Heartbeat

Heartbeat is a demo project I created to experiment with gRPC. The idea is a simple server accepting heartbeats, alive messages, from clients.

protoc

To generate Protocol Buffer support code I used protoc plugins. The script /proto/generate-types.sh is used every time we make changes to the heartbeat.proto file. This will update the generated types and services for the different applications.

For the server and API applications I used the proto-loader node package.

The plugin for Swift is included here, guide here. I fetched it useing homebrew and added the plugin to the repo under /proto/swift.

Up and running

For the first run you may run $ docker-compose up -d postgres first to initialize the Postgres database. This takes some time so we run this command manually to let it have some time to get things done.

Then you can use the up.sh script to start all containers. There's also a down.sh to shut down all containers.

gRPC streaming

I wanted to explore and test the streaming features of gRPC. To do so I had to have some data to pass from the server to the client. My idea is that whenever a new heartbeat is created all connected clients may listen to the stream and get updates. I used the Supabase Realtime library to do this together with PostgreSQL. With the Supabase Realtime it's possible to set up listeners on the database and get notified about changes. For the Heartbeat server I set up a listener on INSERT operations to the heartbeat table in the database. Then I'm able to push updates to every client listening on the heartbeat count stream.

Environment

To set up the desired environment copy the .env.example, modify and name it .env.

iOS app

Installed the GRPC-Swift package using Xcode 11 package manager. https://github.com/grpc/grpc-swift