gRPC Example

A simple project to create a simple bootstrap for Android apps using gRPC and Protocol Buffers.

Submodules

• proto contains proto definitions and generated classes
• api-server serves as a gRPC endpoint
• user-app is an android application

Android client

To connect with running local gRPC instance you will have to forward back device localhost port to PC port:

adb reverse tcp:8800 tcp:8800

API server

Server can be run straight from gradle, or as a part of the distribution.

Gradle CLI

cd <root folder>
gradle :api-server:build  # Only builds
gradle :api-server:run    # Builds and starts the server

Running as distribution

cd <root folder>
gradle :api-server:distZip
cp api-server/build/distributions/api-server.zip <destination>

cd <destination>
unzip api-server.zip
cd api-server
./bin/api-server

Running as distribution from Android Studio

Gradle cannot handle two projects with common dependency at the same time. You can use api-server run configuration (or type gradle :api-server:runServer) to start server from Android Studio.

CLI for RPCs

You can use Polyglot to test calls. Just send JSON-formatted input to the script:

echo {} | java -jar polyglot.jar --command=call --endpoint=localhost:8800 \
    --full_method="com.kantoniak.examplegrpc.proto.EntryService/GetAll" \
    --proto_discovery_root="<project-root>/proto/src/main/proto"

java -jar polyglot.jar --command=list_services \
    --proto_discovery_root="<project-root>/proto/src/main/proto"

Dependency on protos

If your module needs to use classes generated from proto, remember to add

apply from: project(':proto').file("proto-deps.gradle")

dependencies {
    implementation project(":proto")
}

to build.gradle of the module.