I am trying to learn the blockchain technology and implement it in our existing product ecosystem. Bitcoin is the best example of blockchain technology.
I have read multiple articles on the internet and found that blockchain is a distributed ledger and every participant in it will maintain a copy of the ledger.
There are around millions of people holding bitcoins.
So all these customers maintain copy of ledger at their end ?
And when we make a new bitcoin transaction we need every other customer's consensus to make transaction successful ?
Or is it that there are a set of bitcoin minors who act on behalf of these customer's and maintain these ledger at their end ?
A Blockchain is a network where everyone is at the same level, i.e. there isn't a centralized authority that holds the system. So, everyone stores all the information.
And when we make a new bitcoin transaction we need every other
customer's consensus to make transaction successful ? Or is it that there are a set of bitcoin minors who act on behalf of these customer's and maintain these ledger at their end ?
The consensus is reached among all the participants of the Blockchain. In the case of Bitcoin, the mechanism used for it is the Proof of Work (PoW).
When a node of Bitcoin gets a new transaction, it verifies the transaction. If all is ok, the node broadcast the transaction to the rest of the nodes of Bitcoin. Every node, when it receives a new transaction, validates it.
The nodes of Bitcoin are miners. They are trying to generate a block. That block will store many transactions. When a node generates a block, the block is broadcast to the rest of the Bitcoin nodes.
When a node receives a new block, it verifies the block, i.e, verifies that all the transactions are valid and the block is correct. If so, the node adds the new block to its blockchain.
All the nodes store the same Blockchain. Also, all the nodes verify all the transactions and all blocks.
Related
Does anyone know what's a hashgraph and the difference from blockchain? If you could explain it to me how it works, I would be pleased!
Thank you in advance!
Hedera Hashgraph is very much different from a regular Blockchain (which is a chain of blocks as its name suggests), it is a DAG (Directed Acyclic Graph).
You can read more about what a DAG is in the link provided but apart from that how Hedera is different is that it is solving the below problems that any DLT should overcome to become Scalable, Secure and Fast without losing Trust:
(1) Performance,
(2) Security,
(3) Governance,
(4) Stability,
(5) Regulatory Compliance.
How is it solving all this simultaneously without losing Trust is something that you can read more in their whitepaper which explains beautifully or refer this article from Rejolut.
One primary problem with any Public Blockchain is the TPS or Transaction per second it can handle and Hedera Hashgraph is miles ahead of the others with being able to clock 100,000 TPS which makes it valuable and preferred option as it offers services like Crypto Service, File Service, Smart Contract Service and Consensus Service.
You can have a look at some of the explorers like Kabuto and Dragonglass to get an idea of the transaction speed and other details.
If you want to play around with Hedera Hashgraph, their docs are very well written or you can use console playground to work on Smart contract and Consensus services directly and maybe use fairorder to do the account management for you to begin with.
Hedera does not use blockchain. It uses DAG, "Directed Acyclic Graph. it keeps the records of communication of all the nodes in Dag and time stamps all these messages. Sending messages between nodes is called gossiping`. Its source code is not open source.
How does the gossip protocol work
In hashgraph, when sending information between nodes, "Alice" will
choose another member at random, such as "Bob". Then Alice will tell
Bob all of the information she knows so far. Alice then repeats this
information with a different random member. Bob repeatedly does the
same, and all other members do the same. In this way, if a single
member becomes aware of new information, it will spread exponentially
fast through the community, until every member is aware of it.
The synchronization of information between two members through the
gossip protocol is called a gossip sync. Upon completion of a gossip
sync, each participating member commemorates the gossip sync with an
event. An event is stored in memory as a data structure composed of a
timestamp, an array of zero or more transactions, two parent hashes,
and a cryptographic signature. The two parent hashes are the hash of
the last event created by the self-parent prior to the gossip sync and
the hash of the last event created by the other-parent prior to the
gossip sync.
Gossiping is the basis of the hashgrap consensus algorithm which uses asynchronous byzantine fault tolerant (abft) . this indicates that there is no specific time when all the nodes reach consensus. In other words abft consensus mechanism has no block time. (there is no blockchain here. neither a block reward)
Since gossiping the fastest way of sperading information, it takes 3-5 seconds for the entire network to reach a consensus.
Hedera claims that the network achieves 10,000 HBAR cryptocurrency transactions per second. (i personally do not believe those claims)
You can also write smart contracts on Hedera. But you cannot execute 10000 smart contract operations per second because Hedera uses EVM and EVM is very slow.
Hedera has no slashing. If validators misbehave, they will not lose any of their crypto holdings. because they claim that hedera hashgraph gives validators less opportunity to misbehave. validators receive the 90% of the network fees.
I have searched and searched and can't find the answer. If you are running a full node, can you confirm transactions. Or do you just verify/relay transactions? Or is it only miners that can confirm transactions? When I say confirm, I mean, when you spend some bitcoin, you need X confirmations (usually 6) for it to go through. Who does the confirmations? Can it be full nodes? Or is it only miners?
What I mean is, in the wallet, you see X confirmations. Who makes that number go up? (Say, for example, from 0 to 1). Is it miners, full nodes, or both. Realizing that miners run full nodes. But I mean, full nodes that are not miners. Can they add a confirmation? Or does it have to be a miner?
Transactions are confirmed by blocks being added to the blockchain. A transaction's first confirmation is when it is included in a block and that block is mined (added to the blockchain). Each subsequent block added to the blockchain on top of that transaction's block means another confirmation. So a transaction has a number of confirmations equal to its depth in the blockchain.
