Chaincode development

Chaincode is Hyperledger Fabric's implementation of smart contracts, enabling business logic execution in private networks.

Core concepts

Chaincode Features

Smart contract logic
State management
Access control
Private data collections

Development Languages

Go (recommended)
Node.js
Java
JavaScript

Implementation

Basic structure

package main
 
import (
    "github.com/hyperledger/fabric-contract-api-go/contractapi"
)
 
type SmartContract struct {
    contractapi.Contract
}
 
func (s *SmartContract) InitLedger(ctx contractapi.TransactionContextInterface) error {
    // Initialization logic
    return nil
}

State management

func (s *SmartContract) CreateAsset(ctx contractapi.TransactionContextInterface, id string, value string) error {
    exists, err := s.AssetExists(ctx, id)
    if err != nil {
        return err
    }
    if exists {
        return fmt.Errorf("asset already exists")
    }
 
    asset := Asset{
        ID:    id,
        Value: value,
    }
    assetJSON, err := json.Marshal(asset)
    if err != nil {
        return err
    }
 
    return ctx.GetStub().PutState(id, assetJSON)
}

Key features

1. Private data collections

Confidential data storage
Hash-based verification
Collection-level policies

2. Channel capabilities

Isolated execution
Separate ledgers
Targeted distribution

3. Endorsement policies

Multi-party validation
Flexible policies
Custom requirements

Best practices

Performance
- Efficient queries
- Batch operations
- State optimization
- Composite keys
Security
- Access control
- Input validation
- Error handling
- Logging
Testing
- Unit tests
- Integration tests
- Network simulation
- Performance testing

Always consider network topology and endorsement policies when designing chaincode.

Chaincode development

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