The growing complexity of software systems and the influence of software-supported decisions in our society awoke the need for software that is transparent, accountable, and trust-worthy. Explainability has been identified as a means to achieve these qualities. It is recognized as an emerging non-functional requirement (NFR) that has a significant impact on system quality. However, in order to incorporate this NFR into systems, we need to understand what explainability means from a software engineering perspective and how it impacts other quality aspects in a system. This allows for an early analysis of the benefits and possible design issues that arise from interrelationships between different quality aspects. Nevertheless, explainability is currently under-researched in the domain of requirements engineering and there is a lack of conceptual models and knowledge catalogues that support the requirements engineering process and system design. In this work, we bridge this gap by proposing a definition, a model, and a catalogue for explainability. They illustrate how explainability interacts with other quality aspects and how it may impact various quality dimensions of a system. To this end, we conducted an interdisciplinary Systematic Literature Review and validated our findings with experts in workshops.

Exploring Explainability: A Definition, a Model, and a Knowledge Catalogue

The advance of Ubiquitous Computing (UbiComp) and Internet of Things (IoT) brought a new set of Non-Functional Requirements (NFRs), especially related to Human-Computer Interaction (HCI). Invisibility is one of these NFRs, and it refers to either the merging of technology in the user environment or the decrease of the interaction workload. This new NFR may impact traditional NFRs (e.g., Usability), revealing positive correlations, when one NFR helps another, and negative correlations, when a procedure favors an NFR but creates difficulty for another one. Software engineers need to know about these correlations, so they can select appropriate strategies to satisfy Invisibility and traditional NFRs. Correlations between NFRs are usually stored in catalogs, which is a well-defined body of knowledge gathered from previous experience. Although Invisibility has been recently cataloged with development strategies, the literature still lacks catalogs with correlations for this NFR. Therefore, this work aims at capturing and cataloging invisibility correlations for UbiComp and IoT systems. To do that, we also propose to systematize the definition of correlations using the following well-defined research methods: Interview, Content Analysis and Questionnaire. As a result, we defined a catalog with 110 positive and negative correlations with 9 NFRs. This well-defined body of knowledge is useful for supporting software engineers to select strategies to satisfy Invisibility and other NFRs related to user interaction.

How developers believe Invisibility impacts NFRs related to User Interaction

Resumo. A elicitacao e especificacao de requisitos sao fundamentais para que o sistema pretendido funcione de acordo com as necessidades dos stakeholders e as restricoes sob as quais se encontre submetido. Os sistemas embarcados tem sido usados em diferentes finalidades (automoveis, medicina, entre outros.). Apesar de avancos em desenvolvimento de sistemas embarcados, sao poucas as iniciativas de engenharia de requisitos que atendam as particularidades desses sistemas. Neste trabalho, foi conduzida uma revisao sistematica da literatura, com o intuito de realizar um diagnostico mais aprofundado e sistematico sobre a elicitacao e especificacao de requisitos em sistemas embarcados. Na fase inicial da revisao sistematica as strings de busca aplicadas, retornaram 441 trabalhos. Apos aplicacao dos criterios de selecao nas fases da conducao da revisao e a inclusao de 2 trabalhos manualmente, apenas 15 trabalhos foram identificados e analisados.

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Elicitação e Especificação de Requisitos em Sistemas Embarcados: Uma Revisão Sistemática.

Abstract The growing complexity of software systems and the influence of software-supported decisions in our society sparked the need for software that is transparent, accountable, and trustworthy. Explainability has been identified as a means to achieve these qualities. It is recognized as an emerging non-functional requirement (NFR) that has a significant impact on system quality. Accordingly, software engineers need means to assist them in incorporating this NFR into systems. This requires an early analysis of the benefits and possible design issues that arise from interrelationships between different quality aspects. However, explainability is currently under-researched in the domain of requirements engineering, and there is a lack of artifacts that support the requirements engineering process and system design. In this work, we remedy this deficit by proposing four artifacts: a definition of explainability, a conceptual model, a knowledge catalogue, and a reference model for explainable systems. These artifacts should support software and requirements engineers in understanding the definition of explainability and how it interacts with other quality aspects. Besides that, they may be considered a starting point to provide practical value in the refinement of explainability from high-level requirements to concrete design choices, as well as on the identification of methods and metrics for the evaluation of the implemented requirements. 

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Explainable software systems: from requirements analysis to system evaluation

At present, there are a large number of embedded systems (ES) which need to modify their behavior at run time in response to changing environmental conditions (sensor failures, noisy networks, malicious threats, unexpected input…etc.) or in the cases where the requirements themselves needs to change. i.e. ES require self-adaptive capabilities. This kind of ES has been widely used in different domain, for instance in the smart home systems, automotive systems, telecommunication systems, environmental monitoring and others. Unfortunately, up to now, there are few researchers which interest for the high level design process of the self-adaptive embedded systems (SAES) specifically in the field of requirement engineering (RE). For this reason, the objectives of this paper is to try as much as possible to recall and compare between existing works build around the RE of SAES in the sake of identifying advantages and weak points of each work.

Towards Requirements Engineering Process for Self-adaptive Embedded Systems

Non-functional requirements (NFR) are related to the user satisfaction about the quality attributes of the information system. In some cases these requirements are ignored or implemented by the end of the project in a chaotic way. It happens because, in many cases, the user does not have enough contact with the information system to solve these requirements, such as nonfunctional requirements for Radio-Frequency Identification (RFID) middleware. This study presents the preparation of non-functional requirements catalogues for RFID middleware supported by Non-Functional Requirements Framework (NFR-Framework). Two case studies were performed to evaluate the Requirements Engineering process in the creation of the NFR catalogues and the effectiveness of the reuse of the catalogues. As a result, a set of non-functional requirements are presented and organized into catalogues that work as the foundation for RFID system developers in the identification and validation of non-functional requirements for RFID middleware in information systems context.

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NFR catalogues for RFID middleware

This paper presents the results of studies that made possible to propose a particular contribution to improve the quality on developing automotive embedded systems through a requirements specification template of a communication network based on CAN protocol. The whole template structure is composed by sections that specify the controlling units, the subnetworks, the data dictionary and the general aspects of the communication network. A study case was performed to test the proposed template and a study of the requirements of an embedded automotive environment was specified. The conclusions of this study and the evaluation are presented and further studies are suggested. This template can be used by engineers and designers with industrial or scientific purposes.

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Luiz Eduardo Galvão Martins

Papers

NFR catalogues for RFID middleware

A Requirements Specification Template of a Communication Network Based on CAN Protocol to Automotive Embedded Systems