But it is often used for block storage in datacenters. Using it for anything else is going to be hard, as it is incompatible with TCP.
The problem with not using TCP is the same thing HOMA will face - anything already speaks TCP, nearly all potential hires know TCP and most problems you have with TCP have been solved by smart engineers already. Hardware is also easily available. Once you drop all those advantages, either your scale or your gains need to be massive to make that investment worth it, which is why TCP replacements are so rare outside of FAANG.
https://en.wikipedia.org/wiki/Unix_domain_socket#:~:text=The....
Puma creates a `UnixServer` which is a ruby stdlib class, using the defaults, which is extending `UnixSocket` which is also using the defaults
https://github.com/puma/puma/blob/fba741b91780224a1db1c45664...
Those defaults are creating a socket of type `SOCK_STREAM`, which is a tcp socket
> SOCK_STREAM will create a stream socket. A stream socket provides a reliable, bidirectional, and connection-oriented communication channel between two processes. Data are carried using the Transmission Control Protocol (TCP).
https://github.com/ruby/ruby/blob/5124f9ac7513eb590c37717337...
You still have the tcp overhead when using a local unix socket with puma, but you do not have any network overhead.
UDS using SOCK_STREAM does not do that; ie, it is not using IPPROTO_TCP.
> SOCK_STREAM will create a stream socket. A stream socket provides a reliable, bidirectional, and connection-oriented communication channel between two processes. Data are carried using the Transmission Control Protocol (TCP).
> SOCK_DGRAM will create a datagram socket.[b] A Datagram socket does not guarantee reliability and is connectionless. As a result, the transmission is faster. Data are carried using the User Datagram Protocol (UDP).
> SOCK_RAW will create an Internet Protocol (IP) datagram socket. A Raw socket skips the TCP/UDP transport layer and sends the packets directly to the network layer.
I don't claim to be an expert, I just have a certain confidence that I'm able to comprehend words I read. It seems you can have 3 types of sockets, raw, udp, or tcp.