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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 >>

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 >>

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 >>

App Deve (java, Node.js, Javascript) Will Train In Blockchain!

App Deve (java, Node.js, Javascript) Will Train In Blockchain!

The team is located in an agile open space and uses physical and virtual tools to collaborate and manage their work. The secret to success is our people and culture. We enjoy building quality products, crafting an amazing user experience, continually reinventing and evolving how we work and having lots of fun in the process. Will consider relocation for candidates with the right skills/experience Must have the ability to work in the US without current/future need for IBM sponsorship Currently seeking Application Developers to become part of a team supporting the IBM Finance Systems Blockchain COE supporting Indirect Tax and Intercompany Accounting who will help us build, enhance and maintain our Blockchain Cloud solutions using skills such as JavaScript, Node.js, Angular, Java, Restful API, HTML, CSS, CouchDB and use a variety of tooling, including jUnit, Mocha, Chai, GitHub, Travis CI, Docker in the IBM Cloud environment. In addition youll have a chance to learn Hyperledger Fabric Composer. Design, develop, deploy and maintain the IT Technical Solution Demonstrate a clear pride of ownership for the IT Technical solution Actively participate in the Agile and DevOps development process Propose new ideas, relentless focus on quality and continuous improvement Perform root cause analysis of technical and process issues 3+ years Application Development experience Java, Angular, HTML, CSS, node.JS, Restful Webservices, HTML, CSS, Github, CouchDB, Mango Couch Queries, BlueCloud and High Security Business Network (HSBN), GitHub Agile Development Practices (Scrum), Behavior Driven and Test Driven Development DevOps Practices including Automated Build, Test and Deployment and Static Analysis using tools and practices such as jUnit, Mocha, Chai, Mockito and/or Selenium, Jenkins Continue reading >>

With A Great Language Comes Great Usability: Making Blockchain More Accessible With Javascript

With A Great Language Comes Great Usability: Making Blockchain More Accessible With Javascript

Interview with Will Clark, Full Stack Developer at Lisk With a great language comes great usability: Making blockchain more accessible with JavaScript JavaScript is seen as the go-to language for newcomers to learn programming; meanwhile, blockchain still has this hard to understand label attached to its name. JavaScript is not always the right choice for blockchain projects, though. For Lisk, it ensures wide platform adoption. Heres how. JAXenter: Lisk is written in JavaScript using NodeJS. But why JavaScript and not another language? What does it have that Java doesnt? Will Clark: Our mission at Lisk is to make blockchain technology accessible to all. Choosing JavaScript as Lisks main programming language ensures wide platform adoption once the tools are released. JavaScript is increasingly seen as the go-to language for newcomers to learn programming, with a lot of focus from major industry players in recent years Facebook, Microsoft, Google and so on. The community behind this language has a very strong open source tradition, which is a major priority for us in the decentralization space. In addition, JavaScript is the only language included in all browsers by default. Once you write a function, you can use it everywhere you need it on a node, in browsers, in command-line clients, or on auxiliary servers. This enables a greater level of efficiency in writing code, and greater consistency across projects. JAXenter: Were there other languages that you took into consideration before you decided to use JavaScript? Will Clark: This decision was taken long before I joined the team, and even before Lisk was born, given that Lisk forked its codebase from the preceding Crypti project. However, most of the benefits of this widely popular language all applied back then, and I 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 >>

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 >>

Is Javascript Enough To Work On Cryptocurrency And Blockchain?

Is Javascript Enough To Work On Cryptocurrency And Blockchain?

Answered Nov 17, 2015 Author has 712 answers and 779k answer views Javascript and Node.js are enough to build programs that interact with cryptocurrency APIs in real time. If you want to build your own cryptocurrency platform from scratch then C++ (Bitcoin), Go (Ethereum), Java (Nxt), etc might be better. 1.4k Views View Upvoters Answer requested by Answered Dec 1, 2017 Author has 98 answers and 44k answer views I can answer for Ethereum blockchain. In Ethereum, Web3 is a JavaScript framework to do transactions on the Blockchain. Apart from that, there is a programming language called Solidity to write smart contracts. Contracts are nothing but codified transactions on the blockchain. And for managing contracts as well as writing tests, Truffle NPM package is useful. For more info on Ethereum for JavaScript developers, please check Blockchain and Ethereum for JavaScript and React developers - Vijay T Yes it is! As a matter of fact, there is a powerfull cryptocurrency dApp platform running entirely in javascript - ShiftNRG When you look at the shift core, you can see that it is written in javascript. Also, their flagship IPFS decentralized application platform (Phantom) is made in javascript. And you can implement their shift-js library to make a API calls. You can find more info in provided links (Github repo, Landing page and Market cap info - Shift is one of the top 10 crypto for invest in 2018) Continue reading >>

