= libnng(3)
:doctype: manpage
:manmanual: nng
:mansource: nng
:copyright: Copyright 2018 Staysail Systems, Inc. <info@staysail.tech> \
            Copyright 2018 Capitar IT Group BV <info@capitar.com> \
            This software 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

libnng - nanomsg next generation library

== SYNOPSIS

*cc* ['flags'] 'files' *-lnng* ['libraries']


== DESCRIPTION

The <<nng#,nng(7)>> library provides a common messaging framework
intended to solve common communication problems in distributed applications.

It provides a C language API.

=== Common Functions

The following common functions exist in _libnng_.

|===
|<<nng_alloc#,nng_alloc(3)>>|allocate memory
|<<nng_dial#,nng_dial(3)>>|create and start a dialer
|<<nng_free#,nng_free(3)>>|free memory
|<<nng_strerror#,nng_strerror(3)>>|return an error description
|===

=== Socket Functions

The following functions operate on sockets.

|===
|<<nng_close#,nng_close(3)>>|close a socket
|<<nng_closeall#,nng_closeall(3)>>|close all open sockets
|<<nng_dial#,nng_dial(3)>>|create and start a dialer
|<<nng_getopt#,nng_getopt(3)>>|get a socket option
|<<nng_listen#,nng_listen(3)>>|create and start a listener
|<<nng_recv#,nng_recv(3)>>|receive data
|<<nng_send#,nng_send(3)>>|send data
|<<nng_setopt#,nng_setopt(3)>>|set a socket option
|===

=== Message Handling Functions

Applications desiring to use the richest part of _libnng_ will want to
use the message API, where a message structure is passed between functions.
This API provides the most power support for zero-copy.

Messages are divided into a header and body, where the body generally carries
user-payload and the header carries protocol specific header information.
Most applications will only interact with the body.

|===
|<<nng_msg_alloc#,nng_msg_alloc(3)>>|allocate a message
|<<nng_msg_append#,nng_msg_append(3)>>|append to message body
|<<nng_msg_body#,nng_msg_body(3)>>|return message body
|<<nng_msg_chop#,nng_msg_chop(3)>>|remove data from end of message body
|<<nng_msg_clear#,nng_msg_clear(3)>>|clear message body
|<<nng_msg_dup#,nng_msg_len(3)>>|duplicate a message
|<<nng_msg_free#,nng_msg_free(3)>>|free a message
|<<nng_msg_insert#,nng_msg_insert(3)>>|prepend to message body
|<<nng_msg_len#,nng_msg_len(3)>>|return the message body length
|<<nng_msg_realloc#,nng_msg_realloc(3)>>|reallocate a message
|<<nng_msg_trim#,nng_msg_trim(3)>>|remove data from start of message body
|<<nng_recv_msg#,nng_recvmsg(3)>>|receive a message
|<<nng_sendmsg#,nng_sendmsg(3)>>|send a message
|===

==== Message Header Handling

TIP: Few applications will need these functions, as message headers are only
used to carry protocol-specific content.  However, applications which use raw
mode may need to access the header of messages.

|===
|<<nng_msg_header#,nng_msg_header(3)>>|return message header
|<<nng_msg_header_append#,nng_msg_header_append(3)>>|append to message header
|<<nng_msg_header_chop#,nng_msg_header_chop(3)>>|remove data from end of message header
|<<nng_msg_header_clear#,nng_msg_header_clear(3)>>|clear message header
|<<nng_msg_header_insert#,nng_msg_header_insert(3)>>|prepend to message header
|<<nng_msg_header_len#,nng_msg_header_len(3)>>|return the message header length
|<<nng_msg_header_trim#,nng_msg_header_trim(3)>>|remove data from start of message header
|===

=== Asynchronous Operations

Most applications will interact with _nng_ synchronously; that is that
functions such as <<nng_send#,nng_send()>> will block the calling
thread until the operation has completed.

NOTE: Synchronous operations which send messages may return before the
message has actually been received, or even transmitted.  Instead, These
functions return as soon as the message was successfully queued for
delivery.

