N2O

Endpoints

Here is a list of types of endpoints which are supported by EMQ and accessible to N2O apps: WebSockets, MQTT, MQTT-SN, TCP, UDP, CoAP. Normal use of N2O as a Web Framework or a Web Application Server is through WebSockets, but for IoT and MQTT applications it could be served through UDP or SCTP protocols, providing application level message delivery consistency. By using MQTT as a transport we extend the supported set of endpoint protocols.

MQTT

EMQ is an open-source MQTT broker implemented by Feng Lee. N2O is EMQ compatible plugin that acts as predefined MQTT clients that form a ring of virtual nodes, process all the protocol requests, and answer to client topics according to classical RPC over MQ schema. This list of modules forms a core of N2O that is common for both MQTT and WebSocket versions:

n2o — N2O Application
: MQTT and WS — 10KB
n2o_pi — N2O Processes
— 4KB
n2o_proto — N2O Loop
: — 1KB
n2o_ring — N2O Ring
: Hash Ring — 1KB


  $ mad app zero review
  $ cd review
  $ mad dep com pla rep
  $ open http://127.0.0.1:8000

The list of MQTT specific modules:

n2o_auth — N2O MQTT Authentication
: MQTT auth module — 1KB
n2o_mqtt — MQTT DHT Processing Node

WebSocket

COWBOY is small, fast, and modern HTTP server implemented by Loïc Hoguin. In this version, N2O loop is integrated as WebSocket cowboy handler that routes all incoming messages to N2O. The list of WebSocket specific modules:

n2o_cowboy — COWBOY API
n2o_ws — WebSocket DHT Processing Node


  $ mad app nitro sample
  $ cd sample
  $ mad dep com pla rep
  $ open https://127.0.0.1:8001/app/index.htm

Protocols

n2o_heart — PING protocol
n2o_ftp — N2O File Protocol
: FTP — 4KB
n2o_nitro — N2O Nitrogen Web Framework Protocol
: — 3KB

Services

n2o_session — ETS sessions backend
n2o_secret — AES/GCM-256 encoder/decoder
n2o_gproc — GPROC MQ backend
n2o_syn — SYN MQ backend

JavaScript

utf8.js — UTF-8 encoder/decoder
zlib.js — ZLIB inflate algorithm
ieee754.js — IEEE-754 encoder/decoder
bert.js — BERT encoder/decoder
n2o.js — N2O protocol looper
heart.js — HEART protocol
nitro.js — NITRO protocol
ftp.js — FTP protocol
mq.js — MQTT client

SPEC

N2O:


  -type n2o()       :: #bert{} | #json{} | #binary{} | #default{}.
  -type cx()        :: #cx{}.
  -type formatter() :: binary | json | bert | text | default | atom().
  -type response()  :: { formatter(), binary() }.

  -record(ok,      { data :: term() }).
  -record(error    { data :: term() }.
  -record(reply,   { msg  :: n2o(), req :: term(), ctx :: cx() } ).
  -record(unknown, { msg  :: n2o(), req :: term(), ctx :: cx() } ).

  -spec start(#pi{})              -> {pid(),term()} | #error{}.
  -spec stop(term(),atom())       -> #pi{} | #error{}.
  -spec proc(atom(),#pi{})        -> term().
  -spec info(term(),term(),#cx{}) -> #reply{} | #unknown{}.

  -record(pi, { name   :: term(),
                table  :: atom(),
                sup    :: atom(),
                module :: atom(),
                state  :: term() }).

  -record(cx, { handlers   = [] :: list({atom(),atom()}),
                actions    = [] :: list(tuple()),
                req        = [] :: [] | term(),
                module     = [] :: [] | atom(),
                lang       = [] :: [] | atom(),
                path       = [] :: [] | binary(),
                session    = [] :: [] | binary(),
                formatter  = bert :: bert | json | atom(),
                params     = [] :: [] | list(tuple()),
                node       = [] :: [] | atom(),
                client_pid = [] :: [] | term(),
                state      = [] :: [] | term(),
                from       = [] :: [] | binary(),
                vsn        = [] :: [] | binary() }).

  -type memtable()  :: atom().
  -spec encode(tuple())                 -> binary().
  -spec decode(binary())                -> tuple().
  -spec session(term(),term())          -> term().
  -spec session(term())                 -> term().
  -spec cache(memtable(),term(),term()) -> term().
  -spec cache(memtable(),term())        -> term().