Here Is How You Can Develop Your Very First Blockchain App - MobileAppDaily
Blockchain

Here Is How You Can Develop Your Very First Blockchain Application

Get your hands on Blockchain application.

https://dk2dyle8k4h9a.cloudfront.net/Here Is How You Can Develop Your Very First Blockchain Application

The hype around blockchain emerged like the technology is going to create never-seen-before innovation in the tech industry. Well, It actually did. And to make this revolution keep growing we need skilled engineers at the work. Let me put the stats here, as per the recent study on the requirement of blockchain engineers, currently there are 14 jobs available for a single professional. This speaks of the scarcity we have today in the industry. 

The talent scarcity in the industry is one of the reasons why I have decided to jot down this blog taking references from various sources. So, here is the foundation blog to help you give the basic understanding of how to develop a blockchain application.

Editor’s Note: Serve Yourself With The Technical Jargons    

Contents

Before we go further to know more about coding a basic blockchain application, allow me to offer you an insight on the use of blockchain apps in different industries, the considerations in blockchain app development, and the process that developers follow to create such apps with the following infographic.

Blockchain app development

There is not a hint of doubt that we are in the era of blockchain but the golden era is yet to come. I remember the hype that felt like the tsunami when blockchain was introduced a few years back. The recent boom in the industry is another example of how much the technology is adorned by the tech enthusiasts, the developers and even by a normal user. 

The blockchain is here to stay for long. And, my attempt, as explained earlier with this blog is to educate even a non-tech user to get the hang of the technology. So, let the coding begin but after a preview on How blockchain technology works. 

How blockchain worksImg Source: Blockgeeks

Let’s Roll On!!

The blockchain is still enjoying the status of being an innovative and revolutionary technology that is not known to many (even I am also learning the curves from various tutorials). As I have already given the disclaimer above in the write-up that this article is going to have a lot of jargons, let me explain some basic terms that I will use further in the write-up. Here are the terms to help beginners and veterans alike.

Let me divide the iterations as “milestones” to make the things easier for you.

#MIlestone 1: The Basic Understanding Of Blockchain

What Is Blockchain?

I will not go into technicalities to explain the same. As the article aims to give the understanding to the beginners also, here is the blockchain definition in the simplest form. Blockchain is the chain of blocks wherein each block has a certain value. The transaction in blockchain is made through bitcoins and other cryptocurrencies.

What Is The Meaning Of Decentralization?

The blockchain technology is said to be decentralized as there is no central authority that covers the things. All the blocks connected to each other in a blockchain system get the information that a transaction is being done but they do not get the information about the person making the transaction.

Who Are Miners?

In the blockchain technology, the blocks are mined and the users mining the same are called miners. 

The blockchain sphere is much wider than a normal user’s imagination and therefore it is advisable to go through the blockchain glossary here. And, to have a comprehensive understanding of what blockchain technology is all about, go through our guide here. If that seems a drop in the ocean, go through the Satoshi Nakamoto’s whitepaper of bitcoin.

#Milestone 2: Let’s Start The Coding

Just like any other application, Blockchain apps follow the similar structure including the coding for the front-end and the similar structure for back-end too. Worth mentioning, you will come across tons of challenges. 

Before presenting the coding blocks here are the keywords to remember:

This: The keyword has been invoked inside a function to access its value inside a specific object in order to call that particular function.  

Constructor: The object creates an object inside a class. Each class is limited to only one constructor.

Now the basics are clear, allow me to move further to the coding charts.

const SHA256 = require("crypto-js/sha256"); 

class Block 

constructor(index, timestamp, data, previousHash = '') 

this.index = index; 

this.previousHash = previousHash; 

this.timestamp = timestamp; 

this.data = data; 

this.hash = this.calculateHash(); 

calculateHash() 

return SHA256(this.index + this.previousHash + this.timestamp + JSON.stringify(this.data)).toString(); 

}

Code Investigation: The Analysis

  • The first line of code is to call the crypto-js library as the sha256 hash function is not available in JavaScript.
  • Next, a constructor is invoked inside the class to call for objects having certain values. Now, let’s check out more on calculateHash() function. 
  • The code has been done to get the hash of a particular block. The JSON.stringify function has been used to turn the data of the block into a string to hash it.
  • With this setting, we have the blocks ready, now let’s connect these blocks together to a blockchain. 

Creating The Blockchain

class Blockchain

{

//Section 1 Genesis block creation

 constructor() 

this.chain = [this.createGenesisBlock()]; 

createGenesisBlock() 

{

 return new Block(0, "01/01/2017", "Genesis block", "0"); 

//section 2 adding new blocks

getLatestBlock() 

return this.chain[this.chain.length - 1]; 

addBlock(newBlock) { 

newBlock.previousHash = this.getLatestBlock().hash; 

newBlock.hash = newBlock.calculateHash(); 

this.chain.push(newBlock); 

//section 3 validating the chain

isChainValid() 

for (let i = 1; i < this.chain.length; i++)

const currentBlock = this.chain[i]; 

const previousBlock = this.chain[i - 1]; 

if (currentBlock.hash !== currentBlock.calculateHash()) { 

return false; 

if (currentBlock.previousHash !== previousBlock.hash) 

return false; 

return true; 

}

Code Investigation: The Analysis

I will be breaking the codes here to offer you a better insight.

