NAME

       nng_dial - create and start dialer

SYNOPSIS

           #include <nng/nng.h>

           int nng_dial(nng_socket s, const char *url, nng_dialer *dp, int flags);

DESCRIPTION

       The nng_dial() function creates a newly initialized nng_dialer object, associated with socket s, and
       configured to dial the address specified by url, and starts it. If the value of dp is not NULL, then the
       newly created dialer is stored at the address indicated by dp.

       Dialers initiate a remote connection to a listener. Upon a successful connection being established, they
       create a pipe, add it to the socket, and then wait for that pipe to be closed. When the pipe is closed,
       the dialer attempts to re-establish the connection. Dialers will also periodically retry a connection
       automatically if an attempt to connect asynchronously fails.

           Tip

           While it is convenient to think of dialers as clients, the relationship between the listener or
           dialer is orthogonal to any server or client status that might be associated with a given protocol.
           For example, a req socket might have associated dialers, but might also have associated listeners. It
           may even have some of each at the same time!

       Normally, the first attempt to connect to the address indicated by url is done synchronously, including
       any necessary name resolution. As a result, a failure, such as if the connection is refused, will be
       returned immediately, and no further action will be taken.

       However, if the special value NNG_FLAG_NONBLOCK is supplied in flags, then the connection attempt is made
       asynchronously.

       Furthermore, if the connection was closed for a synchronously dialed connection, the dialer will still
       attempt to redial asynchronously.

           Tip

           While NNG_FLAG_NONBLOCK can help an application be more resilient, it also generally makes diagnosing
           failures somewhat more difficult.

       Because the dialer is started immediately, it is generally not possible to apply extra configuration; if
       that is needed applications should consider using nng_dialer_create() and nng_dialer_start() instead.

RETURN VALUES

       This function returns 0 on success, and non-zero otherwise.

ERRORS

       NNG_EADDRINVAL
           An invalid url was specified.

       NNG_ECLOSED
           The socket s is not open.

       NNG_ECONNREFUSED
           The remote peer refused the connection.

       NNG_ECONNRESET
           The remote peer reset the connection.

       NNG_EINVAL
           An invalid set of flags or an invalid url was specified.

       NNG_ENOMEM
           Insufficient memory is available.

       NNG_EPEERAUTH
           Authentication or authorization failure.

       NNG_EPROTO
           A protocol error occurred.

       NNG_EUNREACHABLE
           The remote address is not reachable.

SEE ALSO

       nng_dialer_close(3), nng_dialer_create(3) nng_dialer_start(3), nng_listen(3), nng_strerror(3),
       nng_dialer(5), nng_pipe(5), nng(7)

                                                   2025-04-20                                        NNG_DIAL(3)