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Objective

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The NodeJS Middleware provides the ability to modernize existing API with SOAJ when these APIs are this API is built using NodeJs as a development language.

The middleware exposes several functionality and configuration that SOAJS offers and which can be consumed by the Microservice API upon initialization or during runtime when requests to its APIs arrive.

This page explains the NodeJs middleware; the functionality and configuration that it offers, how to install it and how to use it.

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1. How to Install 
2. Features
   1. Configuration
   2. Functionality
3. How does it work
   1. on init
   2. on request
4. Using the Middleware
   1. Initialization State
   2. Runtime State
5. Examples
   1. NodeJs Express
   2. NodeJs Hapi

1- How to Install

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Source Code: The SOAJS NodeJs middleware is open source and is available under Github, you can use the following reference to pull the source code → https://github.com/soajs/soajs.nodejs

The middleware is also available as an NPM package and can be download for free.

# install from npm
npm install soajs.nodejs

The middleware can also be used as a dependency in your package.json file

{
	"dependencies": {
		"soajs.nodejs": "*"
	}
}

2- Features

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Once the mw middleware is initialized, the following list of functions will be available to use through 'req.soajs.reg'

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functionality becomes available:

This middleware functionality is accessible via the request that is made to the API. The middleware traps the request once it hits the API, injects its functionality and then hands it back to you to add your business logic. 

3-How does it work

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On Init

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Using The Middleware requires the following environment variables :to be set prior to starting your service

Environment Variable	Description	Example	Reference
SOAJS_REGISTRY_API	The location of the SOAJS API Gateway along with the maintenance port value that it is using in the environment where the service will run in	127.0.0.1:5000/	Environment Variables
SOAJS_ENV

the middleware is going to invoke the controller and get the registry. Using the service configuration provided, the mw will auto reload the registry every "serviceConfig.awareness.autoRelaodRegistry"

Once the registry is loaded, the middleware is now ready to act on request.

On request:

Once a request is reached, the SOAJS controller will be passing through the request headers a 'soajsinjectobj' which will be mapped within the middleware to the following standard object:

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language	js

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environment code that this service will run in

DEV

Environment Variables

Once your service starts, the middleware will make a call to the CON and retrieve the registry of the environment, it will cache it in memory.

From this registry, it uses variable autoReloadRegistry (which represents the auto reload duration in seconds) and every time this value is met, the middleware automatically pulls the new version of the registry and updates its cached version.

On request

SOAJS midlleware augments your service by trapping all arriving requests and injecting additional data then hands the updated version of request to your business logic.

The following table illustrates the data that gets injected by the middleware on every request:

tenant : {
    id : '',
    code : ''

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}

key : {
    config : {},
    iKey : '',
    eKey : ''
},
device : 

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'',
geo : {}

application : {
    product : '',
    package : '',
    appId : '',
    acl : {},
    acl_all_env : {}

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}

package :{
    acl :{},
    acl_all_env : {}

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}

urac : {}

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awareness : {
    host : '',
    port : '',
    getHost : 'function',
	connect : 

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'function'
}

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4- Using the Middleware

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Require this Middle Ware in your restful nodejs service, and append it to your appOnce you download the middleware, simply require it and instruct the web application server to use it.

Consequently, anywhere in your APIs you can get your soajs object and use the data / functions as follows:, invoke req.soajs to access the data and functions that it offers.

// require the mw
const soajsMW = require('soajs.nodejs');

// pass it to your service app
app.use(soajsMW({ 	serviceName : 'testmy_service' }));

//...
use
it// ininvoke yourreq.soajs
requests
app.post('/helloworldfoo', function(req, res) => { 
	var//...

	let soajs = req.soajs;
	// soajs.key.iKey;
	// soajs.reg.getDatabases();console.log( JSON.stringify( soajs, null, 2 ) );

	//...
});
});

5- Examples

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NodeJs Express

The following code snippets shows a basic example built using NodeJs Express Library and how the SOAJS NodeJs Middleware was added to the code to augment the web server created by express.

Full Example on: https://github.com/soajs/soajs.nodejs.express

'use strict';

//Create Express varApp
const express = require('express');
varconst app = express();

//Require SOAJS Middleware for NodeJs
const soajsMW = require('soajs.nodejs');

varconst url = require('url');

//Instruct the Express App to use the SOAJS Middleware
app.use(soajsMW({ serviceName : 'testmy_service' }));

//Invoke the middleware and use it in the Express app API
app.get('/tidbit/hello', function(req, res) => {
var
	let url_parts = url.parse(req.url, true);
var	let query = url_parts.query;

var	let username = query.username;
var	let lastname = query.lastname;

	res.send({
		"message": "Hello`Hello DEMO, I am an EXPRESS service, you are ["+username+" ${username} ] and your last name is : ["+lastname+"]",
dbs ${lastname} ]`,
		"dbs" : req.soajs.reg.getDatabases()
	});
});

//Invoke the middleware and use it in the Express app API
app.post('/tidbit/hello', function(req, res){

var	let response = req.soajs;

	req.soajs.awareness.getHost(function (host) => {

		response.controller = host;
		res.send(response);
	});
});

//Start the Express app and set it to listen on port 4382
app.listen(4382);

NodeJs Hapi

The following code snippets shows a basic example built using NodeJs Hapi Library and how the SOAJS NodeJs Middleware was added to the code to augment the web server created by hapi.

Full Example on: https://github.com/soajs/soajs.nodejs.expresshapi

Hapi Example

'use strict';

const Hapiurl = require('hapiurl');
const
soajsMW = require('soajs.nodejs')({serviceName : 'test'});
var url//Create Hapi  App
const Hapi = require('urlhapi');

const server = new Hapi.Server();

//Instruct the Hapi app to listen on port 4380
server.connection({
    host: '0.0.0.0', port: 4380 });

//Require SOAJS Middleware for NodeJs
const soajsMW  port: 4380
});
= require('soajs.nodejs')({serviceName : 'my_service'});

//Instruct the Hapi App to use the SOAJS Middleware
server.ext({
    type: 'onRequest',
    method: function (request, reply) => {
        soajsMW(request, reply, function (err) => {
            if (err) {
                throw err;
            }
            return reply.continue();
        });
    }
});

//Invoke the middleware and use it in the Express app API
server.route({
    method: 'GET',
    path: '/tidbit/hello',     handler: function (request, reply) => {

	    varlet url_parts = url.parse(request.url, true);
	    varlet query = url_parts.query;

	    varlet username = query.username;
	    varlet lastname = query.lastname;

        return reply({
	        		"message": "Hello`Hello DEMO, I am aan HAPIHapi service, you are ["+username+" ${username} ] and your last name is : ["+lastname+"]"
  ${lastname} ]`,
			"dbs" : req.soajs.reg.getDatabases()
        });
    }
});

//Invoke the middleware and use it in the Express app API
server.route({ 	method: 'POST', 	path: '/tidbit/hello', 	handler: function (request, reply) => {

		varlet response = request.soajs;
		request.soajs.awareness.getHost(function (host) => {
			response.controller = host;
			return reply(response);
		});
	}
});

//Start the Hapi app server
server.start((err) => {

    if (err) {
        throw err;
    }
    console.log('Server running at:', server.info.uri);
});

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