metaplex-program-library VS digital-asset-rpc-infrastructure

You can also check out the program but I'm actively working on porting metaplex auction house as the backbone. A "BOYNC" version of the MPL Auction House will soon follow.

All NFT modifications must happen through the Bubblegum program.

My auction contract required doing some Metaplex metadata checks, so testing required creating an NFT just like they do in mainnet. However, your localnet doesn't come with the program deployed so you have to set that up yourself. Clone https://github.com/metaplex-foundation/metaplex-program-library and run anchor build inside the token-metadata directory. This will output a target/deploy/mpl_token_metadata.so binary that you can import into your project.

[1]: https://github.com/metaplex-foundation/metaplex-program-libr...

The DAS indexer listens to all Bubblegum transactions, parses them, and updates an off-chain database. For example, when a compressed NFT is minted the indexer will parse that transaction and extract all of the NFT info (name, collection, owner). If a tree was never seen before or it is missing an update, the indexer will fetch the tree's transaction history and reconstruct the state.The indexer code can be found here.