Introduces an example project using Kotlin

examples/local-grpc-kt/build.gradle.kts

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+import com.google.protobuf.gradle.generateProtoTasks
+import com.google.protobuf.gradle.id
+import com.google.protobuf.gradle.ofSourceSet
+import com.google.protobuf.gradle.plugins
+import com.google.protobuf.gradle.protobuf
+import com.google.protobuf.gradle.protoc
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    kotlin("jvm")
+    id("org.springframework.boot")
+    id("io.spring.dependency-management")
+    kotlin("plugin.spring")
+    id("com.google.protobuf")
+}
+
+group = "net.devh"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+    mavenCentral()
+    mavenLocal()
+}
+
+val grpcVersion: String by project
+val jakartaAnnotationApiVersion: String by project
+val protobufVersion: String by project
+val grpcKotlinVersion: String by project
+val grpcSpringBootStarterVersion: String by project
+val kotlinCoroutinesVersion: String by project
+dependencies {
+    implementation(kotlin("reflect"))
+    implementation(platform("org.jetbrains.kotlinx:kotlinx-coroutines-bom:$kotlinCoroutinesVersion"))
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-jdk8")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core")
+    implementation("org.springframework.boot:spring-boot-starter")
+    implementation("net.devh:grpc-spring-boot-starter:$grpcSpringBootStarterVersion")
+    implementation(platform("io.grpc:grpc-bom:$grpcVersion"))
+    implementation("jakarta.annotation:jakarta.annotation-api:$jakartaAnnotationApiVersion")
+    implementation("com.google.protobuf:protobuf-java:$protobufVersion")
+    implementation("io.grpc:grpc-kotlin-stub:$grpcKotlinVersion")
+    implementation("io.grpc:grpc-protobuf")
+    implementation("io.grpc:grpc-stub")
+    testImplementation("org.springframework.boot:spring-boot-starter-test") {
+        exclude(group = "org.junit.vintage", module = "junit-vintage-engine")
+    }
+}
+
+tasks.withType<Test> {
+    useJUnitPlatform()
+}
+
+tasks.withType<KotlinCompile> {
+    kotlinOptions {
+        freeCompilerArgs = listOf("-Xjsr305=strict")
+        jvmTarget = "1.8"
+    }
+}
+
+protobuf {
+    protoc {
+        artifact = "com.google.protobuf:protoc:$protobufVersion"
+    }
+    plugins {
+        id("grpc") {
+            artifact = "io.grpc:protoc-gen-grpc-java:$grpcVersion"
+        }
+        id("grpckt") {
+            artifact = "io.grpc:protoc-gen-grpc-kotlin:$grpcKotlinVersion"
+        }
+    }
+    generateProtoTasks {
+        ofSourceSet("main").forEach {
+            it.plugins {
+                id("grpc")
+                id("grpckt")
+            }
+        }
+    }
+}
+
+sourceSets {
+    main {
+        java {
+            srcDirs(
+					file("build/generated/source/proto/main")
+							.walkTopDown()
+							.maxDepth(1)
+							.asIterable()
+			)
+        }
+    }
+}
+

examples/local-grpc-kt/gradle.properties

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+kotlinVersion=1.4.0
+springBootVersion=2.3.3.RELEASE
+springDependencyManagementPluginVersion=1.0.10.RELEASE
+protobufPluginVersion=0.8.13
+protobufVersion=3.13.0
+grpcVersion=1.31.1
+jakartaAnnotationApiVersion=1.3.5
+grpcKotlinVersion=0.1.5
+grpcSpringBootStarterVersion=2.10.0.RELEASE
+kotlinCoroutinesVersion=1.3.9

examples/local-grpc-kt/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.4.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

examples/local-grpc-kt/gradlew

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+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or 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 UN*X
+##
+##############################################################################
+
+# 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"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$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" = "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" ;;
+    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, 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"
+
+exec "$JAVACMD" "$@"