feat: add Go client application for full-stack-asset-transfer-guide

full-stack-asset-transfer-guide/applications/trader-go/commands.go

@@ -0,0 +1,15 @@
+package main
+
+import "github.com/hyperledger/fabric-gateway/pkg/client"
+
+type Command func(gw *client.Gateway, args []string) error
+
+var commands = map[string]Command{
+	"create":       cmdCreate,
+	"delete":       cmdDelete,
+	"getAllAssets": cmdGetAllAssets,
+	"listen":       cmdListen,
+	"read":         cmdRead,
+	"transact":     cmdTransact,
+	"transfer":     cmdTransfer,
+}

full-stack-asset-transfer-guide/applications/trader-go/commands_impl.go

@@ -0,0 +1,296 @@
+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"math/big"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/hyperledger/fabric-gateway/pkg/client"
+)
+
+// cmdCreate creates a new asset on the ledger.
+// Arguments: <assetId> <ownerName> <color>
+func cmdCreate(gw *client.Gateway, args []string) error {
+	if len(args) < 3 {
+		return fmt.Errorf("arguments: <assetId> <ownerName> <color>")
+	}
+
+	network := gw.GetNetwork(channelName())
+	contract := network.GetContract(chaincodeName())
+
+	smartContract := NewAssetTransfer(contract)
+	return smartContract.CreateAsset(Asset{
+		ID:             args[0],
+		Owner:          args[1],
+		Color:          args[2],
+		Size:           1,
+		AppraisedValue: 1,
+	})
+}
+
+// cmdDelete deletes an asset from the ledger.
+// Arguments: <assetId>
+func cmdDelete(gw *client.Gateway, args []string) error {
+	if len(args) < 1 {
+		return fmt.Errorf("arguments: <assetId>")
+	}
+
+	network := gw.GetNetwork(channelName())
+	contract := network.GetContract(chaincodeName())
+
+	smartContract := NewAssetTransfer(contract)
+	return smartContract.DeleteAsset(args[0])
+}
+
+// cmdGetAllAssets queries and prints all assets currently on the ledger.
+func cmdGetAllAssets(gw *client.Gateway, _ []string) error {
+	network := gw.GetNetwork(channelName())
+	contract := network.GetContract(chaincodeName())
+
+	smartContract := NewAssetTransfer(contract)
+	assets, err := smartContract.GetAllAssets()
+	if err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(assets, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal assets: %w", err)
+	}
+
+	for _, line := range strings.Split(string(data), "\n") {
+		fmt.Println(line)
+	}
+	return nil
+}
+
+const startBlock = uint64(0)
+
+func cmdListen(gw *client.Gateway, _ []string) error {
+	network := gw.GetNetwork(channelName())
+
+	checkpointFile := os.Getenv("CHECKPOINT_FILE")
+	if checkpointFile == "" {
+		checkpointFile = "checkpoint.json"
+	}
+
+	simulatedFailureCount, err := getSimulatedFailureCount()
+	if err != nil {
+		return err
+	}
+
+	checkpointer, err := client.NewFileCheckpointer(checkpointFile)
+	if err != nil {
+		return fmt.Errorf("failed to create checkpointer: %w", err)
+	}
+	defer checkpointer.Close()
+
+	displayBlock := checkpointer.BlockNumber()
+	if displayBlock == 0 {
+		displayBlock = startBlock
+	}
+
+	fmt.Println("Starting event listening from block", displayBlock)
+	fmt.Println("Last processed transaction ID within block:", checkpointer.TransactionID())
+	if simulatedFailureCount > 0 {
+		fmt.Println("Simulating a write failure every", simulatedFailureCount, "transactions")
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	events, err := network.ChaincodeEvents(ctx, chaincodeName(),
+		client.WithStartBlock(startBlock),
+		client.WithCheckpoint(checkpointer),
+	)
+	if err != nil {
+		return fmt.Errorf("failed to start chaincode event subscription: %w", err)
+	}
+
+	eventCount := 0
+	for event := range events {
+		if simulatedFailureCount > 0 {
+			eventCount++
+			if eventCount >= simulatedFailureCount {
+				eventCount = 0
+				return &ExpectedError{Message: "Simulated write failure"}
+			}
+		}
+		fmt.Printf("Chaincode event: BlockNumber=%d TxID=%s Name=%s Payload=%s\n",
+			event.BlockNumber, event.TransactionID, event.EventName, string(event.Payload))
+	}
+
+	return nil
+}
+
+func getSimulatedFailureCount() (int, error) {
+	value := os.Getenv("SIMULATED_FAILURE_COUNT")
+	if value == "" {
