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Ethereum For Web Developers

Ethereum For Web Developers

Techie, Foodie, Traveler, Founder www.zastrin.com I have been learning about Ethereum blockchain platform for some time and the more I learn, the more exciting it looks. There are lots of resources (articles, videos, platform documentation) about Ethereum, its easy to get overwhelmed. But, many of them are outdated understandably because the platform is still evolving at a rapid pace. It took me some time to piece together and get a complete picture of what Ethereum is and how it works. Talking to developers in meetup groups and other online communities, it feels like there are many people who would like to get their hands dirty with this new technology but have the same issue. This article is my attempt at explaining Ethereum from a web developers point of view. If you are a web developer, you know how a webapp with its client server architecture works at a very high level. You have your web application hosted on a hosting provider like AWS, Heroku or a VPS. All the clients interact with this one central application. Clients can be a browser, another api consuming your service etc. When a client makes a request to the server, the server does its magic, talks to the database and/or cache, reads/writes/updates the database and serves the client. This architecture works very well most of the times. However, there are certain applications where it would be really helpful if that database was publicly and securely accessible by everyone and you dont have to rely on this webapp owner for your data. For example, lets look at eBay. If you are a power seller who has earned hundreds of good reviews and for some reason eBay suspends your account. That would be very bad and could severely impact your business. What would be really nice is the ability for you take all your reviews Continue reading >>

Interacting With A Smart Contract Through Web3.js (tutorial)

Interacting With A Smart Contract Through Web3.js (tutorial)

Interacting with a Smart Contract through Web3.js (Tutorial) The following tutorial is a part of our 100% free course: Developing Ethereum Smart Contracts for Beginners In the previous lesson, we created a very simple smart contract using the Remix IDE and the Javascript VM. In this lesson, we're going to install Ethereum TestRPC along with Web3.js to create a simple user interface that will allow us to interact with our ethereum smart contract. Be sure to Subscribe to the Official Coursetro Youtube Channel for more videos. Installing & Running the Ethereum TestRPC The Ethereum TestRPC is a Node.js Ethereum client for the testing and developingsmart contracts. Because it's based on Node.js, we need Node.js installed along with NPM (Node Package Manager) to install it. Open up your command line or console and run the following 2 commands: If either of these commands go unrecognized, visit Nodejs.org and download the appropriate installer. Run it through all of the default options. Once finished, close and reload your console and re-run the commands above. They should now provide you with version numbers. Next, let's use NPM to install the Ethereumjs-testrpc: Once finished, run the following command to start it: This provides you with 10 different accounts and private keys, along with a local server at localhost:8545. Web3.js is the official Ethereum Javascript API. You use it to interact with your Ethereum smart contracts. Before we can install it, let's create a project folder in a new console window: Next, run the npm init command to create a package.json file, which will store project dependencies: Hit enter through all of the prompts. Next, run the following command to install web3.js: Switch over to the Remix IDE, click on the Run tab, and then change the Environme Continue reading >>

Crer Une Applation Avec Angular Et La Blockchain Ethereum 2/3 : Le Service

Crer Une Applation Avec Angular Et La Blockchain Ethereum 2/3 : Le Service

Jeune ingnieur, fondateur de Treviz , partisan d'un internet plus libre, ouvert, dcentralis et respectueux de la vie prive. Suit des cours pour devenir social justice warrior et prpare des cookies vegan. Crer une applation avec Angular et la blockchain Ethereum 2/3 : le service Last week, we covered how we could write smart contracts usingTruffle . Today,we will see how we can deploy and interact with this smart contract inside anAngular application. For those not familiar with it, Angular is a front-end, component-basedframework written in Typescript (a superset of Javascript developed byMicrosoft). As such, it is made to be executed directly into the browser of theuser. The components refer to classes that control a piece of the display;they are linked to a template (an HTML file) and some style files (css or scss).The idea behind components is to make them as atomic and re-usable as possible,in order not to write the same code twice. They can be assisted by other classes,like services, models... If you are not familiar with Angular and want to learn more, I can onlyrecommend you to look at the Angular documentation ,which is filled with example and detailed explanations of how the frameworkworks. To develop our Angular application, we will rely on the Angular CLI , that eases the project creation and build. Once the CLI is installed, create the new project: Now, launch the development webserver and navigate to 127.0.0.1:4200 We could interact with some Ethereum network by simply using the official API, web3js . But sincewe've started using the abstraction provided by Truffle in the test we wrotelast time, let's continue using it. It will allow us to work with Promisesinstead of having to deal with callbacks every time we interact with ourcontract. The abstraction la Continue reading >>

