What is the relationship between assets created in a composer network to the assets in fabric chaincode?

Question

How do composer network represented in fabric runtime. Is the assets instances created in composer network have one to one relationship with assets created in actual fabric runt

Answer 1

Fabric doesn't have the concept of assets -- it uses a key/value store (LevelDB) or can use CouchDB (JSON store).

When a Composer transaction is processed (which corresponds to an invokeChaincode transaction for Fabric), any assets that are created are stored as new keys in the key-value store, or documents in the JSON store.

Composer organises assets and participants into "registries", which are used to construct compound key names, keeping related assets together and preventing naming conflicts.

Answer 2

The key feature within Fabric and other blockchains is the Distributed Ledger. From the Fabric documentation:

The ledger is the sequenced, tamper-resistant record of all state transitions in the fabric. State transitions are a result of chaincode invocations (‘transactions’) submitted by participating parties. Each transaction results in a set of asset key-value pairs that are committed to the ledger as creates, updates, or deletes.

The ledger is comprised of a blockchain (‘chain’) to store the immutable, sequenced record in blocks, as well as a state database (or world state) to maintain current fabric state.

When an Asset is created from the via Hyperledger Composer, the structure of this object is serialised and stored to ensure that the ledger is used to track this asset creation. Likewise other operations on Hyperledger Composer assets are translated such that they are tracked by the ledger.

In addition to just tracking the assets, and their updates either through the Composer API, or via submitting Composer transactions, Composer adds abilities to permit ACLs to enforced. These are ACLs at the scope of the assets defined in Composer.

In summary, if you view fabric as providing a Distributed Ledger with the concepts of finality, provenance, immutability etc. then Hyperledger Composer is an abstraction on top of the ledger that maps from the concepts of assets, participants etc. to a format that is persisted on the ledger.