diff --git a/scalardb-kotlin-sample/build.gradle.kts b/scalardb-kotlin-sample/build.gradle.kts
new file mode 100644
index 0000000..1bc59a6
--- /dev/null
+++ b/scalardb-kotlin-sample/build.gradle.kts
@@ -0,0 +1,35 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    kotlin("jvm") version "1.8.21"
+    application
+}
+
+group = "com.scalar-labs"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("com.scalar-labs", "scalardb", "3.13.0")
+    testImplementation(kotlin("test"))
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
+
+tasks.withType<KotlinCompile> {
+    kotlinOptions.jvmTarget = "1.8"
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
+application {
+    mainClass.set("MainKt")
+}
diff --git a/scalardb-kotlin-sample/database.properties b/scalardb-kotlin-sample/database.properties
new file mode 100644
index 0000000..16a8f86
--- /dev/null
+++ b/scalardb-kotlin-sample/database.properties
@@ -0,0 +1,41 @@
+# For MySQL
+# scalar.db.storage=jdbc
+# scalar.db.contact_points=jdbc:mysql://localhost:3306/
+# scalar.db.username=root
+# scalar.db.password=mysql
+
+# For PostgreSQL
+# scalar.db.storage=jdbc
+# scalar.db.contact_points=jdbc:postgresql://localhost:5432/
+# scalar.db.username=postgres
+# scalar.db.password=postgres
+
+# For Oracle
+# scalar.db.storage=jdbc
+# scalar.db.contact_points=jdbc:oracle:thin:@//localhost:1521/FREEPDB1
+# scalar.db.username=SYSTEM
+# scalar.db.password=Oracle
+
+# For SQL Server
+# scalar.db.storage=jdbc
+# scalar.db.contact_points=jdbc:sqlserver://localhost:1433;encrypt=true;trustServerCertificate=true
+# scalar.db.username=sa
+# scalar.db.password=SqlServer22
+
+# For DynamoDB Local
+# scalar.db.storage=dynamo
+# scalar.db.contact_points=sample
+# scalar.db.username=sample
+# scalar.db.password=sample
+# scalar.db.dynamo.endpoint_override=http://localhost:8000
+
+# For Cosmos DB
+# scalar.db.storage=cosmos
+# scalar.db.contact_points=<COSMOS_DB_FOR_NOSQL_URI>
+# scalar.db.password=<COSMOS_DB_FOR_NOSQL_KEY>
+
+# For Cassandra
+# scalar.db.storage=cassandra
+# scalar.db.contact_points=localhost
+# scalar.db.username=cassandra
+# scalar.db.password=cassandra
diff --git a/scalardb-kotlin-sample/docker-compose.yml b/scalardb-kotlin-sample/docker-compose.yml
new file mode 100644
index 0000000..b7094bb
--- /dev/null
+++ b/scalardb-kotlin-sample/docker-compose.yml
@@ -0,0 +1,42 @@
+services:
+  mysql:
+    image: mysql:8.1
+    container_name: "mysql-1"
+    environment:
+      MYSQL_ROOT_PASSWORD: mysql
+    ports:
+      - "3306:3306"
+  postgres:
+    image: postgres:15
+    container_name: "postgres-1"
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+    ports:
+      - "5432:5432"
+  oracle:
+    image: container-registry.oracle.com/database/free:23.4.0.0
+    container_name: "oracle-1"
+    environment:
+      ORACLE_PWD: Oracle
+    ports:
+      - "1521:1521"
+  sqlserver:
+    image: mcr.microsoft.com/mssql/server:2022-latest
+    container_name: "sqlserver-1"
+    environment:
+      MSSQL_PID: "Express"
+      SA_PASSWORD: "SqlServer22"
+      ACCEPT_EULA: "Y"
+    ports:
+      - "1433:1433"
+  dynamodb:
+    image: amazon/dynamodb-local:2.5.2
+    container_name: "dynamodb-1"
+    ports:
+      - "8000:8000"
+  cassandra:
+    image: cassandra:3.11
+    container_name: "cassandra-1"
+    ports:
+      - "9042:9042"
diff --git a/scalardb-kotlin-sample/gradle.properties b/scalardb-kotlin-sample/gradle.properties
new file mode 100644
index 0000000..7fc6f1f
--- /dev/null
+++ b/scalardb-kotlin-sample/gradle.properties
@@ -0,0 +1 @@
+kotlin.code.style=official
diff --git a/scalardb-kotlin-sample/gradle/wrapper/gradle-wrapper.jar b/scalardb-kotlin-sample/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..e644113
Binary files /dev/null and b/scalardb-kotlin-sample/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/scalardb-kotlin-sample/gradle/wrapper/gradle-wrapper.properties b/scalardb-kotlin-sample/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..b82aa23
--- /dev/null
+++ b/scalardb-kotlin-sample/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/scalardb-kotlin-sample/gradlew b/scalardb-kotlin-sample/gradlew
new file mode 100755
index 0000000..1aa94a4
--- /dev/null
+++ b/scalardb-kotlin-sample/gradlew
@@ -0,0 +1,249 @@
+#!/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/HEAD/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
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&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: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$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
+
+
+# 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"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$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 "$JAVACMD" "$@"
diff --git a/scalardb-kotlin-sample/gradlew.bat b/scalardb-kotlin-sample/gradlew.bat
new file mode 100644
index 0000000..7101f8e
--- /dev/null
+++ b/scalardb-kotlin-sample/gradlew.bat
@@ -0,0 +1,92 @@
+@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=.
