Node.js is an open-source, cross-platform runtime environment that uses JavaScript for building scalable network applications. It provides an event-driven and non-blocking I/O model that makes it optimized for data-intensive real-time applications that run across distributed devices. Node.js uses Google's V8 JavaScript engine and allows coding in JavaScript along with a package manager called npm. It was created by Ryan Dahl in 2009 and is well-suited for building applications with high throughput and scalability like chat applications, message queuing, and IoT.

1. Anupam Datta | 593455 | datta.anupam@tcs.com
TCS Innovation Lab | Kolkata
[ #GetFact ]

2.  Open Source
 Cross-platform runtime environment.
 Provides event driven architecture & Non-blocking I/O
API. Asynchronous with callback ()
 Optimized throughput & increased scalability.
 Uses Google V8 javascript engine.
 Coding on Javascript.
 Most libraries are in Javascript.

3.  Invented in Joyent
 package manager npm
 primarily used for network application and server
 single thread [ concurrency | zero context switching cost ]
 Module does the job [ file R/W , networking and ++ ]
After over 20 years of stateless-web based on the
stateless request-response paradigm, we finally have web
applications with real-time, two-way connections.
-Ryan Dahl [ the man behind node.js ]

4. Traditional Web server :
2 MB/thread | theoretical concurrent connection 4000 for
8GB RAM + context switching cost
Node.js :
over 1M concurrent connection
Node.js is not good for CPU intensive Heavy
Computation
Node.js was never created to solve the compute scaling
problem. It was created to solve the I/O scaling problem

5. Example : Myntra uses Node.js
 Chat [ real time | multi user | high traffic | data intensive |
low computation ]
 Message Queuing [ data intensive | concurrent resource ]
 Data Streaming [ process data while in stream ]
 Proxy [ concurrent connection | high load ]
 Real time monitor [ large data set | concurrent | scalable ]
 IoT [ fast data | realtime ]

6. NodeFunda :
 module [ similar to #include <>, import ]
 callback [ continuation passing style | continue program
execution ]
 events [ event driven hence subscribing to EventEmitter
can change program execution ]
 stream [ .pipe () | manipulate on data flow | reduce
memory usage ]
 error handling [ must or else crashed ]

7. Resources :
 https://nodejs.org [ official site ]
 http://nodeschool.io [ tutorials ]
 azure.microsoft.com/en-us/develop/nodejs [ MS dev ]
 http://cylonjs.com/ [ JavascriptRobotics ]
 http://nodered.org/ [ Wiring IoT visually ]
 https://tessel.io/ [ High Level Hardware API for coding
small devices in node.js #IoT ]