Platform Chain#

Overview#

The platform chain is the Drive component responsible for replicating the platform state across all evonodes participating in the network. Evonodes (the high-performance masternode tier) operate this Proof of Service (PoSe) chain to provide layer 2 consensus and support Dash Platform-specific requirements without impacting layer 1 functionality. Although the platform chain can read from the Dash layer 1 core blockchain, the core blockchain is not dependent on it or aware of it.

Details#

Evolution of design#

Early designs of Drive were based on using on the layer 1 core blockchain and IPFS to replicate layer 2 data. As the design matured, a number of challenges led to a re-evaluation of how to efficiently secure, propagate, and finalize this data. Ultimately, meeting the requirements for a trustless, decentralized system led to choosing a blockchain-based solution over some seemingly obvious choices that work fine in a centralized setting.

Characteristics#

In order to support Dash Platform’s performance requirements, the platform chain has the following design characteristics:

  • Relies on masternode Proof of Service, not miner Proof of Work (PoW)

  • Hosted exclusively on evonodes (the high-performance masternode tier)

  • Uses a practical Byzantine Fault Tolerance (pBFT) consensus algorithm

  • Has a deterministic fee structure

  • Provides fast (~5 second target block spacing) and absolute block finality (no reorgs)

Blocks and Transitions#

Similar to transactions on the Dash core chain, state transitions are aggregated and put into blocks periodically on the platform chain. Each block has a header that points back to the previous block, thus forming a chain of blocks that is shared among all masternodes. The platform’s pBFT consensus algorithm is responsible for ordering the state transitions into a block and then committing the block. As soon as a block is accepted by a ⅔ + 1 majority of validators, it becomes final and cannot be changed. Thus, the platform chain is not susceptible to blockchain reorganizations.