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Developing Blockchain Applications
- 1. Developing Blockchain Applications November 28,2018 getting started with ethereum
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- 3. few questions before we start… • Have you transacted ETH? • Do you know what dappsare? • Have you used a dapp? • Have you written a smart contract or developed a dapp?
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- 5. Some Definitions… Ethereum Network Collection of nodesthat transact Ether and store data Node Any computer running the Ethereum client Ethereum Client Piece of software that communicates with Ethereum Network
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- 7. Tale of an ebay seller… • Can the seller take their ratings and feedback history and join another online marketplace? • Should they be able to? •What’s the incentive for ebay to make this possible? • An ebay seller with excellent ratings • ebay bans the seller for violation of their T&Cs • Let’s assume that the seller was not at fault but they were banned/suspended anyway
- 8. Centralized vs. Decentralized Apps Centralized (Client-Server) Decentralized(Dapps) Logic Cluster of servers contain the entire logic. All logic is contained in the contract. Once the contract is mined, all nodes have the exact same logic, saved on their copy of the blockchain. Data Integrity Maintained by strict set of rules enforced by the infrastructure, tools, and services. Taken care via redundancy of the nodes in the network.
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- 12. Getting Metamask • Go to https://metamask.io/ • Get Chrome Extension •Add to Chrome • Launch Metamask and follow the setup guide
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- 19. Dapp Examples WeiFund WeiFund is a crouwdsourcingapp on the Ethereum Ecosystem. http://weifund.io/
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- 23. How is Ethereum different from Bitcoin blockchain? Bitcoin Ethereum Bitcoin usesa simple scripting system for transactions. Bitcoin script is simple, stack-based, and is intentionally not Turing-complete, with no loops. Ethereum platform is built with a Turing- complete language. Send bitcoin from Alice to Bob Send ether from Alice to Bob if… • Bob’s balance is less than 2 eth • Date > 2019/01/01
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- 26. Ecosystem, tools, terms, products… ETH Ethereum networks’native crypto-currency EVM Ethereum Virtual Machine providing decentralized computation service Swarm Provides P2P file sharing and storage services Whisper Protocol used by nodes to communicate with each other Solidity, Serpent, LLL Smart contract programming languages eth, geth, pyethapp Main ethereum software written in C++, Go, Python respectively.
- 27. Serverless Stack Whisper Encrypted messagingprotocol that allows nodes to send messages directly to each other in a secure way; hides sender and receiver identity from snoopers Swarm P2P file sharing, similar to BitTorrent, but rewarded with micropayments of ETH (Storage Layer) Ethereum Virtual Machine (EVM) Runs the contract logic
- 28. There are many different Ethereum Networks • One main Ethereum network – used for deployment of production applications •Test Networks – Ropsten, Rinkeby, Kovan • Private Network on your own computer • Create your own network and open it for others to use.
- 29. Test Networks Ropsten • Resemblesthe main network • Uses Proof of Work consensus algorithm • Supported by Geth and Parity • https://ropsten.etherscan.io/ Rinkeby • Uses Proof of Authority; you need to prove your existence (social media) to retrieve ethers • All ethers are already mined and only distributed on demand • Supported by Geth • https://rinkeby.etherscan.io/ Kovan • Uses Proof of Authority; requires Github account • Supported by Parity • https://kovan.etherscan.io/
- 30. Tools we need Node Packet Manager (npm) NPMis a package manager for Node.js packages and modules Ganache • Ethereum client for testing and development • Runs locally and simulates a full Ethereum client • Fast • Well supported ecosystem of tools Truffle • Dev environment, testing framework, and asset pipeline for Ethereum • Helps deploy contracts to the blockchain • Help connect front-end to your deployed contracts MetaMask • Ethereum light client • Allows you to interact with Dapps via Chrome
- 31. Development workflow 1. Download and start an ethereum node 2. Code and compile your smart contract 3.Deploy your compiled contract on the network using a framework like truffle 4. Call stuff in the contract using web3.js
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- 40. workflow truffle compile Thiscommand compiles the contracts in your contracts folder and will create artifacts (JSON files) that contain the bytecode that can be executed on the network. truffle migrate Deploy the contract on your test network. Migrations are scripts that follow a series of steps that are needed to deploy your contracts and setup the projects like you need them to setup. truffle console To inspect the contract
- 42. workflow truffle compile Thiscommand compliles the contracts in your contracts folder and will create artifacts (JSON files) that contain the bytecode that can be executed on the network. truffle migrate Deploy the contract on your test network. Migrations are scripts that follow a series of steps that are needed to deploy your contracts and setup the projects like you need them to setup. truffle console To inspect the contract
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- 45. workflow truffle compile Thiscommand compliles the contracts in your contracts folder and will create artifacts (JSON files) that contain the bytecode that can be executed on the network. truffle migrate Deploy the contract on your test network. Migrations are scripts that follow a series of steps that are needed to deploy your contracts and setup the projects like you need them to setup. truffle console To inspect the contract
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