Menu
I'm just starting with socket programming in UNIX and I was reading the man pages for the socket system call. I'm a bit confused about the AF_LOCAL argument and when it is used. The manual just says local communication. Wouldn't an AF_INET format also work for local communication?
632
AF_INET is an address family that is used to designate the type of addresses that your socket can communicate with (in this case, Internet Protocol v4 addresses). When you create a socket, you have to specify its address family, and then you can only use addresses of that type with the socket.
The difference is that an INET socket is bound to an IP address-port tuple, while a UNIX socket is "bound" to a special file on your filesystem. Generally, only processes running on the same machine can communicate through the latter.
The AF_UNIX (also known as AF_LOCAL) socket family is used to communicate between processes on the same machine efficiently. Traditionally, UNIX domain sockets can be either unnamed, or bound to a filesystem pathname (marked as being of type socket).
Unix sockets are bidirectional. This means that every side can perform both read and write operations. While, FIFOs are unidirectional: it has a writer peer and a reader peer. Unix sockets create less overhead and communication is faster, than by localhost IP sockets.
AF_LOCAL uses UNIX domain sockets which are local to the filesystem and can be used for internal communications. AF_INET is an IP socket. AF_LOCAL will not incur some performance penalties related to sending data over IP. See this old but very nice discussion of the topic.
184
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
