Vischain

A visualisation of a toy blockchain network.

Todo blockchain

• Fix node crash, sometimes hangs
• If an incoming block is verified and added to the chain, remove any transactions in pool which have already been mined and start again
• If a longer chain is selected, ensure we pool any unmined transactions which were in our "lost" blocks to mine later
• Handle BadGateway errors (offline peers): manage peer connections centrally on API
• Choice of whether to be a miner or not
• Implement a block size limit
• Once block size limit reached, keep collecting transactions anyway to mine later
• Sign transations
• Confirm transaction validity when adding to list
• Ensure all transactions in block are valid when new block received from network (https://en.bitcoin.it/wiki/Protocol_rules#.22tx.22_messages)
• Peer discovery
• Separate block header
  • Fixed size block header (only the header is hashed + mined, to ensure consistent difficulty regardless of # transactions in a block)
  • Transactions stored in merkel tree in block body
  • Store Merkle root in Block header only
  • Build Merkle tree when collecting transactions
  • Verify transaction included in block using only necessary Merkle branches in transaction tree
  • Set block size limit
• Transaction fees
• Implement UXTO + balance system https://www.cryptocompare.com/mining/guides/bitcoin-transaction-inputs-and-outputs/

Todo visualiser

• Visualise:
  • Block mined
  • Transaction rejected/accepted
  • Block rejected/accepted
  • Chain divergences
  • Balances
• Edit:
  • Difficulty
  • Nodes in network + connections
  • Which nodes are miners

Protocol

API

All requests proxied from node A to node B will forward the X-Sender header in the request to B.

POST /transaction

Transaction will be sent to recipient and their response returned in payload.

Example request:

POST /transaction
{
	"sender": "8081",
	"recipient": "8080",
	"amount": "1"
}

Response example:

{
    "payload": {
        "Code": 1
    },
    "title": "OK"
}

POST /block

Block in data will be sent to all recipients and responses returned in payload.

Example request:

POST /block
{
    originalSender: "8080",
    recipients: ["8081", "8082"],
    data: {
        "index": "5",
        "timestamp": "1510332444551936900",
        "transactions": [{
            "sender": "8081", "recipient": "8080", "amount": "1"
        },{
            "sender": "8081", "recipient": "8080", "amount": "1"
            
        }],
        "proof": "T5AEAA==",
        "prevHash": "tDw6oL/3BxXN+pTY6o/8M6eVBcKsUow3YTQgl88BscY="
    }
}

Response example:

{
    "payload": {
        "8081": {
            Code: 1
        },
        "8082": {
            Code: 1
        }
    },
    "title": "OK"
}

GET /chain

Fetch a chain of blocks from a peer.

Example request:

GET /chain?peer=8081&lastBlockHash=tDw6oL/3BxXN+pTY6o/8M6eVBcKsUow3YTQgl88BscY=

// TODO: Response example

Nodes

POST /transaction

Example request:

POST /transaction
{
	"sender": "8081",
	"recipient": "8080",
	"amount": "1"
}

Response example:

{
    Code: 1
}

Response codes:

Code	Description
1	The transaction was received successfully
2	The request body could not be parsed
3	The transaction could not be parsed from the body

POST /block

Example request:

POST /block
{
	"index": "5",
	"timestamp": "1510332444551936900",
	"transactions": [{
		"sender": "8081", "recipient": "8080", "amount": "1"
	},{
    	"sender": "8081", "recipient": "8080", "amount": "1"
		
	}],
	"proof": "T5AEAA==",
	"prevHash": "tDw6oL/3BxXN+pTY6o/8M6eVBcKsUow3YTQgl88BscY="
}

Response example:

{
    Code: 1
}

Response codes:

Code	Description
1	The block was received successfully
2	The request body could not be parsed
3	The block could not be parsed from the body

GET /chain

Fetch a chain of blocks from this node. If a lastBlockHash is provided, return Code: 1 with all the blocks on the chain after and not including the specified block. If lastBlockHash is not found in the chain, the chain may have forked. Return Code: 2 with the entire chain.

Example request:

GET /chain?lastBlockHash=tDw6oL%2F3BxXN%2BpTY6o%2F8M6eVBcKsUow3YTQgl88BscY%3D

Response example:

{
    Code: 1,
    Payload: [{
        "index": "2",
        "timestamp": "1510332444551936900",
        "transactions": [{
            "sender": "8081", "recipient": "8080", "amount": "1"
        },{
            "sender": "8081", "recipient": "8080", "amount": "1"
            
        }],
        "proof": "T5AEAA==",
        "prevHash": "tDw6oL/3BxXN+pTY6o/8M6eVBcKsUow3YTQgl88BscY="
    }, ...]
}

Response codes:

Code	Description
1	The tail of the chain was returned
2	The hash was not found, and the entire chain was returned