= nn_socket(3compat)
//
// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
//
// This document is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt).  A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//

== NAME

nn_socket - create socket (compatible API)

== SYNOPSIS

[source,c]
----
#include <nanomsg/nn.h>

int nn_socket(int af, int proto);
----

== DESCRIPTION

The `nn_socket()` function creates socket using the address family _af_ and
protocol _proto_ and returns it.

NOTE: This function is provided for API
<<nng_compat.3compat#,compatibility>> with legacy _libnanomsg_.
Consider using the relevant <<libnng.3#,modern API>> instead.

IMPORTANT: Mixing the compatibility API and the modern API is not supported
on a given socket.

NOTE: Some protocols, transports, and features are only available in the modern API.

The address family _af_ can be one of two values:

[horizontal]
`AF_SP`:: Normal socket.
`AF_SP_RAW`:: <<nng.7#raw_mode,"`Raw mode`">> socket.

The protocol indicates the protocol to be used when creating the socket.
The following protocols are defined:

[horizontal]
`NN_PAIR`:: <<nng_pair.7#,Pair>> protocol.
`NN_PUB`:: <<nng_pub.7#,Publisher>> protocol.
`NN_SUB`:: <<nng_sub.7#,Subscriber>> protocol.
`NN_REQ`:: <<nng_req.7#,Requestor>> protocol.
`NN_REP`:: <<nng_rep.7#,Replier>> protocol.
`NN_PUSH`:: <<nng_push.7#,Push>> protocol.
`NN_PULL`:: <<nng_pull.7#,Pull>> protocol.
`NN_SURVEYOR`:: <<nng_surveyor.7#,Surveyor>> protocol.
`NN_RESPONDENT`:: <<nng_respondent.7#,Respondent>> protocol.
`NN_BUS`:: <<nng_bus.7#,Bus>> protocol.

== RETURN VALUES

This function returns a valid socket number on success, and -1 on failure.

== ERRORS

[horizontal]
`ENOMEM`:: Insufficient memory is available.
`ENOTSUP`:: The protocol is not supported.
`ETERM`:: The library is shutting down.

== SEE ALSO

<<nng_socket.5#,nng_socket(5)>>,
<<nn_close.3compat#,nn_close(3compat)>>,
<<nn_errno.3compat#,nn_errno(3compat)>>,
<<nng_compat.3compat#,nng_compat(3compat)>>,
<<nng.7#,nng(7)>>