Server Backend Concepts Exploration

Node JS
JavaScript is a compiled programming language that runs in the browser by Chrome’s V8 engine. If we run JavaScript outside of a browser then it needs a runtime. Node JS is a JavaScript runtime that helps JavaScript to run outside of a browser. It is used for non-blocking and event-driven servers as it has single-threaded or asynchronous nature. It is used for websites and back-end API services.

CRUD Operations
In any persistent storage, there are four types of operations that could be happened. They are - create, read, update, and delete. And these four operations are called CRUD operations. It is implemented by databases or maybe in the HTTP methods known as RESTful APIs.

1. Create: This create operation allows users to create new records in the database. Depending on the data storage, it can be specified different name. A user can create a new row and populate it with data depending on each attribute. But users can’t create the attribute. This is handled by the database admin. In SQL it is known as INSERT and in HTTP it is known as PUT.

2. Read: Read operation mostly like as search operation. It allows to user to retrieve specific data from the database and read it. Users read the data from the database table based on the criteria. In SQL it is known as SELECT and in HTTP it is known as GET.

3. Update: The update operation is used to modify the users’ or users’ related information in the database. From the database table under the attribute, the user is able to change the attribute value. In SQL it is known as UPDATE and in HTTP it is known as PUT.

4. Delete: The delete operation allows the users to remove specific data or the users’ info from the database. Depending on the attribute user can remove other information. In SQL it is known as DELETE and in HTTP it is known as DELETE.
   In a user interactive website, this CURD operation is used mostly.

JWT
JSON Web Token is shortly known as JWT. It is used to share security information within a client and a server. It is useful for Authorization and Information Exchange. Each JWT holds encoded JSON objects including a set of claims. JWTs are signed using a cryptographic algorithm to ensure the claims cannot be altered after the token is issued. JWT web structures are -

• Header: It has two parts. One is the type of token and the other is the signing algorithm.

• Payload: It contains the claims. The claims are statements about an entity and additional data. There are three types of claims: registered, public, and private claims.

• Signature: Signature is the combination of the encoded header and the encoded payload, a secret, the algorithm specified in the header, and sign that.
  Each JWT looks like xxxxx.yyyyy.zzzzz.

Express
Node JS is a platform for building I/O applications that are server-side event-driven and made using JavaScript. And Express JS is a fast and minimalist web framework for Node JS. Express JS is provide server-side logic for web and mobile applications.