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Creating An App On Blockchain Technology Using Javascript

Creating An App On Blockchain Technology Using Javascript

Creating an app on Blockchain technology using JavaScript Blockchain technology is difficult, but with new JavaScript APIs Lisky hopes to make decentralization easier to program for developers. Creating an app on Blockchain technology using JavaScript As Blockchain technology comes into its own, it is becoming increasingly important for software developers and programmers to acquaint themselves with the benefits which blockchain can provide the architects and users of digital platforms and applications. Lisk is an application platform whose Software Development Kit allows users to code in JavaScript to build Blockchain applications, without needing to beBlockchainliterate. Fully customizable, apps built on Lisk can take any form, from new social media networks, games, and online stores to financial or accounting applications. In simplifying the creation of blockchain applications, Lisk is democratizing blockchain, extending the technologys benefits to all - even those with just rudimental programming experience. We sat down with Will Clark, Full Stack Lead at Lisky, to learn more about how developing blockchain-enabled applications through blockchain APIs is becoming easier. ADM: From a developers standpoint how has Blockchain technology changed the approach of creating platforms? Clark: Traditional platforms require a central authority to facilitate user interactions, whether it is a messaging platform (Twitter), a marketplace (eBay), or whatever. That hands a lot of control and responsibility to the central authority, because they essentially own the data. They are responsible for handling it securely, but they also have the power to modify or censor that data as they see fit. Building a platform on top of a blockchain removes the need for a central authority, and th Continue reading >>

Javascript Is Eating The Blockchain

Javascript Is Eating The Blockchain

Javascript is showing up more and more in the cryptocurrency world. Theres a famous saying in the software development world called Atwoods Law: Any application that can be written in JavaScript, will eventually be written in JavaScript.. Jeff Atwood said it back in 2007, and its even more true today. Node.js , which is server-side Javascript, has been the hot new thing ever since it was released in 2009, and these days when a developer needs to build a cross-platform desktop application theyll reach for Electron , which uses Javascript as its programming language. And of course, every website you visit will surely use it as well. Cryptocurrencies were immune from this trend for a long time, because they rely on cryptographic functions that have been historically written in other languages. Bitcoins core has no Javascript, nor do most of its descendants. Ethereum is mostly Go, NEM is Java, and even Haskell makes an appearance with Cardano . But Javascript has started to slowly chip away at that wall. Lisk was started in 2016 and was the first Javascript-based cryptocurrency to make it into the top 20 coins by market cap (now at over $3 billion). Its an ambitious project. Its creating a way for Javascript developers to easily create blockchain based applications that will run on side chains, blockchains tied to, but separate from, the main Lisk blockchain. The developers of Lisk chose Javascript because they felt that blockchain technology wasnt being adopted into the larger software development world fast enough, and that by building a blockchain in Javascript theyd be able to tap into a huge pool of Javascript developers. According to Github, Javascript is, by far, the most used development language . Ark is another new cryptocurrency using Javascript, with the aim of Continue reading >>

Blockchain Technology Expert (ethereum, Node.js, Javascript, Angularjs, Bootstrap, Java, Python Jobs In 10001

Blockchain Technology Expert (ethereum, Node.js, Javascript, Angularjs, Bootstrap, Java, Python Jobs In 10001

blockchain technology expert (ethereum, node.js, javascript, angularjs, bootstrap, java, python jobs in 10001 blockchain technology expert (ethereum, node.js, javascript, angularjs, bootstrap, java, python jobs in 10001 Minimum Required Skills: JavaScript, Python, Ethereum, Go, Angular, C++, React Native, Smart Contracts If you... Minimum Required Skills: JavaScript, Python, Ethereum, Go, Angular, C++, React Native, Smart Contracts If you... full-time JavaScript, Python, Ethereum, Go, Angular, C++, React Native, Smart Contracts - JavaScript, Python, Ethereum, Go, Angular, C++, React Native, Smart Contracts IT Software IT Diploma/Degree/Certification Minimum Required Skills: JavaScript, HTML5, CSS3, RESTful APIs, SASS, LESS, AngularJS, Grunt, Gulp Based in... Minimum Required Skills: JavaScript, HTML5, CSS3, RESTful APIs, SASS, LESS, AngularJS, Grunt, Gulp Based in... full-time JavaScript, HTML5, CSS3, RESTful APIs, SASS, LESS, AngularJS, Grunt, Gulp - JavaScript, HTML5, CSS3, RESTful APIs, SASS, LESS, AngularJS, Grunt, Gulp IT Software IT Diploma/Degree/Certification One of the Top Hedge Funds in the world is looking for a Senior JavaScript... One of the Top Hedge Funds in the world is looking for a Senior JavaScript... full-time JavaScript, React.JS ReactJS Angular AngularJS Software Developer Engineer IOS Android HTML5 CSS Mobile IOS Android Computer Science IT Software IT Diploma/Degree/Certification Minimum Required Skills: Building event/message-driven architecture, Fault tolerant financial trading systems, Scalable... Minimum Required Skills: Building event/message-driven architecture, Fault tolerant financial trading systems, Scalable... full-time Building event/message-driven architecture, Fault tolerant financial trading systems, Scalable systems/AWS/WC2/load- Continue reading >>

