doganbolivar / pbft-2

An implementation of the Practical Byzantine Fault Tolerance consensus algorithm

Practical Byzantine Fault Tolerance

PBFT is a consensus algorithm used by some of the biggest Blockchains.

It's known for being a more scalable alternative to the traditional Proof of Work.

Execution

It is possible to start many nodes in the same machine or in different VMs, the initialization is the same, as follows:

$ node networkNode.js <node_type> <blockchain_type> <ip_address> <any_master_node_ip>

Example:

node networkNode.js master full 192.168.0.1 192.168.0.2

Node type should be either master or network. Only master nodes are allowed to create blocks in PBFT. Any node will take part in the voting though.

Blockchain type should be either full or light. The full type gets the entire blockchain from master node, but this is more time and network consuming. full's counter part is light, that is fast and lightweight with the main downside of not receiving the entire blockchain (only the last 10 blocks from master node).

any_master_node_ip should be a reachable master node ip address. If it is the first node in the network, use this, the node will then start as the first master node. Don't do this if you intend to connect to an active network, as the node will just start its own network and won't connect to any running nodes.

Both the ip_address and the any_master_node_ip passed in initialization should be only the ip itself (eg. 10.10.0.1). Do not specify http:// or the port in the end, this will result in a request error.

To test, you can reach http://ip:port/ in your browser, it will return a json containing information on the node you requested, and the active nodes on the network.

To see the current blockchain, reach http://ip:port/blockchain.

To add a block to the blockchain, make a post request to http://ip:port/createBlock with a json payload as follows:

{
	"timestamp": "YYYY-MM-DD HH:MM:SS",		// optional
	"carPlate": "<plate>",
	"block": {
		"data": "any data, can be an array, or json, str..."
	}
}

You can define an optional timestamp for testing purposes. If not specified, the timestamp will be the current time.

The response will contain the whole created block that was broadcast to the network, however, this does not mean the block was accepted. You can request the /blockchain to any node to check if the block was accepted.

There are a number of reasons for a block to be rejected, you can check the results of the voting process in any node log.

Docker Example

Building docker container for pbft and starting n nodes.

docker build . pbft/algo
docker-compose scale node=<total-num-of-nodes> #starts n containers

Let's see the steps to follow for n=4 nodes with 2 master nodes.

Use docker ps for viewing the container ids. To get the ip of the container processes use:

docker exec -it pbft_node_1 ip addr
docker exec -it pbft_node_2 ip addr
docker exec -it pbft_node_3 ip addr
docker exec -it pbft_node_4 ip addr

Copy the container ip:

docker exec -it pbft_node_1 node networkNode.js master full <container-ip> this
docker exec -it pbft_node_2 node networkNode.js master full <container-ip> <pbft_node_1's_IP>
docker exec -it pbft_node_3 node networkNode.js network full <container-ip> <pbft_node_1or2's_IP>
docker exec -it pbft_node_4 node networkNode.js network full <container-ip> <pbft_node_1or2's_IP>

These will start 2 master node and 2 network nodes.

Interacting with blockchain

View

curl <node_ip>:3002/blockchain # for viewing the blockchain

Append

curl -XPOST <master_node_ip>:3002/createblock -H "Content-Type: application/json" -d '{
 "timestamp": "YYYY-MM-DD HH:MM:SS",  // optional
 "carPlate": "<plate>",
 "block": {
  "data": "any data, can be an array, or json, str..."
 }
}' # for creating a new block

View

curl <node_ip>:3002/blockchain # for viewing the blockchain after the adding of new block is completed

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Further repositories of the CarChain Project:

Blockchain Visualizer

CarChain Dashboard

Car Simulator