Java off-chain data store sample using Fabric Gateway (#749)

Also minor implementation changes to TypeScript sample for better consistency between implementations.

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

ci/scripts/run-test-network-basic.sh

@@ -123,3 +123,14 @@ SIMULATED_FAILURE_COUNT=1 npm start getAllAssets transact getAllAssets listen
 SIMULATED_FAILURE_COUNT=1 npm start listen
 popd
 stopNetwork
+
+# Run off-chain data Java application
+createNetwork
+print "Initializing Typescript off-chain data application"
+pushd ../off_chain_data/application-java
+rm -f app/checkpoint.json app/store.log
+print "Running the output app"
+SIMULATED_FAILURE_COUNT=1 ./gradlew run --quiet --args='getAllAssets transact getAllAssets listen'
+SIMULATED_FAILURE_COUNT=1 ./gradlew run --quiet --args=listen
+popd
+stopNetwork

off_chain_data/README.md

@@ -16,11 +16,17 @@ This sample uses the block event listening capability of the [Fabric Gateway cli
 
 The client application provides several "commands" that can be invoked using the command-line:
 
-- **getAllAssets**: Retrieve the current details of all assets recorded on the ledger. See `application-typescript/src/getAllAssets.ts`.
-- **listen**: Listen for block events, and use them to replicate ledger updates in an off-chain data store. See `application-typescript/src/listen.ts`.
-- **transact**: Submit a set of transactions to create, modify and delete assets. See `application-typescript/src/transact.ts`.
-
-To keep the sample code concise, the **listen** command writes ledger updates to an output file named `store.log` in the current working directory. A real implementation could write ledger updates directly to an off-chain data store of choice. You can inspect the information captured in this file as you run the sample.
+- **getAllAssets**: Retrieve the current details of all assets recorded on the ledger. See:
+  - TypeScript: `application-typescript/src/getAllAssets.ts`
+  - Java: `application-java/app/src/main/java/GetAllAssets.java`
+- **listen**: Listen for block events, and use them to replicate ledger updates in an off-chain data store. See:
+  - TypeScript: `application-typescript/src/listen.ts`
+  - Java: `application-java/app/src/main/java/Transact.java`
+- **transact**: Submit a set of transactions to create, modify and delete assets. See:
+  - TypeScript: `application-typescript/src/transact.ts`
+  - Java: `application-java/app/src/main/java/Transact.java`
+
+To keep the sample code concise, the **listen** command writes ledger updates to an output file named `store.log` in the current working directory (which for the Java sample is the `application-java/app` directory). A real implementation could write ledger updates directly to an off-chain data store of choice. You can inspect the information captured in this file as you run the sample.
 
 Note that the **listen** command is is restartable and will resume event listening after the last successfully processed block / transaction. This is achieved using a checkpointer to persist the current listening position. Checkpoint state is persisted to a file named `checkpoint.json` in the current working directory. If no checkpoint state is present, event listening begins from the start of the ledger (block number zero).
 
@@ -34,13 +40,13 @@ The Fabric test network is used to deploy and run this sample. Follow these step
 
 1. Create the test network and a channel (from the `test-network` folder).
 
-   ```
+   ```bash
    ./network.sh up createChannel -c mychannel -ca
    ```
 
 1. Deploy one of the asset-transfer-basic smart contract implementations (from the `test-network` folder).
 
-   ```
+   ```bash
    # To deploy the TypeScript chaincode implementation
    ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-typescript/ -ccl typescript
 
@@ -53,31 +59,45 @@ The Fabric test network is used to deploy and run this sample. Follow these step
 
 1. Populate the ledger with some assets and use eventing to capture ledger updates (from the `off_chain_data` folder).
 
-   ```
+   ```bash
    # To run the TypeScript sample application
    cd application-typescript
    npm install
    npm start transact listen
+
+   # To run the Java sample application
+   cd application-java
+   ./gradlew run --quiet --args='transact listen'
    ```
 