Access The Power Of Blockchain | Lisk

Access The Power Of Blockchain | Lisk

Lisk makes it easy for developers to build and deploy blockchain applications in JavaScript. Join the leading ecosystem for world-changing dapps. What can you build with Lisk? Get inspired with a selection of use cases. Lisk's decentralized network allows you to exchange value quicker and more economical than before. Build an internet of value. True scarcity and new possibilities for ownership revolutionize how digital content can be monetized. Blockchain transactions on Lisk provide insights into systems that previously lacked information, were obscured or unavailable. Military-level cryptography and distributed databases make Lisk a highly-secure solution for permission management and storage. Lisk's decentralized network is always online and eliminates the possibility for data loss. Data stored with Lisk is permanent and cannot be changed. Live data and archives finally have a secure digital home. Lisk's decentralized network allows you to exchange value quicker and more economical than before. Send value around the world in seconds and with much lower fees. Predict plot twists on Game of Thrones with people around the world using crowdsourced data. Build an internet of value. True scarcity and new possibilities for ownership revolutionize how digital content can be monetized. Trade rare items directly with other gamers. Those who create, curate and share content can finally be fairly rewarded for their contributions. Blockchain transactions on Lisk provide insights into systems that previously lacked information, were obscured or unavailable. Know precisely where your seafood came from, what it contains and how it got to you. Charity organizations can offer tracking for you to see exactly how your donation is being put to use. Military-level cryptography and distri Continue reading >>

Nodejs Blockchain Implementation: Brewchain: Chain+websockets+http Server

Nodejs Blockchain Implementation: Brewchain: Chain+websockets+http Server

DB Dev Blog - Javascript, NodeJS, React, Blockchain NodeJS blockchain implementation: BrewChain: Chain+WebSockets+HTTP Server I am going to create BrewChain. A verifiable chain of which member of the team made a brew and when. Protecting the history of events from any swindlers who may attempt to claim they have made more brews than they actually did. Our application will consist of the following: A Node which will run on team members machines, listening for new blocks broadcast and also broadcasting new blocks and updating the chain. An HTTP server and web interface for interacting with brew activities, the log and other data Blockchain is essentially a linked list in which each item contains a hash of the previous item. The fundamental element in this chain is the block. Each block contains data, and a hash of the previous block. This hashed pointer maintains the integrity of the data and makes the list immutable. To start with we need to determine the essential elements of our block. data - whatever we wish to store in the block hash - (a hash of the timestamp,index,data and previous hash) previous hash - the hash of the previous block const createBlock = (lastBlock, data) =>{ myBrew.addToChain(myBrew.createBlock('The 2nd block')); (The code in this post is in somewhat rough form while I workout exactly how it is going to work) This will setup our chain object, creating a genesis block and adding it to the chain. Our Brewchain contains the ability to create new blocks, add new blocks to our chain and also check the validity of a block. The test code at the end adds two blocks and then outputs the chain to check that the blocks are successfully being created. Well now begin building our P2P brewNode server.. Each BrewNode server will have a chain, a web socket server Continue reading >>

