# Eclipse's Celestia Publisher

## Block Indexing and Data Availability Layer

Eclipse's Celestia Publisher takes blocks from the Eclipse sequencer, indexes them in a local database, compresses and batches them, and posts the resulting blobs to Celestia. To ensure verifiability, it anchors span sequence commitments to Ethereum via BatchHeaders.

This module decouples execution from data availability, allowing for cost-effective scalability without sacrificing verifiability. The Publisher acts as the first bridge between the execution layer and the DA layer. By anchoring BatchHeaders with Celestia span sequence data to Ethereum, the publisher gives Eclipse strong reconstructibility guarantees.

**Processing steps**

* The Eclipse sequencer continuously processes transactions and produces Eclipse blocks.
* The Celestia publisher first retrieves blocks from the sequencer, then compresses them using zstd (level 3), and then batches them.
* The publisher submits individual block blobs to Celestia, receiving span sequence data.
* For gateway sync: The publisher submits an index blob to Celestia for the batch range.
* Finally, it creates and posts BatchHeaders containing span sequence information to the Ethereum Gateway contract.

**Flow Diagram**

{% @mermaid/diagram content="flowchart LR
D\["CelestiaPublisher"] --> E\["Batch & Compress Blocks"]
E --> F\["Publish Block Blobs to Celestia"]
F --> G\["Submit Index Blob to Celestia"]
G --> H\["Create BatchHeader with span\_sequence"]
H --> I\["Post BatchHeader to Ethereum Gateway"]" fullWidth="false" %}

***

We refer the reader to this blog [post](https://www.eclipselabs.io/blogs/leveraging-celestia-blobstream-for-data-availability-proofs) for some extra details related to Blobstream and availablity proofs. 

***


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