Access Chaincode Functions

Posted By : Aman Sharma | 30-Nov-2022

Access Chaincode Functions


Objective: To create a class to access the chaincode functions in the project

Tools required: Eclipse IDE

Prerequisites: fabricjavaclient project, Hyperledger Fabric Test network


Steps to be followed:

  1. Setting up the Hyperledger Fabric Test network

  2. Creating a new Class with Name ClientApp

  3. Accessing chaincode functions of Carshowroom smart contract


Step 1: Setting up the Hyperledger Fabric Test network

  1. Navigate to the test-network folder by using the following command:

cd eclipse-workspace/fabric-samples/test-network

  1. Stop the previously running test network by running the following command:

sudo ./ down

  1. Remove the unused docker images by running the following command:

sudo docker system prune

  1. Start the test network by executing the following command:

sudo ./ up -ca -s couchdb

  1. To create a communication channel for the peers in the test network use the following command:

sudo ./ createChannel -c samplechannel

  1. Check the list of the channels for the test network by executing the following commands:

sudo chmod 666 /var/run/docker.sock

docker exec peer channel list


Step 2: Creating a new Class with Name ClientApp

  1. Right-click on fabricjavaclient project and navigate to New > Class to create a new class with the name ClientApp

  2. Add the following code to import the libraries to ClientApp class:

import java.nio.file.Path;

import java.nio.file.Paths;

import org.hyperledger.fabric.gateway.Contract;

import org.hyperledger.fabric.gateway.Gateway;

import org.hyperledger.fabric.gateway.Network;

import org.hyperledger.fabric.gateway.Wallet;

import org.hyperledger.fabric.gateway.Wallets;


  1. Add the following code under the class ClientApp to set the property:

static {

System.setProperty("org.hyperledger.fabric.sdk.service_discovery.as_localhost", "true");



  1. Write the following code to create a gateway connect with the Carshowroom smart contract and access its chaincode functions:

public static void main(String[] args) throws Exception {

// Load a file system based wallet for managing identities.

Path walletPath = Paths.get("wallet");

Wallet wallet = Wallets.newFileSystemWallet(walletPath);

// load a CCP

Path networkConfigPath = Paths.get("..", "..", "test-network", "organizations", "peerOrganizations", "", "connection-org1.yaml");


Gateway.Builder builder = Gateway.createBuilder();

builder.identity(wallet, "appUser").networkConfig(networkConfigPath).discovery(true);


// create a gateway connection

try (Gateway gateway = builder.connect()) {


// get the network and contract

Network network = gateway.getNetwork("samplechannel");

Contract contract = network.getContract("CarShowroom");


byte[] result;

contract.submitTransaction("addNewCar", "1", "Ford", "Grey", "7890");

result = contract.evaluateTransaction("queryCarById", "1");

System.out.println(new String(result));


contract.submitTransaction("changeCarOwnership", "1", "Joe");

result = contract.evaluateTransaction("queryCarById", "1");

System.out.println(new String(result));




Note: Press Ctrl+S to save the file


Step 3: Accessing chaincode functions of Carshowroom chaincode

  1. Now install, approve, and commit Carshowroom chaincode

  2. In Eclipse, run the ClientApp file to access the chaincode functions

About Author

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Aman Sharma

Aman is an accomplished Backend developer with extensive industry experience, specializing in Odoo technology. He has a profound understanding and expertise in Python, Odoo ERP, Flask, MySQL, PostgreSQL, JavaScript, and payment gateway integration, particularly with Stripe. Aman's exceptional contributions to projects like Mymandi, Pando store, Markivia, DataInsite, and Tundra have been instrumental in driving the growth of his company. His strong analytical skills are pivotal in ensuring the success of his work, as he is able to identify and solve complex problems efficiently. Beyond his professional endeavors, he possesses a genuine passion for learning new technologies.

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