 1. Interrupt the listener process using **Control-C**.
 
 1. View the current world state of the blockchain (from the `off_chain_data` folder). You may want to compare the results to the ledger updates captured by the listener in the `store.log` file.
 
-   ```
+   ```bash
    # To run the TypeScript sample application
    cd application-typescript
    npm --silent start getAllAssets
+
+   # To run the Java sample application
+   cd application-java
+   ./gradlew run --quiet --args=getAllAssets
    ```
 
 1. Make some more ledger updates, then observe listener resume capability (from the `off_chain_data` folder). Note from the transaction IDs recorded to the console that the listener resumes from exactly after the last successfully processed transaction.
 
-   ```
+   ```bash
    # To run the TypeScript sample application
    cd application-typescript
    npm start transact
    SIMULATED_FAILURE_COUNT=5 npm start listen
    npm start listen
+
+   # To run the Java sample application
+   cd application-java
+   ./gradlew run --quiet --args=transact
+   SIMULATED_FAILURE_COUNT=5 ./gradlew run --quiet --args=listen
+   ./gradlew run --quiet --args=listen
    ```
 
 1. Interrupt the listener process using **Control-C**.

off_chain_data/application-java/.gitignore

@@ -0,0 +1,12 @@
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build
+
+# IntelliJ IDEA files
+.idea
+
+# Files generated by the application at runtime
+checkpoint.json
+store.log

off_chain_data/application-java/app/build.gradle

@@ -0,0 +1,38 @@
+/*
+ * Copyright IBM Corp. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+plugins {
+    id 'application' // Support for building a CLI application in Java.
+    id 'checkstyle'
+}
+
+repositories {
+    mavenCentral()
+    maven {
+        url 'https://hyperledger-fabric.jfrog.io/artifactory/fabric-maven'
+    }
+}
+
+dependencies {
+//    implementation 'com.google.guava:guava:30.1.1-jre'
+    implementation 'io.grpc:grpc-netty-shaded:1.46.0'
+    implementation 'org.hyperledger.fabric:fabric-gateway:1.0.2-dev-20220518-1'
+    implementation 'com.google.code.gson:gson:2.9.0'
+}
+
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(11)
+    }
+}
+
+checkstyle {
+    toolVersion '10.2'
+}
+
+application {
+    mainClass = 'App'
+}

off_chain_data/application-java/app/src/main/java/App.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright IBM Corp. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import java.io.PrintStream;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import io.grpc.ManagedChannel;
+
+public final class App {
+    private static final long SHUTDOWN_TIMEOUT_SECONDS = 3;
+    private static final Map<String, Command> COMMANDS = Map.ofEntries(
+            Map.entry("getAllAssets", new GetAllAssets()),
+            Map.entry("transact", new Transact()),
+            Map.entry("listen", new Listen())
+    );
+
+    private final List<String> commandNames;
+    private final PrintStream out = System.out;
+
+    App(final String[] args) {
+        commandNames = List.of(args);
+    }
+
+    public void run() throws Exception {
+        List<Command> commands = getCommands();
+        ManagedChannel grpcChannel = Connections.newGrpcConnection();
+        try {
+            for (Command command : commands) {
+                command.run(grpcChannel);
+            }
+        } finally {
+            grpcChannel.shutdownNow().awaitTermination(SHUTDOWN_TIMEOUT_SECONDS, TimeUnit.SECONDS);
+        }
+    }
+
+    private List<Command> getCommands() {
+        List<Command> commands = commandNames.stream()
+                .map(name -> {
+                    Command command = COMMANDS.get(name);
+                    if (command == null) {
+                        printUsage();
+                        throw new IllegalArgumentException("Unknown command: " + name);
+                    }
+                    return command;
+                })
+                .collect(Collectors.toList());
+
+        if (commands.isEmpty()) {
+            printUsage();
+            throw new IllegalArgumentException("Missing command");
+        }
+
+        return commands;
+    }
+
+    private void printUsage() {
+        out.println("Arguments: <command1> [<command2> ...]");
+        out.println("Available commands: " + COMMANDS.keySet());
+    }
+
+    public static void main(final String[] args) {
+        try {
+            new App(args).run();
+        } catch (ExpectedException e) {
+            e.printStackTrace(System.out);
+        } catch (Exception e) {
+            System.err.print("\nUnexpected application error: ");
+            e.printStackTrace();
+            System.exit(1);
+        }
+    }
+}

