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> How does consensus work in an enterprise blockchain? It doesn't, because blockchain doesn't solve consensus problem.

by dozzie 9y ago

econner 9y ago
What's the point of using a blockchain then?
- prepend 9y ago
  There’s tons of answers to this, but one example I’m interested in is as a good shared, accessible audit log for data throughout an organization. Just having a stable history for all data helps with investigation and master data management. In this case consensus isn’t really necessary because all participants are trusted and should rarely differ (since they all have the same boss at some level).
  - russdpale 9y ago
    I agree. But working at a huge company I can honestly say they don't really want an immutable ledger. They want to fudge and change things.
    - prepend 9y ago
      I suppose maybe it depends on the organization. I’ve worked at companies that do want an immutable ledger. But probably not have it be public.
    - slake 9y ago
      Typically a ledger should be immutable. That's what retains its auditability. Any fudging/changing should be done through reverse entries that explain why the reversal occurs.
- dozzie 9y ago
  To tell which document (transaction) of a given pair correlated ones was issued earlier, which is called "timestamping". But you don't need consensus (as in Byzantine generals problem) to do that, you just need timestamping protocol.
blueplanet200 9y ago
Maybe explain a little more? Obviously in your opinion the OP is confused, but this answer is short and unhelpful.
- dozzie 9y ago
  First and foremost: what is consensus problem?
YuriNiyazov 9y ago
A trustless blockchain most certainly does. https://news.ycombinator.com/item?id=15915957 https://news.ycombinator.com/item?id=15915957
- dozzie 9y ago
  It most certainly doesn't. You even confuse blockchain and Merkle trees, and call into existence some weird term "distributed blockchain". But then, consensus problem is a problem of establishing a specific value for almost all participants. Which implies that the value is established, which means that the protocol terminates. Blockchain was not designed to ever terminate, so it's not a consensus protocol even if for no other reason. Otherwise, what parts of blockchain exactly establish a common value among participants and what exactly is this common value?
  - zero-x 9y ago
    What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. In smaller chains, there can certainly be consensus, it just won't be as trusted as a public chain and 51% attacks are potentially more feasible due to it having a smaller economic barrier.
    - dozzie 9y ago
      > What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. It's a name used for Bitcoin's protocol. It doesn't mean it's consensus. How does the established value by this "consensus" protocol look like? And why do you consider it established, when other participants can have a totally different view of the list of documents in the protocol, or your view can change completely with next message? How is it an agreed value? And at what point should we look at the views of two different participants to see the same value? And how does it relate to Lamport's original publication about the consensus problem?
      - 9y ago

> How does consensus work in an enterprise blockchain? It doesn't, because blockchain doesn't solve consensus problem.

by dozzie 9y ago

> How does consensus work in an enterprise blockchain? It doesn't, because blockchain doesn't solve consensus problem.

econner 9y ago

What's the point of using a blockchain then?

prepend 9y ago
There’s tons of answers to this, but one example I’m interested in is as a good shared, accessible audit log for data throughout an organization. Just having a stable history for all data helps with investigation and master data management. In this case consensus isn’t really necessary because all participants are trusted and should rarely differ (since they all have the same boss at some level).
- russdpale 9y ago
  I agree. But working at a huge company I can honestly say they don't really want an immutable ledger. They want to fudge and change things.
  - prepend 9y ago
    I suppose maybe it depends on the organization. I’ve worked at companies that do want an immutable ledger. But probably not have it be public.
  - slake 9y ago
    Typically a ledger should be immutable. That's what retains its auditability. Any fudging/changing should be done through reverse entries that explain why the reversal occurs.
dozzie 9y ago
To tell which document (transaction) of a given pair correlated ones was issued earlier, which is called "timestamping". But you don't need consensus (as in Byzantine generals problem) to do that, you just need timestamping protocol.

blueplanet200 9y ago

Maybe explain a little more? Obviously in your opinion the OP is confused, but this answer is short and unhelpful.

dozzie 9y ago
First and foremost: what is consensus problem?

YuriNiyazov 9y ago

A trustless blockchain most certainly does. https://news.ycombinator.com/item?id=15915957 https://news.ycombinator.com/item?id=15915957

dozzie 9y ago
It most certainly doesn't. You even confuse blockchain and Merkle trees, and call into existence some weird term "distributed blockchain". But then, consensus problem is a problem of establishing a specific value for almost all participants. Which implies that the value is established, which means that the protocol terminates. Blockchain was not designed to ever terminate, so it's not a consensus protocol even if for no other reason. Otherwise, what parts of blockchain exactly establish a common value among participants and what exactly is this common value?
- zero-x 9y ago
  What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. In smaller chains, there can certainly be consensus, it just won't be as trusted as a public chain and 51% attacks are potentially more feasible due to it having a smaller economic barrier.
  - dozzie 9y ago
    > What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. It's a name used for Bitcoin's protocol. It doesn't mean it's consensus. How does the established value by this "consensus" protocol look like? And why do you consider it established, when other participants can have a totally different view of the list of documents in the protocol, or your view can change completely with next message? How is it an agreed value? And at what point should we look at the views of two different participants to see the same value? And how does it relate to Lamport's original publication about the consensus problem?
    - 9y ago