utils (version 3.5.3)

make.socket: Create a Socket Connection

Description

With server = FALSE attempts to open a client socket to the specified port and host. With server = TRUE the R process listens on the specified port for a connection and then returns a server socket. It is a good idea to use on.exit to ensure that a socket is closed, as you only get 64 of them.

Usage

make.socket(host = "localhost", port, fail = TRUE, server = FALSE)

Arguments

host

name of remote host

port

port to connect to/listen on

fail

failure to connect is an error?

server

a server socket?

Value

An object of class "socket", a list with components:

socket

socket number. This is for internal use. On a Unix-alike it is a file descriptor.

port

port number of the connection.

host

name of remote computer.

Warning

I don't know if the connecting host name returned when server = TRUE can be trusted. I suspect not.

References

Adapted from Luke Tierney's code for XLISP-Stat, in turn based on code from Robbins and Robbins “Practical UNIX Programming”.

See Also

close.socket, read.socket.

Compiling in support for sockets was optional prior to R 3.3.0: see capabilities("sockets") to see if it is available.

Examples

# NOT RUN {
daytime <- function(host = "localhost"){
    a <- make.socket(host, 13)
    on.exit(close.socket(a))
    read.socket(a)
}
## Official time (UTC) from US Naval Observatory
# }
# NOT RUN {
daytime("tick.usno.navy.mil")
# }