Fixes to TypeScript asset-transfer-events to match Go sample (#619)

Changed:
- Console output formatting
- Transaction arguments
- Readability and comments of code
- Linting rules
- Missing semicolons
- Package name and descrption

Signed-off-by: Mark S. Lewis <mark_lewis@uk.ibm.com>

asset-transfer-events/application-gateway-typescript/.eslintrc.json

@@ -1,7 +1,7 @@
 {
     "env": {
       "node": true,
-      "es6": true
+      "es2020": true
     },
     "root": true,
     "ignorePatterns": [
@@ -30,15 +30,16 @@
           "sourceType": "module",
           "ecmaFeatures": {
             "impliedStrict": true
-          }
+          },
+          "project": "./tsconfig.json"
         },
         "plugins": [
           "@typescript-eslint"
         ],
         "extends": [
           "eslint:recommended",
-          "plugin:@typescript-eslint/eslint-recommended",
-          "plugin:@typescript-eslint/recommended"
+          "plugin:@typescript-eslint/recommended",
+          "plugin:@typescript-eslint/recommended-requiring-type-checking"
         ]
       }
     ]

asset-transfer-events/application-gateway-typescript/package.json

@@ -1,7 +1,7 @@
 {
-    "name": "asset-transfer-basic",
+    "name": "asset-transfer-events",
     "version": "1.0.0",
-    "description": "Asset Transfer Basic Application implemented in typeScript using fabric-gateway",
+    "description": "Asset Transfer Events Application implemented in typeScript using fabric-gateway",
     "main": "dist/index.js",
     "typings": "dist/index.d.ts",
     "engines": {

asset-transfer-events/application-gateway-typescript/src/app.ts

@@ -7,7 +7,6 @@
 import * as grpc from '@grpc/grpc-js';
 import { ChaincodeEvent, CloseableAsyncIterable, connect, Contract, GatewayError, Network } from '@hyperledger/fabric-gateway';
 import { TextDecoder } from 'util';
-
 import { newGrpcConnection, newIdentity, newSigner } from './connect';
 
 const channelName = 'mychannel';
@@ -19,9 +18,7 @@ const assetId = `asset${now}`;
 
 
 async function main(): Promise<void> {
-    // The gRPC client connection should be shared by all Gateway connections to this endpoint.
     const client = await newGrpcConnection();
-
     const gateway = connect({
         client,
         identity: await newIdentity(),
@@ -43,30 +40,19 @@ async function main(): Promise<void> {
     let events: CloseableAsyncIterable<ChaincodeEvent> | undefined;
 
     try {
-        // Get a network instance representing the channel where the smart contract is deployed.
         const network = gateway.getNetwork(channelName);
-
-        // Get the smart contract from the network.
         const contract = network.getContract(chaincodeName);
 
-        //Start Listening to events.
+        // Listen for events emitted by subsequent transactions
         events = await startEventListening(network);
 
-        // Create a new asset on the ledger.
         const firstBlockNumber = await createAsset(contract);
-
-        // Update an existing asset.
-        await updateAsset(contract)
-
-        // Transfer an existing asset.
+        await updateAsset(contract);
         await transferAsset(contract);
-
-        // Delete asset by assetID.
         await deleteAssetByID(contract);
 
-        // Replay all the events received.
-        await replayChaincodeEvents(network,firstBlockNumber)
-
+        // Replay events from the block containing the first transaction
+        await replayChaincodeEvents(network,firstBlockNumber);
     } finally {
         events?.close();
         gateway.close();
@@ -79,106 +65,91 @@ main().catch(error => {
     process.exitCode = 1;
 });
 
-/**
- * Start listening to events.
- */
 async function startEventListening(network: Network): Promise<CloseableAsyncIterable<ChaincodeEvent>> {
-    console.log('\n*** Start chaincode event listening\n');
+    console.log('\n*** Start chaincode event listening');
 
     const events = await network.getChaincodeEvents(chaincodeName);
 
-    readEvents(events);
+    void readEvents(events); // Don't await - run asynchronously
     return events;
 }
 