Blockchain Technology: How To Develop Dapps With Ethereum

Blockchain Technology: How To Develop Dapps With Ethereum

Its true that the blockchain was initially designed for cryptocurrencies, but Satoshi Nakamoto envisaged a wider scope of application. The emergence of the Ethereum has changed the way people perceive the blockchain. Ethereum is a blockchain designed for the development of Dapps (decentralized applications), whereas the other blockchains are designed for issuing cryptocurrencies based on more evolved concepts of tokens. The blockchain is a disruptive technology empowering companies to digitalize their transactions. Learn more about how the blockchain will transform your business . Developing Dapps (decentralized applications) involves developing smart contracts Developing Dapps (decentralized applications) involves developing smart contracts since an Ethereum application is a smart contract. Nowadays, there is an entire Dapps development ecosystem with various programming languages, the most popular of which is Solidity , an object-oriented language allowing to write smart contracts via a quite simple syntax. and the possibility to define data structures. How to deploy a smart contract on a blockchain? Each smart contract has a data area to manage. It is a sort of specific and private hash table of the smart contract that will use it to store a certain amount of information. Once the source code is ready, it is first compiled in the classic way in order to be deployed on the blockchain. To this purpose, we can use various compilers available on the Internet. a binary code that will be executed on the VM. And were not referring here to a VM in the Java sense, but rather to a program executing compiled bytecode, an ABI (Application Binary Interface) which describes the contract interface and the methods that can be called by other applications or smart contracts. When de Continue reading >>

Ethereum Development Walkthrough (part 5: Making Adapp)

Ethereum Development Walkthrough (part 5: Making Adapp)

Dapps, web, and games developer. Interested in AI, blockchain, and smart contracts. You can reach me at [email protected] or @dev_zl Ethereum Development Walkthrough (Part 5: Making aDApp) If you have read every part of this tutorial series, you already know how to make a decentralized application on Ethereum, and in this tutorial, Ill just guide you to use that knowledge together. On Ethereum, a DApp is a web application that will interact with smart contracts deployed on the blockchain. You can do it using python or other programming languages, but these will not be covered in this tutorial. We will focus only on JavaScript. We saw how to make a smart contract, in the first part , and how to deploy it in the second . And in this tutorial, I assumed that you have a JavaScript background, it doesnt matter how advanced you are, or which frameworks you use, we will use vanilla JavaScript, and a bit of JQuery to make our life easier. One thing that we will need, is, a tool that let us interact with the deployed smart contract, for that, we have a great API named Web3.js . We have seen Web3.js, both on the Truffle console in part 2, and when we performed a test on our contract in part 3 . Create a new folder for the project, and run the truffle init command. Next, create a folder named src where we will store our web application files. Inside the folder src, create an index.html file. Paste the following code inside: Create a folder named JShelpers, and create the following three files inside: You can find their content in the source code for this tutorial on Github . Now, back to the src folder, create a new file named app.js. app.js will hold our JS logic, we will use a bit of JQuery with vanilla JavaScript to keep it simple, but of course in a real DApp, you can use the Continue reading >>

Is Meteor The Best Framework To Build Ethereum Dapps?

Is Meteor The Best Framework To Build Ethereum Dapps?

