Add README to asset-transfer-basic sample (#638)

Also: - Refactor application-gateway-java slightly to reflect more idiomatic Java class structure, in line with asset-transfer-events sample. - Correctly handle unexpected error case where key file is missing. - Update Gradle wrapper for application-gateway-java. Signed-off-by: Mark S. Lewis <mark_lewis@uk.ibm.com>
2026-06-17 07:25:10 +00:00 · 2022-02-10 13:52:46 +00:00 · 2022-02-10 13:52:46 +00:00 · bee24a7615
commit bee24a7615
parent 58606efc06
8 changed files with 326 additions and 256 deletions
--- a/asset-transfer-basic/README.md
+++ b/asset-transfer-basic/README.md
@ -0,0 +1,78 @@
+# Asset transfer basic sample
+
+The asset transfer basic sample demonstrates:
+
+- Connecting a client application to a Fabric blockchain network.
+- Submitting smart contract transactions to update ledger state.
+- Evaluating smart contract transactions to query ledger state.
+- Handling errors in transaction invocation.
+
+## About the sample
+
+This sample includes smart contract and application code in multiple languages. This sample shows create, read, update, transfer and delete of an asset.
+
+For a more detailed walk-through of the application code and client API usage, refer to the [Running a Fabric Application tutorial](https://hyperledger-fabric.readthedocs.io/en/latest/write_first_app.html) in the main Hyperledger Fabric documentation.
+
+### Application
+
+Follow the execution flow in the client application code, and corresponding output on running the application. Pay attention to the sequence of:
+
+- Transaction invocations (console output like "**--> Submit Transaction**" and "**--> Evaluate Transaction**").
+- Results returned by transactions (console output like "**\*\*\* Result**").
+
+### Smart Contract
+
+The smart contract (in folder `chaincode-xyz`) implements the following functions to support the application:
+
+- CreateAsset
+- ReadAsset
+- UpdateAsset
+- DeleteAsset
+- TransferAsset
+
+Note that the asset transfer implemented by the smart contract is a simplified scenario, without ownership validation, meant only to demonstrate how to invoke transactions.
+
+## Running the sample
+
+The Fabric test network is used to deploy and run this sample. Follow these steps in order:
+
+1. Create the test network and a channel (from the `test-network` folder).
+   ```
+   ./network.sh up createChannel -c mychannel -ca
+   ```
+
+1. Deploy one of the smart contract implementations (from the `test-network` folder).
+   ```
+   # To deploy the TypeScript chaincode implementation
+   ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-typescript/ -ccl typescript
+
+   # To deploy the Go chaincode implementation
+   ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-go/ -ccl go
+
+   # To deploy the Java chaincode implementation
+   ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-java/ -ccl java
+   ```
+
+1. Run the application (from the `asset-transfer-basic` folder).
+   ```
+   # To run the Typescript sample application
+   cd application-gateway-typescript
+   npm install
+   npm start
+
+   # To run the Go sample application
+   cd application-gateway-go
+   go run .
+
+   # To run the Java sample application
+   cd application-gateway-java
+   ./gradlew run
+   ```
+
+## Clean up
+
+When you are finished, you can bring down the test network (from the `test-network` folder). The command will remove all the nodes of the test network, and delete any ledger data that you created.
+
+```
+./network.sh down
+```
--- a/asset-transfer-basic/application-gateway-java/build.gradle
+++ b/asset-transfer-basic/application-gateway-java/build.gradle
@ -6,8 +6,6 @@
 * User Manual available at https://docs.gradle.org/6.5/userguide/tutorial_java_projects.html
 */
 plugins {
-    // Apply the java plugin to add support for Java
-    id 'java'
    // Apply the application plugin to add support for building a CLI application.
    id 'application'
    
