Is there actually a significant user base for them though?
I know Messenger was pretty much forced onto users, but other than that I don't know anyone who uses Paper, nor do I think any of my friends will start using Slingshot - especially when there are well established alternatives such as Snapchat.
I'm doubtful many of them have even heard of these new apps, and this is coming from someone relatively young (20 y/o).
At the risk of reigniting an old flame war, it seems to me that a microkernel in which core OS functions such as process management and the virtual file system are in separate servers would be more complicated than a monolithic kernel. Having device drivers and specific file systems in user space may be useful, though.
The impression I get (university class on OSes) is that the microkernel/modular approach is more about making it simpler to port than making a specific instance simple? Similarly it'd be less complicated to extend since that's just a case of adding a new loadable module. In terms of a learning OS I'm not sure exactly which should be prioritised - extendability/portability or a simple structure? If this is a topic with a lot of depth I'm obviously not getting I'd definitely be interested in a discussion - my exam is soon :)
Have you read the debate between Andy Tanenbaum and Linus Torvalds from about 1992? It's a discussion of the tradeoffs between microkernels (Tanenbaum) and monolithic kernels (Torvalds). You can find it here:
The claim that microkernels improve portability makes no sense to me, since Linux itself is very portable, as are the BSDs (especially NetBSD and OpenBSD).
