What is the Application to Buy Paper, buy.js?

buy.js is a client application using the Hyperledger Fabric Node.js SDK library to invoke the buy() function of the papercontract running on the PaperNet.

1. View buy.js source code:

(balaji)$ cd ~/hyperledger-binaries/fabric-samples
(balaji)$ cd commercial-paper/organization/digibank/application

(balaji)$ more buy.js
/* SPDX-License-Identifier: Apache-2.0
 * This application has 6 basic steps:
 * 1. Select an identity from a wallet
 * 2. Connect to network gateway
 * 3. Access PaperNet network
 * 4. Construct request to issue commercial paper
 * 5. Submit transaction
 * 6. Process response
 */

'use strict';

// Bring key classes into scope, most importantly Fabric SDK network class
const fs = require('fs');
const yaml = require('js-yaml');
const { FileSystemWallet, Gateway } = require('fabric-network');
const CommercialPaper = require('../contract/lib/paper.js');

// A wallet stores a collection of identities for use
const wallet = new FileSystemWallet('../identity/user/balaji/wallet');

// Main program function
async function main() {

  // A gateway defines the peers used to access Fabric networks
  const gateway = new Gateway();

  // Main try/catch block
  try {

    // Specify userName for network access
    // const userName = 'isabella.issuer@magnetocorp.com';
    const userName = 'Admin@org1.example.com';

    // Load connection profile; will be used to locate a gateway
    let connectionProfile = yaml.safeLoad(fs.readFileSync('../gateway/networkConnection.yaml', 'utf8'));

    // Set connection options; identity and wallet
    let connectionOptions = {
      identity: userName,
      wallet: wallet,
      discovery: { enabled:false, asLocalhost: true }

    };

    // Connect to gateway using application specified parameters
    console.log('Connect to Fabric gateway.');

    await gateway.connect(connectionProfile, connectionOptions);

    // Access PaperNet network
    console.log('Use network channel: mychannel.');

    const network = await gateway.getNetwork('mychannel');

    // Get addressability to commercial paper contract
    console.log('Use org.papernet.commercialpaper smart contract.');

    const contract = await network.getContract('papercontract', 'org.papernet.commercialpaper');

    // buy commercial paper
    console.log('Submit commercial paper buy transaction.');

    const buyResponse = await contract.submitTransaction('buy', 'MagnetoCorp', '00001', 'MagnetoCorp', 'DigiBank', '4900000', '2020-05-31');

    // process response
    console.log('Process buy transaction response.');

    let paper = CommercialPaper.fromBuffer(buyResponse);

    console.log(`${paper.issuer} commercial paper : ${paper.paperNumber} successfully purchased by ${paper.owner}`);
    console.log('Transaction complete.');

  } catch (error) {

    console.log(`Error processing transaction. ${error}`);
    console.log(error.stack);

  } finally {

    // Disconnect from the gateway
    console.log('Disconnect from Fabric gateway.')
    gateway.disconnect();

  }
}
main().then(() => {

  console.log('Buy program complete.');

}).catch((e) => {

  console.log('Buy program exception.');
  console.log(e);
  console.log(e.stack);
  process.exit(-1);

});

2. Run buy.js:

(balaji)$ node buy.js

Connect to Fabric gateway.
Use network channel: mychannel.
Use org.papernet.commercialpaper smart contract.
Submit commercial paper buy transaction.
Process buy transaction response.
MagnetoCorp commercial paper : 00001 successfully purchased by DigiBank
Transaction complete.
Disconnect from Fabric gateway.
Buy program complete.

Note that how the gateway uses the networkConnection.yaml file to store the connection addresses and port number of PaperNet.

⇒ redeem.js - Application to Redeem Paper

⇐ Create Identity Wallet for Balaji

⇑ commercial-paper Sample Network

⇑⇑ Hyperledger Tutorials