DEPRECATED: Proof of Claim Explained: Part 5 — The DAG and the Miner

This article is deprecated and no longer accurate. Visit https://versatus.io/blog for Versatus updates and news.

Introduction

This is the 5th part in our series about the Versatus Consensus Algorithm, called Proof of Claim (PoC). In Part 1, Part 2, and Part 3, we discussed PoC elections, provided an analogy for them, and then explained how they are used in the protocol. In the most recent installment in the series, we discussed Farmer & Harvester Validators, the role each plays, and how they help to scale the network.

In this 5th and final part of our discussion on Proof of Claim, we aim to tie it all together with a discussion on the DAG and the role of “Miner” nodes in our network.

The DAG

The DAG in in Versatus’s protocol differs quite significantly from other DAG based chains, though there are also similarities. The majority of the differences come from two core aspects:

First, Pre-Validation of transactions and the appending of blocks of certified transactions to the DAG. In many networks that use a DAG based chain, individual transactions, or blocks of transactions, are appended to the DAG, and then validators vote on the validity and/or “weight” of a specific “chain” of transactions.

In the Versatus network, this is not how it works. As we discussed in part 4, Farmer Validators collect transactions and vote on the validity of the transactions. The votes are sent to Harvester nodes who collect the votes, and upon a given transaction reaching a specific threshold of votes from a given farmer quorum for that transaction, include said transaction in a block, called a proposal block. That proposal block is appended to the DAG.

The second major difference between the Versatus DAG and other DAGs is the concept of Convergence. In the Versatus DAG, at the end of each round, a Convergence block is produced by a “Miner” (more on this in a little bit). That convergence block plays a few roles.

First, and foremost, it signals the end of one round and the election of a new miner for the next round can begin. Second, it signals a firm state transition (once certified). Third it provides a finalized point of reference for all the transactions included in the round, and lastly, it is a place for the inclusion of data required to be known globally, such as quorum public keys upon the inauguration of newly elected quorums. It also serves other purposes, but for now, we’ll leave it to these, as they are the most important.

     /-> Proposal ->\          / -> Proposal ->\ 
    /                \        /                 \
Genesis -> Proposal - > Convergence -> Proposal- > Convergence
    \                /        \                 /
     \-> Proposal ->/          \ -> Proposal ->/ 

Convergence blocks, unlike proposal blocks, don’t actually include any transaction data, only a map of the proposal block hash to the hashes of the transactions it was responsible for, as well as new miner and validator claims it was responsible for. Everything else included in a Convergence block is proof data, certification and metadata. Convergence blocks ensure that, even in the event of a conflict, i.e. a transaction included in more than one proposal block, that only a single proposal block is granted credit for that transaction, and it is only included in the state transition once.

The Miner

The elected miner of a given round is responsible for consolidating all the proposal blocks it knows about into a single convergence block. This can include blocks orphaned by an earlier round, for which additional fees can be earned by the miner (and validators involved in building it and validating the transactions in it). The miner is also responsible for resolving conflicts between proposal blocks, both in the current round and earlier rounds.

The miner is a vital part of the Versatus ecosystem, as it serves the purpose of ensuring each round comes to a timely end, contains a single point of reference for all the transactions completed during the round, and marks the finality of said transactions. The miner is also a completely permissionless entry point for the Versatus network. Participating as a miner requires no stake, no reputation, and only requires that the miner node’s claim object be known to the network.

This is extremely important, as newcomers can participate in the network, enhance the decentralization and fault tolerance of the data availability of the network. These newcomers can earn tokens which can then be used to become a validator node at some point in the future, and/or to support projects deployed to the network by transacting with them. It provides a decentralized, permissionless on-ramp into Web3, which has largely disappeared since the move to PoS has become so ubiquitous among smart contract platforms. The only other way to “earn” tokens without buying them first has been airdrops, which have a whole host of issues, including the fact that they are not legally accessible to many participants due to regulations and laws in the jurisdiction in which they reside.

                                                    _______
                                           /------>| Miner |
                                          /        |_______|
                                         /             |
                                        /              |
     /-> Proposal ->\          / -> Proposal ->\       | 
    /                \        /                 \      V
Genesis -> Proposal - > Convergence -> Proposal -> Convergence 
    \                /        \                 /
     \-> Proposal ->/          \ -> Proposal ->/

Conclusion

This concludes our series on Proof of Claim consensus. We hope that throughout the 5 part series, it has helped you understand how and why it works, how and why it scales, and the important components within. The Proof of Claim algorithm is one of many innovations across the stack that Versatus is implementing to build a truly scalable, decentralized and secure blockchain. Combined with the unique approach to compute, Versatus is positioned to dramatically improve both developer and user experience.

We have some extremely exciting announcements coming up, so be sure to follow us on Twitter and to join our Telegram group

About Versatus Labs, Inc.

Versatus Labs is the development company building Versatus, an innovative blockchain protocol. Versatus is a fast, scalable Layer 1 built on top of a novel consensus mechanism called Proof of Claim. Versatus aims to make the developer experience frictionless by bringing ‘Build, Ship, Run’ DevOps to Web3 with its isolated, composable smart contracts containers, complete with a unikernel VM enabling developers to build in the language of their choice.