Blockchain for Healthcare: A Proof of Concept

Note: A lot has changed in the Ethereum world since this project was completed and the setup instructions might not work now. If you, being a good samaritan, run into an error during setup and are able to fix it, please raise a pull request to help others. Big big thanks from me!

Installation

The projects requires NodeJS and npm to work. Instructions to install all other dependencies are given below.

Note: The instructions given below are for Linux (specifically Ubuntu 18.04). You should be able to find similar instructions for MacOS and Windows. Although support is available for Windows, I recommend using Linux or MacOS. Windows has some difficulty playing with npm.

Node modules

1. Move to the project directory and open it in your terminal.
2. Run npm install.

Ganache

1. Go to Ganache homepage and download.
2. If you are on Linux, you must have received an .appimage file. Follow installation instructions available here.

IPFS

1. Go to the download page of IPFS and follow the instructions given.

Local server

1. You can use any local server to deploy the web application.
2. I used PHP but feel free to choose anything of your liking.
3. To install PHP on your Linux machine, run sudo apt-get install php. Detailed instructions available here.
4. One more great option is lite-server which is available as a node module.
5. Install lite-server by running the following command on your terminal npm install -g lite-server

Metamask

1. Metamask is a browser extension available for Google Chrome, Mozilla Firefox and Brave Browser.
2. Go to the this link and add Metamask to your browser.

Getting the dApp running

Configuration

1. Ganache

• Open Ganache and click on settings in the top right corner.
• Under Server tab:
  • Set Hostname to 127.0.0.1 -lo
  • Set Port Number to 8545
  • Enable Automine
• Under Accounts & Keys tab:
  • Enable Autogenerate HD Mnemonic

2. IPFS

• Fire up your terminal and run ipfs init
• Then run

  ipfs config --json API.HTTPHeaders.Access-Control-Allow-Origin "['*']"
  ipfs config --json API.HTTPHeaders.Access-Control-Allow-Credentials "['true']"
  ipfs config --json API.HTTPHeaders.Access-Control-Allow-Methods "['PUT', 'POST', 'GET']"
  

3. Metamask

• After installing Metamask, click on the metamask icon on your browser.
• Click on TRY IT NOW, if there is an announcement saying a new version of Metamask is available.
• Click on continue and accept all the terms and conditions after reading them.
• Stop when Metamask asks you to create a new password. We will come back to this after deploying the contract in the next section.

Deploying the contract

I purposely haven't used any development framework so as to keep the code as raw as possible. This will also be easier to understand for any newcomer who is already having a tough time understanding the many technologies the application is built on.

1. Starting your local development blockchain

• Open Ganache.
• Make sure to configure it the way mentioned above.

Moving on, to deploy the contract on the blockchain you have two options:

• Use any available development framework for dApps. I recommend the Truffle framework. Embark is another great alternative.
• Go full on geek mode and deploy it yourself with a few lines of code.

I'll be explaining the second method here.

2. Deploying the contract and linking it to the frontend

• Fire up your terminal and move to the project directory

• Now open up /YOUR_PROJECT_DIRECTORY/src/js/run.js in your favourite text editor

• You have to make two changes:

  1. Make sure the address in line number 3 is the same as your RPC server address on Ganache. If you have configured Ganache as instructed above, the code should look like this:

  var web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
  

  2. The path in this line should point to where your solidity contract is located:

  var code = fs.readFileSync('/YOUR_PROJECT_DIRECTORY/contracts/Agent.sol').toString();
  

• Go back to your terminal, type node and hit enter

• Copy and paste all the contents of run.js to the terminal

• If all goes well, you should see some few lines as output of the command

  console.log(compiledCode.contracts[':Agent'].interface);
  

• This is the ABI of the contract, copy and paste these lines in line number 10 of app.js. The code should look like:

  abi = JSON.parse('PASTE_YOUR_ABI_HERE')
  

• Go back to the terminal and type deployedContract.address;, which is also the last command of your run.js file. The output is the address where the contract is deployed on the blockchain.

• Copy the output and paste it on line number 13 of app.js. The code should look like:

  contractInstance = AgentContract.at('PASTE_YOUR_ADDRESS_HERE');
  

• That's it for this part. Now lets set up Metamask.

Running the dApp

1. Connecting Metamask to our local blockchain

• Let's go back to the configuration section of Metamask.
• If done correctly, you would have stopped at the part where Metamask asks you to create a new password.
• Just below the CREATE button, click on the Import with seed phrase.
• A form should open up, asking you to enter Wallet Seed.
• Open Ganache, copy the twelve words that make up the MNEMONIC on the ACCOUNTS tab.
• Paste the twelve words in Wallet Seed. Create a new password and click IMPORT.

2. Starting IPFS

• Open a new terminal window.
• Make sure you have configured IPFS as mentioned above.
• Run ipfs daemon.

3. Start a local server

• Open a new terminal window and navigate to /YOUR_PROJECT_DIRECTORY/src/.
• Run php -S locahost:3000.
• Open localhost:3000/register.html on your browser.
• That's it! The dApp is up and running locally.