@ -30,14 +28,5 @@ dependencies {

 application {
    // Define the main class for the application.
-    mainClassName = 'application.java.App'
+    mainClass = 'App'
 }
-
-// task for running the app after building dependencies
-task runApp(type: Exec) {
-    dependsOn build
-    group = "Execution"
-    description = "Run the main class with ExecTask"
-    commandLine "java", "-classpath", sourceSets.main.runtimeClasspath.getAsPath(), javaMainClass
-}
-
--- a/asset-transfer-basic/application-gateway-java/gradle/wrapper/gradle-wrapper.jar
+++ b/asset-transfer-basic/application-gateway-java/gradle/wrapper/gradle-wrapper.jar
--- a/asset-transfer-basic/application-gateway-java/gradle/wrapper/gradle-wrapper.properties
+++ b/asset-transfer-basic/application-gateway-java/gradle/wrapper/gradle-wrapper.properties
@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
--- a/asset-transfer-basic/application-gateway-java/gradlew
+++ b/asset-transfer-basic/application-gateway-java/gradlew
@ -1,7 +1,7 @@
-#!/usr/bin/env sh
+#!/bin/sh

 #
-# Copyright 2015 the original author or authors.
+# 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.
@ -17,67 +17,101 @@
 #

 ##############################################################################
-##
-##  Gradle start up script for UN*X
-##
+#
+#   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
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
+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
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit

 APP_NAME="Gradle"
-APP_BASE_NAME=`basename "$0"`
+APP_BASE_NAME=${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"
+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
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
 esac

 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
@ -87,9 +121,9 @@ CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 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="$JAVA_HOME/jre/sh/java"
+        JAVACMD=$JAVA_HOME/jre/sh/java
    else
-        JAVACMD="$JAVA_HOME/bin/java"
+        JAVACMD=$JAVA_HOME/bin/java
    fi
    if [ ! -x "$JAVACMD" ] ; then
        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
@ -98,7 +132,7 @@ Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
    fi
 else
-    JAVACMD="java"
+    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
@ -106,80 +140,95 @@ location of your Java installation."
 fi

 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
-    if [ $? -eq 0 ] ; then
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
-            MAX_FD="$MAX_FD_LIMIT"
-        fi
-        ulimit -n $MAX_FD
-        if [ $? -ne 0 ] ; then
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
-        fi
-    else
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
-    fi
-fi
-
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
-
-# For Cygwin or MSYS, switch paths to Windows format before running java
-if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-    
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
-        fi
-        i=`expr $i + 1`
-    done
-    case $i in
-        0) set -- ;;
-        1) set -- "$args0" ;;
-        2) set -- "$args0" "$args1" ;;
-        3) set -- "$args0" "$args1" "$args2" ;;
-        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+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

-# Escape application args
-save () {
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
-    echo " "
-}
-APP_ARGS=`save "$@"`
+# 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.

-# Collect all arguments for the java command, following the shell quoting and substitution rules
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+# 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 "$JAVACMD" "$@"
--- a/asset-transfer-basic/application-gateway-java/gradlew.bat
+++ b/asset-transfer-basic/application-gateway-java/gradlew.bat
@ -40,7 +40,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome

 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
+if "%ERRORLEVEL%" == "0" goto execute

 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@ -54,7 +54,7 @@ goto fail
 set JAVA_HOME=%JAVA_HOME:"=%
 set JAVA_EXE=%JAVA_HOME%/bin/java.exe

-if exist "%JAVA_EXE%" goto init
+if exist "%JAVA_EXE%" goto execute

 echo.
 echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
@ -64,21 +64,6 @@ echo location of your Java installation.

 goto fail

-:init
-@rem Get command-line arguments, handling Windows variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-
 :execute
@rem Setup the command line

@ -86,7 +71,7 @@ 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 %CMD_LINE_ARGS%
+"%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
--- a/asset-transfer-basic/application-gateway-java/src/main/java/application/java/App.java
+++ b/asset-transfer-basic/application-gateway-java/src/main/java/application/java/App.java
@ -1,16 +1,9 @@
- 
 /*
 * Copyright IBM Corp. All Rights Reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

