Tech Talks

Introduction REST defines REpresentational State Transfer protocol. Nouns vs actions. REST services are not action based though HTTP verbs being used to perform different operations on the same resource. Resource are identified by a URI. Multiple URIs may refer the same resource. JSON or XML is used to pass data.  HTTP Verbs HTTP Status Codes Architectural constraints of REST services Client-server architecture Statelessness Cacheability Layered system Code on demand Uniform interface What is Express JS Express JS is a Node JS based web application framework.  Express.js was founded by TJ Holowaychuk.  Express provides a thin layer of fundamental web application features. Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

Introduction to React JS React is a JavaScript library for creating user interfaces. Serves as the view of MVC architecture. Developed and maintained by Facebook and Instagram.  React was created by Jordan Walke.  React Native , which enables native  Android ,  iOS , and  UWP  development with React. Notable features of React JS One-way data flow Virtual DOM JSX Props and State of React JS Props are short for  Properties and  State is internal to a component, while props are passed to a component. Props are unchangeable but States can change.  Props and State are the two types of data that control a component.  Props essentially help you write reusable code.  React component life cycle In React each component has several life cycle methods that you can override to run code at particular times in the process. These methods are called in the following order when an instance of a component i...

Introduction to NoSQL NoSQL is an approach to database design that can accomodate a wide variety of data models, including key-value, document, columnar and graph formats. NoSQL, which stand for "not only SQL," is an alternative to traditional relational databases in which data is placed in tables and data schema is carefully designed before the database is built. NoSQL databases are especially useful for working with large sets of distributed data. A NoSQL database includes simplicity of design, simpler horizontal scaling to clusters of machines and finer control over availability. The data structures used by NoSQL databases are different from those used by default in relational databases which makes some operations faster in NoSQL. Advantages of NoSQL High scalability High availability Disadvantages of NoSQL Narrow focus Open-source Management challenge GUI is not available Large document size Types of NoSQL database ...

Node.js Introduction   As an asynchronous event driven JavaScript runtime, Node is designed to build scalable network applications. ·          Node.js is an open source server environment ·          Developed by Ryan Dahl. ·          Node.js runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.) ·          Node.js uses JavaScript on the server ·          Build on V8 engine, Chrome’s JavaScript engine. ·          NodeJS eco-system ‘npm’ is the largest in the world for open source libraries. Node.js Event Loop Simple Node.js "Hellow World" example . const http = require ( 'http' );   const hostname = '127.0.0.1' ; const port = 3000 ;   const server = http. createS...

Javascript Basic Concepts Function Declarations vs Function Expressions Function Declarations Function declarations define named function variables without the need for variable assignments. Function declarations occur as independent components and can not be nested within non-function blocks. It is useful to think of them as siblings of variable declarations. Function declarations must begin with "function", as variable declarations begin with "var". example :- function testFunction(){   console.log("Hello World"); } To execute this function we can call it as "  testFunction() "  Function Expressions  A function expression defines a function as part of the syntax of a larger expression (usually variable assignment). Functions defined by function expressions can be named or anonymous. Function expressions must not begin with "function" example :-  Anonymous function expression var x = function (){     ...