Introduction to OP Stack integration ​

Optimism is a low-cost and lightning-fast Ethereum L2 blockchain, built with the OP Stack.

Celestia is a modular consensus and data availability (DA) network, built to enable anyone to easily deploy their own blockchain with minimal overhead.

Together, they allow developers to create rollups that post data to Celestia and settle on Ethereum.

About the integration ​

Optimism uses Ethereum as a DA layer. Currently, settlement and DA for Optimism are on Ethereum, both onchain. op-batcher batches up rollup blocks and posts to Ethereum.

The integration of OP Stack with Celestia underneath for DA allows rollup operators to reduce overhead that is associated with posting data as calldata on Ethereum. Instead, op-batcher batches up rollup blocks and posts them to Celestia's DA network.

Data is managed in two ways. First, data is written to the data availability (DA) layer i.e. in this case Celestia, then the data commitment is written to the op-batcher. When reading op-node simply reads the data back from the DA layer by reading the data commitment from the op-batcher first, then reading the data from the DA layer using the data commitment. While previously op-node was reading from calldata on Ethereum, it now reads data from Celestia.

There are a few tools involved in the data handling process. op-batcher batches up rollup blocks and posts them to Ethereum. op-geth handles execution, while op-proposer is responsible for state commitment submission.

By using Celestia as a DA layer, existing L2s can switch from posting their data as calldata on Ethereum, to posting to Celestia. The commitment to the block is posted on Celestia, which is purpose-built for data availability. This is a more scalable than the traditional method of posting this data as calldata on monolithic chains.

GitHub repository ​

Find the repository for this integration at https://github.com/celestiaorg/optimism.

Next steps ​

Now that you understand the integration, you can start learning about the Bubs testnet, built with OP Stack and Celestia! This testnet is a great way to explore the possibilities of this integration and test your applications in a live environment.