Developers reuse programming-related knowledge (e.g., code snippets) on Q&A sites (e.g., Stack Overflow) that functionally matches the programming problems they encounter in their development. Despite extensive research on Q&A sites, being a high-level and important type of development-related knowledge, architectural solutions (e.g., architecture tactics) and their reuse are rarely explored. To fill this gap, we conducted a mixed-methods study that includes a mining study and a survey study. For the mining study, we mined 984 commits and issues (i.e., 821 commits and 163 issues) from 893 Open-Source Software (OSS) projects on GitHub that explicitly referenced architectural solutions from Stack Overflow (SO) and Software Engineering Stack Exchange (SWESE). For the survey study, we identified practitioners involved in the reuse of these architectural solutions and surveyed 227 of them to further understand how practitioners reuse architectural solutions from Q&A sites in their OSS development. Our main findings are that: (1) OSS practitioners reuse architectural solutions from Q&A sites to solve a large variety (15 categories) of architectural problems, whereinComponent design issue,Architectural anti-pattern, andSecurity issueare dominant; (2) Seven categories of architectural solutions from Q&A sites have been reused to solve those problems, among whichArchitectural refactoring,Use of frameworks, andArchitectural tacticare the three most reused architectural solutions; (3) OSS developers often rely on ad hoc ways (e.g., informal, improvised, or unstructured approaches) to reuse architectural solutions from SO, drawing on personal experience and intuition rather than standardized or systematic practices; (4) Reusing architectural solutions from SO comes with a variety of challenges, e.g., OSS practitioners complain that they need to spend significant time to adapt such architectural solutions to address design concerns raised in their OSS development, and it is challenging to reuse architectural solutions that are not tailored to the design context of their OSS projects. Our findings pave the way for future research directions, including the design and development of approaches and tools (such as IDE plugin tools) to facilitate the reuse of architectural solutions from Q&A sites, and could also be used to offer guidelines to practitioners when they contribute architectural solutions to Q&A sites. Our dataset is publicly available athttps://doi.org/10.5281/zenodo.10936098.

Building software systems often requires knowledge and skills beyond what developers already possess. In such cases, developers have to leverage different sources of information to seek help. A growing number of researchers and practitioners have started investigating what programming-related information developers seek during software development. However, being a high level and a type of the most important development-related information, architectural information search activity is seldom explored. To fill this gap, we conducted an industrial survey completed by 103 participants to understand how developers search for architectural information to solve their architectural problems in development. Our main findings are: (1) searching for architectural information to learn about the pros and cons of certain architectural solutions (e.g., patterns, tactics) and to make an architecture decision among multiple choices are the most frequent purposes or tasks; (2) developers find difficulties mostly in getting relevant architectural information for addressing quality concerns and making design decisions among multiple choices when seeking architectural information; (3) taking too much time to go through architectural information retrieved from various sources and feeling overwhelmed due to the dispersion and abundance of architectural information in various sources are the top two major challenges developers face when searching for architectural information. Our findings (1) provide researchers with future directions, such as the design and development of approaches and tools for searching architectural information from multiple sources, and (2) can be used to provide guidelines for practitioners to refer to when seeking architectural information and providing architectural information that could be considered useful.