Researchers worldwide have extensively investigated the influence of Human-Computer Interaction (HCI) on Mobile Instant Messaging applications, exploring aspects such as usability issues and user behaviour. However, traditional HCI challenges remain in these applications today (ie, usability issues and lack of specific usability guidelines). In this paper, we present a contextual and methodological contribution measuring user performance (with a controlled experiment on a set of structured tasks following a within-subjects design) and user behaviour (with a user satisfaction questionnaire) on Mobile Instant Messaging applications with end users. Most of the current studies on Mobile Instant Messaging are focused on only one application at a time and in a specific region of the world. This experiment originally measures over four apps: Three in-market apps (apps with good usability results, selected from previous studies) and one app developed following usability recommendations. In addition, this research originally adds to the current literature results with participants from two different countries. The results show, as practical implications, that the application of specific usability recommendations for Mobile Instant Messaging applications (eg, adding a new contact only with the ID, or providing a visual distinction between individual and group chats, among others) significantly facilitates user performance with these applications. However, further dissemination is needed among researchers and developers. The findings on user behaviour show that the number of close contacts using a particular Mobile Instant Messaging application strongly determines the user’s intention to continue using an application. And not the features offered or the acceptance of the user interface, as most current studies suggest.

Microservice-based systems are usually developed according to agile practices like DevOps, which enables rapid and frequent releases to promptly react and adapt to changes. Monitoring is a key enabler for these systems, as they allow to continuously get feedback from the field and support timely and tailored decisions for a quality-driven evolution. In the realm of monitoring tools available for microservices in the DevOps-driven development practice, each with different features, assumptions, and performance, selecting a suitable tool is an as much difficult as impactful task. This article presents the results of a systematic study of the grey literature we performed to identify, classify and analyze the available monitoring tools for DevOps and microservices. We selected and examined a list of 71 monitoring tools, drawing a map of their characteristics, limitations, assumptions, and open challenges, meant to be useful to both researchers and practitioners working in this area. Results are publicly available and replicable. Editor's note: Open Science material was validated by the Journal of Systems and Software Open Science Board.

Abstract Mobile Instant Messaging applications noted a growing number of active users recently. Although having millions of users, the previous research results have shown usability flaws in this type of mobile applications. Difficulties when performing tasks, poor design of user interfaces, or lack of information about privacy and security methods were some of the identified flaws. Consequently, a collection of usability recommendations was proposed. The goal of these recommendations is to improve the experience in the use of these mobile applications and, thus, enhancing the usability of this kind of apps. These recommendations were taken into account during the development process of a new instant messaging application. Thus, in this study, the authors present the resulting application, its characteristics, how usability recommendations were covered through design and development phases, and a preliminary usability evaluation performed by conducting two research methods: KLM and Mobile Heuristic Evaluation. Both methods ranked the prototype at top positions (i.e. good usability results) when compared with the results obtained in previous studies about other existing instant messaging applications.