+		return 0, nil
+	}
+	count, err := strconv.Atoi(value)
+	if err != nil || count < 0 {
+		return 0, fmt.Errorf("invalid SIMULATED_FAILURE_COUNT value: %s", value)
+	}
+	return count, nil
+}
+
+// cmdRead reads and prints a single asset from the ledger.
+// Arguments: <assetId>
+func cmdRead(gw *client.Gateway, args []string) error {
+	if len(args) < 1 {
+		return fmt.Errorf("arguments: <assetId>")
+	}
+
+	network := gw.GetNetwork(channelName())
+	contract := network.GetContract(chaincodeName())
+
+	smartContract := NewAssetTransfer(contract)
+	asset, err := smartContract.ReadAsset(args[0])
+	if err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(asset, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal asset: %w", err)
+	}
+
+	fmt.Println(string(data))
+	return nil
+}
+
+var (
+	colors         = []string{"red", "green", "blue"}
+	maxInitialSize = 10
+	maxInitialVal  = 1000
+)
+
+// cmdTransact runs a batch of concurrent create/update/delete transactions to demonstrate
+func cmdTransact(gw *client.Gateway, _ []string) error {
+	network := gw.GetNetwork(channelName())
+	contract := network.GetContract(chaincodeName())
+
+	smartContract := NewAssetTransfer(contract)
+	app := &transactApp{smartContract: smartContract, batchSize: 6}
+	return app.run()
+}
+
+type transactApp struct {
+	smartContract *AssetTransfer
+	batchSize     int
+}
+
+func (a *transactApp) run() error {
+	var wg sync.WaitGroup
+	errCh := make(chan error, a.batchSize)
+
+	for i := 0; i < a.batchSize; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			if err := a.transact(); err != nil {
+				errCh <- err
+			}
+		}()
+	}
+
+	wg.Wait()
+	close(errCh)
+
+	var failures []string
+	for err := range errCh {
+		failures = append(failures, err.Error())
+	}
+	if len(failures) > 0 {
+		return fmt.Errorf("%d failures:\n- %s", len(failures), strings.Join(failures, "\n- "))
+	}
+	return nil
+}
+
+func (a *transactApp) transact() error {
+	asset := a.newAsset()
+
+	if err := a.smartContract.CreateAsset(asset); err != nil {
+		return err
+	}
+	fmt.Printf("Created asset %s\n", asset.ID)
+
+	if randomInt(2) == 0 {
+		oldColor := asset.Color
+		asset.Color = differentElement(colors, oldColor)
+		if err := a.smartContract.UpdateAsset(asset); err != nil {
+			return err
+		}
+		fmt.Printf("Updated color of asset %s from %s to %s\n", asset.ID, oldColor, asset.Color)
+	}
+
+	if randomInt(4) == 0 {
+		if err := a.smartContract.DeleteAsset(asset.ID); err != nil {
+			return err
+		}
+		fmt.Printf("Deleted asset %s\n", asset.ID)
+	}
+
+	return nil
+}
+
+func (a *transactApp) newAsset() Asset {
+	return Asset{
+		ID:             randomHexString(8),
+		Color:          randomElement(colors),
+		Size:           randomInt(maxInitialSize) + 1,
+		AppraisedValue: float64(randomInt(maxInitialVal) + 1),
+	}
+}
+
+func randomHexString(length int) string {
+	b := make([]byte, (length+1)/2)
+	if _, err := rand.Read(b); err != nil {
+		panic(fmt.Sprintf("failed to generate random bytes: %v", err))
+	}
+	return hex.EncodeToString(b)[:length]
+}
+
+func randomInt(max int) int {
+	n, err := rand.Int(rand.Reader, big.NewInt(int64(max)))
+	if err != nil {
+		panic(fmt.Sprintf("failed to generate random int: %v", err))
+	}
+	return int(n.Int64())
+}
+
+func randomElement(values []string) string {
+	return values[randomInt(len(values))]
+}
+
+func differentElement(values []string, currentValue string) string {
+	var candidates []string
+	for _, v := range values {
+		if v != currentValue {
+			candidates = append(candidates, v)
+		}
+	}
+	return randomElement(candidates)
+}
+
+// cmdTransfer transfers ownership of an asset to a new owner in a different organisation.
+// Arguments: <assetId> <ownerName> <ownerMspId>
+func cmdTransfer(gw *client.Gateway, args []string) error {
+	if len(args) < 3 {
+		return fmt.Errorf("arguments: <assetId> <ownerName> <ownerMspId>")
+	}
+
+	network := gw.GetNetwork(channelName())
+	contract := network.GetContract(chaincodeName())
+
+	smartContract := NewAssetTransfer(contract)
+	return smartContract.TransferAsset(args[0], args[1], args[2])
+}

