Using the socketR R6 Interface

The Socket class provides a method-oriented interface over the functional socket API. This example creates a TCP server and client on the IPv4 loopback interface, exchanges a message, and closes every object explicitly.

library(socketR)

server <- Socket$new("inet", "stream")
client <- Socket$new("inet", "stream")
peer <- NULL

on.exit({
  if (!is.null(peer)) peer$close()
  client$close()
  server$close()
}, add = TRUE)

server$set_option("socket", "reuseaddr", TRUE, "logical")
server$bind("127.0.0.1", 0L)
server$listen()

client$connect("127.0.0.1", server$local_name()$port)
peer <- server$accept()

client$send("hello from the R6 API")
peer$poll("read", timeout_ms = 1000L)
rawToChar(peer$receive(n = 21L))

Options and socket metadata are available as methods on the same object:

client$info()
client$fd()
client$set_blocking(FALSE)
client$get_option("socket", "keepalive", "logical")
client$set_options(list(
  list(level = "socket", option = "keepalive",
       value = TRUE, type = "logical"),
  list(level = "tcp", option = "nodelay",
       value = TRUE, type = "logical")
))

For APIs that expect a base R connection, use as_connection(). The adapter can be passed to writeBin(), readBin(), readLines(), and writeLines(); closing the adapter does not close the underlying Socket, so close both objects explicitly.

connection <- client$as_connection()
writeBin(charToRaw("bytes through an R connection"), connection)
close(connection)
client$close()