-// Running TestApp: 
-// gradle runApp 
-
-package application.java;
-
-import java.io.File;
 import java.io.IOException;
 import java.io.Reader;
 import java.nio.charset.StandardCharsets;
@ -22,8 +15,16 @@ import java.security.PrivateKey;
 import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;
 import java.time.Instant;
+import java.util.List;
 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 io.grpc.netty.shaded.io.grpc.netty.GrpcSslContexts;
+import io.grpc.netty.shaded.io.grpc.netty.NettyChannelBuilder;
 import org.hyperledger.fabric.client.CallOption;
 import org.hyperledger.fabric.client.CommitException;
 import org.hyperledger.fabric.client.CommitStatusException;
@ -32,9 +33,9 @@ import org.hyperledger.fabric.client.EndorseException;
 import org.hyperledger.fabric.client.Gateway;
 import org.hyperledger.fabric.client.GatewayException;
 import org.hyperledger.fabric.client.Network;
+import org.hyperledger.fabric.client.Status;
 import org.hyperledger.fabric.client.SubmitException;
 import org.hyperledger.fabric.client.SubmittedTransaction;
-import org.hyperledger.fabric.client.Status;
 import org.hyperledger.fabric.client.identity.Identities;
 import org.hyperledger.fabric.client.identity.Identity;
 import org.hyperledger.fabric.client.identity.Signer;
@ -42,43 +43,29 @@ import org.hyperledger.fabric.client.identity.Signers;
 import org.hyperledger.fabric.client.identity.X509Identity;
 import org.hyperledger.fabric.protos.gateway.ErrorDetail;

-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 io.grpc.netty.shaded.io.grpc.netty.GrpcSslContexts;
-import io.grpc.netty.shaded.io.grpc.netty.NettyChannelBuilder;
-
-public class App {
-
+public final class App {
 	private static final String mspID = "Org1MSP";
 	private static final String channelName = "mychannel";
 	private static final String chaincodeName = "basic";

-	public static String assetId = "asset" + Instant.now().toEpochMilli();
-
 	// Path to crypto materials.
-	private static final Path cryptoPath = Paths.get("..", "..", "test-network", "organizations", "peerOrganizations",
-			"org1.example.com");
+	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"));
+	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 keyPath = cryptoPath
-			.resolve(Paths.get("users", "User1@org1.example.com", "msp", "keystore"));
+	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"));
+	private static final Path tlsCertPath = cryptoPath.resolve(Paths.get("peers", "peer0.org1.example.com", "tls", "ca.crt"));

 	// Gateway peer end point.
-	public static String peerEndpoint = "localhost:7051";
-	public static String overrideAuth = "peer0.org1.example.com";
+	private static final String peerEndpoint = "localhost:7051";
+	private static final String overrideAuth = "peer0.org1.example.com";

-	public static void main(String[] args)
-			throws Exception {
+	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 {
 		// The gRPC client connection should be shared by all Gateway connections to
 		// this endpoint.
 		ManagedChannel channel = newGrpcConnection();
@ -91,39 +78,12 @@ public class App {
 				.commitStatusOptions(CallOption.deadlineAfter(1, TimeUnit.MINUTES));

 		try (Gateway gateway = builder.connect()) {
-
-			// Get a network instance representing the channel where the smart contract is
-			// deployed.
-			Network network = gateway.getNetwork(channelName);
-
-			// Get the smart contract from the network.
-			Contract contract = network.getContract(chaincodeName);
-
-			// Initialize a set of asset data on the ledger using the chaincode 'InitLedger'
-			// function.
-			initLedger(contract);
-
-			// Return all the current assets on the ledger.
-			getAllAssets(contract);
-
-			// Create a new asset on the ledger.
-			createAsset(contract);
-
-			// Update an existing asset asynchronously.
-			transferAssetAsync(contract);
-
-			// Get the asset details by assetID.
-			readAssetById(contract);
-
-			// Update an asset which does not exist.
-			updateNonExistentAsset(contract);
-
+			new App(gateway).run();
 		} finally {
 			channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
-
 		}
 	}
-	
+
 	private static ManagedChannel newGrpcConnection() throws IOException, CertificateException {
 		Reader tlsCertReader = Files.newBufferedReader(tlsCertPath);
 		X509Certificate tlsCert = Identities.readX509Certificate(tlsCertReader);
@ -141,24 +101,42 @@ public class App {
 	}

