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Introduction to NodeJS




NodeJS is know as a  highly scalable, data intensive and  a real time back-end service. NodeJS is an open source, cross platform runtime environment for server-side and networking applications. To build a back-end services there are other tools and framework such as rails, Django, asp.net etc.. Node is not a programming language not a framework. There are few characteristics that make Node more popular.

Characteristics of NodeJS.


  • Easy to get started.
  • Can be used for prototyping and agile development.
  • It is good to build super fast and highly scalable services.
         Eg -: Paypal, Uber, Netflix, Walmart
  • It use JavaScript.
  • Source code will be cleaner and more consistence.
  • Large Eco-system of open source library.

Node is a runtime environment for executing JavaScript code.

Runtime environment of NodeJs. 

In JavaScript the application runs inside the browser . Browser has a JavaScript engine taht convert the code to machine code.
e => ChakraFirefox => SpidermonkeyChrome => V8  

Browser provide the runtime environment. NodeJs is created as a C++ program that is embedded in V8. Similar to a browser Node is a runtime environment for JavaScript.

Node is a program that includes V8 JvaScript engine and additional modules that give the capabilities that are not available in a browser.


Event loop.

Uses event-driven, non-blocking I/O model which makes NodeJS lightweight and efficient. Node handles multiple requests using a single thread asynchronously.  Frameworks such as asp.net, rails are synchronous/Blocking.

Single thread to handle multiple requests.
In synchronous/blocking thread is allocated to each and every request. If in a scenario where all the threads are allocated to requests the new client (request) must wait until a thread is released or if we do not need the clients to wait then we must allocate more hardware which will not be utilized well.


Event loop.
When a request arrives the thread handles the request. As an example while the database executes the query, that same thread is used to serve another client. When the database response with the result it will pit to the event loop. Node continuously monitors the event loop in the background. When an event is found in the event loop , take it out and process. Using this technique it helps to serve more clients without throwing more hardware makes Node more scalable.


Advantages and Disadvantages of NodeJS.



Advantages of NodeJS.

  • Ability to use single programming language from one end of the application to the other end.
  • NodeJS applications are easy to scale both horizontally and vertically.
  • Delivers improved performance since V8 engine compile the JavaScript code into machine code directly.
  • Performance increased via caching modules into memory after the first use.
  • Easily extensible.
  • Support for common tools like unit testing.
  • Well build ‘npm’ package manager and it’s large number of reusable modules.

Disadvantages of NodeJS.

  • Even though there are number of libraries available, the actual number of robust libraries is comparatively low.
  • Not suitable for computationally intensive tasks.
  • Asynchronous programming model is complex than synchronous model.



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