nanonext (version 0.5.1)

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", autostart = TRUE)

Arguments

socket

a Socket or nano object.

url

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

autostart

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

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 or nano object if successful.

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 setopt 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.

This function may be used to bind a new Listener to a Socket, or else a nano object. If called on a nano object, the listener is attached to the object rather than the socket for ease of access, e.g. $listener[[1]] rather than $socket$listener[[1]], but is otherwise equivalent to calling listen() on the object's socket directly.

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

# NOT RUN {
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")
listen(nano, url = "tcp://127.0.0.1:6548", autostart = FALSE)
nano$listener
start(nano$listener[[1]])
nano$listener
close(nano$listener[[1]])
nano$close()

# }