nanonext (version 1.4.0)

listen: Listen to an Address from a Socket

Description

Creates a new Listener and binds it to a Socket.

Usage

listen(
  socket,
  url = "inproc://nanonext",
  tls = NULL,
  autostart = TRUE,
  error = FALSE
)

Value

Invisibly, an integer exit code (zero on success). A new Listener (object of class ‘nanoListener’ and ‘nano’) is created and bound to the Socket if successful.

Arguments

socket

a Socket.

url

[default 'inproc://nanonext'] a URL to dial, specifying the transport and address as a character string e.g. 'inproc://anyvalue' or 'tcp://127.0.0.1:5555' (see transports).

tls

[default NULL] for secure tls+tcp:// or wss:// connections only, provide a TLS configuration object created by tls_config.

autostart

[default TRUE] whether to start the listener. Set to FALSE if setting configuration options on the listener as it is not generally possible to change these once started.

error

[default FALSE] behaviour on error: if FALSE, returns an integer exit code accompanied by a warning, or, if TRUE, generates an error and halts execution.

Further details

Dialers and Listeners are always associated with a single socket. A given socket may have multiple Listeners and/or multiple Dialers.

The client/server relationship described by dialer/listener is completely orthogonal to any similar relationship in the protocols. For example, a rep socket may use a dialer to connect to a listener on an req socket. This orthogonality can lead to innovative solutions to otherwise challenging communications problems.

Any configuration options on the dialer/listener should be set by opt<- before starting the dialer/listener with start.

Dialers/Listeners may be destroyed by close. They are also closed when their associated socket is closed.

Details

To view all Listeners bound to a socket use $listener on the socket, which returns a list of Listener objects. To access any individual Listener (e.g. to set options on it), index into the list e.g. $listener[[1]] to return the first Listener.

A listener is an external pointer to a listener object, which accepts incoming connections. A given listener object may have many connections at the same time, much like an HTTP server can have many connections to multiple clients simultaneously.

Examples

socket <- socket("req")
listen(socket, url = "tcp://127.0.0.1:6547", autostart = FALSE)
socket$listener
start(socket$listener[[1]])
socket$listener
close(socket$listener[[1]])
close(socket)

nano <- nano("bus")
nano$listen(url = "tcp://127.0.0.1:6548", autostart = FALSE)
nano$listener
nano$listener_start()
nano$listener
close(nano$listener[[1]])
nano$close()