of this framework is to help in understanding the activities that are important for correcting different types of spreadsheet errors and how different visualization tools can help in error correction by effectively supporting these activities. An experiment is designed to test the effectiveness of a visualization tool that supports one of the most important activities from the framework – chaining activity. Two groups of subjects, with and without the visualization tool, are required to correct two types of errors. Our hypotheses are derived based on the notion of cognitive fit between problem representation and task, and the results of the experiment support most of the hypotheses. Thus, this study demonstrates the usefulness of the activity-based framework for spreadsheet error correction, and also provides guidelines for designing and developing tools for spreadsheet audit. It also provides empirical evidence to the cognitive fit theory by showing that performance is significantly better when visual support tools result in a match between problem representation and the task in hand, as in the case of correcting link errors with the tool used in this study. Theoretical and practical implications of the findings are discussed

Don't Treat the Symptom, Find the Cause! Efficient Artificial-Intelligence Methods for (Interactive) Debugging

In the modern world, we are permanently using, leveraging, interacting with, and relying upon systems of ever higher sophistication, ranging from our cars, recommender systems in e-commerce, and networks when we go online, to integrated circuits when using our PCs and smartphones, the power grid to ensure our energy supply, security-critical software when accessing our bank accounts, and spreadsheets for financial planning and decision making. The complexity of these systems coupled with our high dependency on them implies both a non-negligible likelihood of system failures, and a high potential that such failures have significant negative effects on our everyday life. For that reason, it is a vital requirement to keep the harm of emerging failures to a minimum, which means minimizing the system downtime as well as the cost of system repair. This is where model-based diagnosis comes into play. Model-based diagnosis is a principled, domain-independent approach that can be generally applied to troubleshoot systems of a wide variety of types, including all the ones mentioned above, and many more. It exploits and orchestrates i.a. techniques for knowledge representation, automated reasoning, heuristic problem solving, intelligent search, optimization, stochastics, statistics, decision making under uncertainty, machine learning, as well as calculus, combinatorics and set theory to detect, localize, and fix faults in abnormally behaving systems. In this thesis, we will give an introduction to the topic of model-based diagnosis, point out the major challenges in the field, and discuss a selection of approaches from our research addressing these issues.Comment: Habilitation Thesi

Project portfolio evaluation and selection using mathematical programming and optimization methods

Project portfolio selection is an essential process for portfolio management and plays an important role in accomplishing organizational goals. This research explores the feasibility of developing a project portfolio selection tool by using mathematical programming and optimization models, specifically 0-1 integer programming (one objective portfolio) and goal programming (multiple objectives portfolio). These methods select the set of projects which deliver the maximum benefit (e.g., net present value, profit, etc.) represented for objective functions subjected to a series of constraints (e.g., technical requirements and/or resources availability) considering the scheduling of selected projects in a planning horizon, interdependence relationship among projects (e.g., complementary projects and mutually exclusive projects) and especial cases like mandatory and ongoing projects. ^ Based on the proposed model, a Decision Support System (DSS) will be developed and tested for accuracy, flexibility and ease of use. This computational tool will be designed for decision makers and users that are not familiar with mathematical programming models

"What It Wants Me To Say": Bridging the Abstraction Gap Between End-User Programmers and Code-Generating Large Language Models

Code-generating large language models translate natural language into code. However, only a small portion of the infinite space of naturalistic utterances is effective at guiding code generation. For non-expert end-user programmers, learning this is the challenge of abstraction matching. We examine this challenge in the specific context of data analysis in spreadsheets, in a system that maps the users natural language query to Python code using the Codex generator, executes the code, and shows the result. We propose grounded abstraction matching, which bridges the abstraction gap by translating the code back into a systematic and predictable naturalistic utterance. In a between-subjects, think-aloud study (n=24), we compare grounded abstraction matching to an ungrounded alternative based on previously established query framing principles. We find that the grounded approach improves end-users' understanding of the scope and capabilities of the code-generating model, and the kind of language needed to use it effectively

MeCoSim: A general purpose software tool for simulating biological phenomena by means of P Systems

In recent years, the increasing importance of the computational systems biology is leading to an impressive growth of the knowledge of several real-life phenomena. In this framework, membrane computing is an emergent branch within natural computing that has been succesfully used to model biological phenomena. The study of these phenomena usually requires the execution of virtual experiments using mechanisms of simulation, implying the development of ad-hoc tools to simulate. However, the advance of the research is demanding general solutions to avoid the necessity of custom software developments for each matter of study, when there are some common problems to resolve. MeCoSim (Membrane Computing Simulator) is a first step in this direction providing the users a customizable application to generate custom simulators based on membrane computing by simply writing a configuration file.Ministerio de Educación y Ciencia TIN2009–13192Junta de Andalucía P08–TIC-0420

Improvement of Spreadsheet Quality through Reduction of End-User Overconfidence: Case Study

This paper is prompted by and based on earlier research into developers' overconfidence as one of the main causes of spreadsheet errors. Similar to related research, the aim of the paper was to ascertain the existence of overconfidence, and then examine the possibility of its reduction by means of experimental treatment designed for the needs of the research. A quasi-experiment was conducted to this end, in which 62 students of the Faculty of Economics of the University of Novi Sad participated, divided into the experimental and control group. Participants of both groups developed domain free spreadsheets in two iterations each. After the first iterations, students in the experimental group were subjected to experimental treatment: they attended lectures on spreadsheet errors taxonomies supported by real-life examples, and about spreadsheet best practices in the area of spreadsheet error prevention. Results showed that spreadsheet developers who were informed about spreadsheet error taxonomies and spreadsheet best practices create more accurate spreadsheets and are less self-confident in terms of accuracy of their spreadsheets

Leveraging Distributed Tracing and Container Cloning for Replay Debugging of Microservices

Microservice architectures have gained prominence in recent years for building large-scale industrial distributed systems. However, microservice architectures make the usage of replay debugging, a powerful technique for finding root causes of faults, very challenging because of the polyglot (written in several languages) services, large accumulated state of services, and tight latency limits imposed by long hop-chains. This work attempts to provide a framework for enabling replay debugging in production microservice applications. We study 25 real-world faults in microservice systems collected from diverse sources, categorize these faults by fault symptoms, and create 15 application agnostic mutation operators for microservices. We then propose a language agnostic replay debugging framework for microservice applications that uses a distributed tracing system to record network requests and enables replay of those requests on cloned service containers running in a debug environment. A key component of this framework is an anomaly detector that uses span-level and container-level monitoring to detect fault symptoms found in our study and localizes faults to trace level so that faulty traces can be easily replayed to find the root cause. An open-source microservices application injected successively with the mutation operators is used for an evaluation that shows that our framework is upto an order of magnitude lighter-weight than language-specific recording tools such as Chrome DevTools or VisualVM and can help in finding root causes of 9 out of 15 mutations at a line or function level