gRPC Kotlin examples

Examples

This directory contains several Kotlin gRPC examples. You can find detailed instructions for building and running the two main examples from the grpc.io Kotlin/JVM pages:

• Greeter ("hello world"): for details, see Quick start.
• Route guide: for details, see Basics tutorial

Instructions for the remaining examples are provided below.

File organization

The example sources are organized into the following top-level folders:

• protos: .proto files (shared across examples)
• stub: regular Java & Kotlin stub artifacts from protos
• stub-lite: lite Java & Kotlin stub artifacts from protos
• stub-android: Android-compatible Java & Kotlin stub artifacts from protos
• client: Kotlin clients based on regular stub artifacts
• server: Kotlin servers based on regular stub artifacts
• native-client : GraalVM Native Image clients based stub-lite
• android: Kotlin Android app based on stub-android

Instructions for running other examples

• Multiple-services animals example

  Start the server:

  ./gradlew :server:AnimalsServer

  In another console, run the client against the "dog", "pig", and "sheep" services:

  ./gradlew :client:AnimalsClient --args=dog
  ./gradlew :client:AnimalsClient --args=pig
  ./gradlew :client:AnimalsClient --args=sheep

• GraalVM native image example

  Start the server:

  ./gradlew :server:HelloWorldServer

  In another console, create the native image client and run it:

  ./gradlew :native-client:nativeImage
  native-client/build/graal/hello-world

• Android example

  NOTE: You must use JDK 11 or higher

  Start the server:

  ./gradlew :server:HelloWorldServer

  Run the Client:

  1. Download Android Command Line Tools

  2. Install the SDK:

     mkdir android-sdk
     cd android-sdk
     unzip PATH_TO_SDK_ZIP/sdk-tools-linux-VERSION.zip
     mv cmdline-tools latest
     mkdir cmdline-tools
     mv latest cmdline-tools
     cmdline-tools/latest/bin/sdkmanager --update
     cmdline-tools/latest/bin/sdkmanager "platforms;android-31" "build-tools;31.0.0" "extras;google;m2repository" "extras;android;m2repository"
     cmdline-tools/latest/bin/sdkmanager --licenses

  3. Set an env var pointing to the android-sdk

     export ANDROID_SDK_ROOT=PATH_TO_SDK/android-sdk

  4. Run the build from this project's dir:

     ./gradlew :android:build

  5. You can either run on an emulator or a physical device and you can either connect to the server running on your local machine, or connect to a server you deployed on the cloud.

     • Emulator + Local Server:

       • From the command line:

         ./gradlew :android:installDebug

       • From Android Studio / IntelliJ, navigate to android/src/main/kotlin/io/grpc/examples/helloworld and right-click on MainActivity and select Run.

     • Physical Device + Local Server:

       • From the command line:

         1. Setup adb
         2. ./gradlew :android:installDebug -PserverUrl=http://YOUR_MACHINE_IP:50051/

       • From Android Studio / IntelliJ:

         1. Create a gradle.properties file in your root project directory containing:

            serverUrl=http://YOUR_MACHINE_IP:50051/

         2. Navigate to android/src/main/kotlin/io/grpc/examples/helloworld and right-click on MainActivity and select Run.

     • Emulator or Physical Device + Cloud:

       • From the command line:

         1. setup adb
         2. ./gradlew :android:installDebug -PserverUrl=https://YOUR_SERVER/

       • From Android Studio / IntelliJ:

         1. Create a gradle.properties file in your root project directory containing:

            serverUrl=https://YOUR_SERVER/

         2. Navigate to android/src/main/kotlin/io/grpc/examples/helloworld and right-click on MainActivity and select Run.