To make communication as clear and efficient as possible, we make sure to use a single term for every Walrus entity/concept and do not use any synonyms. The following table lists various concepts, their canonical name, and how they relate to or differ from other terms.
Italicized terms in the description indicate other specific Walrus terms contained in the table.
| Approved name | Description |
|---|---|
| storage node (SN) | entity storing data for Walrus; holds one or several shards |
| blob | single unstructured data object stored on Walrus |
| shard | (disjoint) subset of erasure-encoded data of all blobs; at every point in time, a shard is assigned to and stored on a single SN |
| sliver | erasure-encoded data of one shard corresponding to a single blob for one of the two encodings; this contains several erasure-encoded symbols of that blob but not the blob metadata |
| blob ID | cryptographic ID computed from a blob’s slivers |
| blob metadata | metadata of one blob; in particular, this contains a hash per shard to enable the authentication of slivers and recovery symbols |
| (end) user | any entity/person that wants to store or read blobs on/from Walrus; can act as a Walrus client itself or use the simple interface exposed by publishers and caches |
| publisher | service interacting with Sui and the SNs to store blobs on Walrus; offers a simple HTTP POST endpoint to end users |
| aggregator | service that reconstructs blobs by interacting with SNs and exposes a simple HTTP GET endpoint to end users |
| cache | an aggregator with additional caching capabilities |
| (Walrus) client | entity interacting directly with the SNs; this can be an aggregator/cache, a publisher, or an end user |
| (blob) reconstruction | decoding of the primary slivers to obtain the blob; includes re-encoding the blob and checking the Merkle proofs |
| (shard/sliver) recovery | process of an SN recovering a sliver or full shard by obtaining recovery symbols from other SNs |
| storage attestation | process where SNs exchange challenges and responses to demonstrate that they are storing their currently assigned shards |
| certificate of availability (CoA) | a blob ID with signatures of SNs holding at least (2f+1) shards in a specific epoch |
| point of availability (PoA) | point in time when a CoA is submitted to Sui and the corresponding blob is guaranteed to be available until its expiration |
| inconsistency proof | set of several recovery symbols with their Merkle proofs such that the decoded sliver does not match the corresponding hash; this proves an incorrect/inconsistent encoding by the client |
| inconsistency certificate | an aggregated signature from 2/3 of SNs (weighted by their number of shards) that they have seen and stored an inconsistency proof for a blob ID |
| storage committee | the set of SNs for a storage epoch, including metadata about the shards they are responsible for and other metadata |
| member | an SN that is part of a committee at some epoch |
| storage epoch | the epoch for Walrus as distinct to the epoch for Sui |
| availability period | the period specified in storage epochs for which a blob is certified to be available on Walrus |
| expiry | the end epoch at which a blob is no longer available and can be deleted |