-/**
- * Read events.
- */
 async function readEvents(events: CloseableAsyncIterable<ChaincodeEvent>): Promise<void> {
     try {
         for await (const event of events) {
-            const payload = utf8Decoder.decode(event.payload);
-            console.log(`\n<-- Chaincode event received, name: ${event.eventName}, payload: ${payload}, txID: ${event.transactionId}, blockNumber:${event.blockNumber}`);
+            const payload = parseJson(event.payload);
+            console.log(`\n<-- Chaincode event received: ${event.eventName} -`, payload);
         }
     } catch (error: unknown) {
+        // Ignore the read error when events.close() is called explicitly
         if (!(error instanceof GatewayError) || error.code !== grpc.status.CANCELLED) {
             throw error;
         }
     }
 }
 
-/**
- * Submit a transaction asynchronously to create a new asset.
- */
-async function createAsset(contract: Contract): Promise<bigint> {
-    console.log(`\n --> Submit Transaction: CreateAsset, creates ${assetId} owned by Tom with appraised value 100`);
+function parseJson(jsonBytes: Uint8Array): unknown {
+    const json = utf8Decoder.decode(jsonBytes);
+    return JSON.parse(json);
+}
 
-    const result = await contract.submitAsync('CreateAsset',
-        {arguments: [assetId,'yellow','5','Tom','100',]});
+async function createAsset(contract: Contract): Promise<bigint> {
+    console.log(`\n--> Submit Transaction: CreateAsset, ${assetId} owned by Sam with appraised value 100`);
+
+    const result = await contract.submitAsync('CreateAsset', {
+        arguments: [ assetId, 'blue', '10', 'Sam', '100' ],
+    });
 
     const status = await result.getStatus();
     if (!status.successful) {
         throw new Error(`failed to commit transaction ${status.transactionId} with status code ${status.code}`);
     }
 
-    console.log('\n*** CreateAsset committed successfully\n')
+    console.log('\n*** CreateAsset committed successfully');
 
     return status.blockNumber;
 }
-/**
- * Submit transaction synchronously, to updateAsset the asset appraised value.
- */
+
 async function updateAsset(contract: Contract): Promise<void> {
     console.log(`\n--> Submit transaction: UpdateAsset, ${assetId} update appraised value to 200`);
 
-    await contract.submitTransaction('UpdateAsset',
-        assetId,'yellow','5','Tom','200',);
+    await contract.submitTransaction('UpdateAsset', assetId, 'blue', '10', 'Sam', '200');
 
-    console.log('\n*** UpdateAsset committed successfully\n')
+    console.log('\n*** UpdateAsset committed successfully');
 }
 
-/**
- * Submit transaction synchronously, to transfer the asset.
- */
 async function transferAsset(contract: Contract): Promise<void> {
-    console.log(`\n--> Submit transaction: TransferAsset, ${assetId} to Saptha\n`);
+    console.log(`\n--> Submit transaction: TransferAsset, ${assetId} to Mary`);
 
-    await contract.submitTransaction('TransferAsset',
-        assetId, 'Saptha',);
+    await contract.submitTransaction('TransferAsset', assetId, 'Mary');
 
-    console.log('\n*** TransferAsset committed successfully\n')
+    console.log('\n*** TransferAsset committed successfully');
 }
 
-/**
- * Submit a transaction synchronously to delete an asset by ID.
- */
 async function deleteAssetByID(contract: Contract): Promise<void>{
-    console.log(`\n--> Submit transaction: DeleteAsset ${assetId}`);
+    console.log(`\n--> Submit transaction: DeleteAsset, ${assetId}`);
 
-    await contract.submitTransaction('DeleteAsset',
-        assetId
-    );
+    await contract.submitTransaction('DeleteAsset', assetId);
 
-    console.log('\n*** DeleteAsset committed successfully\n')
+    console.log('\n*** DeleteAsset committed successfully');
 }
 
-/**
-  * Replay all the events from the start block.
-  */
 async function replayChaincodeEvents(network: Network, startBlock: bigint): Promise<void>{
 
     const events = await network.getChaincodeEvents(chaincodeName, {
-        startBlock
+        startBlock,
     });
+
     try {
         for await (const event of events) {
-            const payload = utf8Decoder.decode(event.payload);
-            console.log(`<-- Chaincode event replayed: ${event.eventName}, payload: ${payload}`);
+            const payload = parseJson(event.payload);
+            console.log(`\n<-- Chaincode event replayed: ${event.eventName} -`, payload);
+
             if (event.eventName === 'DeleteAsset') {
-                break
+                break;
             }
         }
     } finally {
-        events.close()
+        events.close();
     }
 }