Differences between Coinweb and rollups
(a typical L1 blockchain using decentralised consensus to secure the consistency of the blockchain state)
Coinweb, unlike rollups, has a dispute mechanism, the referee, in the client (on your phone), not as a smart contract on L1.
This makes it easy to run on a diverse set of blockchains, including bitcoin-derived chains, it removes the delay associated with the dispute period in rollups, dispute resolution does not depend on the L1 smart contract language, results become deterministic in time, and by not having a sequencer responsible for posting transactions, certain availability and censorship issues are eliminated.
A good background on rollups can be found in this post: https://research.paradigm.xyz/rollups
In rollups there is a sequencer that posts transactions and the results to the L1 chain. If the result is invalid/wrong, then there is a dispute period where some ETH amount (called a fidelity bond) can be won by detecting the fraudulent result.
Example: The sequencer posts the following data to the L1 chain: "given
transactions: Transfer 3 from A to B, Transfer 1 from B to C, Transfer 1 from C
to A, the state of all accounts is
After the sequencer has done this, then a verifier can post a statement "it's
This dispute protocol requires smart contract support.
If we look at this from the point of view of the Ethereum client in your phone,
the client would connect to multiple Ethereum nodes to first figure out what the
latest correct block is. After having found the correct last block, it will look
inside the block to find the
When starting this process, when the client wants to understand what the latest
block is, it can be given different possible "tips" on the last block, and it
needs to figure out which one is correct. In PoW systems, this is (easily) done
by having the client calculate the total work the miners have done since the
start of the system, and trust that to be the last tip. The point is, that a
client needs to understand which block is the latest by evaluating some
consensus algorithm. When this is done, it can extracted
In Coinweb, we post the data "Transfer 3 from A to B, Transfer 1 B to C,
Transfer 1 C to A" to the l1 chain. Similar to the rollups, this is just data
posted to L1, not transactions executed by L1. We do not necessarily post the
result "… after which the state is
So how can the clients (on your phone) read that the L2 state is
The Coinweb light client will, a bit similar to the Ethereum light client, need
to figure out what the "tip" is, but instead of trying to find the latest
Ethereum block by asking a set of Ethereum network nodes, it will ask the
Coinweb network nodes for the latest coinweb state, the
The client as the referee
At this point, things start to differ. The client (on your phone) will do a divide-and-conquer protocol similar to the dispute resolution that is done in rollups. This type of dispute resolution iteratively narrows the disputed part of the computation in order to find where the dispute lies.
When the dispute is narrowed enough, there is one "atom" left, something that cannot be further subdivided. Examples of atoms can be that the two nodes disagree on what the tip of Ethereum is, or they disagree on the result of executing a WebAssembly instruction, or they disagree on the contents of an L1 block.
For each of these atoms, the client is equipped with a way to evaluate that atom itself. In the case of a disagreement on what the tip of Ethereum is, the client will evaluate that itself, similar to what an Ethereum client will do (i.e. connecting to nodes and evaluating the consensus). If there is disagreement on executing a WebAssembly instruction, the inputs and outputs for the instruction are gathered and evaluated. If there is disagreement on the contents of a block, Merkle proofs are evaluated by the client.
Implications for dApps - unifying interoperability and data-availability
Moving the dispute resolution mechanism out of L1 smart contracts not only makes it more effective it also becomes blockchain-agnostic, meaning that the output from dApps can now be verified against any L1 blockchain input. This is very significant since the availability of verifiable data is one of the drivers of network effects. Coinweb dApps can now tap into the aggregated network effects from all the connected chains, making them immediately more powerful and easier to bootstrap. You can read more about this here