Traditional web applications can be divided into two parts – client side and server side.
As shown in Figure, the server is a centralized system and has full control over the application .
A Blockchain application is decentralized and is distributed across all nodes in the Blockchain network. There is no concept of central web server.
Blockchain application is accessed using web browser and frontend files HTML, css and js are hosted on a webserver.
For the frontend, we can also use Bootstrap or any other framework. However, these frontend HTML files directly access the data and business logic in the publicly distributed Blockchain database.
There are 4 participating nodes in the network and the Blockchain application is present in every Blockchain node and executed independently and simultaneously.
There is no central server system controlling the application.
As shown in Figure2, both business logic written in smart contracts and data reside on each of the node of the Blockchain. Hence, the processing of the application happens on each node.
So, a Blockchain application is a decentralized application and hence these applications are also called Dapps. Generally, a Dapp is a two-tier application, comprised of two main components:
Developing the Dapp application is explained in the book titled:Develop Ethereuem Blockchain application. This book explains both frontend and backend of the Blockchain application.