Hi all,
I've managed to port one of our existing network applications to use the socket fs from 17.02 now, starting from the echo_udp scenario and got it working. It looks a lot better now.
Following this, we would like to share our findings about the socket fs so far:
1. In the release notes you describe the support for async file I/O. However, it seems that while asynchronous I/O works now, synchronous I/O is no longer possible. When I remove the select() call in the echo scenario, the call to recvfrom() will fail saying the socket is not connected (even though it is an UDP socket and should not have the notion of connections at all).
Of course this means it is not posix compatible; the intended behaviour is to block until data becomes available.
2. Currently there are two ways an application can use tcp/ip sockets from the lxip stack: By using libc sockets, and by directly opening a file system session and writing to the right socket files. For any new Genode application that does not already depend on libc, the first way means you unnecessarily add the entirety of libc to your component. So the second way seems preferred.
However, when programming an application using a file system session directly adds a lot of code with many open()s, read()s and write()s that could be abbreviated into single calls such as connect() and recv(). Have you thought of providing a more convenient API (such an object-oriented Socket class that hides the vfs calls from the application programmer)? Or do you consider using the fs session interface to be better? If so, why?