Is Meteor the best framework to build Ethereum Dapps? Probably not. While the concept of Meteor could adapted to EVM currently it is not very useful for DApps. D stands for decentralized, and Meteors core value proposition is an improvement on a centralized problem: how to sync a backend with a frontend. It does so by providing a surrogate database on the client side that syncs with the backend as often as it can. But the backend in a pure decentralized app is the contract. And precomputing contract state and syncing it back to the Ethereum Network is a own challenge that Meteor will not fulfill soon. That said: if your DApp has some centralized functionality that goes into a conventional database, nothing speaks against Meteor. So what is the best web framework to interact with Ethereum? Its a homegrown stack. You definitly want to embrace Promises, integrate with a nice wrapper and lifecycle management tool like Embark, Truffle or Dapple. Then you chose between Angularjs 1/2 and ReactJS (a lot of people go React currently). Maybe you pick a template project which already has some libs integrated and start from there Here you have a half-assed React/Truffle/Bluebird/MaterialDesign template we made at the TR HackETHon: Starbuckers/starbuckers Continue reading >>

A 101 Noob Intro To Programming Smart Contracts Onethereum

A 101 Noob Intro To Programming Smart Contracts Onethereum

A 101 Noob Intro to Programming Smart Contracts onEthereum Originally published at consensys.github.io/developers (where some of the code formatting might be easier to read). Some people say Ethereum is too logic-heavy and hard to use, but heres a write-up to give you a feel for building smart contracts and applications with it. Tools, wallets, applications and the ecosystem are still in development and itll get easier! Part I is an overview of key terms and discusses Ethereum Clients and Smart Contract Languages. Part II discusses overall workflow and some current DApp Frameworks and Tools and Part III is the Programming Part, a quick walkthrough of writing tests and building a DApp for a smart contract using Truffle. If youre new to all this cryptocurrency stuff, including Bitcoin and how it works, check out the first couple chapters of Andreas Antonopoulos Bitcoin Book to dip your toe in the water. Then head over to the Ethereum Whitepaper . If you start getting into some murky sections and would rather build something to get familiar first, then just read on. You dont have to understand all the crypto economic computer science to start building, and a lot of that paper is about Ethereums improvements over Bitcoins architecture. The official place to start is ethereum.org which has a starter tutorial and follow-up token and crowdsale tutorials. Theres also the official Solidity docs . Another good place to start with smart contracts (where I started) is dappsForBeginners , although it might be outdated. The goal of this write-up is to complement those tutorials and introduce some helpful dev tools that make starting out with Ethereum, smart contracts and building DApps (decentralized apps) easier. And to try to explain the overall flow of whats going on. This is fro Continue reading >>

Happyfuncorp | Ethereum Programming For Web Developers

Happyfuncorp | Ethereum Programming For Web Developers

Hello, fellow web developer! If you're reading this, you're probably interested in blockchains, smart contracts, etc., as someone who actually wants to write some smart-contract code. I'm going to walk you through setting up, writing, and deploying a smart contract to a real live Ethereum blockchain, and then interacting with that contract in a browser via a web service. I'm not going to explain Blockchains 101 or Ethereum 101: there are many other places to go for that. But it's probably worth discussing Ethereum at a very high level from a developer's perspective. You don't need to care about mining or Proof-of-Work vs. Proof-of-Stake, or anything like that. But you should know that Ethereum is a decentralized virtual machine that runs on many nodes scattered around the world, and so-called "smart contracts" are code which runs (along with data which is stored) within that virtual machine, i.e. on every single node. This is obviously hugely inefficient, but it has advantages; everyone in the world can rely on this code/data, because no central service or system can tamper with it; and anyone can submit code/data to this machine without the registering or asking permission. They do, however, need to pay. Every line of code and byte of storage in Ethereum has a price. Ethereum, like Bitcoin, has a native currency, called "ether"; this is the same Ether currency that is traded on exchanges like Coinbase. When used to pay for Ethereum computing/storage, it is called "gas." For any given smart contract, gas has a "limit" and a "price." This is pretty confusing at first, but don't worry, you'll wrap your head around it eventually, and anyway this tutorial uses free fake money on a so-called "testnet" Ethereum blockchain. In principle many languages can be compiled down to Continue reading >>

