NodeJs MW

Objective

The NodeJS Middleware provides the ability to modernize existing API with SOAJS when 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 API upon initialization or during runtime when requests arrive.

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

Scenario

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

1- How to Install

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.

SOAJS NodeJs NPM Package

# install from npm
npm install soajs.nodejs

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

Package.json

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

2- Features

Once the middleware is initialized, the following functionality becomes available:

Function	Type	Input	Output	Remarks

Function	Type	Input	Output	Remarks
getDatabases	Method	dbName (optional)	returns database object if dbName provided returns all core and tenant meta databases otherwise	Mongo Client Driver
getServiceConfig	Method	-	returns service configuration object	Services Config
getDeployer	Method	-	returns deployer object	Registry
getCustom	Method	-	returns custom object	Services Config
getResources	Method	resourceName (optional)	returns resource object if resourceName provided returns all resources otherwise	Registry
getServices	Method	serviceName (optional)	returns service object if serviceName provided returns all services otherwise	Service
getDaemons	Method	daemonName (optional)	returns daemon object if daemonName provided returns all daemons otherwise	Daemon
reload	Method	-	void (reload registry only)	Registry

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

On Init

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

Environment Variable	Description	Example	Reference

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	environment code that this service will run in	DEV	Environment Variables

Once your service starts, the middleware will make a call to the API Gateway 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:

Property	Code Snippet	Description	Reference

Property	Code Snippet	Description	Reference
Tenant	req.soajs.tenant `tenant : { id : '', code : '' }`	Represents the tenant that is making the call to the API.	Multitenancy
Key Device Geo	req.soajs[ key \| device \| geo ] `key : { config : {}, iKey : '', eKey : '' }, device : '', geo : {}`	Represents the key configuration which belongs to the tenant making the call to the API.	Security Services Config
Application	req.soajs.application `application : { product : '', package : '', appId : '', acl : {}, acl_all_env : {} }`	Represents the application information which belongs to the tenant making the call to the API.	Multitenancy Access Levels
Package	req.soajs.package `package :{ acl :{}, acl_all_env : {} }`	Represents the Productization that the tenant making the call to the API is using.	Productization Access Levels
URAC	req.soajs.urac `urac : {}`	Represents the User whose access token was found in the request.	URAC v2
Awareness	req.soajs.awareness `awareness : { host : '', port : '', getHost : 'function', connect : 'function' }`	Represents the SOAJS API Gateway internal network host & port based on the environment where the API is deployed and running in.	Request

4- Using the Middleware

Once you download the middleware, simply require it and instruct the web application server to use it.

Consequently, anywhere in your APIs, invoke req.soajs to access the data and functions that it offers.

Using the Middleware with NodeJs

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

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

//...

// invoke req.soajs
app.post('/foo', (req, res) => { 
	//...

	let soajs = req.soajs;
	console.log( JSON.stringify( soajs, null, 2 ) );

	//...
});

5- Examples

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

NodeJs Express & SOAJS NodeJs Middleware

'use strict';

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

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

const url = require('url');

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

//Invoke the middleware and use it in the Express app API
app.get('/hello', (req, res) => {

	let url_parts = url.parse(req.url, true);
	let query = url_parts.query;

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

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

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

	let response = req.soajs;

	req.soajs.awareness.getHost( (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.hapi

'use strict';

const url = require('url');

//Create Hapi  App
const Hapi = require('hapi');
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 = require('soajs.nodejs')({serviceName : 'my_service'});

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

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

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

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

        return reply({
			"message": `Hello DEMO, I am an Hapi service, you are [ ${username} ] and your last name is : [ ${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: (request, reply) => {

		let response = request.soajs;
		request.soajs.awareness.getHost( (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);
});