NN_DEVICE

Section: nanomsg 1.1.5 (3)
Updated: 2021-01-26
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NAME

nn_device - start a device

SYNOPSIS

int nn_device (int s1, int s2);

DESCRIPTION

Starts a device to forward messages between two sockets. If both sockets are valid, nn_device function loops and sends any messages received from s1 to s2 and vice versa. If only one socket is valid and the other is negative, nn_device works in a "loopback" mode --- it loops and sends any messages received from the socket back to itself.

To break the loop and make nn_device function exit use the nn_term(3) function.

RETURN VALUE

The function loops until it hits an error. In such a case it returns -1 and sets errno to one of the values defined below.

ERRORS

EBADF

: One of the provided sockets is invalid.

EINVAL

: Either one of the socket is not an AF_SP_RAW socket; or the two sockets don't belong to the same protocol; or the directionality of the sockets doesn't fit (e.g. attempt to join two SINK sockets to form a device).

EINTR

: The operation was interrupted by delivery of a signal.

ETERM

: The library is terminating.

EXAMPLE

int s1 = nn_socket (AF_SP_RAW, NN_REQ);
nn_bind (s1, "tcp://127.0.0.1:5555");
int s2 = nn_socket (AF_SP_RAW, NN_REP);
nn_bind (s2, "tcp://127.0.0.1:5556");
nn_device (s1, s2);