# nng_pipe(5) Manual Page

## NAME

nng_pipe - communications pipe

## SYNOPSIS

    #include <nng/nng.h>

    typedef struct nng_pipe_s nng_pipe;

## DESCRIPTION

An `nng_pipe` is a handle to a pipe object, which can be thought of as a single connection. (In most cases this is actually the case — the pipe is an abstraction for a single TCP or IPC connection.) Pipes are associated with either the listener or dialer that created them, and therefore are also automatically associated with a single socket.

| The `nng_pipe` 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.

| Most applications should never concern themselves with individual pipes. However it is possible to access a pipe when more information about the source of a message is needed, or when more control is required over message delivery.

Pipe objects are created by dialers (`nng_dialer` objects) and listeners (`nng_listener` objects).

Pipe objects may be destroyed by the `nng_pipe_close()` function. They are also closed when the dialer or listener that created them is closed, or when the remote peer closes the underlying connection.

### Initialization

A pipe may be initialized using the macro `NNG_PIPE_INITIALIZER` before it is opened, to prevent confusion with valid open pipes.

For example:

    nng_pipe p = NNG_PIPE_INITIALIZER;

## SEE ALSO

nng_msg_get_pipe(3), nng_pipe_close(3), nng_pipe_getopt(3), nng_pipe_dialer(3), nng_pipe_id(3), nng_pipe_listener(3), nng_pipe_socket(3), nng_dialer(5), nng_listener(5), nng_options(5), nng(7)