The BlockChain program created is meant to simulate a simple cryptocurreny blockchain. The user will run a web API in their localhost that allows them to host, create their own BlockChain, and communicate with other BlockChains.
\nThe current version of the downloadable program only runs on Mac OS X.
\nDownload the program here
\nThe program runs the API on the user's localhost on port 5000.
\nAfter the download and successful execution of the program, the user must have a way to make POST or GET requests to their API or another node's API. Something like Postman or cURL are good tools to use.
\nThe following API request codes found in this documentation will be sent to their localhost:5000 running the program. Alternatively, they can try posting the requests to a registered node created for testing purposes at laurenkwa.pythonanywhere.com.
\nUsers can also communicate and sync their nodes to this sample testing node.
\nReadme: Github Link
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\nThe miner will be rewarded with one coin.
\nFlask Python Code:
\n @node.route('/mine', methods=['GET'])\n def mine():\n\n last_block = blockchain.last_block()\n proof = blockchain.proof_of_work(last_block[\"proof\"], last_block[\"hash\"])\n \n blockchain.new_transaction(sender=\"0\",recipient = node_id, amount = 1,)\n \n previous_hash = last_block[\"hash\"]\n block = blockchain.new_block(proof, previous_hash)\n \n file_object = open(text_path, 'wb')\n pickle.dump(blockchain.chain, file_object)\n \n response = {\n 'message': \"New Block Added To Chain\",\n 'index': block.index,\n 'transaction': block.transaction,\n 'proof': block.proof,\n 'previous_hash': block.previous_hash,\n }\n return jsonify(response), 200\nCheck the BlockChains of other registered nodes and reach a consensus of which chain is more authoritative.
\nThe most authoritative chain is the longest BlockChain with the most Blocks.
\nThe authoritative chain is copied as the new BlockChain.
\nFlask Python Code:
\n @node.route('/nodes/resolve', methods=['GET'])\n def consensus():\n\n replaced = blockchain.get_consensus()\n \n if replaced:\n response = {\n 'message': 'Our chain was replaced',\n 'new_chain': blockchain.chain\n }\n else:\n response = {\n 'message': 'Our chain is authoritative',\n 'chain': blockchain.chain\n }\n \n return jsonify(response), 200 \nRegister another node computer to this BlockChain.
\nThe \"nodes\" parameter posted will be the IP address of the node you wish to add. In this example, it is \"http://localhost:8888\"
\nFlask Python Code:
\n#registers new nodes that will be tracked for consensus\n@node.route('/nodes/register', methods=['POST'])\ndef register_nodes():\n values = request.get_json(force=\"true\")\n\n nodes = values.get('nodes')\n\n if nodes:\n answer = values['nodes']\n blockchain.register_node(answer)\n print (\"true\")\n \n response = {\n 'message': 'New nodes have been added',\n 'total_nodes': list(blockchain.nodes),\n }\n return jsonify(response), 201\n \n else: \n return \"Error: Please supply a valid list of nodes\", 400\nCopies the chain of the posted node.
\nFlask Python Code:
\n#syncs this node with another node\n#sync means we will copy the current chain of the other node\n@node.route('/nodes/sync', methods=['POST'])\ndef get_current_chain():\n\n value = request.get_json(force=\"true\")\n \n nodes = value.get(\"nodes\")\n \n if nodes:\n answer = value['nodes']\n parsed_url = urlparse(answer).netloc\n \n response = requests.get('http://{}/chain'.format(parsed_url))\n \n if response.status_code == 200:\n length = response.json()['length']\n blockchain.chain = response.json()['chain'] \n \n new_chain = {\n \"message\": \"Sync successful.\",\n \"chain\": blockchain.chain,\n \"length\": len(blockchain.chain)\n }\n \n return jsonify(new_chain), 201\nReturns the current BlockChain of this node computer.
\nFlask python code:
\n #returns the current blockchain of this node\n @node.route('/chain', methods=['GET'])\n def chain():\n \n response = {'length': len(blockchain.chain),\n 'chain': blockchain.chain}\n \n file_object = open(text_path, 'wb')\n pickle.dump(blockchain.chain, file_object)\n \n return jsonify(response), 200\nCreate a new transaction that will be stored in the next Block created.
\nFlask python code:
\n #create a new transaction to be stored in the blockchain\n \n @node.route('/transaction', methods=['POST'])\n def transaction():\n\n if request.method == 'POST':\n data = request.get_json(force=\"true\")\n required = [\"sender\", \"recipient\", \"amount\"]\n \n if data['sender'] and data['recipient'] and data['amount']: \n \n index = blockchain.new_transaction(data[\"sender\"], data[\"recipient\"], data[\"amount\"] )\n \n response = {'message: Transaction will be added to Block {}'.format(index)}\n \n return jsonify(data), 201\n else:\n return 'Wrong Transaction Format', 400\n