timf34 / 3d3-project-3

Project 3 - 3D3 - Blockchain messaging network

General TODO - Project 3

Note: these would still be nice TODOs - get round to them over summer

• Need to improve the robustness of the network nodes
  • The best way to do this is to post status responses, to the terminal is probably not the best way to do this but enough for now. We would probably want to have a constant status response displayed on the webpage!
• Need to show robustness to content types in the network
  • Show that our network can handle different input types.
• Refamiliarize myself with the code base to spot where the improvements are needed.

Programming TODO

• Add test cases directly in the code rather than having to use the web interface.
• Post the https response status to the web interface.

Project 3 - Global Problem

With this project we are looking to contribute to the global problem that is Cancel Culture and Free Speech. In order to help combat this problem we are looking to build a network of nodes that can be used to communicate and publish to a public message board where all messages are stored forever.

Instructions

Setup:

Clone the project (or not, we will keep this repository private till the deadline)

git clone https://github.com/satwikkansal/python_blockchain_app.git

Set up a virtual environment if you would like to

virtualenv venv

Install the requirments - we will use pip

pip install -r requirements.txt

This was tested with Python 3.7.3

Running the code:

Ensure you're in the project directory

cd 3D3-project-2

Now open a terminal and set the flask_app variable to network.py - this will depend on your OS/ terminal, we will consider powershell

# On Windows PowerShell
$env:FLASK_APP = "network.py"

# On Bash 
export FLASK_APP=network.py

On Windows CMD 
set FLASK_APP=network.py

Then run (note that the port isn't important, we will use port 8000). It is important to do this in the same terminal that you set the environment variable aove/

flask run --port 8000

Now in another terminal run the app. This will start the server and it is this link that you follow for the web app!

python run_app.py

Now you should be able to access the app at http://localhost:5000.

Setting up multiple nodes

We can set up multiple nodes by using multiple terminals. Also note that for these instructions, its best to use a bash terminal for the curl commands as command prompt and powershell seem to act strangely to the quotes ' and ".

Follow from the instructions above where we have a node set up at local port 8000. We can now repeat the process setting up nodes with ports 8001, 8002, 8003 etc.

Ensure to set the environment variable FLASK_APP to network.py in each terminal.

Run flask run --port 8001

Then to register the nodes, and ensure you do this in a bash terminal (such as Git Bash) (to avoid issues with parsing the " and ') run

curl -X POST http://127.0.0.1:8001/register_with -H 'Content-Type: application/json' -d '{"node_address": "http://127.0.0.1:8000"}'

It should say registration successful. Also make sure to do this before you have posted to the message board.

You can repeat this process on as many ports as you want.

To check whether this is working, we can query the nodes for a copy of their blockchain. So after we have posted a few messages to the message board, we can run:

curl -X GET http://localhost:8001/chain

This will show us whether the multiple nodes are working or not - we can query it to see if the other nodes (8001, 8002, etc.) are updating their blockchain!

For example, run the above code with multiple nodes running, then post some messages to the web app - watch the blockchain be updated!

Functionality

1. Type your message in the text box, and your name in the name box, and then click post.
   1. The message will be posted to the blockchain.
2. Now click 'Request to mine'
   1. The node will request all other nodes to mine the block.
3. Then click 'Resync'
   1. Our message board will refresh and the message will be posted to the page.

Resources

This project was inspired by:

• Blockchain
• Blockchain basics
• Python Blockchain App
  • It was inspired by this repo in particular, from which we modified the web app interface. Much larger changes were made to the blockchain code, which we refactored quite a bit to produce cleaner and more modular code - this really helped with our understanding of blockchain. We also refactored the networking code to suit our needs, and once again, make it more 'clean' and readable.