Calling Your First Smart Contract Function With Web3 Andangular5

Calling Your First Smart Contract Function With Web3 Andangular5

Calling your first Smart Contract function with Web3 andAngular5 Communicating with smart contracts on the Ethereum blockchain is hard. There is already a bit to read about this on the Interwebs, but here is my approach using the latest stable version of Web3 (0.18.4) along with Angular and TypeScript. Our goal here is getting the balance of a token contract Some things youll need that I wont explain are an angular project (we use version 5.0.0) a smart contract, ill be using a token contract on the Rinkeby test network with address 0xbc84f3bf7dd607a37f9e5848a6333e6c188d926c . (More info on creating contracts: ) First create a service that will be used to call the contracts Import web3 and declare window (well use that later) and require Use require to get a.json containing the contracts ABI. The ABI of the used token contract can be found here: contract code . We will always use this function if we need the current account, but we dont want to always do the async call, so first check if we already have the current account. Then well wrap the async call with a new Promise and use the resolve function to let the promise know what the result of the call is. If the account is already known, we create a dummy promise that resolves to that known account address. We still need to use the callback function in here, but from, getAccount can be used like a promise. Now we really can call the smart contract. Like the getAccount function, also all calls to a contract is asynchronous, like a HTTP call to a REST api, we do a call to the contract on the blockchain and wait for the result. public async getUserBalance(): Promise { Continue reading >>

Angular Developer In North London, London | Teksystems - Cwjobs

Angular Developer In North London, London | Teksystems - Cwjobs

Ethereum, ERC20 tokens, Typescript, JavaScript, Webpack 2, NPM, web3.js, git, Node.js, Node, NodeJS, JSON, Solidity, Angular, Angular2, Truffle.js, C#, Front End, Blockchain, Digital, Web Application, Product, Casino, Gaming, Start Up, Start-up, Cryptocurrency. My client is building the world's first B2B casino platform powered by Ethereum blockchain technology. It is the first platform to solve the big challenges that have made other blockchain casinos unplayable: Their mission is to deliver online gaming that's fun, fast, and most importantly - provably fair. Using their first-of-a-kind technology and Ethereum smart contracts, they offer the ultimate casino experience - complete transparency, astonishing efficiency, and unrivalled game play. They develop the platform, protocol and games, then license these games to operators. From player wagers to operator licence fees and developer rewards, their own Ethereum-based cryptocurrency powers every aspect of the platform. We are looking for someone experienced in TypeScript and Angular development with a keen interest in blockchain technology, ERC20 tokens and online casino gaming. You will need to demonstrate the initiative to work as part of tightly focused, multi-disciplinary team. Tech: Ethereum, ERC20 tokens, Typescript, JavaScript, Webpack 2, npm, web3.js, git, Node.js, JSON, Solidity, Angular2/4, Truffle.js Can you visualise yourself working in a brand new office of c20 people in Camden, working with like-minded, forward thinking developers in a relaxed atmosphere? Send your CV to me, Samuel Taylor, if you'd like further information on this job opportunity. Allegis Group Limited and Aston Carter Limited operate Employment Businesses and Agencies and are companies within the Allegis Group Inc. group of companies, th Continue reading >>

Angular 4 + Truffle: Write, Compile & Deploy Smart Contracts On Ethereum Based Blockchains

Angular 4 + Truffle: Write, Compile & Deploy Smart Contracts On Ethereum Based Blockchains

