I am currently looking for a good documentation to learn how exactly OSGi works. I have already downloaded the OSGi API given in the openhab documentation.
I found the book “OSGi in Action: Creating Modular Applications in Java”. Is it a good book?
Does anyone know a better book? Or is the book I mentioned the right one?
I see the book was published in 2011, is there a newer one or is it still very good? I can’t find any more recent ones.
I’m ready to buy it that’s why I’m asking.
And if anyone knows of any good tutorials/courses/lectures on the web, I am also interested. (I have already watched some of them but I am open to others)
It really depends what you looking for. If you seek for quick introduction to get started with openHAB development you shall consider Karaf related publications first. This will allow you to understand the basics of the tool and the environment. Then, if you find it necessary, you can go into titles you found.
Based on my personal feeling™, from titles you mentioned the first one is worth to read, later not much. As far I remember it focuses a lot on specifications which did not gain major traction in OSGi ecosystem. If you work with full blown application servers which permit you to run OSGi, sure you can get with it, but openHAB is not like that.
I can recommend you two more titles:
“Instant OSGi Starter” by Jammie Goodyear and Johan Edstrom
“Learning Apache Karaf” by Jammie Goodyear, Johan Edstorm and Heath Kesler
Eventually “Apache Karaf Cookbook” also by Achim Nierbeck, Jammie Goodyear, Johan Edstorm and Heath Kesler (this one is really about twisting Karaf into message broker, router and so on).
These books come from long term contributors to Apache Karaf project, Achim for very long time maintained HTTP server implementation used in Karaf. While first two publications seem to be old, the truth is - base specs which are mentioned in the book did not change much since then. They received some polishing and new features, however fundamentals remain same.
Pay attention to reviews which show two different sides of audience - very happy and unhappy readers.
You can also go with Karaf tutorials for start. They might not answer all your questions, but will teach you how to do basics. The official specs is a good read if you want to verify behavior and sometimes philosophical aspects of framework. For starter it is simply too long.