+@rem This is normally unused
+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% equ 0 goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+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% equ 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!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/scalardb-kotlin-sample/scalardb.properties b/scalardb-kotlin-sample/scalardb.properties
new file mode 100644
index 0000000..b1dbcbd
--- /dev/null
+++ b/scalardb-kotlin-sample/scalardb.properties
@@ -0,0 +1,12 @@
+# Comma-separated contact points
+scalar.db.contact_points=localhost
+
+# Port number for all the contact points. Default port number for each database is used if empty.
+#scalar.db.contact_port=
+
+# Credential information to access the database
+scalar.db.username=cassandra
+scalar.db.password=cassandra
+
+# Storage implementation. Either cassandra or cosmos or dynamo or jdbc can be set. Default storage is cassandra.
+#scalar.db.storage=cassandra
diff --git a/scalardb-kotlin-sample/schema.json b/scalardb-kotlin-sample/schema.json
new file mode 100644
index 0000000..95a8b99
--- /dev/null
+++ b/scalardb-kotlin-sample/schema.json
@@ -0,0 +1,13 @@
+{
+  "emoney.account": {
+    "transaction": true,
+    "partition-key": [
+      "id"
+    ],
+    "clustering-key": [],
+    "columns": {
+      "id": "TEXT",
+      "balance": "INT"
+    }
+  }
+}
diff --git a/scalardb-kotlin-sample/settings.gradle.kts b/scalardb-kotlin-sample/settings.gradle.kts
new file mode 100644
index 0000000..897772e
--- /dev/null
+++ b/scalardb-kotlin-sample/settings.gradle.kts
@@ -0,0 +1,3 @@
+
+rootProject.name = "scalardb-kotlin-sample"
+
diff --git a/scalardb-kotlin-sample/src/main/kotlin/Main.kt b/scalardb-kotlin-sample/src/main/kotlin/Main.kt
new file mode 100644
index 0000000..13a9b37
--- /dev/null
+++ b/scalardb-kotlin-sample/src/main/kotlin/Main.kt
@@ -0,0 +1,67 @@
+import sample.ElectronicMoney
+import java.io.File
+import kotlin.system.exitProcess
+
+fun main(args: Array<String>) {
+    var action: String? = null
+    var amount = 0
+    var to: String? = null
+    var from: String? = null
+    var id: String? = null
+    var scalarDBProperties: String? = null
+    var i = 0
+    while (i < args.size) {
+        if ("-action" == args[i]) {
+            action = args[++i]
+        } else if ("-amount" == args[i]) {
+            amount = args[++i].toInt()
+        } else if ("-to" == args[i]) {
+            to = args[++i]
+        } else if ("-from" == args[i]) {
+            from = args[++i]
+        } else if ("-id" == args[i]) {
+            id = args[++i]
+        } else if ("-config" == args[i]) {
+            scalarDBProperties = args[++i]
+        } else if ("-help" == args[i]) {
+            printUsageAndExit()
+            return
+        }
+        ++i
+    }
+    if (action == null) {
+        printUsageAndExit()
+        return
+    }
+    val eMoney = ElectronicMoney(
+        scalarDBProperties ?: (System.getProperty("user.dir") + File.separator + "database.properties")
+    )
+    if (action.equals("charge", ignoreCase = true)) {
+        if (to == null || amount < 0) {
+            printUsageAndExit()
+            return
+        }
+        eMoney.charge(to, amount)
+    } else if (action.equals("pay", ignoreCase = true)) {
+        if (to == null || amount < 0 || from == null) {
+            printUsageAndExit()
+            return
+        }
+        eMoney.pay(from, to, amount)
+    } else if (action.equals("getBalance", ignoreCase = true)) {
+        if (id == null) {
+            printUsageAndExit()
+            return
+        }
+        val balance = eMoney.getBalance(id)
+        println("The balance for $id is $balance")
+    }
+    eMoney.close()
+}
+
+fun printUsageAndExit() {
+    System.err.println(
+        "ElectronicMoneyMain -action charge/pay/getBalance [-amount number (needed for charge and pay)] [-to id (needed for charge and pay)] [-from id (needed for pay)] [-id id (needed for getBalance)]"
+    )
+    exitProcess(1)
+}
diff --git a/scalardb-kotlin-sample/src/main/kotlin/sample/ElectronicMoney.kt b/scalardb-kotlin-sample/src/main/kotlin/sample/ElectronicMoney.kt
new file mode 100644
index 0000000..15cefaa
--- /dev/null
