CBDH CBDH Smart Contract Development 1 — Questions and Answers
Question 1: In Hyperledger Fabric, what language is primarily used to write chaincode (smart contracts)?
- Python
- Go (Correct answer)
- Ruby
- Rust
Correct answer: Go
Hyperledger Fabric supports chaincode written in Go, JavaScript (Node.js), and Java, with Go being the most commonly used language.
Question 2: Which interface must a Fabric chaincode implement to be valid?
- ChaincodeInterface
- SmartContract
- Chaincode (Correct answer)
- LedgerContract
Correct answer: Chaincode
All Hyperledger Fabric chaincode must implement the Chaincode interface, which requires Init and Invoke methods.
Question 3: What does the `stub.PutState(key, value)` function do in Fabric chaincode?
- Reads a value from the ledger
- Writes or updates a key-value pair on the ledger (Correct answer)
- Deletes a record from the ledger
- Queries historical data
Correct answer: Writes or updates a key-value pair on the ledger
PutState writes or updates a key-value pair in the world state ledger during chaincode execution.
Question 4: Which chaincode function is invoked when the chaincode is first instantiated or upgraded?
- Start()
- Deploy()
- Init() (Correct answer)
- Invoke()
Correct answer: Init()
The Init() function is called during chaincode instantiation or upgrade, allowing initialization of ledger state.
Question 5: What is the purpose of `stub.GetState(key)` in Hyperledger Fabric chaincode?
- Deletes a key from the world state
- Returns the peer's current block height
- Retrieves the value associated with a key from the world state (Correct answer)
- Lists all keys in the ledger
Correct answer: Retrieves the value associated with a key from the world state
GetState retrieves the byte-array value associated with the specified key from the channel's world state.
Question 6: In Fabric chaincode, what does `stub.GetTxID()` return?
- The peer's node ID
- The channel name
- The unique transaction ID of the current invocation (Correct answer)
- The chaincode version number
Correct answer: The unique transaction ID of the current invocation
GetTxID returns the transaction ID that uniquely identifies the current transaction proposal being processed.
CBDH CBDH Smart Contract Development 1
In Hyperledger Fabric, what language is primarily used to write chaincode (smart contracts)?