44 lines
2.6 KiB
Markdown
44 lines
2.6 KiB
Markdown
---
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title: Smart Contracts
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---
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## Smart Contracts
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Cryptocurrency transactions that occur on a blockchain are an example of a very basic contract: one party sends money to another. However, blockchains also have the potential to manage and execute more complicated contracts. On the Ethereum blockchain, for example, one can utilize _smart contracts_ — blocks of code that only execute when their conditions are met. Smart contracts are Turing-Complete and as decentralized as the monetary transactions that occur on the blockchain. The combination of decentralized programs and money make for interesting possibilities.
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As a piece of code that sits on the blockchain, a smart contract can automate tasks in a decentralized and transparent manner. Examples of this include managing the process of recieving and distributing micro-payments for viewing ads (such as with the Basic Attention Token) and managing buy/sell order books for exchanges transparently (such as with the 0x project).
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## Applications of Smart Contacts
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Smart Contracts allows the transfer of goods and services without the need for a independent third party. Logic and rules are built into the smart contract that define the permissions and processes associated with a particular agreement and enforce the obligations attached to it. This provides an opportunity to remove middlemen that are traditionally required to interact with physical property or financial service instruments.
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## Blockchain Technologies
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Two of the most common technologies used are:
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- Ethereum: generally made with Solidity
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- Hyperledger: generally made with Go, or Java
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### Smart Contracts in Ethereum
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Smart contracts in ethereum are written using Solidity, its a high-level, contract-oriented programmng language, and targets Ethereum Virtual Machine, one can use Remix online IDE to try writting and deploying smart contracts
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### Smart Contracts in Hyperledger
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Smart contracts in Hyperledger is called chaincode, and is written in Golang programming language.
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## Hello World Smart Contract
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```solidity
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pragma solidity ^0.4.24;
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contract Hello {
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string public message;
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function Hello(string initialMessage) public {
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message = initialMessage;
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}
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function setMessage(string newMessage) public {
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message = newMessage;
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}
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}
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```
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Pulled from [Medium - How to Write a Simple Smart Contract](https://medium.com/coinmonks/how-to-write-a-simple-smart-contract-25f6d3c1d6db).
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### Ethereum Development Tools
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- [Remix (official Solidity IDE)] (https://remix.readthedocs.io/en/latest/)
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- [Truffle] (https://github.com/trufflesuite/truffle)
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- [MetaMask] (https://metamask.io/)
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- [DAppBoard] (http://dappboard.com/app)
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