Confirmations happen because of blocks being added to the blockchain through the process of mining, so per your question, only miners can confirm transactions. Once a block is added, full nodes verify and relay that block, but only miners do the work of actually confirming the transaction.
If B is transferring bitcoin to C then when will be C receive the bitcoin? Is that after all the miners add that transaction into their local ledger? (I think it is time-consuming and what will happen if some miners are not adding?)
Now, if some miners are finding transaction invalid, while some find it valid so what will be the scenario in that case? When will be C receive the bitcoin?
The blockchain is a public ledger, so B isn't sending the transaction to just C, B is announcing it to everyone in the public network that i am sending bitcoin to C. So everyone in the network can see this transaction and now has to wait to be included in a block.
Miners create blocks of transactions, in every 10 minutes a new block is included into the ledger.and they have to create them in such a way that the rest of the network will accept them. One of the requirements is that the transactions in the block are all valid transactions. So yes, miners will validate that B has send bitcoins to C before they add the transaction to a block.
As all the full nodes in the bitcoin blockchain knows the currect state of bitcoins hold by B, they can easily verify the validity of the transaction.
Note: Each node in the blockchain either accepts or rejects a transaction.
Here's details you may want to have a look
https://en.bitcoin.it/wiki/Protocol_rules#.22tx.22_messages
when will be C receive the bitcoin? Is that after all the minors add
that transaction into their local ledger?
Each minor is trying to mine a block. When someone mines a block, the block is distributed along the network. So, every miner get that block. In a block, there would be some transactions.
However, another block could be mined at the same time. A miner who receives more than one block at the same time will continue mining along a branch. So, after some time, one of the branches will win.
Because of that, a transaction is valid when there are 100 more new blocks (I'm not sure if they are 100 or less) on top of that block.
what will happen if some minors are not adding?
After some time, all the minors will reach consensus about the branch and all of them will have the same blocks.
if some minors are finding transaction invalid, while some find it
valid so what will be the scenario in that case?
When a miner receives a block, verifies if all transactions are valid. If not, it sends a message to the rest of the miners to tell them that the block is invalid.
The result of a transaction (valid or invalid) is the same to all the members of the network.
I have been reading about blockchain and ethereum, but I cannot seem to get my head around a couple of concepts.
First, where in the blockchain is a newly created transaction stored ? So if the blockchain has been on going for some time, and lets say we are on block X right now. If I deploy my contract today, and it gets executed, will my transaction details reside on every block after block X or only on block X + 1 ? And will my transaction details be the only details on that block, or will that block contain every transaction that happened within that time period ? Again, do all of the prior blocks transactions get written to subsequent blocks as well ? What happens if more than 1 transaction gets executed from the same contract, is just written as 2 different blocks or within the same block ?
Second, when designing a contract I have seen that it is usually restricted to two parties that enter into it, and for other people to use the contract a new instance of the contract has to be created, is this understanding correct ? Or should 1 contract be designed in a way that everyone uses it and only one instance of it is ever created ?
where in the blockchain is a newly created transaction stored ?
In the blocks that each node stores.
will my transaction details reside on every block after block X or
only on block X + 1 ?
Each transaction only resides in a block. Each block is related with the previous block, so your transaction is throughout all the blockchain.
And will my transaction details be the only details on that block, or
will that block contain every transaction that happened within that
time period ?
It dependes on the implementation of Blockchain. For example, Bitcoin blocks store all the transactions that have been sent throughout 10 minutes, because each block is mined every 10 minutes (more or less).
Second
Blockchain is a distributed system, where all the members are at the same level. So, they get the consensus about what they are going to do, i.e. all the members have to agree about the functions of their Blockchain.
For each Blockchain, you can have more than one contract. But I'm going to explain it more simply. The Smart Contract is the code that is installed on all the nodes of the Blockchain, and every request is executed against it. So, every node/member must have the same.
In a blockchain system like bitcoin, each peer (participate node) keeps a full copy of the ledger. A peer updates its copy of ledger when it receives and validates a newly arrived block. However, the peers are scattered around the globe, and the network latency among these peers varies a lot. Therefore, how the blockchain system guarantees that all the peers have finished updating their copies of ledger after a block has been propagated?
Bitcoin doesn't guarantee that all ledgers become updated at the same time, bitcoin blockchain provides you with consistent ledger following:
Proof-of-work to cut new block with set of transactions
Longest chain rule
Above guaranties you that if there no more than 51% of the network controlled by one group you will eventually see consistent ledger, e.g. given your ledger at block sequence number 1001 means all nodes in the network will see identical chain of blocks until 1001.
To your question bitcoins use random overlay network to distribute new blocks (pretty similar to gossip algorithm).
UPDATE
See section B. Propagation Method from here:
For the purpose of updating and synchronizing the ledger
replicas only transaction (
tx
) and block (
block
) messages are
relevant. These messages are far more common than any other
message sent on the network and may grow to a considerable
size. In order to avoid sending transaction and block messages
to nodes that already received them from other nodes, they are
not forwarded directly. Instead their availability is announced
to the neighbors by sending them an
inv
message once the
transaction or block has been completely verified. The inv
message contains a set of transaction hashes and block hashes
that have been received by the sender and are now available
to be requested. A node, receiving an inv message for a
transaction or block that it does not yet have locally, will issue
a
getdata
message to the sender of the inv message containing
the hashes of the information it needs. The actual transfer of the block or transaction is done via individual block or tx
messages. Figure 2 visualizes the protocol flow for a single
hop in the broadcast.