I have used Spring Boot in the past. But the principles I see in a Lagom framework are more involved.
There are immutables and inherent support for event stores and asynchronous API’s are used everywhere.
Where can I read about these and many others I may have missed ? Is there a book ?
How is Play API used in this framework ? Is it both in the backend as well as frontend tiers ? I have many questions like this and also about how to implement OAuth specifically with Lagom. I have used OAuth before,
To get a grounding in the principles behind Lagom, I recommend hitting the Lightbend website and reading through some eBooks by Jonas Boner, etc.
Another good set of resources are the free reactive architecture training courses, these are also linked to from the Lightbend site.
I went through all that first recently before discovering Lagom, and it certainly helps to know the principles before trying to make sense of the code-level stuff.