Lab 03 Add usage script or instructions how to interact with multi-node network

[jsolderitsch]

I figured our how to use postman to send post requests to the first node created by the setup-docker script. This causes a block to be mined if you add enough transactions.

But I am unsure of the process of building out a multi-node network where transactions posted to node 2 will cause node 1 and node 2 to have a common view of the blockchain. Seems like each node will have its own genesis block for example.

Also not clear on how peers are declared/detected. Maybe this should be obvious by reading the code, but it is not obvious to me.

I am teaching a blockchain course at Villanova University in the state of Pennsylvania.

[jsolderitsch]

There is a test.py file in the project. I suggest that an assignment challenge might be to add an @app.route declaration for getBalance where the there is an argument for an address. Also a method to return just the size of the blockchain. I might take up the challenge myself to see if I know enough based on the current README and examining the code.

[jsolderitsch]

I did implement getBalance and getLength app.route implementations and this was straight forward. I now believe that the simple lab 03 implementation does not support a multi-node network with each node having a common blockchain view of blocks mined by any of the nodes in the network.

@app.route('/length', methods=['GET'])
def get_length():
    response = {
        'length': len(blockchain.chain),
    }
    return json.dumps(response), 200

@app.route('/getBalance', methods=['GET'])
def get_balance():
    address = request.args.get('address')
    balance = blockchain.get_balance(address)
    response = {
        'address': address,
        'balance': balance
    }
    return json.dumps(response), 200