 	private static Signer newSigner() throws IOException, InvalidKeyException {
-		File dir = new File(keyPath.toString());
-		File[] listOfFiles = dir.listFiles();
-		Path path = Paths.get(listOfFiles[0].getPath());
-		Reader keyReader = Files.newBufferedReader(path);
+		Path keyPath = Files.list(keyDirPath)
+				.findFirst()
+				.orElseThrow();
+		Reader keyReader = Files.newBufferedReader(keyPath);
 		PrivateKey privateKey = Identities.readPrivateKey(keyReader);

 		return Signers.newPrivateKeySigner(privateKey);
 	}

-	private static final Gson gson = new GsonBuilder().setPrettyPrinting().create();
+	public App(final Gateway gateway) {
+		// Get a network instance representing the channel where the smart contract is
+		// deployed.
+		Network network = gateway.getNetwork(channelName);

-	private static String prettyJson(byte[] json) {
-		return prettyJson(new String(json, StandardCharsets.UTF_8));
+		// Get the smart contract from the network.
+		contract = network.getContract(chaincodeName);
 	}

-	private static String prettyJson(String json) {
-		JsonElement parsedJson = JsonParser.parseString(json);
-		return gson.toJson(parsedJson);
+	public void run() throws GatewayException, CommitException {
+		// Initialize a set of asset data on the ledger using the chaincode 'InitLedger' function.
+		initLedger();
+
+		// Return all the current assets on the ledger.
+		getAllAssets();
+
+		// Create a new asset on the ledger.
+		createAsset();
+
+		// Update an existing asset asynchronously.
+		transferAssetAsync();
+
+		// Get the asset details by assetID.
+		readAssetById();
+
+		// Update an asset which does not exist.
+		updateNonExistentAsset();
 	}
 	
 	/**
@ -166,44 +144,44 @@ public class App {
 	 * the first time it was started after its initial deployment. A new version of
 	 * the chaincode deployed later would likely not need to run an "init" function.
 	 */
-	private static void initLedger(Contract contract) throws GatewayException, CommitException {
-
-		System.out.println(
-				"\n" + "--> Submit Transaction: InitLedger, function creates the initial set of assets on the ledger");
+	private void initLedger() throws EndorseException, SubmitException, CommitStatusException, CommitException {
+		System.out.println("\n--> Submit Transaction: InitLedger, function creates the initial set of assets on the ledger");

 		contract.submitTransaction("InitLedger");

 		System.out.println("*** Transaction committed successfully");
-
 	}

 	/**
 	 * Evaluate a transaction to query ledger state.
 	 */
-	private static void getAllAssets(Contract contract) throws GatewayException {
-
-		System.out.println(
-				"\n" + "--> Evaluate Transaction: GetAllAssets, function returns all the current assets on the ledger");
+	private void getAllAssets() throws GatewayException {
+		System.out.println("\n--> Evaluate Transaction: GetAllAssets, function returns all the current assets on the ledger");
 		
 		byte[] result = contract.evaluateTransaction("GetAllAssets");
 		
 		System.out.println("*** Result: " + prettyJson(result));
+	}

+	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);
 	}

 	/**
 	 * Submit a transaction synchronously, blocking until it has been committed to
 	 * the ledger.
 	 */
-	private static void createAsset(Contract contract) throws GatewayException, CommitException {
-
-		System.out.println("\n"
-				+ "--> Submit Transaction: CreateAsset, creates new asset with ID, Color, Size, Owner and AppraisedValue arguments");
+	private void createAsset() throws EndorseException, SubmitException, CommitStatusException, CommitException {
+		System.out.println("\n--> Submit Transaction: CreateAsset, creates new asset with ID, Color, Size, Owner and AppraisedValue arguments");

 		contract.submitTransaction("CreateAsset", assetId, "yellow", "5", "Tom", "1300");

 		System.out.println("*** Transaction committed successfully");
-		
 	}

 	/**
@ -211,9 +189,8 @@ public class App {
 	 * smart contract response (e.g. update a UI) while waiting for the commit
 	 * notification.
 	 */
-	private static void transferAssetAsync(Contract contract) throws GatewayException {
-
-		System.out.println("\n" + "--> Async Submit Transaction: TransferAsset, updates existing asset owner");
+	private void transferAssetAsync() throws EndorseException, SubmitException, CommitStatusException {
+		System.out.println("\n--> Async Submit Transaction: TransferAsset, updates existing asset owner");
 		
