# nng_socket(5) Manual Page

## NAME

nng_socket - socket handle

## SYNOPSIS

    #include <nng/nng.h>

    typedef struct nng_socket_s nng_socket;

## DESCRIPTION

An `nng_socket` is a handle to an underlying socket object. All communication between the application and remote Scalability Protocol peers is done through sockets. A given socket can have multiple dialers (`nng_dialer`) and/or listeners (`nng_listener`), and multiple pipes (`nng_pipe`), and may be connected to multiple transports at the same time. However, a given socket will have exactly one protocol associated with it, and is responsible for any state machines or other protocol-specific logic.

| The `nng_socket` structure is always passed by value (both for input parameters and return values), and should be treated opaquely. Passing structures this way gives the compiler a chance to perform accurate type checks in functions passing values of this type.

Each `nng_socket` is created by a protocol-specific constructor, such as `nng_rep_open()`. When the socket is no longer needed, it can be closed with `nng_close()`.

### Initialization

A socket may be initialized using the macro `NNG_SOCKET_INITIALIZER` before it is opened, to prevent confusion with valid open sockets.

For example:

    nng_socket s = NNG_SOCKET_INITIALIZER;

## SEE ALSO

libnng(3), nng_close(3), nng_getopt(3), nng_setopt(3), nng_socket_id(3), nng_dialer(5), nng_listener(5), nng_options(5), nng(7)