Having available a high quality documentation is critical for software projects. This is why documentation tools such as Javadoc are so popular. As for code, documentation should be reused when possible to increase developer productivity and simplify maintenance. In this paper, we perform an empirical study of duplications in JavaDoc documentation on a corpus of seven famous Java APIs. Our results show that copypastes of JavaDoc documentation tags are abundant in our corpus. We also show that these copy-pastes are caused by four different kinds of relations in the underlying source code. In addition, we show that popular documentation tools do not provide any reuse mechanism to cope with these relations. Finally, we make a proposal for a simple but efficient automatic reuse mechanism.

Docker is becoming a popular tool used by developers and end-users to deploy and run software applications. Dockerfiles are now found alongside projects' source code. Several projects are even starting to maintain families of Dockerfiles, like the Python project that maintains a family of 43 Dockerfiles, each for a specific Python version on a specific Linux distribution. In some situations, Dockerfiles family maintainers have to propagate a change to several, if not all, Dockerfiles of the family (for instance a bugfix applying on all Dockerfiles targeting Python 2.7). This need to propagate changes is usually due to the presence of duplicates between several Dockerfiles of the family. In this paper, our goal is to provide practitioners a clear explanation for why Dockerfile duplicates arise in projects, and what are the different means to handle duplicates with their pros and cons. To perform a grounded analysis, we observe the practices of expert Dockerfile maintainers of Official Docker projects, which are setting the best-practices for Dockerfile maintenance. We show that duplicates in Dockerfiles are frequent in our corpus, that maintainers are aware of their existence, are frequently facing them and have a mixed opinion regarding them (error-prone when not using any tool, but easy to maintain with the right tools). Finally, we describe and analyse the tools used by maintainers to handle duplicates.

A large set of mobile applications (apps) heavily rely on services accessible through the Web via REST APIs. The mobile apps market is therefore becoming a key market for service providers. However, the way in which mobile apps use services in practice has never been studied. In this paper, we perform an empirical study in the Android ecosystem in which we analyze 500 popular applications and 15 popular services. We also conducted an online survey to identify which are the best practices for Android developers. Our results show that Android developers generally favor invoking services by using an official service library instead of directly invoking services with a generic HTTP client.Our study shows that Android developers prefer to use a dedicated library developed by the service provider if it exists. The main advantages of such a library are that it simplifies the calls of the REST services but also provides added-value such as Android Views for example.