Lotion - Smooth, Easy Blockchain Apps In Javascript

Lotion - Smooth, Easy Blockchain Apps In Javascript

Smooth, easy blockchain apps. Powered by Tendermint consensus. Lotion is a new way to create blockchain apps in JavaScript, which aims to make writing new blockchains fast and fun. It builds on top of Tendermint using the ABCI protocol. Lotion lets you write secure, scalable applications that can easily interoperate with other blockchains on the Cosmos Network using IBC . Lotion itself is a tiny framework; its true power comes from the network of small, focused modules built upon it. Adding a fully-featured cryptocurrency to your blockchain, for example, takes only a few lines of code . Note: the security of this code has not yet been evaluated. If you expect your app to secure real value, please use Cosmos SDK instead. A lotion application is usually a single function of signature (state, tx) which mutates your blockchain's state in response to a transaction. All of your application state is contained within a single JavaScript object. As a developer, all you need to do is design your application's initial state, then write the function to compute the next state when a transaction happens. Here's a minimal hello world example which simply counts the number of transactions that have occurred so far: let app = require('lotion')({ initialState: { count: 0 }})app.use((state, tx) => { state.count++})app.listen(3000) This will start the lotion application http server on port 3000, which you can use to query the state of the blockchain and create new transactions. The goal of a blockchain is to represent a single state being concurrently edited. In order to avoid conflicts between concurrent edits, it represents the state as a ledger: a series of transformations applied to an initial state. The blockchain must allow all connected nodes to agree about which transformations ar 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 >>

Job Application For Js Developer At Blockchain

Job Application For Js Developer At Blockchain

By clicking the I Accept button you expressly make the following representations and warranties and give your consents as described below: Blockchain collects your personal data for the purposes of managing Blockchains recruitment related activities as well as for organizational planning purposes globally. Consequently, Blockchain may use your personal data in relation to the evaluation and selection of applicants including for example setting up and conducting interviews and tests, evaluating and assessing the results thereto and as is otherwise needed in the recruitment processes including the final recruitment. Blockchain does not disclose your personal data to unauthorized third parties. However, as a global corporation consisting of multiple affiliated companies in various countries, Blockchain has international sites and Blockchain uses resources located throughout the world. Blockchain may from time to time also use third parties to act on Blockchains behalf. You agree to the fact that to the extent necessary your personal data may be transferred and/or disclosed to any company within Blockchain group of companies as well as to third parties acting on Blockchains behalf, including also transfers to servers and databases outside the country where you provided Blockchain with your personal data. Such transfers may include for example transfers and/or disclosures outside the European Economic Area and in the United States of America. 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 - 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 >>

How To Use Bitcoin Blockchain Be Useful To Authenticate Documents?

How To Use Bitcoin Blockchain Be Useful To Authenticate Documents?

have read a little about blockchains and found there is lot of blockchain npm libraries available. How can I take benefit of the bitcoin blockchain to authenticate documents : to obtain a proof a document has not been alterated ot changed. Any clues, suggestions, ideas and remarks are welcome. What do you mean "a document has not been altered or changed"? What's the difference between altering or changing a document and just having two different documents? Do you want to prove that a particular document is the documented someone signed or agreed to? Do you want to prove that a particular documented existed at a particular time? It's not clear what you're actually trying to do. David Schwartz Jul 6 '17 at 3:23 I'd suggest taking a look at chainpoint.org (Full disclosure, I'm the VP Engineering at Tierion, the creators of the Chainpoint open standard). Chainpoint currently uses the Tierion HashAPI, and you can submit hashes to the API for free. We'll provide you with a proof that you can store alongside your original document. We have a Javascript library you can use to access the HashAPI. We are getting ready to release a brand new v3 version of Chainpoint that has some great new features that we've announced (and some we haven't). Chainpoint v3 will be fully open source (clients and server), and free to use. I think you'll find it solves your needs quite nicely and we'd love your feedback. You can make a transaction with the hash (of the document) as a comment. That would proof that the file existed at that time. It doesn't however magically proof that a document hasn't been changed. Once you get the document, you can store the hash on the blockchain, then to check if it hasn't been changed, you can retrieve the hash and check if the current version of the file still h 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 >>

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