If youve been keeping up with the cryptocurrency game, odds are youve heard about Ethereum. Ethereum is, in short, a platform that allows you to write smart contracts to be executed on their blockchain(s). Firstly, what is a smart contract? Vitalik explains it best, so Ill let him do the explaining - check this out . In short, a smart contract is a self-executing contract. You give it some terms, like Bob must transfer Alice 5 ether by December 30th, 2024. And you define rules, like Alice must use the correct password, as provided by Bob, before the deadline. Then, if you want an easier life, you program these terms and rules with a smart contract language called Solidity . What I just described is super high level. To really achieve all this, your contract needs to be compiled into bytecode understood by the EVM (Ethereum Virtual Machine), provide an ABI (Ethereum Virtual Machine), and migrated to the proper chain network. All of this is quite tedious and time-consuming. Thats where Truffle comes in. Truffle is an Ethereum development framework that does all the headache of compiling and migrating your contract for you. The cool thing about Truffle is that its written entirely in JavaScript and makes use of Web3 . Web3 is an Ethereum JavaScript API that allows you to execute ethereum based commands. For example, while connected to an Ethereum client, if you want to get the balance of a your home account, you just do: const coinbase = web3.eth.coinbase; web3.eth.getBalance(coinbase); Back to Truffle. Truffle also allows you to seamlessly integrate a front end for your smart contract based application, with the help of webpack . Great, you can now user Truffle, Web3 and a front end to write your smart contract application. But wait, this is 2017, you also want to use a Continue reading >>

Ethereum Blockchain Tutorial From Scratch

Ethereum Blockchain Tutorial From Scratch

Ethereum Blockchain Tutorial From Scratch Ethereum Blockchain Tutorial From Scratch Ethereum Blockchain Tutorial From Scratchis todays leading topic.Blockchainis right nowgooglesone of the most search keywords, and many of you have already heard ofBitcoin or Ethereum.All these cryptocurrencies are based on this technology calledBlockchain. Blockchainis one of the best technological inventions of the 21st century. The brain behind the Blockchainisa person or group of people known by the pseudonym, Satoshi Nakamoto .Blockchainallows digital information to be distributed, but not copied, and decentralized.Blockchain technology has created the new type of internet. We will useEthereum Blockchainto start our programming and understand the different libraries around it. In this tutorial, we just see what the language we will use to begin the development in the Ethereum Blockchain and how we can create a server and fetch the data into the webpage is. We will dive deeper into the following tutorials. Itis a just basic overview of the Ethereum. First, we will create a project folder, and in that, we will create apackage.jsonfile by typing the following command. You need to haveNode.jsinstalled on your machine. It will create apackage.jsonfile. Now install the following package. When we save the Node.js server file then it will restart the server automatically, so we do not need to restart the server manually. Now, we will install theexpress node.js web frameworkby typing the following command. Okay, also create one folder calledpublicin the root directory and in that folder, make oneHTML filecalledindex.html. { "name": "ethereum-blockchain", "version": "1.0.0", "description": "", "main": "index.js", "scripts": { "start": "nodemon server" }, "author": "KRUNAL LATHIYA", "license" Continue reading >>

How To Make Ethereum Decentralized Application

How To Make Ethereum Decentralized Application

03/24/2018 05:15 PM 135 truffle-config.js Now we will create smart contract file. we use solidity as contract programminng language version 0.4.19. The purpose of this contract is to initiate a state variable called name in the blockchain and manipulating that value of that variable by invoking our smart contract method from a dapp. User changes the name variable value and shows the change on the page. Lets create NameChange.sol file under contracts folder in our project folder(ethereumdapp). add this content to the NameChange.sol Use truffle compile to compile the contract D:\blockchain\ethereum\ethereumdapp>truffle compile It creates a NameChange.json into the /build folder, this files contains the ABI details for the contract, meaning that Application Binary Interface. The Application Binary Interface (ABI) is a data encoding scheme used in Ethereum for working with smart contract. This can be used in later stage of this process. Till now, we have created smart contract and compiled. Now the time for deploy the contract to blockchain which is the ganache, the test blockchain. For that, we need to configure this project with the blockchain address and port number which is available in ganache settings. We can provide this information truffle.js or truffle-config.js in the project folder. Saving successful migration to network... ... 0xf36163615f41ef7ed8f4a8f192149a0bf633fe1a2398ce001bf44c43dc7bdda0 At this stage contract is deployed to the ganache and generated a contract address. This can confirmed in ganache trasaction list This is angular 5 app that we provide user interface to the user to interact with blockchain t. We use angular-cli commands to create / run the app. Change directory back a level and execute ng new ethereumdapp D:\blockchain\ethereum>ng new ethe Continue reading >>

