Linux Foundation HFCP - Hyperledger Fabric Certified Practitioner (HFCP) Exam

In Hyperledger Fabric, if a user submits a transaction with no matching function specified in the smart contract, theunknownTransactionfunction is invoked by default. This function serves as a catch-all method that can be used to handle cases where the transaction type is not recognized, providing a mechanism to manage or log these occurrences effectively .

The last step in the Hyperledger Fabric transaction flow is the commitment of the transaction to the ledger and the subsequent notification to the client application1. Once the transaction has been endorsed and ordered, it is committed to the ledger on all peers. After the transaction is committed, the peers asynchronously notify the client application of the success or failure of the transaction. This ensures that the client application is aware of the outcome and can take appropriate actions based on the result of the transaction1

Hyperledger Fabric allows different versions of the platform to coexist and interoperate on the same network through the use of channel capabilities. Channel capabilities enable organizations running different versions of Fabric binaries to participate on the same channel. These capabilities govern the features that are used by peer nodes and set the minimum version of the Fabric binaries that can be run by peers joined to the channel. This allows for heterogeneousnetwork environments where different nodes might be running different versions of Fabric software .

In Hyperledger Fabric, to send information that should be stored only in a private data collection during a transaction submission, the information must be included as transient data. Transient data is sent along with the transaction proposal but is not recorded on the ledger; instead, it is used within the chaincode for processing and can then be stored in private collections as needed. This method ensures that sensitive information is kept out of the public ledger and is only available to authorized parties as defined in the private data collection configuration. Transient data provides a secure way to handle sensitive or confidential information within the network without exposing it on the shared ledger​​.

In Hyperledger Fabric, "private data collections" are used to manage sensitive information between organizations. This feature allows specified subsets of data to be shared among a defined group of network participants while keeping it hidden from others, thus maintaining confidentiality and privacy across the network. Private data collections enable organizations to transact privately without having to establish a separate channel, significantly reducing the overhead associated with channel management .

In Hyperledger Fabric, when a transaction that includes thedelState("A")function is committed, it results in the removal of the state of the key "A" from the current state database. However, the history of all transactions that have affected the key "A" remains intact in the ledger. This operation ensures that while the current state reflects the deletion, the immutability and traceability of the ledger are preserved, allowing for auditability and verification of past states. Options such as setting an empty value to the key or altering the transaction history are not supported, as they would violate the principles of immutability and transparency central to blockchain technology. Therefore, the correct outcome of adelState("A")operation is that the current state of "A" is deleted, but its transaction history remains accessible in the ledger​​.

For developers looking to iteratively test and develop smart contracts in Hyperledger Fabric without the overhead of the full lifecycle process for each update, the recommended approach is to run the chaincode in development mode. This mode allows developers to test and debug chaincode directly on their machines without having to package, install, approve, and commit changes on the network each time. Development mode simplifies the iterative development process by allowing direct interaction with the chaincode during its development, making it easier to make and test changes quickly and efficiently. This contrasts with other methods that involve manual updates, redeployments, or using a production network, all of which are more time-consuming and complex​​.

In a production environment of Hyperledger Fabric, it is essential to monitor all peer containers comprehensively, including their CPU, network, and memory usage. This is because each peer node plays a critical role in maintaining the network's overall health and efficiency. Monitoring these resources helps in detecting potential bottlenecks or failures early, ensuring the smooth operation of the blockchain network. Focusing only on specific components like the orderer service or chaincode containers would provide a limited view of the network's health and could lead to issues being overlooked. Comprehensive monitoring enables administrators to maintain optimal performance and reliability across the entire network​​.