Asynchronous operations behave differently.  These operations are
initiated by the calling thread, but control returns immediately to
the calling thread.  When the operation is subsequently completed (regardless
of whether this was successful or not), then a user supplied function
("callback") is executed.

A context structure, called an _aio_, is allocated and associated for
each asynchronous operation.  Only a single asynchronous operation may
be associated with an _aio_ at any time.

The following functions are used in the asynchronous model:

|===
|<<nng_aio_alloc#,nng_aio_alloc(3)>>|allocate asynchronous I/O context
|<<nng_aio_cancel#,nng_aio_cancel(3)>>|cancel asynchronous I/O operation
|<<nng_aio_free#,nng_aio_free(3)>>|free asynchronous I/O context
|<<nng_aio_get_msg#,nng_aio_get_msg(3)>>|get message from an asynchronous receive
|<<nng_aio_result#,nng_aio_result(3)>>|return result from asynchronous operation
|<<nng_aio_stop#,nng_aio_stop(3)>>|stop asynchronous I/O operation
|<<nng_aio_wait#,nng_aio_wait(3)>>|wait for an asynchronous I/O operation
|<<nng_aio_set_msg#,nng_aio_set_msg(3)>>|set message for an asynchronous send
|<<nng_aio_set_timeout#,nng_aio_set_timeout(3)>>|set timeout for an asynchronous send
|<<nng_recv_aio#,nng_recv_aio(3)>>|receive a message asynchronously
|<<nng_send_aio#,nng_send_aio(3)>>|send a message asynchronously
|===

=== Protocols

The following functions are used to construct a socket with a specific
protocol:

|===
| <<nng_bus#,nng_bus_open(3)>>|open a bus socket
| <<nng_pair#,nng_pair_open(3)>>|open a pair socket
| <<nng_pub#,nng_pub_open(3)>>|open a pub socket
| <<nng_rep#,nng_rep_open(3)>>|open a rep socket
| <<nng_req#,nng_req_open(3)>>|open a req socket
| <<nng_respondent#,nng_respondent_open(3)>>|open a respondent socket
| <<nng_sub#,nng_sub_open(3)>>|open a sub socket
| <<nng_surveyor#,nng_surveyor_open(3)>>|open a surveyor socket
|===

=== Transports

The following functions are used to register a transport for use.

|===
| <<nng_inproc#,nng_inproc_register(3)>>|register inproc transport
| <<nng_ipc#,nng_ipc_register(3)>>|register IPC transport
| <<nng_tcp#,nng_tcp_register(3)>>|register TCP transport
| <<nng_tls#,nng_tls_register(3)>>|register TLS transport
| <<nng_ws#,nng_ws_register(3)>>|register WebSocket transport
| <<nng_wss#,nng_wss_register(3)>>|register WebSocket Secure transport
| <<nng_zerotier#,nng_zerotier_register(3)>>|register ZeroTier transport
|===

=== URL Object

Common functionality is supplied for parsing and handling
universal resource locators (URLS).

|===
| <<nng_url_clone#,nng_url_clone(3)>>|clone URL structure
| <<nng_url_free#,nng_url_free(3)>>|free URL structure
| <<nng_url_parse#,nng_url_parse(3)>>|create URL structure from string
|===


=== HTTP Support

The library may be configured with support for HTTP, and this will
be the case if WebSocket support is configured as well.  In this case,
it is possible to access functionality to support the creation of
HTTP (and HTTP/S if TLS support is present) servers and clients.