Programming Blockchain In Javascript

Programming Blockchain In Javascript

In the last few posts I talked about implementing Blockchain in iOS using Swift. A lot of people emailed me and asking about the Javascript implementation of the Blockchain. This post shows how to implement the core engine of the Blockchain in Javascript using Node. The first step is to define the models associated with domain objects, represented in the Blockchain. These models consists of the following: Transaction: A transaction represents a transfer of value. This can be money, merchandise, medical records etc. Block: A block is mined by a miner which is later filled with transactions and added to the blockchain. Blockchain: A blockchain represents the linked list of blocks. A blockchain is immutable, which means once the block is added to the blockchain it cannot be altered. Once, our basic models have been created we can move on to implementing the core functionality of the Blockchain. We will start by allowing our blocks to add transactions. This is done by adding a addTransaction function to the Block class as shown below: A block is mined based on its key which comprises of the following properties: index: The current index of the block in the blockchain. previousHash: The hash of the previous block in the blockchain. nonce: The magic number which is incremented to find the secret hash which is used to sign the block. transactions: A list of transactions added to the block. The key property is a getter property on the Block class as shown below: Next, we will move to the Blockchain class. Below you can find the complete implementation of the Blockchain class. To generate a SHA256 hash we will use help from a node package js-sha256 . You can install the package by running the following command: Lets go ahead and test out our Blockchain by adding few transaction Continue reading >>

How To Create An Application On Blockchain Using Hyperledger

How To Create An Application On Blockchain Using Hyperledger

How to create an application on blockchain using Hyperledger We are going to build a digital bank using Hyperledger Composer. It will have customers and accounts. At the end of it, youll be able to transfer funds and record all transactions on blockchain. Well expose a RESTful API for the same, so that even a person who has no clue what blockchain is can make a beautiful user interface (UI) around it. Well also create this applications UI in Angular. Im super excited to share this step-by-step guide with you. So lets get started right away! Source: When I was first coding this out, I ran into errors. Lots and lots of them. But I think thats good, because it made me learn a lot of things. Errors are essential. I got to a point where I felt switching it on and off would make things better. It almost made me lose my mind, but its an integral part in every hackers life. Before getting started, you need to ensure that the machine youre using is equipped with the required configurations. You may need to download certain prerequisites and set up a basic dev environment. Below are the links to do that. Follow those steps before starting to develop an application, otherwise youll definitely run into stupid errors. First install the Hyperledger composer . Then install the development environment . Theres no need to start Playground while youre installing the environment. Make sure docker is running, and when you run./startFabric.sh its going to take a couple of minutes. So be patient. Now that your machine is all set, we can start coding! Source: Our Business Network Definition (BND) consists of the data model, transaction logic, and access control rules. The data model and access control rules are coded in domain specific language (which is very simple to catch up with). The tr Continue reading >>

Github - Ltearno/blockchain-js: A Generic And Simple Blockchain Distributed Consensus Implementation In Typescript

Github - Ltearno/blockchain-js: A Generic And Simple Blockchain Distributed Consensus Implementation In Typescript

A generic and simple blockchain distributed consensus implementation in typescript A simple typescript implementation of a Bitcoin-like distributed blockchain consensus algortihm. The aim is to have a working code base to make demoes and experiments with it. It has a node with many of the bitcoin concepts implemented, and some more (branches, merches, and so on). The code woks both on server (NodeJS) and client (browser) environments so it is fit for doing demoes. A demo application is available at . It is a chat (web) application using the underlying blockchain asthe data storage. This is perfect for showing simple code on how the bitcoin works, so this can be used as a support for demoes. This program maintains a distributed database accross active nodes, interconnected by the network. Since this is written in typescript, blockchain nodes can either run on NodeJS or in the browser. Traditionnal blockchain implemented concepts : proof of work (proof of stake can also be implementation as well as other algorithms, Concepts not in Bitcoin (as far as I know) branches : like with git, the blockchain structure supports branches. There is a master branchcalled master, then any branch can be built on it ! Continue reading >>

The Blockchain Explained To Web Developers, Part 1: The Theory

The Blockchain Explained To Web Developers, Part 1: The Theory

The Blockchain Explained to Web Developers, Part 1: The Theory The blockchain is the new hot technology. If you haven't heard about it, you probably know Bitcoin. Well, the blockchain is the underlying technology that powers Bitcoin. Experts say the blockchain will cause a revolution similar to what Internet provoked. But what is it really, and how can it be used to build apps today? This post is the first in a series of three, explaining the blockchain phenomenon to web developers. We'll discuss the theory, show actual code, and share our learnings, based on a real world project. To begin, let's try to understand what blockchains really are. Although the blockchain was created to support Bitcoin , the blockchain concept can be defined regardless of the Bitcoin ecosystem. The literature usually defines a blockchain as follows: A blockchain is a ledger of facts, replicated across several computers assembled in a peer-to-peer network. Facts can be anything from monetary transactions to content signature. Members of the network are anonymous individuals called nodes. All communication inside the network takes advantage of cryptography to securely identify the sender and the receiver. When a node wants to add a fact to the ledger, a consensus forms in the network to determine where this fact should appear in the ledger; this consensus is called a block. I don't know about you, but after reading these definitions, I still had troubles figuring out what this is all about. Let's get a bit deeper. Decentralized peer-to-peer networks aren't new. Napster and BitTorrent are P2P networks. Instead of exchanging movies, members of the blockchain network exchange facts. Then what's the real deal about blockchains? P2P networks, like other distributed systems, have to solve a very dif Continue reading >>

