System Architecture & Design Flashcards

Which sequence correctly describes Fabric's transaction flow model?

Answer: Execute, order, validate

Fabric uses execute-order-validate: endorse by simulation, order, then validate and commit.

Which world state database supports rich JSON queries in Fabric?

Answer: CouchDB

CouchDB supports rich queries against JSON values, while LevelDB supports only key and range queries.

A transaction is marked MVCC_READ_CONFLICT at commit time. What most likely happened?

Answer: A key it read was changed by an earlier transaction in the same or prior block

Validation fails when the version of a key read during simulation no longer matches the committed version.

In the Fabric v2 chaincode lifecycle, what must happen before a chaincode definition can be committed to a channel?

Answer: Enough organizations approve the definition according to the lifecycle endorsement policy

Organizations approve the definition, and commit succeeds once the lifecycle policy, by default a majority, is satisfied.

What role does the leader peer in an organization play?

Answer: Pulls blocks from the ordering service and distributes them to other peers via gossip

The leader peer connects to the orderer and disseminates blocks to the org's other peers.

What does Fabric CA primarily issue?

Answer: X.509 enrollment certificates for network identities

Fabric CA registers and enrolls identities by issuing X.509 certificates.

What is the main benefit of running chaincode as an external service in Fabric 2.x?

Answer: The chaincode runs outside the peer's Docker-managed build and launch, simplifying Kubernetes deployments

External chaincode lets operators launch and manage chaincode independently from the peer.