Application Framework with Koa.js and Rest API
Overview of this blog?
This is written to get knowledge about koa.js and Rest API.
What is koa.js?
Koa.js is a new web framework.
Koa.js is open source, minimal and flexible Node.js web framework developed by the creators of express.js.
Koa allows to ditch callbacks and greatly increase error handling.
Koa.js features
Koa.js is modern and future proof.
Koa.js uses ES6 generators to simplify synchronous programming and facilitate the flow of controls.
Koa.js has a small footprint compared to other Node.js framework.
Koa.js has built in catchall for errors that helps prevent website crashes.
Koa.js uses a context object which is an encapsulation of request and response objects.
Who uses koa.js?
Many companies use koa.js framework for their websites and web API.
Ex: paralect
Pubu
Bulb
GAPO
Clovis
Advantages of koa.js
It provides a very good user experience.
No callback hell.
Cleaner, more readable async code.
Koa is extremely light with just 550 lines of code.
Koa increase interoperability and robustness while still making middleware creation more fun .
ES6 generators will tidy up the code and make it more it more manageable by removing the created by all those callbacks.
Disadvantages of koa.js
The open-source community is relatively small.
Koa makes use of generators that are incompatible with all other Node.js framework middleware.
Not compatible with express-style middleware.
Express.js vs koa.js
Koa is a very light and flexible system that can be moduled to suit the application requirements due to the absence of unnecessary boilerplate code and middleware.
The inclusion of libraries increases the applications modularity.
Koa removes callback hell and simplifies error management by using promises and async features.
Instead of the node.js req and res objects, it exposes its own ctx. request and ctx. response objects.
Express adds additional properties and methods to node.js req and res objects, as well as many other framework features including routing and templating that Koa lacks.
How is Koa different from express?
Koa depends less on middle.
Koa is more modular.
No callback hell.
Absence of boilerplate codes.
Better overall user experience.
Routing is not available, unlike express.
Proper stream handling.
Better error handling using try / catch.
How to install and write koa.js programme
Node install Koa
After Koa package has been successfully installed type the below code in your JavaScript file to display Hello Koa in the browser.
//Require the Koa package
Const Koa = require (“Koa”);
Const app = new Koa ();
App.use (ctx => {
//display Hello Koa in the body
Ctx.body=” Hello Koa”;
})
// Listen to the server in port 3000
App.listen(3000);
Rest Api
Restful services
REST — Representational state transfer protocol.
Client and server communication.
Lightweight, scalable, and maintainable.
Resource based. Resource is identified by a URI.
XML and JSON is used to pass data.
HTTP verbs
GET — Fetch a resource
POST- Insert a resource
PUT- Replacing existing resource
PATCH- Update resource
DELETE- Remove resource
OPTIONS- Get all allowed options
HEAD- Get only the response header
Constraints
Uniform interface
Stateless
Cacheable
Client-server
Layered system
Compliance with REST Constraints
Performance
Visibility
Modifiability
Scalability
Simplicity
Portability
Reliability
Conclution
You can get some basic knowledge about koa.js and Rest API. Mainly these essential points are discussed here.
Thank You!