full-stack-asset-transfer-guide/applications/trader-go/config.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func gatewayEndpoint() (string, error) {
+	return requireEnv("ENDPOINT")
+}
+
+func mspID() (string, error) {
+	return requireEnv("MSP_ID")
+}
+
+func clientCertPath() (string, error) {
+	return requireEnv("CERTIFICATE")
+}
+
+func privateKeyPath() (string, error) {
+	return requireEnv("PRIVATE_KEY")
+}
+
+func tlsCertPath() string {
+	return os.Getenv("TLS_CERT")
+}
+
+func channelName() string {
+	if v := os.Getenv("CHANNEL_NAME"); v != "" {
+		return v
+	}
+	return "mychannel"
+}
+
+func chaincodeName() string {
+	if v := os.Getenv("CHAINCODE_NAME"); v != "" {
+		return v
+	}
+	return "asset-transfer"
+}
+
+func hostAlias() string {
+	return os.Getenv("HOST_ALIAS")
+}
+
+func requireEnv(name string) (string, error) {
+	v := os.Getenv(name)
+	if v == "" {
+		printEnvUsage()
+		return "", fmt.Errorf("environment variable %s not set", name)
+	}
+	return v, nil
+}
+
+func printEnvUsage() {
+	fmt.Fprintln(os.Stderr, "The following environment variables must be set:")
+	fmt.Fprintln(os.Stderr, "    ENDPOINT       - Endpoint address of the gateway service")
+	fmt.Fprintln(os.Stderr, "    MSP_ID         - User's organization Member Services Provider ID")
+	fmt.Fprintln(os.Stderr, "    CERTIFICATE    - User's certificate file")
+	fmt.Fprintln(os.Stderr, "    PRIVATE_KEY    - User's private key file")
+	fmt.Fprintln(os.Stderr, "")
+	fmt.Fprintln(os.Stderr, "The following environment variables are optional:")
+	fmt.Fprintln(os.Stderr, "    CHANNEL_NAME   - Channel to which the chaincode is deployed")
+	fmt.Fprintln(os.Stderr, "    CHAINCODE_NAME - Chaincode deployed to the channel")
+	fmt.Fprintln(os.Stderr, "    TLS_CERT       - TLS CA root certificate (only if using TLS and private CA)")
+	fmt.Fprintln(os.Stderr, "    HOST_ALIAS     - TLS hostname override (only if TLS cert does not match endpoint)")
+}