BlockchainFramework

Content

Description

Methodology

networkmngr Instructions

Node Instructions

Personal To Do List

Description

Initially a learning experience, turned project, turned hobby.
I decided I'll best understand blockchain technology by making my own.

Based on Satoshi Nakamoto’s Bitcoin: A Peer-to Peer Electronic Cash System.

Its a basic blockchain framework including:

• Timeserver stamp
• Proof of Work
• HTTP requests
• Consensus
• Chain Validation

Using packages:

• Flask
• Requests

This version DOES NOT run on multiple IP addresses but rather on multiple ports on your Macbook Pro.
The framework comes with a set up manager tool called networkmngr.py. It's used to initialise a network of nodes, instruct to mine, setup a block or shut them down.

Later on I will implement IP nodes and convert from HTTP infrastructure to TCP ensuring less overhead and faster responses.

Useful Tools

• Postman.app

Methodology

Prerequisites

You need to have the following installed before attempting to run this program:

• python 3.7 (at least)
• pip
• pipenv

Open Terminal. Go to the working directory this repository is stored in. Before starting the program, optionally, run the below command to remove unecessary 'Courtesy Notices' being displayed. Or add it to your .bash_profile file.

export PIPENV_IGNORE_VIRTUALENVS=0

Start up

To create your network of nodes execute:

pipenv run python networkmngr.py -p 4999 -a 6

Background action

This will start the node manager client on localhost:4999 with 6 initial node clients (node ports start from 5000 and increment by 1). Firstly, they're started as processes in the background, next they are initialised by:

• Genereting a random hash ID for itself
• The manager downloads each node's ID and address
• Manager compiles the list of all available nodes in the network and sends a copy to each so they're all aware of each other
• Manager and Nodes all wait for requests

Example use of networkmngr

1. Open Postman.app

2. Start creating requests.

Firstly, we'll query one of the nodes for it's ID and then for it's chain.

3. Use the GET 0.0.0.0:5000/node/id then GET 0.0.0.0:5000/chain

What do the received json files show?

Now we can start adding some blocks to the existing chain in the network.

4. Call GET 0.0.0.0:4999/start/mining

Wait for a response from the server to notify of sent mining requests (should be 6)

5. Call GET 0.0.0.0:5002/chain

Probe a different node's chain to see how the chain has progressed (chain should be 7 blocks long)

6. Call GET 0.0.0.0:4999/shutdown/all

When ready to shut the whole network use this request.

You can find the output and example outputs of networkmngr.py and all Nodes in the Log folder

networkmngr Instructions

• Send Mining requests to all nodes

[address]:[port]/start/mining

Preset to a specfic number of times to mine a block in network, in random 1-3s intervals

• Shutdown Network

[address]:[port]/shutdown/all

Stops all node clients

Node Instructions

• Notify node of new block being successfully mined

[address]:[port]/block/new

The node will run ResolveConflicts.py to update it's chain based on the established Consensus

• Get chain

[address]:[port]/chain

Returns the current chain

• Replace chain

[address]:[port]/chain/replace

Will replace node's chain w/ the one provided in this POST request (json format only)

• Register nodes list

[address]:[port]/nodes/register

Adds listed supplied json list of nodes to the node's registry

• Mine

[address]:[port]/mine

One last time run ResolveConflicts.py before Node starts proof of work on HEAD block's hash (current master chain)

• Get Node Status

[address]:[port]/node/id

Returns the node's ID, address and their known record of other nodes (should make it a limit and give group bands of IP addresses eg. 100.0.3.xxx = 255 group members)

• Shutdown Node

[address]:[port]/shutdown

Shuts the node down and sends response (need more secure and checks)

Personal To Do List

• Convert to TCP/UDP
• Make Timestamp in Logs more readable
• Add content in blocks
• Implement a check to see if childprocesses terminated before shutting Manager.
• Node ID, addresses and etc need to be put into files.
• Create Flowchart
• Add error handling
• Change order of mining response in networkmngr.py
• Learn threading in python to improve request handling on server-side -Implement java server architecture