/Blossom-SummerSchool-2019

This repo contains all important information and files for the Blossom-Blockchain Summer school 2019 at Talinn

Primary LanguagePythonGNU General Public License v3.0GPL-3.0

Blossom Summer School 2019

Tutorial on token creation and usage for supply chain management

Offered by Mayutan Arumaithurai on behalf of Chaindrium




This repository has three parts. You can choose one of the three parts or do all the parts at this tutorial. However, we suggest that you do the parts in order, especially do the part for "For programmers" before doing the "For hard-coders" part.

  • For non-programmers
  • For programmers
  • For hard-coders

For non-programmers

This tutorial is to demonstrate how payments can be made from one address to another address in the Etheream Test Network. This part of the tutorial is for those participants who have no programming expertise but would still like to experience first hand how transactions take place in Ethereum. It is also applicable for those who would like to ease into the tutorials by performing an easier tasks first.

Please do the following:

  • Create a MyEtherWallet Account

    • Go to the following website in your browser: https://www.myetherwallet.com/
    • Click on Create a New Wallet
    • Select Mnemonic Phrase and click on continue
    • Please store the 12 words that you can see.
    • No need for "passowrd"
    • Click on I wrote down My Mnemonic Phrase

  • Access a MyEtherWallet Account (option I)

    • Go to the following website in your browser: https://www.myetherwallet.com/
    • Click on Access My Wallet
    • Click on Software
    • Select Mnemonic Phrase and click on continue
    • Please give the 12 words that you can see on the beamer.
      • now, in 1, please choose the testnet ROP - myetherwallet.com
      • in 2, please select on the top right hand corner Ethereum Testnet (Ropsten)
      • now, you should see a list with addresses and corresponding balance
      • choose one of the addresses (in case you have already transferred some coins, use that account)
        • then click on Access My Wallet

  • Faucet: Send some test coins (Option I) - Go to the following website in your browser: https://faucet.ropsten.be/ - Copy paste the selected address from above and paste it in this site - click on Send me test Ether - You can click on the transaction id provided to monitor the transaction - Wait till the balance shows up on your MyEtherWallet for that particular address - In case it takes a while or if you have issues getting the coins, continue to option II (Option II also provides other means of getting faucets/test-coins)

  • Access a MyEtherWallet Account via Metamask and obtain faucets (option II)

    • Install metamask extension on your browser
    • Click on the metamask extension
    • Click on "import using account seed phrase"
    • Enter the 12 words and add a password (you can use the account next time with just the password)
    • The First time, you will have to click on allow metamask to connect with myetherwallet (Else go to myEtherWallet -> Access my account -> metamask)
    • Then go to the webpage https://faucet.metamask.io/ and click on request faucet (Here, you can get multiple faucets).
    • Check the balance in metamask

  • Send A Single Transaction (Try it out both on myetherwallet and metamask)

    • Take a look at your account balance. Then, click on Send Transaction in order to make a transaction
    • Please fill in the following fields
      • in the To Address, please add the address to which you would like to make the transaction to. You could choose the address of the person sitting next to you in order to make it easy to verify.
      • in Amount, please enter the amount you will like to send. Note that your account has a balance of approx. 0.5 ROP (The currency in the test network). Therefore, choose a value lesser than what you have in the account so that you have some money to pay as transaction fee too. Best to therefore enter a very low value so that you have more money to perform more experiments.
    • Now, click on Send Transaction
    • A new window will open up. Here, you can double check the values and confirm the transaction.

  • Done, You have now successfully made a transaction to transfer money from one account to another. You will be able to view the transaction on the testnet in a few seconds.

  • View the transaction on etherscan.io

    • After confirming the transaction, please click on Check Status on Etherscan.io
    • Now, a new tab should open up with details of the transaction.
    • You can for example see the hash of your transaction
    • You can also take a look at the block in which your transaction was added and take a look at other transactions in there.




For Programmers

This step by step tutorial is to demonstrate the creation of a token, transfer tokens and to retrieve some features of the token. It demonstrates the basic interactions one could perform with blockchain. This tutorial is for people familiar with programming. In case you have any queries or require assistance, feel free to speak to me.

Requirements:

  • python3.6
  • Please install the following library:
    • pip3 install web3
  • Alternatively, you could use python-virtualenv: pip install virtualenv
    • source ./virtual_env/bin/activate
    • You will now find yourseld in the python virtual environment

What are we going to develop here:

Let's assume that you have a Blossom-Ticket that you would like to gift someone. The person could further gift this ticket. However, you would like to know who has the ticket at any point of time. Let's develop this on blockchain.

Let's do the following steps:

  • Download the repository from https://github.com/chaindrium-inc/Blossom-SummerSchool-2019. You could either use git clone or click on download and then extract the files from the zip file.

  • go to /src/01_basic/

  • Create your own wallet

    • Open the file generate_wallet.py
      • This will help create a wallet for you. Take a look at the code and the documentation.
      • Change the variable random_string. This helps to create a secure wallet.
    • Execute the file
      • You will now see that the script outputs an address. Copy and save this address. This is the address (it is in fact a public key) of your wallet and you will need it later.
      • Moreover, the script has stored a file named wallet/private.key. In this file, you will find the private key for your address. Take care of this file. In case you lose this, you won't be able to access your wallet. Or in case some one else gets hold of this key, they can access your wallet and steal your coins.
    • Note that everytime you rerun the script generate_wallet.py, a new wallet address is being generated and therefore the privat key in wallet/private.key is being overwritten.

