Thursday, March 9, 2017

Overview of Restify

Restify is a node.js module built specifically to enable you to build correct REST web services. It intentionally borrows heavily from express as that is more or less the de facto API for writing web applications on top of node.js

Sunday, March 5, 2017

Arrow functions in java script

One parameters syntax

Crud operations in Express

These are the middleware needed for CRUD operations in express
//web framework for node.js
var express= require('express')
//Gives an instance of express
var app=express();
//Used for post request and forms
var bodyParser=require('body-parser');
//MongoDB Object modeling tool designed to work in asynchronous environment
var mongoose = require('mongoose');

Custom middleware in Node

Middleware would inject between the call and the Route.

  • When a client sends a request, it is handled by the route in the router
  • This router would send a response back to the client
  • When we have a middleware it would take the request process it and and then forward that request to the route. Then the route would send the response to the client

Models in express

Steps involved in creating models in express js

  • First we need to import mongooose
  • To make it modular, Lets create a new folder named models and then create a new js file . In this example I am creating model named  user. It has 2 properties firstName and lastName.
  • Load the model into mongoose

Friday, March 3, 2017

Call back hell in node

Callback hell is a phenomenon that afflicts a JavaScript developer when he tries to execute multiple asynchronous operations one after the other. Some people call it to be the pyramid of doom.

Cheat sheet for Node

1) Specify starting file for our application

  •  In package.json file we can specify the starting file for our application

Overview of Hadoop Map Reduce

  • Apache Hadoop  is an open-source software framework used for distributed storage and processing of big data sets using the MapReduce programming model. 
  • It consists of computer clusters built from commodity hardware. 
  • All the modules in Hadoop are designed with a fundamental assumption that hardware failures are common occurrences and should be automatically handled by the framework.

Nested component angular 2

For creating nested component we need to create the component under the shared folder.
When we use a component as a directive, we need to tell angular how to find that directive.We do that by declaring the nested component in an angular module as shown below

In the import we need to specify the path of the file and then add it in the declarations with the ngModule

import { StarComponent }  from './shared/star.component';

  imports:      [ BrowserModule,FormsModule ],
  declarations: [ AppComponent , 
  bootstrap:    [ AppComponent ]