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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

Publications with usage examples

• Service-oriented Hyperledger Fabric application development using gRPC definitions
• Hyperledger Fabric smart contract data model: protobuf to chaincode state mapping
• Hyperledger Fabric chaincode test driven development (TDD) with unit testing
• ERC20 token as Hyperledger Fabric Golang chaincode
• CCKit: Routing and middleware for Hyperledger Fabric Golang chaincode
• Developing and testing Hyperledger Fabric smart contracts [RUS]

Installation

CCKit requires Go 1.16+

Standalone

git clone git@github.com:hyperledger-labs/cckit.git

go mod vendor

As dependency

go get github.com/hyperledger-labs/cckit