Aim : Create a global finance block chain application with IBM Block chain Platform Extension for VS Code. Develop a Node.js smart contract and web app for a Global Finance with block chain use case
financeContract.js
'use strict';
const { Contract } = require('fabric-contract-api');
class FinanceContract extends Contract {
async initLedger(ctx) {
console.log('Initializing Ledger with sample assets...');
const assets = [
{ id: 'ASSET1', owner: 'BankA', value: 100000, currency: 'USD' },
{ id: 'ASSET2', owner: 'BankB', value: 200000, currency: 'EUR' }
];
for (const asset of assets) {
await ctx.stub.putState(asset.id, Buffer.from(JSON.stringify(asset)));
}
}
async createAsset(ctx, id, owner, value, currency) {
const exists = await this.assetExists(ctx, id);
if (exists) {
throw new Error(`Asset ${id} already exists`);
}
const asset = { id, owner, value: parseFloat(value), currency };
await ctx.stub.putState(id, Buffer.from(JSON.stringify(asset)));
return JSON.stringify(asset);
}
async readAsset(ctx, id) {
const assetJSON = await ctx.stub.getState(id);
if (!assetJSON || assetJSON.length === 0) {
throw new Error(`Asset ${id} does not exist`);
}
return assetJSON.toString();
}
async assetExists(ctx, id) {
const assetJSON = await ctx.stub.getState(id);
return assetJSON && assetJSON.length > 0;
}
async transferAsset(ctx, id, newOwner) {
const assetJSON = await this.readAsset(ctx, id);
const asset = JSON.parse(assetJSON);
asset.owner = newOwner;
await ctx.stub.putState(id, Buffer.from(JSON.stringify(asset)));
return JSON.stringify(asset);
}
async getAllAssets(ctx) {
const allResults = [];
const iterator = await ctx.stub.getStateByRange('', '');
let result = await iterator.next();
while (!result.done) {
const strValue = Buffer.from(result.value.value.toString()).toString('utf8');
allResults.push(JSON.parse(strValue));
result = await iterator.next();
}
return JSON.stringify(allResults);
}
}
module.exports = FinanceContract;
app.js
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
const port = 3000;
app.use(bodyParser.json());
app.use(express.static('public'));
// Simulated blockchain storage
let blockchain = [];
// API to create asset
app.post('/createAsset', (req, res) => {
const { id, owner, value, currency } = req.body;
if (!id || !owner || !value || !currency) return res.status(400).send('Missing fields');
const exists = blockchain.find(a => a.id === id);
if (exists) return res.status(400).send('Asset already exists');
const asset = { id, owner, value, currency, timestamp: new Date().toISOString() };
blockchain.push(asset);
res.json(asset);
});
// API to transfer asset
app.post('/transferAsset', (req, res) => {
const { id, newOwner } = req.body;
const asset = blockchain.find(a => a.id === id);
if (!asset) return res.status(404).send('Asset not found');
asset.owner = newOwner;
res.json(asset);
});
// API to get all assets
app.get('/getAssets', (req, res) => {
res.json(blockchain);
});
app.listen(port, () => console.log(`Server running at http://localhost:${port}`));
index.html
Global Finance Blockchain
Global Finance Blockchain
Create Asset
Transfer Asset
All Assets
| Asset ID |
Owner |
Value |
Currency |
Timestamp |