I wrote an extensive OSGi / Amdatu tutorial that covers all the topics that you need to build modular (web) applications. The tutorial should be a deep-dive introduction in the concepts, tools and libraries that you need, and should fast track you to developing real applications.
- Bundles and module boundaries
- OSGi services
- RESTful web services with JAX-RS
- Unit and integration testing
- Using MongoDB
- Scheduled tasks
- Configuration with Managed Services
- Building with Gradle
- Docker deployment
The tutorial comes with a git repository that you can use for each step if you get stuck. But of course also feel free to ask questions! Also, we already had a large collection of videos that cover many of these topics (and more), so have a look at those as well.