Ethereum Dapp Essentials Part 1

Ethereum Dapp Essentials Part 1

Tutorial for Ethereum Contracts and Static Github Pages It was exactly two weeks ago, when I was with an old friend on the phone and he introduced ethereum to me. The conversation went like this: "Hey, do you have a day or two to hack something fun?" - "Yeah, why not". Two weeks later, I had finished what he asked me for. I cannot really say here what I was doing, because its confidential, but I can talk about the things I learned along the way and can introduce a few things. Things which are important to newcomers at the DApps-Land. First, I will cover some misconceptions to people who are completely new. Then I will show some basic stuff you can do with Solidity. Then we will deploy a simple contract and try to call a function from an angular app. This should be enough for this tutorial. In the next tutorial we are going to see how events work and how we can call a contract from another contract and send an ether-value (with address.call.value()() - my new favorite). Ethereum, Blockchain, Clients and JavaScript It was very difficult for me to understand (and see the difference between) the terms Web3 is, as far as I understand, meant as a library of JavaScript functions. It's a library actually. When you use bower for your projects you could do like bower install --save web3 and it would install the web3-js library. Then you can do things like You can also do other things, which I will cover in the next chapter below. The Ethereum Blockchain has to be accessed by clients. And all of those are clients do (more or less) exactly the same. GETH (Go-Ethereum) is written in go and does the same as CPP-Ethereum (written in C++). The only major difference is that with CPP-Ethereum there is AlethZero and Mix included. Which you might need, or not. See here for an overview. I Continue reading >>

Javascript - How Can I Setup Angular With Truffle? - Ethereum Stack Exchange

Javascript - How Can I Setup Angular With Truffle? - Ethereum Stack Exchange

I've been looking for a way to hook up Angular with Truffle for a demo dApp I'm thinking of building but I'm unsure as to how to setup the development environment that would allow me to work with both frameworks. Would really appreciate if someone could help me set it up. Cheers! I'd like to bring to everyone's attention that there's now an official TruffleBox for Angular integration: please if you find the answer write some explaining post :D Arslan Smal May 4 '17 at 10:57 @ArslanSmal Unfortunately doesn't look like people know how to do it.... ZeroDarkThirty May 6 '17 at 4:18 mmm nice question Gawey Jun 14 '17 at 10:20 Please see the newly edited original post. There's now an official Trufflebox for Angular available :) ZeroDarkThirty Oct 14 '17 at 3:38 I've used truffle with react. The process will be similar for angular. Truffle offers two ways to integrate with other frameworks: truffle-solidity-loader : a webpack plugin which will build and deploy your contracts if needed, then provide you with a deployed truffle-contract contract when required. truffle-contract : a javascript library which gives you access to the nice contract API. It's the same API used for testing and the truffle console. Here is an example of using it: // any web3 providervar provider = new Web3.providers.HttpProvider("the truffle-contract packagevar contract = require("truffle-contract");// include the file created by truffle build in `build/`var myContractDef = require('myContract.json');// Create the wrapped contractvar MyContract = contract(myContractDef);// give it web3 powers!MyContract.setProvider(provider);// use the contractMyContract.deployed(instance => // do stuff... All you will need to do is make the built json file accessible to your runtime and wrap it in a truffle-contract. T Continue reading >>

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