Java gateway application sample for asset-transfer-events (#628)

Co-authored-by: deeptiraom <41100100+deeptiraom@users.noreply.github.com>
Signed-off-by: Mark S. Lewis <mark_lewis@uk.ibm.com>

Co-authored-by: deeptiraom <41100100+deeptiraom@users.noreply.github.com>

asset-transfer-events/README.md

@@ -66,6 +66,10 @@ Like other samples, the Fabric test network is used to deploy and run this sampl
    cd application-gateway-typescript
    npm install
    npm start
+
+   # To run the Java sample application
+   cd application-gateway-java
+   ./gradlew run
    ```
 
 ## Clean up

asset-transfer-events/application-gateway-go/app.go

@@ -66,7 +66,7 @@ func main() {
 }
 
 func startChaincodeEventListening(ctx context.Context, network *client.Network) {
-	fmt.Printf("\n*** Start chaincode event listening\n")
+	fmt.Println("\n*** Start chaincode event listening")
 
 	events, err := network.ChaincodeEvents(ctx, chaincodeName)
 	if err != nil {
@@ -106,7 +106,7 @@ func createAsset(contract *client.Contract) uint64 {
 		panic(fmt.Errorf("failed to commit transaction with status code %v", status.Code))
 	}
 
-	fmt.Printf("\n*** CreateAsset committed successfully\n")
+	fmt.Println("\n*** CreateAsset committed successfully")
 
 	return status.BlockNumber
 }
@@ -119,7 +119,7 @@ func updateAsset(contract *client.Contract) {
 		panic(fmt.Errorf("failed to submit transaction: %w", err))
 	}
 
-	fmt.Printf("\n*** UpdateAsset committed successfully\n")
+	fmt.Println("\n*** UpdateAsset committed successfully")
 }
 
 func transferAsset(contract *client.Contract) {
@@ -130,7 +130,7 @@ func transferAsset(contract *client.Contract) {
 		panic(fmt.Errorf("failed to submit transaction: %w", err))
 	}
 
-	fmt.Printf("\n*** TransferAsset committed successfully\n")
+	fmt.Println("\n*** TransferAsset committed successfully")
 }
 
 func deleteAsset(contract *client.Contract) {
@@ -141,11 +141,11 @@ func deleteAsset(contract *client.Contract) {
 		panic(fmt.Errorf("failed to submit transaction: %w", err))
 	}
 
-	fmt.Printf("\n*** DeleteAsset committed successfully\n")
+	fmt.Println("\n*** DeleteAsset committed successfully")
 }
 
 func replayChaincodeEvents(ctx context.Context, network *client.Network, startBlock uint64) {
-	fmt.Printf("\n*** Start chaincode event replay\n")
+	fmt.Println("\n*** Start chaincode event replay")
 
 	events, err := network.ChaincodeEvents(ctx, chaincodeName, client.WithStartBlock(startBlock))
 	if err != nil {
@@ -162,6 +162,7 @@ func replayChaincodeEvents(ctx context.Context, network *client.Network, startBl
 			fmt.Printf("\n<-- Chaincode event replayed: %s - %s\n", event.EventName, asset)
 
 			if event.EventName == "DeleteAsset" {
+				// Reached the last submitted transaction so return to stop listening for events
 				return
 			}
 		}

asset-transfer-events/application-gateway-java/build.gradle

@@ -0,0 +1,20 @@
+plugins {
+    // Apply the application plugin to add support for building a CLI application.
+    id 'application'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    // This dependency is used by the application.
+    implementation 'org.hyperledger.fabric:fabric-gateway:1.0.0'
+    implementation 'io.grpc:grpc-netty-shaded:1.42.0'
+    implementation 'com.google.code.gson:gson:2.8.9'
+}
+
+application {
+    // Define the main class for the application.
+    mainClass = 'App'
+}

asset-transfer-events/application-gateway-java/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

asset-transfer-events/application-gateway-java/gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

asset-transfer-events/application-gateway-java/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

asset-transfer-events/application-gateway-java/settings.gradle

@@ -0,0 +1,10 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/6.5/userguide/multi_project_builds.html
+ */
+
+rootProject.name = 'application-gateway-java'

