Back in May, POA Network launched its POA Bridge, allowing users to convert POA tokens on the POA Network to POA20 tokens on Ethereum. The team noted that "this was the first milestone in [its] long-term vision for blockchain interoperability."
POA is an Ethereum sidechain with an open-source EDCC (aka smart contract) framework. It aims to make the execution of smart contracts easier, cheaper, and faster. The network is a bit different than other chains in that it uses a proof of authority consensus mechanism, which is a variant of proof of stake. The network's POA tokens are essentially represented on Ethereum as POA20 coins.
Now, POA has announced its ERC20-to-ERC20 TokenBridge. The POA Bridge, although an important first step toward cross-chain interoperability, only allows individuals to swap tokens native to POA with POA20 tokens native to Ethereum. However, the new TokenBridge works with any Ethereum-based ERC20 token, thus enabling networks built on Ethereum to interact with one another.
As for transaction validation, POA indicated that each project would account for its own validators. "It's absolutely necessary for the project(s) [deploying the bridge] to identify the set of individuals/nodes assigned to validate the bridge transactions," the team continued.
Additionally, POA identified a few use cases for its new TokenBridge. One such example is Swarm City, a decentralized commerce platform, which used the bridge to move tokens from Ethereum to the Kovan testnet. A Swarm City architect noted that conducting transactions on the bridge and then resolving them on the mainnet "keeps transaction costs down."
Virtue Poker, a decentralized poker platform, also used the bridge, saying it allows the crew "to eliminate costly on-chain Ethereum transactions in relation to hand result data." Virtue Poker added, "This will minimize Ethereum gas costs by only requiring main network transactions when a player wishes to enter and exit our sidechain via the POA bridge."
POA is working with other projects to implement its bridge as a solution for high gas costs and network congestion, and the team has created step-by-step instructions (available via GitHub) for folks looking to use the TokenBridge.
The network has been busy as of late. Last month, POA collaborated with MakerDAO to launch xDai Chain, "the first ever blockchain where the native currency of the chain is USD-stable," according to the POA team. The sidechain is based on Maker's Dai stablecoin, though the cryptocurrency is represented by XDAI on the xDai Chain (POA has a bridge to convert Ethereum-based Dai to XDAI).