What is Node.js?

• Event-driven, non-blocking I/O model that makes it lightweight and efficient
• Uses google's  Chrome's V8 JavaScript engine 
• JavaScript which runs on your computer
• Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world

Declarative vs imperative programming

Declarative :

• Write code what you want but not  necessarily how to get it (Declare the desired results but not the step-by-step)
• A style of building the structure and elements of computer programs—that expresses the logic of a computation without describing its control flow.
• Minimize or eliminate the side effects by describing what program should accomplish 
• How is left to the problem implementation
• Only thing a function can do is calculate something and return it as a result.

   Declarative languages include, SQL, React, Functional programming like haskell

Functional Prgramming

•  In purely functional programming you don't tell the computer what to do as such but rather you tell it what stuff is
• if a function is called twice with the same parameters, it's guaranteed to return the same result. That's called referential transparency and not only does it allow the compiler to reason about the program's behavior, but it also allows you to easily deduce (and even prove) that a function is correct and then build more complex functions by gluing simple functions together

var results = collection.Where( num => num % 2 != 0);

Imperative :

• Tell the compiler what you want to happen step by step
• Java, C, C#  is imperative
• Main method of computation is assignment variable
• Implements algorithms in explicit steps.

Machine learning

-Is a science of getting computers to learn, without being explicitly programmed

-Grew out of work in AI

-New capability of the computers

Supervised Learning ML

Supervised learning is a type of machine learning algorithm that uses a known dataset (called the training dataset) to make predictions. 

The training dataset includes input data and response values. From it, the supervised learning algorithm seeks to build a model that can make predictions of the response values for a new dataset. A test dataset is often used to validate the model. Using larger training datasets often yield models with higher predictive power that can generalize well for new datasets.

Supervised learning includes two categories of algorithms:

Intents, Entities, and Model Training LUIS

One of the key problems in human-computer interactions is the ability of the computer to understand what a person wants, and to find the pieces of information that are relevant to their intent. 

Ex : " Get the stock price for msft". In this case the intent is to get the stock price of the company and entity is msft.

Intent -> What we want to do.
StockPrice
IstheMarketUpOrDown
RepeatLastStock

Entity -> an object that exists and is distinguishable from other objects

Overview of LUIS ( Language Understanding Integration Services )

Is a service provided by Microsoft cognitive services, Formally known as project Oxford.They are a set of intelligent services with the vision of democratizing machine learning. 

MessageController in Bot Framework

  The Message Controller is the meat of  Bot application

• It resides in an asp.net application
• It can accept a message and return a message

The message controller monitors the different activities of the User

The default type of activity is is Activity.message.