iopa-connect
v1.4.4
Published
Middleware to connect to Express/Connect style-middleware, and/or to build IOPA apps on top of built-in node HTTP Server
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iopa-connect
About
This repository contains a Node Package Manager (NPM) package with helper functions for:
- Connect app bridge: An IOPA -> Connect/Express application bridge
- HTTP server bridge: A Node.js Http Server --> IOPA application bridge
This package is intended for use in Node.js applications that either run on a web server that conform to the IOPA specifications (such as the embedded webserver inside nodekit.io) or run using the included iopa-http bridge for node-coap and node Http servers respectively.
Middleware/Application Pipeline Builder: AppBuilder
app.use(middleware)Adds a middleware node to the IOPA function pipeline. The middleware are
invoked in the order they are added: the first middleware passed to app.use will
be the outermost function, and the last middleware passed to Use will be the
innermost.
middleware
The middleware parameter determines which behavior is being chained into the pipeline.
If the middleware given to use is a function that takes one argument, then it will be invoked with the
nextcomponent in the chain as its parameter, and with thethiscontext set to the IOPA context. It MUST return a promise that conforms to the Promise/A specification.If the middleware given to use is a function that takes two arguments, then it will be invoked with the
nextcomponent in the chain as its parameter, with a Node-based callback (function(err, result){})as its second parameter, and with thethiscontext set to the IOPA context. This type of middleware should return void.Legacy middleware can also be invoked with
app.use( function(req,res){ ... } ),app.use( function(req, res, next){ ... } )orapp.use( function(err, req, res, next){ ... } ). The AppBuilder is smart enough to detect the two argument function with parameters named req and res in this case (use of different naming conventions need to be wrapped in afunction(req,res){}), and assumes three and four argument functions are legacy.
Bridges
Three simple functions iopa.connect(), iopa.COAP() and iopa.REST() are provided to bridge between IOPA context applications/middleware and Node.js COAP and HTTP REST-style function(req,res) based applications/middleware. Often these are not used directly as the AppBuilder functionality automatically wraps legacy middleware and can even return a node.js-ready pipeline with .buildREST()
Note: The bridges are low overhead functions, binding by reference not by value wherever possible, so middleware can be interwoven throughout the pipeline, and open up the IOPA world to the entire Connect/Express based ecosystem and vice versa.
We have not ported to Koa, Mach, Kraken or other similar frameworks but it would be relatively straightforward to do so.
iopa.connect()consumes a Connect-based application function (one that would normally be passed to the http.CreateServer method) and returns an IOPA AppFunc.iopa.http()consumes an IOPA AppFunc and returns a function (that takes http.requestMessage and http.requestMessage as arguments) and one that can be passed directly to the http.createServer methodapp.buildHttp()is syntactic sugar to build the pipleine and returns a node.js-ready function (that takes http.requestMessage and http.requestMessage as arguments) and one that can be passed directly to the http.createServer method
Example Usage
Installation
npm install iopaTo run HTTP demo:
git clone https://github.com/limerun/iopa.git
cd iopa
npm install
node demo.jsHello World Example
const iopa = require('iopa'),
http = require('iopa-connect').http;
var app = new iopa.App();
app.use(http);
app.use(function(context, next){
context.response["iopa.WriteHead"](200, {'Content-Type': 'text/html'});
context.response["iopa.Body"].end("<html><head></head><body>Hello World from HTTP Server</body>");
return next();
});
app.createServer("http:").listen();Automatic Connect Bridge to Legacy Connect/Express Middleware
var iopa = require('iopa')
, http = require('http');
require('iopa-connect');
var app = new iopa.App();
app.use(function(req, res) {
response.writeHead(200, {"Content-Type": "text/html"});
response.end("<html><head></head><body>Hello World</body>");
});
http.createServer(app.buildHttp()).listen(); IOPA - HTTP Bridge
var iopa = require('iopa')
, http = require('http');
var http = require('http');
var app = new iopa.App();
app.use(function(next){
this.response.writeHead(200, {'Content-Type': 'text/html'});
this.response.end("<html><head></head><body>Hello World</body>");
return next();
});
http.createServer(app.buildHttp()).listen();Definitions
- appFunc =
(Promise) function(context) - app.use =
(app)function(middleware) - middleware =
(Promise) function(context, next)withnext=appFunc - OR middleware =
fn(req, res, next)for compatibility with Connect/ExpressJS middleware - OR middleware =
fn(err, req, res, next)for compatibility with Connect/ExpressJS middleware - app.build =
(appFunc) function(context)// builds middleware - app.buildHttp =
(function(req, res)) function()// builds middleware for compatibility with Connect/ExpressJS hosts - context = IOPA context dictionary
API Reference Specification