# README

Hyperledger Fabric chaincode kit (CCKit)

Overview

A smart contract is code, invoked by a client application external to the blockchain network – that manages access and modifications to a set of key-value pairs in the World State. In Hyperledger Fabric, smart contracts are referred to as chaincode.

CCKit is a programming toolkit for

developing and testing Hyperledger Fabric golang chaincodes
generating access layer for query / invoke chaincodes and chaincode event streaming

It enhances the development experience while providing developers components for creating more readable and secure smart contracts. Getting started

CCKit features

Chaincode method router with invocation handlers and middleware capabilities
Chaincode state modeling (like ORM for chaincode data) using protocol buffers or plain golang struct with private data support
Chaincode state serializing customization
Designing chaincode in gRPC service notation with code generation of chaincode SDK, gRPC and REST-API
MockStub testing, allowing to immediately receive test results

Extensions

Encryption data on application level
Implementation of UTXO and account balance storage model token balance models
Chaincode method access control
Signing and verifying chaincode method payload with envelope

Examples

There are several chaincode "official" examples available:

Commercial paper from official Hyperledger Fabric documentation
Blockchain insurance application (testing tutorial: how to write tests for "insurance" chaincode)

and others

Main problems with existing examples are:

Working with chaincode state at very low level
Lots of code duplication (JSON marshalling / unmarshalling, validation, access control, etc)
Chaincode methods routing appeared only in HLF 1.4 and only in Node.Js chaincode
Uncompleted testing tools (MockStub)

Examples based on CCKit

Cars - car registration chaincode, simplest example
Commercial paper, service-oriented approach - recommended way to start new application. Code generation radically simplifies building on-chain and off-chain applications.
Commercial paper - faithful reimplementation of the official example
Commercial paper extended example - with protobuf chaincode state schema and other features
ERC-20 - tokens smart contract, implementing ERC-20 interface
ERC-20 UTXO - tokens smart contract, implementing ERC-20 interface with UTXO state keys
Cars private - car registration chaincode with private data
Payment - a few examples of chaincodes with encrypted state