neuIP-4: Music NFT Ownersship

neuIPs/neuIP-4.md

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+---
+eip: 4
+title: Music NFT Ownersship
+description: A primitive to identify music NFTs ownership on EVM chains.
+author: Piérre Reimertz (@reimertz)
+discussions-to:
+status: Draft
+created: 2022-11-09
+---
+
+## Abstract
+
+musicOS has been experimenting with NFT ownership and relationship features by extending incoming neume data with a `owners` property. We are now confident how to ingest said properties and want to share learnings and support neume in implementing it.
+
+## Motivation
+
+One of the major features of on-chain data / NFTs is the tracability and relationship created between entitites.
+This enables many use cases, but importantly, surfaces the relationship between an artist and their consumers / fans.
+
+## Specification
+
+IMO, the most obvious path to release this new feature is to split up the work into two phases; **Realtime Ownership Extraction** and **Historical Ownership Extraction**.
+
+### Phase 1: Realtime Ownership Extraction
+
+Similarly how we currently platform-specific extraction strategies to extract NFT metadata, we'd add another strategy that would exctract the current owner of a NFT for each platform.
+
+As of now, all platforms is some form of a `ERC721` contract which allows us to call `ownerOf(uint256 _tokenId) external view returns (address);` extract the current owner.
+
+Below is how we currenly extend incoming neume data with a `owners` attribute
+
+```
+owners: [{
+  address: 'address'
+  tokenId: 'number',
+  contractAddress: 'address',
+  nid: 'string' // internal UID for ingested neume tracks in the form of `chainId.contractAddress.tokenId `
+}]
+```
+
+```
+owners: [{
+
+  // v0.0.1 of the strategy
+  address: 'address',
+  tokenId: 'number',
+  contractAddress: 'address',
+
+
+  // v0.1.0 of the strategy
+  amount: 'number', // the price paid to buy the NFT
+  blockNumber: 'number',
+  timestamp: 'number',
+  transactionHash: 'string',
+}]
+```
+
+
+### Phase 2: Historical Ownership Extraction
+
+This is has not been explored yet and is therefore intentionally left open for discussion.
+
+* Extract and export the full ownership history separately
+* Extract and bundle full ownership history together with each track
+
+
+```
+transactions: [{
+  fromAddress: 'address',
+  toAddress: 'addres',
+
+  tokenId: 'number',
+  contractAddress: 'address',
+
+  amount: 'number', // the price paid to buy the NFT
+
+  blockNumber: 'number',
+  timestamp: 'number',
+  transactionHash: 'string',
+}]
+```