Microservices-based Architectures (MSAs) are gaining popularity since, among others, they enable rapid and independent delivery of software at scale, facilitating the delivery of business value. Additionally, there are attempts towards understanding practitioners’ roles and technical knowledge. MSAs call for affinity in several technologies as well as business domains. This diversity makes it challenging to scope and describe the roles of practitioners. In addition, practitioners often do not receive training and contents of MSA training remain largely undefined, even though there are challenges in finding or developing relevant technical expertise. In this research, we determine the different technical roles that are required in MSAs, along with their detailed competences. We use public online forums (e.g., StackOverflow), where developers share technical knowledge. We analyze 13,517 public profiles of software engineers, deriving their technical competences. Our taxonomy of technical competences in MSAs, contains 11 competences clusters, organized in 3 collections of competences — Web Technologies, DevOps, and Data Technologies. In addition, we derive the roles of microservice practitioners and the characteristics of their roles. Our findings organize the technical competences of MSAs practitioners and determine the training topics and combination of topics that can prepare engineers for MSAs.

Context: As many organizations modernize their software architecture and transition to the cloud, migrations towards microservices become more popular. Even though such migrations help to achieve organizational agility and effectiveness in software development, they are also highly complex, long-running, and multi-faceted. Objective: In this study we aim to comprehensively map the journey towards microservices and describe in detail what such a migration entails. In particular, we aim to discuss not only the technical migration, but also the long-term journey of change, on a systemic level. Method: Our research method is an inductive, qualitative study on two data sources. Two main methodological steps take place - interviews and analysis of discussions from StackOverflow. The analysis of both, the 19 interviews and 215 StackOverflow discussions, is based on techniques found in grounded theory. Results: Our results depict the migration journey, as it materializes within the migrating organization, from structural changes to specific technical changes that take place in the work of engineers. We provide an overview of how microservices migrations take place as well as a deconstruction of high level modes of change to specific solution outcomes. Our theory contains 2 modes of change taking place in migration iterations, 14 activities and 53 solution outcomes of engineers. One of our findings is on the architectural change that is iterative and needs both a long and short term perspective, including both business and technical understanding. In addition, we found that a big proportion of the technical migration has to do with setting up supporting artifacts and changing the paradigm that software is developed.

Testing has a prominent role in revealing faults in software based on microservices. One of the most important discussion points in MSAs is the granularity of services, often in different levels of abstraction. Similarly, the granularity of tests in MSAs is reflected in different test types. However, it is challenging to conceptualize how the overall testing architecture comes together when combining testing in different levels of abstraction for microservices. There is no empirical evidence on the overall testing architecture in such microservices implementations. Furthermore, there is a need to empirically understand how the current state of practice resonates with existing best practices on testing. In this study, we mine Github to find different candidate projects for an in-depth, qualitative assessment of their test artifacts. We analyze 16 repositories that use microservices and include various test artifacts. We focus on four projects that use consumer-driven-contract testing. Our results demonstrate how these projects cover different levels of testing. This study (i) drafts a testing architecture including activities and artifacts, and (ii) demonstrates how these align with best practices and guidelines. Our proposed architecture helps the categorization of system and test artifacts in empirical studies of microservices. Finally, we showcase a view of the boundaries between different levels of testing in systems using microservices.

Background: Microservices migrations are challenging and expensive projects with many decisions that need to be made in a multitude of dimensions. Existing research tends to focus on technical issues and decisions (e.g., how to split services). Equally important organizational or business issues and their relations with technical aspects often remain out of scope or on a high level of abstraction.

Human, social, organizational, and technical aspects are intertwined with each other in software teams during the software development process. Practices that teams actually adopt often deviate from those of the used frameworks, such as Scrum. However, currently there is little empirical insight explaining typical deviations, including their reasons and consequences. In this paper we use observations to investigate selected activities of the software development process in two companies that use Scrum. We study identified deviations to understand their reasons and consequences, using a survey and interviews. We identify 13 deviations and we categorize reasons based on type. The deviations' consequences are investigated in terms of their impact. Most deviations can be found in multiple teams. Reasons are doubts of the teams, organizational structures and complexity of the work. Consequences of deviations affect product development and team work.