The very first section of the coding represents the creation of genesis block with the following codes:

createGenesisBlock()

{
return new Block(0, "01/01/2017", "Genesis block", "0");
}

Let Me Give You A Quick Overview Of Genesis Block. 

The genesis is the very first block. The thing that makes it special is it does not point to the previous block as every block in the blockchain structure does. 

Let’s Proceed To Another Section

Adding The Blocks

To add the blocks, we need to know which is the last block in the current blockchain. For the same, we used the following functionality.

getLatestBlock() 

return this.chain[this.chain.length - 1]; 

Now that we have determined the latest block, let’s see how we are going to add new blocks.

addBlock(newBlock) { 

newBlock.previousHash = this.getLatestBlock().hash; 

newBlock.hash = newBlock.calculateHash(); 

this.chain.push(newBlock); 

}

By far we know the hash value of the last block is same as the value of the currently created block. So, how can we find out these values? Simply by measuring their values. 

If both the values are equal it means the blocks are justified.

Chain Validation

Now it comes to checking the validation and the stability of the codes and for the same, the coding goes as displayed below in the table. The “for” loop is to go from block 1 to the last block. 

for (let i = 1; i < this.chain.length; i++)

const currentBlock = this.chain[i]; 

const previousBlock = this.chain[i - 1]; 


In this part of the code we are defining two terms, current block and previous block.  And now we are simply going to find the hash of these two values.

if (currentBlock.hash !== currentBlock.calculateHash()) { 

return false; 

if (currentBlock.previousHash !== previousBlock.hash) 

return false; 

return true; 

}

As explained above, the previous block value must equal the value of the newly created one and in this case, if the value will meet, the function will return true. In case, the value does not meet, it will return to be false. 

Now, The Final Coding

let BlockGeeksCoin = new Blockchain(); 

BlockGeeksCoin.addBlock(new Block(1, "20/07/2017", { amount: 4 })); 

BlockGeeksCoin.addBlock(new Block(2, "20/07/2017", { amount: 8 }));

And, you are done with the basic application

We just coded a new blockchain based cryptocurrency and named it BlockGeeksCoin. The Genesis block was created automatically as the constructor was activated. 

# Milestone 3: Basics On The Smart Contracts

Blockchain app developmentImg Source: Blockgeeks

A Basic Definition Of Smart Contract

The common definition goes as smart contract facilitate the exchange of money, property and other valuable objects without the involvement of a middleman. The smart contracts need to run on multiple nodes without compromising the integrity. The above-illustrated infographic offers an insight on how the technology works.

Now that we are done with the blockchain mobile app development let’s have a look at the key benefits of the blockchain-based applications.

A blockchain application comes with the benefits written as follows:

Transparency

Blockchain apps have transparency as there is no involvement of middleman in any of the transactions. Moreover, the level of transparency may differ from an observer to another. For example, when a transaction is made by a party to another, the transaction remains transparent meaning anyone and everyone in the chain can view the same.

Decentralization

One of the most important benefits of blockchain is there is no requirement of a third party resource or any intermediary to validate the transaction. A consensus mechanism is all that it requires to agreeing on the transaction on a mutual basis.

High Availability

The peer-to-peer blockchain application is based on thousands of nodes and the data is updated on every node. This way the system becomes highly-available. Even if the nodes become inaccessible, the system as a whole continues to work which makes the complete blockchain network highly accessible. 

Highly Secured

Cryptographically all the transaction on a blockchain are secured as each transaction is tied to the previous transaction. 

Faster Dealing

Blockchain plays a vital role in the trade-settlement function to leverage a faster deal as the process of verification is not lengthy as compared to other such processes. There is no middleman and thus the transaction can be done much faster.

Cost saving

No third party involvement is required in blockchain transaction and thus it eliminates the additional cost associated with the middleman in such transactions. 

The Conclusion

One of the most important things that every budding developer should keep into the mind is to stay ahead with every major development in the blockchain sector. It is recommended to join forums where healthy discussions are frequently held. Being a part of the Reddit community will help in this direction. Besides Reddit Forums, Github pages and stock exchange are another source of information for a budding developer. Connecting with other developers is another way to look out for the news in the related domain. 

This beginners guide will help you to become a blockchain developer (of course with the basic level of coding skill). However, this won’t be enough to let you become a comprehensive blockchain coder, do keep your skills polished on the blockchain development news besides reading this guide. 

Neha Baluni
Written By
Neha Baluni

Being a Senior Technical Writer at MobileAppDaily, Neha Baluni loves jotting down her piece of opinion for the advancing technology in mobile app world. Having a journalism background, she is a writer by day and a reader by night. Her passion for writing covers different categories of technical and non-technical genre. In addition to writing, Neha loves traveling a lot.

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