Hyperledger Fabric’s core application is the smart contract (or chaincode), which defines the business logic and governs asset management and transaction execution on the blockchain ledger. Chaincode in Hyperledger Fabric can be written in Go, Java, or JavaScript, with Go being a preferred choice due to its high performance and concurrency support. Using the github.com/hyperledger/fabric-contract-api-go/contractapipackage simplifies the development process, abstracting away much of the boilerplate code. Below is an example of a basic Go smart contract that manages blockchain assets, which can represent anything from tokens to documents.

package main

import (
	"fmt"
	"github.com/hyperledger/fabric-contract-api-go/contractapi"
)

// SmartContract defines the structure for the asset management chaincode
type SmartContract struct {
	contractapi.Contract
}

// CreateAsset function to create an asset
func (s *SmartContract) CreateAsset(ctx contractapi.TransactionContextInterface, id string, value string) error {
	// Save the asset with ID and value to the ledger (world state)
	return ctx.GetStub().PutState(id, []byte(value))
}

// ReadAsset function to retrieve an asset's value by its ID
func (s *SmartContract) ReadAsset(ctx contractapi.TransactionContextInterface, id string) (string, error) {
	// Retrieve the asset from the ledger
	value, err := ctx.GetStub().GetState(id)
	if err != nil {
		return "", fmt.Errorf("failed to read from world state: %v", err)
	}
	return string(value), nil
}

func main() {
	// Initialize the chaincode
	chaincode, err := contractapi.NewChaincode(new(SmartContract))
	if err != nil {
		fmt.Printf("Error creating chaincode: %s", err)
		return
	}

	// Start the chaincode
	if err := chaincode.Start(); err != nil {
		fmt.Printf("Error starting chaincode: %s", err)
	}
}

This example smart contract features two fundamental functions:

• CreateAsset: This function creates a new asset on the ledger. It accepts an asset id and an associated value as input parameters, and it stores
  these as key-value pairs in the ledger’s world state.
• ReadAsset: This function retrieves the value of an asset by its id. It queries the ledger’s world state using the provided ID and returns the
  corresponding value.
  The main function initializes and starts the chaincode, which then becomes a service that runs within the Fabric network, ready to process transactions.
  The error handling in this example is kept minimal for simplicity, but in production scenarios, robust error handling with specific error codes and messages is essential for debugging and maintaining the smart contract effectively.