asset-transfer-events/application-gateway-java/src/main/java/App.java

@@ -0,0 +1,163 @@
+/*
+ * Copyright IBM Corp. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import java.nio.charset.StandardCharsets;
+import java.time.Instant;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParser;
+import io.grpc.ManagedChannel;
+import org.hyperledger.fabric.client.CallOption;
+import org.hyperledger.fabric.client.ChaincodeEvent;
+import org.hyperledger.fabric.client.ChaincodeEventsRequest;
+import org.hyperledger.fabric.client.CloseableIterator;
+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.Gateway;
+import org.hyperledger.fabric.client.Network;
+import org.hyperledger.fabric.client.Status;
+import org.hyperledger.fabric.client.SubmitException;
+import org.hyperledger.fabric.client.SubmittedTransaction;
+
+public final class App {
+	private static final String channelName = "mychannel";
+	private static final String chaincodeName = "events";
+
+	private final Network network;
+	private final Contract contract;
+	private final String assetId = "asset" + Instant.now().toEpochMilli();
+	private final Gson gson = new GsonBuilder().setPrettyPrinting().create();
+
+	public static void main(final String[] args) throws Exception {
+		ManagedChannel grpcChannel = Connections.newGrpcConnection();
+		Gateway.Builder builder = Gateway.newInstance()
+				.identity(Connections.newIdentity())
+				.signer(Connections.newSigner())
+				.connection(grpcChannel)
+				.evaluateOptions(CallOption.deadlineAfter(5, TimeUnit.SECONDS))
+				.endorseOptions(CallOption.deadlineAfter(15, TimeUnit.SECONDS))
+				.submitOptions(CallOption.deadlineAfter(5, TimeUnit.SECONDS))
+				.commitStatusOptions(CallOption.deadlineAfter(1, TimeUnit.MINUTES));
+
+		try (Gateway gateway = builder.connect()) {
+			new App(gateway).run();
+		} finally {
+			grpcChannel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+		}
+	}
+
+	public App(final Gateway gateway) {
+		network = gateway.getNetwork(channelName);
+		contract = network.getContract(chaincodeName);
+	}
+
+	public void run() throws EndorseException, SubmitException, CommitStatusException, CommitException {
+		// Listen for events emitted by subsequent transactions, stopping when the try-with-resources block exits
+		try (CloseableIterator<ChaincodeEvent> eventSession = startChaincodeEventListening()) {
+			long firstBlockNumber = createAsset();
+			updateAsset();
+			transferAsset();
+			deleteAsset();
+
+			// Replay events from the block containing the first transaction
+			replayChaincodeEvents(firstBlockNumber);
+		}
+	}
+
+	private CloseableIterator<ChaincodeEvent> startChaincodeEventListening() {
+		System.out.println("\n*** Start chaincode event listening");
+
+		CloseableIterator<ChaincodeEvent> eventIter = network.getChaincodeEvents(chaincodeName);
+
+		CompletableFuture.runAsync(() -> {
+			eventIter.forEachRemaining(event -> {
+				String payload = prettyJson(event.getPayload());
+				System.out.println("\n<-- Chaincode event received: " + event.getEventName() + " - " + payload);
+			});
+		});
+
+		return eventIter;
+	}
+
+	private String prettyJson(final byte[] json) {
+		return prettyJson(new String(json, StandardCharsets.UTF_8));
+	}
+
+	private String prettyJson(final String json) {
+		JsonElement parsedJson = JsonParser.parseString(json);
+		return gson.toJson(parsedJson);
+	}
+
+	private long createAsset() throws EndorseException, SubmitException, CommitStatusException {
+		System.out.println("\n--> Submit transaction: CreateAsset, " + assetId + " owned by Sam with appraised value 100");
+
+		SubmittedTransaction commit = contract.newProposal("CreateAsset")
+				.addArguments(assetId, "blue", "10", "Sam", "100")
+				.build()
+				.endorse()
+				.submitAsync();
+
+		Status status = commit.getStatus();
+		if (!status.isSuccessful()) {
+			throw new RuntimeException("failed to commit transaction with status code " + status.getCode());
+		}
+
+		System.out.println("\n*** CreateAsset committed successfully");
+
+		return status.getBlockNumber();
+	}
+
+	private void updateAsset() throws EndorseException, SubmitException, CommitStatusException, CommitException {
+		System.out.println("\n--> Submit transaction: UpdateAsset, " + assetId + " update appraised value to 200");
+
+		contract.submitTransaction("UpdateAsset", assetId, "blue", "10", "Sam", "200");
+
+		System.out.println("\n*** UpdateAsset committed successfully");
+	}
+
+	private void transferAsset() throws EndorseException, SubmitException, CommitStatusException, CommitException {
+		System.out.println("\n--> Submit transaction: TransferAsset, " + assetId + " to Mary");
+
+		contract.submitTransaction("TransferAsset", assetId, "Mary");
+
+		System.out.println("\n*** TransferAsset committed successfully");
+	}
+
+	private void deleteAsset() throws EndorseException, SubmitException, CommitStatusException, CommitException {
+		System.out.println("\n--> Submit transaction: DeleteAsset, " + assetId);
+
+		contract.submitTransaction("DeleteAsset", assetId);
+
+		System.out.println("\n*** DeleteAsset committed successfully");
+	}
+
+	private void replayChaincodeEvents(final long startBlock) {
+		System.out.println("\n*** Start chaincode event replay");
+
+		ChaincodeEventsRequest request = network.newChaincodeEventsRequest(chaincodeName)
+				.startBlock(startBlock)
+				.build();
+
+		try (CloseableIterator<ChaincodeEvent> eventIter = request.getEvents()) {
+			while (eventIter.hasNext()) {
+				ChaincodeEvent event = eventIter.next();
+				String payload = prettyJson(event.getPayload());
+				System.out.println("\n<-- Chaincode event replayed: " + event.getEventName() + " - " + payload);
+
+				if (event.getEventName().equals("DeleteAsset")) {
+					// Reached the last submitted transaction so break to close the iterator and stop listening for events
+					break;
+				}
+			}
+		}
+	}
+}