Build A Bitcoin Blockchain In Javascript Part1

Build A Bitcoin Blockchain In Javascript Part1

Former professional basketball player turned financial trader. Currently building software at alkami.io and geeking out about crypto. Build A Bitcoin Blockchain In JavaScript Part1 In this tutorial were going to build a dumbed down version of the Bitcoin blockchain. Were going to be using the bitcoin core developer guide as a reference. The goal is to start with something super simple and gradually build and refactor our way up to something super complicated that resembles the Bitcoin blockchain. I decided to use the Bitcoin blockchain because its the most widely used and well known of them all. Im using node version 8.9.3 and npm version 5.5.1. Feel free to leave comments or questions about anything is this tutorial. The block chain provides Bitcoins public ledger, an ordered and timestamped record of transactions. This system is used to protect against double spending and modification of previous transaction records. Lets run these commands in our terminal: So weve created our BitcoinBlockchain directory and added a node_modules directory that only includes the crypto-js library which is JavaScript library of crypto standards. Now lets create our block class inside block.js const SHA256 = require('crypto-js/sha256'); Bitcoin uses a SHA-256 Cryptographic Hash Algorithm which creates a string of text, called a signature, out of any piece of data. Since each one of our blocks is going to be unique, each block is going to generate its own unique hash using its calculateHash() function. The calculateHash() function is going to take each property of a new block, moosh it together into one string and return a SHA-256 hash of that string. Each block has to also reference its previous blocks hash(Header). This ensures a transaction cannot be modified without modifying the blo Continue reading >>

Learn & Build A Javascript Blockchain Part1

Learn & Build A Javascript Blockchain Part1

Learn & Build a Javascript Blockchain Part1 The best way to understand blockchain is to buildone In this Part 1 of the Javascript Blockchain Series, we will cover the block object and blockchain object and discuss its structure and implications. Im a firm believer in the idea that the best way to learn a technology is to build it. Naturally, my interest in blockchain technology has led me to try to build a blockchain of my own. As a fellow blockchain enthusiast, I will walk you through the steps of building a basic blockchain with a built-in proof of work system. Along the way, I will discuss the implications of the different features. What do you need: the latest version of Node.js (Im using v8.7.0) and npm (Node Package Manager) (Im using v5.6.0) Who is this for: anyone who is interested in learning about blockchain and has some basic understanding of Javascript Where is the repo: the code can be found here . Create a folder called js-blockchain and create a file called main.js In this guide, we will be using one single file so you can always refer to the source code if you encounter any problems. Blockchains are built through a combination of linked lists and merkle trees . The linked list structure allows for the chain to continually build on top of itself and is where the name blockchain derives from. A blockchain is literally a chain of blocks linked to one another through the linked list structure. One thing to note however, is that instead of holding a traditional pointer to refer to the previous block, it uses the hash of the previous block to refer to it. If you are not familiar with what a hash is, here is a primer . Hashes are simply deterministic functions that create specific outputs for each input, and they are usually irreversible meaning it is extremel Continue reading >>

Github - Nambrot/blockchain-in-js: Build Your Own Blockchain!

Github - Nambrot/blockchain-in-js: Build Your Own Blockchain!

In step 1, we saw that in a chain of blocks, the last block basically validates all data in the chain of its ascendents, as any change in the data up the chain would inevitably change the hash of the last block. That is all great, but what do people mean by THE blockchain? By definition, THE blockchain is just the longest chain available in the tree. So at one point, a chain can be the lonest one, but then get superseeded by another. Let's visualize the longest chain in the tree. class Blockchain { longestChain() { const blocks = values(this.blocks) const maxByHeight = maxBy(prop('height')) const maxHeightBlock = reduce(maxByHeight, blocks[0], blocks) const getParent = (x) => { if (x === undefined) { return false } return [x, this.blocks[x.parentHash]] } return reverse(unfold(getParent, maxHeightBlock)) }} So given a tree, the longest chain represents our current view of which history of blocks, and thus which representation of data is the one we deem valid. If real blockchains worked like Step 2, then it would be a chaotic free-for-all where nodes just can abitrarily fork a chain of blocks and add basically infinitely many blocks to it, to make it the longest chain and thus THE blockchain (as you have seen in the above GIF). That would mean that anyone could just change history and effectively mutate past data. How do we avoid that situation? By making it difficult to add a block with a computational puzzle. Instead of accepting any arbitrary block, part of the concensus rules of a blockchain mandate what blocks are valid and which ones aren't. In this case, we want to make adding blocks resource-intensive. The most common way of doing so, and probably the most admirable piece of the original Bitcoin whitepaper), is to pair this with proof-of-work (POW). POW allows us Continue reading >>

