What is true about the historic states in Hyperledger Fabric model?
Answer(s): C
Historic states in the Hyperledger Fabric ledger are immutable, meaning they cannot be altered after they have been committed to the ledger. This immutability ensures the integrity and traceability of all transactions on the network. Once a transaction is recorded, it is permanent, and its history can be audited to trace back all operations affecting any piece of data. This feature is fundamental in blockchain technology, providing a verifiable and tamper-evident record. The immutability of historic states is a key component of the trust and security model in Hyperledger Fabric, contrary to options that suggest these records can be modified or are inaccessible.
In Hyperledger Fabric, Intercommunication is how a smart contract in a channel updates the World State database. It is achieved by what process?
Intercommunication in Hyperledger Fabric regarding how smart contracts update the World State database is primarily achieved by calling other smart contracts, both within the same channel and across different channels. This process allows smart contracts, also known as chaincode, to interact and transact across the network, updating the World State as necessary based on business logic defined in the contracts. This capability is crucial for complex business processes that span multiple contracts and possibly multiple channels. Unlike setting endorsement policies or configuring peer-to- peer options, calling other smart contracts directly facilitates dynamic and direct interaction between business processes, enhancing the modularity and efficiency of the network. Cross-channel communication must be carefully managed within the permissions and policies defined in the network to maintain security and integrity.
What types of events committed to the ledger can client applications receive using the peer's event service?
Answer(s): B
In Hyperledger Fabric, client applications can subscribe to receive both chaincode events and block events using the peer's event service. Chaincode events are generated by the chaincode itself, typically based on specific conditions coded within the chaincode operations, and are used to notify applications of specific state changes or significant occurrences. Block events inform about the addition of new blocks to the ledger, which may contain multiple transactions. This dual capability allows client applications to effectively monitor transaction confirmations and specific chaincode outputs in real time, which is critical for applications that rely on up-to-date blockchain data for processing decisions.
Which of the following is the correct role of orderer nodes?
Answer(s): A
The primary role of orderer nodes in Hyperledger Fabric is to order and package endorsed transactions into blocks. Orderers receive transactions from various peers, ensure that these transactions are in a consistent order, and then package them into blocks that are subsequently appended to the blockchain. This function is crucial for maintaining the consistency and integrity of the ledger across all participating nodes. Orderer nodes do not issue tokens, enforce peer endorsements, or reorder stored blocks for data compression. Instead, their main function is integral to the consensus and ledger maintenance processes within a Hyperledger Fabric network
What gRPC status code might you expect to be associated with an error invoking a transaction as a result of a transient failure, such as a network disconnection between the client application and Gateway peer?
The gRPC status code "UNAVAILABLE" is commonly expected in scenarios involving transient failures in network communication, such as a disconnection between the client application and the Gateway peer. This status code indicates that the service is currently unavailable, often due to network issues or service downtime, making it suitable for situations where the failure is temporary and the request can be retried. This differs from other codes like "ABORTED" or "DEADLINE EXCEEDED," which represent different types of errors related to the transaction logic or timing issues, respectively. "FAILED PRECONDITION" would be inappropriate for network disconnections as it suggests issues with the request's preconditions, not the network status.
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