  • Get some balance and create a new token

    • You will need some ether in your account in order to perform transactions, i.e., to pay the transaction fee.
      • Enter your address here to get an ether on the test network or login via metamask and click here.
    • Now, take a look at the file see_balance.py. Replace the address variable with your address. When you run the file, you will be able to see your balance.
    • As soon as your balance is above zero, you can go on with the next step.
      • In the mean time, you can also take a look at the token creation file token_contract/NConfToken.sol. This is the smart contact that we will use in the next step.

  • Set up a smart contract on Blockchain

    • Take a look at the file deploy_token.py
    • You can observe that some variables are set in the first few rows. Most importantly, set the variable token_name to have the name of the token (e.g. Blossom_myname).
    • Execute the file
    • When everything works fine, you will get a hash code that represents your transaction.
    • Open https://ropsten.etherscan.io/ in your browser
      • In this webstie, you will be able to find all the blocks and transactions belonging to the test network.
    • In the search box, enter the hash of your transaction
    • You will be able to see your transaction now
    • Take a look at the from address. It should be your address since you deployed the smart contract.
    • In the to field, it should be the address of your smart contract
      • Copy this address (Tip: In order to ensure that the correct address is copied, best to click on the contract address and then when etherscan.io displays the contract details, copy the contract address from the top). Note, we refer to this as the token address sometimes later on.

  • Check the name of the token

    • Take a look at the file get_token_name.py
    • Edit the variable token_address: enter the address of your token, i.e., the smart contract
    • Execute the file
    • You will now see that the name of your token is output
      • You could try to redo the experiment to get your partner's token's name

  • Check the owner of the token

    • Take a look at the file get_token_owner.py
    • Edit the variable token_address: Enter the address of your token here
    • Execute the file
    • You will be able to see the address of the owner of the token holder
      • You could redo the experiment for a different token, e.g., that of your partner(s)

  • Give the token to someone else

    • Take a look at the file send_token.py
    • Edit the variable token_address: Enter the address of your token here
    • Edit the variable new_owner: Enter the address of the person you want to give your token to
      • Best to find a partner with whom you can exchange your tokens
    • Execute the file
      • Now, the tokens should no longer belong to you, but it should belong to the person you send it to.
        • Do the previos test Check the owner of the token to verify it.
        • Also execute the file see_balance.py to check your balance. Some of it would have been used to execute the transaction.

  • Done

    • Take a look at your address in https://ropsten.etherscan.io/ -Just enter your address in the search box -You should be able to see your balance and the executed transactions.




For Hard-coders

This is a tutorial for experienced programmers to get a feel of developing their own token. Incase of queries, contact me directly.

Requirements:

  • python3.6
  • Please install the following library:
    • pip3 install web3
  • Alternatively, you could use python-virtualenv: pip install virtualenv
    • source ./virtual_env/bin/activate
    • You will now find yourseld in the python virtual environment

What are we going to develop here:

Let's assume that you are a farmer (producer) and that you produce bio-potatoes. These potatoes will be sent by you to a factory that makes vodka. The vodka is then solde to consumers.

The consumer would like to have the following information about the vodka he/she buys: - Who had produced the potato - Who produced the vodka - Are the potatoes bio - What kind of potatoes were used for producing the vodka




**Initially, you can do this in a group of three such that one is a producer, the other is the factory and the third is the consumer. You could then attempt to play all the three roles. Remember to create multiple keys, a key set for each role. **

  • Go to /src/01_advanced/

Exercise 0:

In order to model this supply chain, we will make use of a smart contract (potato). Take a look at potato/potato.sol. Please understand all the following variables:

  • producer
  • factory
  • is_vodka
  • name
  • owner

and the following functions:

  • constructor
  • send
  • set_factory
  • to_vodka
  • is_potato_vodka
  • who_is_owner
  • who_is_producer
  • who_is_factory
  • get_name
  • is_bio_potato

Exercise 1:

  • Write code (deploy_potato.py) that deploys the potato Smart Contract on blockchain
  • Ensure that all the variables required for the potato Smart Contract contractor is provided
    • For string name, you could use the name of a potato from (https://de.wikipedia.org/wiki/Liste_von_Kartoffelsorten)
    • The address of the producers is automatically set to the one executing the transaction. See potato Smart Contract where producer = msg.sender in the constructor does that.
  • Also print the transaction id
  • Execute the file to create a potato smart contract

Exercise 2:

  • Write code (send_potato_to_factory.py) to send the potato Smart Contract to the factory
  • Execute the function to send the potato to the factory
  • Note: Create a separate address for the factory and keep a copy of the address as well as the private key for Exercise 4

Exercise 3:

  • Write code (produce_vodka.py) to call the function to_vodka in the potato Smart Contract
  • Execute the function to convert the potato into vodka

Exercise 4:

  • Write code (send_vodka_to_consumer.py) to send the vodka from the factory to the consumer
    • Note that the factory and consumer address is right
    • Execute it to send the vodka to the consumer

Exercise 5:

  • Write code (get_potato_information.py) that calls the methods is_vodka, get_producer, get_factory, get_name and dispalys the results in the console.
  • Check if all the displayed information is correct

Note

In case you modify the solidity file (for instance potato.sol), please do the following:

Have fun :)