+++ b/scalardb-kotlin-sample/src/main/kotlin/sample/ElectronicMoney.kt
@@ -0,0 +1,141 @@
+package sample
+
+import com.scalar.db.api.DistributedTransactionManager
+import com.scalar.db.api.Get
+import com.scalar.db.api.Put
+import com.scalar.db.exception.transaction.TransactionException
+import com.scalar.db.io.Key
+import com.scalar.db.service.TransactionFactory
+
+class ElectronicMoney(scalarDBProperties: String) {
+    companion object {
+        private const val NAMESPACE = "emoney"
+        private const val TABLENAME = "account"
+        private const val ID = "id"
+        private const val BALANCE = "balance"
+    }
+
+    private val manager: DistributedTransactionManager
+
+    init {
+        val factory = TransactionFactory.create(scalarDBProperties)
+        manager = factory.transactionManager
+    }
+
+    @Throws(TransactionException::class)
+    fun charge(id: String, amount: Int) {
+        // Start a transaction
+        val tx = manager.start()
+        try {
+            // Retrieve the current balance for id
+            val get = Get.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, id))
+                .build()
+            val result = tx.get(get)
+
+            // Calculate the balance
+            var balance = amount
+            if (result.isPresent) {
+                val current = result.get().getInt(BALANCE)
+                balance += current
+            }
+
+            // Update the balance
+            val put = Put.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, id))
+                .intValue(BALANCE, balance)
+                .build()
+            tx.put(put)
+
+            // Commit the transaction (records are automatically recovered in case of failure)
+            tx.commit()
+        } catch (e: Exception) {
+            tx.abort()
+            throw e
+        }
+    }
+
+    @Throws(TransactionException::class)
+    fun pay(fromId: String, toId: String, amount: Int) {
+        // Start a transaction
+        val tx = manager.start()
+        try {
+            // Retrieve the current balances for ids
+            val fromGet = Get.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, fromId))
+                .build()
+            val toGet = Get.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, toId))
+                .build()
+            val fromResult = tx.get(fromGet)
+            val toResult = tx.get(toGet)
+
+            // Calculate the balances (it assumes that both accounts exist)
+            val newFromBalance = fromResult.get().getInt(BALANCE) - amount
+            val newToBalance = toResult.get().getInt(BALANCE) + amount
+            if (newFromBalance < 0) {
+                throw RuntimeException("$fromId doesn't have enough balance.")
+            }
+
+            // Update the balances
+            val fromPut = Put.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, fromId))
+                .intValue(BALANCE, newFromBalance)
+                .build()
+            val toPut = Put.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, toId))
+                .intValue(BALANCE, newToBalance)
+                .build()
+            tx.put(fromPut)
+            tx.put(toPut)
+
+            // Commit the transaction (records are automatically recovered in case of failure)
+            tx.commit()
+        } catch (e: Exception) {
+            tx.abort()
+            throw e
+        }
+    }
+
+    @Throws(TransactionException::class)
+    fun getBalance(id: String): Int {
+        // Start a transaction
+        val tx = manager.start()
+        return try {
+            // Retrieve the current balances for id
+            val get = Get.newBuilder()
+                .namespace(NAMESPACE)
+                .table(TABLENAME)
+                .partitionKey(Key.ofText(ID, id))
+                .build()
+            val result = tx.get(get)
+            var balance = -1
+            if (result.isPresent) {
+                balance = result.get().getInt(BALANCE)
+            }
+
+            // Commit the transaction
+            tx.commit()
+            balance
+        } catch (e: Exception) {
+            tx.abort()
+            throw e
+        }
+    }
+
+    fun close() {
+        manager.close()
+    }
+}