A Blockchain In 200 Lines Ofcode

A Blockchain In 200 Lines Ofcode

I like programming and Careless Whisper. The basic concept of blockchain is quite simple: a distributed database that maintains a continuously growing list of ordered records. However, it is easy to get mixed up as usually when we talk about blockchains we also talk about the problems we are trying to solve with them. This is the case in the popular blockchain-based projects such as Bitcoin and Ethereum . The term blockchain is usually strongly tied to concepts like transactions , smart contracts or cryptocurrencies . This makes understanding blockchains a necessarily harder task, than it must be. Especially source-code-wisely. Here I will go through a super-simple blockchain I implemented in 200 lines of Javascript called NaiveChain . The first logical step is to decide the block structure. To keep things as simple as possible we include only the most necessary: index, timestamp, data, hash and previous hash. The hash of the previous block must be found in the block to preserve the chain integrity The block needs to be hashed to keep the integrity of the data. A SHA-256 is taken over the content of the block. It should be noted that this hash has nothing to do with mining , since there is no Proof Of Work problem to solve. To generate a block we must know the hash of the previous block and create the rest of the required content (= index, hash, data and timestamp). Block data is something that is provided by the end-user. A in-memory Javascript array is used to store the blockchain. The first block of the blockchain is always a so-called genesis-block, which is hard coded. At any given time we must be able to validate if a block or a chain of blocks are valid in terms of integrity. This is true especially when we receive new blocks from other nodes and must decide whe Continue reading >>

How To Code A Bitcoin Like Blockchain In Javascript

How To Code A Bitcoin Like Blockchain In Javascript

This is a guest post by Michiel Mulders on How To Code a Bitcoin-like Blockchain In JavaScript The basic concept of a blockchain is quite simple: a distributed database that maintains a continuously growing list of ordered records. Add to this mining, mining rewards and blocks containing transactions. I think you get the general idea of a blockchain, right? There is nothing better than coding a blockchain yourself to fully grasp the inner workings of a blockchain. This tutorial will explain you to build a blockchain which returns mining rewards. The full code can be found here . Project Setup:How To Code a Bitcoin-like Blockchain In JavaScript As we like simplicity, we will only use three different files: app.js: contains the Express API for interacting with our blockchain. blockchain.js: contains the classes for constructing our blockchain, blocks, and transactions. package.json : contains our installed npm packages. The most important package we will use is crypto-js . This package contains crypto standards that can be used in JavaScript, like calculating our hash. In my opinion, a hash is the glue between two blocks. A lot of other packages can be found in this package.json file, mainly for compiling JavaScript ES7. Lets take a look at the different classes. A block consists of several properties. First, we pass a timestamp to indicate the moment the block got created. Next parameter is an array of transactions ready to be mined. At last, we define a field that contains the link to the previous block using a hash. This field is optional as the genesis block doesnt have a predecessor. class Block { constructor(timestamp, transactions, previousHash = '') { this.previousHash = previousHash; this.timestamp = timestamp; this.transactions = transactions; this.hash = this. Continue reading >>

Create Your First Blockchain With Javascript

Create Your First Blockchain With Javascript

Create Your First Blockchain with JavaScript This is part of our series of tech talks given by our current immersive students. This talk will be held in English and Japanese. Blockchain is everywhere. The technology came to popularity through its powering of Bitcoin, which was invented in 2008. Now, it's the talk of the world and its areas of application are increasing past cryptocurrencies. The technology is actually a simple concept, though things can quickly get more complicated. So in this work shop, we will understand how this technology works by creating a simple blockchain using JavaScript. Ryuta Udo is a software engineer. After getting a Bachelor's in mechanical engineering, he moved to the Philippines to work for an e-learning company in marketing. He later moved into QA at the same company and became attracted to programming through his experience of working with engineers. After he worked for an advertising agency, he quit and is currently a student at Code Chrysalis. Continue reading >>

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