Private Blockchain Demo

Blockchain is changing the way that the world approaches data. In this demo I developed a simplified private blockchain, where levelDB is used to persist the blockchian dataset using the level Node.js library.

Udacity generated boilerplate code that implements a class containing attributes of a block, and a class that implements functionality that interacts with the blocks and blockchain. Udacity also provided a levelDB boilderplate to demonstrate the Data Access Layer.

Functions found in blockchain.js include:

• addBlock(newBlock): Adds a new block to the chain.

• getBlockHeight(): Returns the blocks in the chain.

• getBlock(blockHeight): Returns a block's JSON striong object

• validateBlock(blockHeight): Validates individual block data integrity

• validateChain(): Validates the entire blockchain

Installation

1. Download or Clone repository

2. Open a terminal and cd into the local directory Private_Blockchain

3. npm install

4. npm install crypto-js --save

5. npm install level --save

Test and play with Blockchain

1. Open a terminal and type node to open the REPL console

2. .load blockchain.js

3. A Blockchain is automatically initalized by code in blockchain.js

4. Use theLoop() to add 10 blocks to the chain.

    (function theLoop (i) {
    setTimeout(function () {
        let blockTest = new Block("Test Block");
        blockchain.addBlock(blockTest)
            i++;
            if (i < 10) theLoop(i);
    }, 500);
  })(0);
  

6. Validate the blockchain to check for chain consistency

   • blockchain.validateChain()

7. Individual blocks can be validated with

   • blockchain.validateBlock(blockHeight)

Acknowledgements

Big thanks to Udacity classroom content, Udacity Knowledge Labs, and levelDB documentation Check out the Blockchain Developer Nanodegree if you're interested in Blockchain development