asset-transfer-events/application-gateway-java/src/main/java/Connections.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright IBM Corp. All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import java.io.IOException;
+import java.io.Reader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.security.InvalidKeyException;
+import java.security.PrivateKey;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+
+import io.grpc.ManagedChannel;
+import io.grpc.netty.shaded.io.grpc.netty.GrpcSslContexts;
+import io.grpc.netty.shaded.io.grpc.netty.NettyChannelBuilder;
+import org.hyperledger.fabric.client.identity.Identities;
+import org.hyperledger.fabric.client.identity.Identity;
+import org.hyperledger.fabric.client.identity.Signer;
+import org.hyperledger.fabric.client.identity.Signers;
+import org.hyperledger.fabric.client.identity.X509Identity;
+
+public final class Connections {
+    // Path to crypto materials.
+    private static final Path cryptoPath = Paths.get("..", "..", "test-network", "organizations", "peerOrganizations",	"org1.example.com");
+    // Path to user certificate.
+    private static final Path certPath = cryptoPath.resolve(Paths.get("users", "User1@org1.example.com", "msp", "signcerts", "cert.pem"));
+    // Path to user private key directory.
+    private static final Path keyDirPath = cryptoPath.resolve(Paths.get("users", "User1@org1.example.com", "msp", "keystore"));
+    // Path to peer tls certificate.
+    private static final Path tlsCertPath = cryptoPath.resolve(Paths.get("peers", "peer0.org1.example.com", "tls", "ca.crt"));
+
+    // Gateway peer end point.
+    private static final String peerEndpoint = "localhost:7051";
+    private static final String overrideAuth = "peer0.org1.example.com";
+
+    private static final String mspID = "Org1MSP";
+
+    private Connections() {
+        // Private constructor to prevent instantiation
+    }
+
+    public static ManagedChannel newGrpcConnection() throws IOException, CertificateException {
+        Reader tlsCertReader = Files.newBufferedReader(tlsCertPath);
+        X509Certificate tlsCert = Identities.readX509Certificate(tlsCertReader);
+
+        return NettyChannelBuilder.forTarget(peerEndpoint)
+                .sslContext(GrpcSslContexts.forClient().trustManager(tlsCert).build()).overrideAuthority(overrideAuth)
+                .build();
+    }
+
+    public static Identity newIdentity() throws IOException, CertificateException {
+        Reader certReader = Files.newBufferedReader(certPath);
+        X509Certificate certificate = Identities.readX509Certificate(certReader);
+
+        return new X509Identity(mspID, certificate);
+    }
+
+    public static Signer newSigner() throws IOException, InvalidKeyException {
+        Path keyPath = Files.list(keyDirPath)
+                .findFirst()
+                .orElseThrow();
+        Reader keyReader = Files.newBufferedReader(keyPath);
+        PrivateKey privateKey = Identities.readPrivateKey(keyReader);
+
+        return Signers.newPrivateKeySigner(privateKey);
+    }
+}

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

@@ -134,8 +134,9 @@ async function deleteAssetByID(contract: Contract): Promise<void>{
     console.log('\n*** DeleteAsset committed successfully');
 }
 
-async function replayChaincodeEvents(network: Network, startBlock: bigint): Promise<void>{
+async function replayChaincodeEvents(network: Network, startBlock: bigint): Promise<void> {
-
+    console.log('\n*** Start chaincode event replay');
+    
     const events = await network.getChaincodeEvents(chaincodeName, {
         startBlock,
     });
@@ -146,6 +147,7 @@ async function replayChaincodeEvents(network: Network, startBlock: bigint): Prom
             console.log(`\n<-- Chaincode event replayed: ${event.eventName} -`, payload);
 
             if (event.eventName === 'DeleteAsset') {
+                // Reached the last submitted transaction so break to stop listening for events
                 break;
             }
         }

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

@@ -56,3 +56,12 @@ print "Executing application"
 go run .
 popd
 stopNetwork
+
+# Run Java gateway application
+createNetwork
+print "Initializing Java gateway application"
+pushd ../asset-transfer-events/application-gateway-java
+print "Executing application"
+./gradlew run
+popd
+stopNetwork