 		SubmittedTransaction commit = contract.newProposal("TransferAsset")
 				.addArguments(assetId, "Saptha")
@ -224,24 +201,20 @@ public class App {
 		byte[] result = commit.getResult();
 		String oldOwner = new String(result, StandardCharsets.UTF_8);

-		System.out.println(
-				"*** Successfully submitted transaction to transfer ownership from " + oldOwner + " to Saptha");
+		System.out.println("*** Successfully submitted transaction to transfer ownership from " + oldOwner + " to Saptha");
 		System.out.println("*** Waiting for transaction commit");
 		
 		Status status = commit.getStatus();
 		if (!status.isSuccessful()) {
-			throw new RuntimeException("Transaction " + status.getTransactionId() + " failed to commit with status code "
-					+ status.getCode());
-
+			throw new RuntimeException("Transaction " + status.getTransactionId() +
+					" failed to commit with status code " + status.getCode());
 		}
 		
 		System.out.println("*** Transaction committed successfully");
-
 	}

-	private static void readAssetById(Contract contract) throws GatewayException {
-
-		System.out.println("\n" + "--> Evaluate Transaction: ReadAsset, function returns asset attributes");
+	private void readAssetById() throws GatewayException {
+		System.out.println("\n--> Evaluate Transaction: ReadAsset, function returns asset attributes");
 		
 		byte[] evaluateResult = contract.evaluateTransaction("ReadAsset", assetId);
 		
@ -252,35 +225,31 @@ public class App {
 	 * submitTransaction() will throw an error containing details of any error
 	 * responses from the smart contract.
 	 */
-	private static void updateNonExistentAsset(Contract contract) {
-
+	private void updateNonExistentAsset() {
 		try {
-			System.out.println("\n"
-					+ "--> Submit Transaction: UpdateAsset asset70, asset70 does not exist and should return an error");
+			System.out.println("\n--> Submit Transaction: UpdateAsset asset70, asset70 does not exist and should return an error");
 			
 			contract.submitTransaction("UpdateAsset", "asset70", "blue", "5", "Tomoko", "300");
 			
 			System.out.println("******** FAILED to return an error");
-
 		} catch (EndorseException | SubmitException | CommitStatusException e) {
 			System.out.println("*** Successfully caught the error: ");
-			
 			e.printStackTrace(System.out);
-			if (!e.getDetails().isEmpty()) {
-				System.out.println("\n" + "Error Details: ");
-				for (ErrorDetail detail : e.getDetails()) {
-					System.out.println("address: " + detail.getAddress() + ", mspId: " + detail.getMspId()
+			System.out.println("Transaction ID: " + e.getTransactionId());
+
+			List<ErrorDetail> details = e.getDetails();
+			if (!details.isEmpty()) {
+				System.out.println("Error Details:");
+				for (ErrorDetail detail : details) {
+					System.out.println("- address: " + detail.getAddress() + ", mspId: " + detail.getMspId()
 							+ ", message: " + detail.getMessage());
 				}
 			}
-			
-			System.out.println("Transaction ID: " + e.getTransactionId());
-			
 		} catch (CommitException e) {
 			System.out.println("*** Successfully caught the error: " + e);
 			e.printStackTrace(System.out);
-			System.out.println("Transaction ID: " + e.getTransactionId() + " status code: " + e.getCode());
+			System.out.println("Transaction ID: " + e.getTransactionId());
+			System.out.println("Status code: " + e.getCode());
 		}
 	}
-
-}
+}
--- a/ci/scripts/run-test-network-basic.sh
+++ b/ci/scripts/run-test-network-basic.sh
@ -46,7 +46,7 @@ createNetwork
 print "Initializing Java application"
 pushd ../asset-transfer-basic/application-gateway-java
 print "Executing Gradle Run"
-gradle run
+./gradlew run
 popd
 stopNetwork