Decentralised Applications


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Photo by Tyler Lastovich on Unsplash

Laurent Hardy

What is the

Killer App?

Network effect

Internet Stack

Blockchain Stack

Protocol layer

Application layer

Application layer

Protocol layer

Fat Protocol

Application layer


Thin Protocol



Blockchain Stack

i.e Linux

Traditional Economy

Token Economy

source: Thin protocols

building blocks





How does a DAPP come into existence?

  • Take the sourceCode of the smart contract
  • Compile the source code into a JSON file
  • Extract the contract ABI (Application Binary Interface)
  • Extract the byte code
  • Instantiate a new contract object
  • Deploy the smart contract to the Ethereum blockchain

Deploy a smart contract

Every node on the Ethereum blockchain network has a copy of the smart contract

But the rest
of the world
has no clue!

How to interact with a DAPP?

State variables

they are defined once and cannot change, they are set in stone


they are used to check the value of a variable, they cost zero gas, they are free


they are used to modify the value of a variable, therefore they consume gas

As of today, smart contract cannot be upgraded once deployed

Solidity documentation 
in English here

documentación de Solidity
en Español aquí

Feedback is welcome.


Decentralised Applications

By Laurent Hardy

Decentralised Applications

A DAPP is the name given to services that run on top of a blockchain. They are called decentralised applications because no authority has control over the service by design. Ethereum is for now the default blockchain infrastructure that services are using to build DAPP by levering the smart contracts architecture.

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