==== Common HTTP Functions

The following functions are used to work with HTTP requests, responses,
and connections.

|===
| <<nng_http_req_add_header#,nng_http_req_add_header(3)>>|add HTTP request header
| <<nng_http_req_alloc#,nng_http_req_alloc(3)>>|allocate HTTP request structure
| <<nng_http_req_copy_data#,nng_http_req_copy_data(3)>>|copy HTTP request body
| <<nng_http_req_del_header#,nng_http_req_del_header(3)>>|delete HTTP request header
| <<nng_http_req_free#,nng_http_req_free(3)>>|free HTTP request structure
| <<nng_http_req_get_header#,nng_http_req_get_header(3)>>|return HTTP request header
| <<nng_http_req_get_method#,nng_http_req_get_method(3)>>|return HTTP request method
| <<nng_http_req_get_uri#,nng_http_req_get_uri(3)>>|return HTTP request URI
| <<nng_http_req_get_version#,nng_http_req_get_version(3)>>|return HTTP request protocol version
| <<nng_http_req_set_data#,nng_http_req_set_data(3)>>|set HTTP request body
| <<nng_http_req_set_header#,nng_http_req_set_header(3)>>|set HTTP request header
| <<nng_http_req_set_method#,nng_http_req_set_method(3)>>|set HTTP request method
| <<nng_http_req_set_uri#,nng_http_req_set_uri(3)>>|set HTTP request URI
| <<nng_http_req_set_version#,nng_http_req_set_version(3)>>|set HTTP request protocol version
| <<nng_http_res_add_header#,nng_http_res_add_header(3)>>|add HTTP response header
| <<nng_http_res_alloc#,nng_http_res_alloc(3)>>|allocate HTTP response structure
| <<nng_http_res_alloc_error#,nng_http_res_alloc_error(3)>>|allocate HTTP error response
| <<nng_http_res_copy_data#,nng_http_res_copy_data(3)>>|copy HTTP response body
| <<nng_http_res_del_header#,nng_http_res_del_header(3)>>|delete HTTP response header
| <<nng_http_res_free#,nng_http_res_free(3)>>|free HTTP response structure
| <<nng_http_res_set_data#,nng_http_res_set_data(3)>>|set HTTP response body
| <<nng_http_res_get_header#,nng_http_res_get_header(3)>>|return HTTP response header
| <<nng_http_res_get_reason#,nng_http_res_get_reason(3)>>|return HTTP response reason
| <<nng_http_res_get_status#,nng_http_res_get_status(3)>>|return HTTP response status
| <<nng_http_res_get_version#,nng_http_res_get_version(3)>>|return HTTP response protocol version
| <<nng_http_res_set_header#,nng_http_res_set_header(3)>>|set HTTP response header
| <<nng_http_res_set_reason#,nng_http_res_set_reason(3)>>|set HTTP response reason
| <<nng_http_res_set_status#,nng_http_res_set_status(3)>>|set HTTP response status
| <<nng_http_res_set_version#,nng_http_res_set_version(3)>>|set HTTP response protocol version
|===

=== TLS Configuration Objects

The following functions are used to manipulate transport layer security
(TLS) configuration objects.

NOTE: These functions will only be present if the library has been built
with TLS support.

|===
| <<nng_tls_config_auth_alloc#,nng_tls_config_alloc(3)>>|allocate TLS configuration
| <<nng_tls_config_auth_mode#,nng_tls_config_auth_mode(3)>>|set authentication mode
| <<nng_tls_config_ca_chain#,nng_tls_config_ca_chain(3)>>|set certificate authority chain
| <<nng_tls_config_ca_file#,nng_tls_config_ca_file(3)>>|load certificate authority from file
| <<nng_tls_config_cert_key_file#,nng_tls_config_cert_key_file_cert(3)>>|load own certificate and key from file
| <<nng_tls_config_own_cert#,nng_tls_config_own_cert(3)>>|set own certificate and key
| <<nng_tls_config_free#,nng_tls_config_free(3)>>|free TLS configuration
| <<nng_tls_config_server_name#,nng_tls_config_server_name(3)>>|set remote server name
|===


== SEE ALSO

<<nng#,nng(7)>>,
<<nng_compat#,nng_compat(3)>>

== COPYRIGHT

Copyright 2018 mailto:info@staysail.tech[Staysail Systems, Inc.] +
Copyright 2018 mailto:info@capitar.com[Capitar IT Group BV]

This document is supplied under the terms of the
https://opensource.org/licenses/MIT[MIT License].