off_chain_data/application-java/app/src/main/java/Asset.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright IBM Corp. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Object representation of an asset. Note that the private member variable names don't follow the normal Java naming
+ * convention as they map to the JSON format expected by the smart contract.
+ */
+public final class Asset {
+    private final String ID; // checkstyle:ignore-line:MemberName
+    private String Color; // checkstyle:ignore-line:MemberName
+    private int Size; // checkstyle:ignore-line:MemberName
+    private String Owner; // checkstyle:ignore-line:MemberName
+    private int AppraisedValue; // checkstyle:ignore-line:MemberName
+
+    public Asset(final String id) {
+        this.ID = id;
+    }
+
+    public String getId() {
+        return ID;
+    }
+
+    public String getColor() {
+        return Color;
+    }
+
+    public void setColor(final String color) {
+        this.Color = color;
+    }
+
+    public int getSize() {
+        return Size;
+    }
+
+    public void setSize(final int size) {
+        this.Size = size;
+    }
+
+    public String getOwner() {
+        return Owner;
+    }
+
+    public void setOwner(final String owner) {
+        this.Owner = owner;
+    }
+
+    public int getAppraisedValue() {
+        return AppraisedValue;
+    }
+
+    public void setAppraisedValue(final int appraisedValue) {
+        this.AppraisedValue = appraisedValue;
+    }
+}

off_chain_data/application-java/app/src/main/java/AssetTransferBasic.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright IBM Corp. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+
+import com.google.gson.Gson;
+import org.hyperledger.fabric.client.CommitException;
+import org.hyperledger.fabric.client.CommitStatusException;
+import org.hyperledger.fabric.client.Contract;
+import org.hyperledger.fabric.client.EndorseException;
+import org.hyperledger.fabric.client.SubmitException;
+
+public final class AssetTransferBasic {
+    private static final Gson GSON = new Gson();
+    private final Contract contract;
+
+    public AssetTransferBasic(final Contract contract) {
+        this.contract = contract;
+    }
+
+    public void createAsset(final Asset asset) throws EndorseException, CommitException, SubmitException, CommitStatusException {
+        contract.submitTransaction(
+                "CreateAsset",
+                asset.getId(),
+                asset.getColor(),
+                Integer.toString(asset.getSize()),
+                asset.getOwner(),
+                Integer.toString(asset.getAppraisedValue())
+        );
+    }
+
+    public String transferAsset(final String id, final String newOwner) throws EndorseException, CommitException, SubmitException, CommitStatusException {
+        byte[] resultBytes = contract.submitTransaction("TransferAsset", id, newOwner);
+        return new String(resultBytes, StandardCharsets.UTF_8);
+    }
+
+    public void deleteAsset(final String id) throws EndorseException, CommitException, SubmitException, CommitStatusException {
+        contract.submitTransaction("DeleteAsset", id);
+    }
+
+    public List<Asset> getAllAssets() throws EndorseException, CommitException, SubmitException, CommitStatusException {
+        byte[] resultBytes = contract.submitTransaction("GetAllAssets");
+        String resultJson = new String(resultBytes, StandardCharsets.UTF_8);
+        Asset[] assets = GSON.fromJson(resultJson, Asset[].class);
+        return assets != null ? List.of(assets) : List.of();
+    }
+}