Transit Tracker API

A real-time GraphQL API for tracking transit information, built with Spring Boot and Kafka.

Features

• GraphQL API: Query for trips, vehicles, and stop times.
• Real-time Updates: Subscribe to live trip updates via GraphQL Subscriptions (WebSockets).
• Kafka Integration: Publishes and consumes GTFS Realtime data using Kafka.
• Automatic Polling: Fetches data from the GTFS Realtime feed every 30 seconds.
• Filtering: Filter trips by routeId and vehicleId.

Prerequisites

• Java 21 or higher
• Docker & Docker Compose (for Kafka)

Getting Started

1. Start Infrastructure

Start the Kafka and Zookeeper containers:

docker-compose up -d # If you do not want to see logs
docker-compose up # If you want to see logs

2. Run the Application

Start the Spring Boot server:

./gradlew bootRun

The server will start on http://localhost:8080.

3. Access the API

Open the custom GraphiQL interface in your browser:

http://localhost:8080/graphiql.html

API Usage

Queries

Get all trips:

query {
  trips {
    tripId
    routeId
    vehicle {
      id
      label
    }
  }
}

Filter trips by Route and Vehicle:

query {
  trips(routeId: "301", vehicleId: "21501") {
    tripId
    routeId
    vehicle {
      label
    }
  }
}

Subscriptions

Subscribe to all updates:

subscription {
  feedUpdates {
    timestamp
    trips {
      tripId
      stopTimeUpdates {
        stopSequence
        arrival {
          delay
        }
      }
    }
  }
}

Subscribe to updates for a specific route:

subscription {
  feedUpdates(routeId: "301") {
    timestamp
    trips {
      tripId
      vehicle {
        label
      }
    }
  }
}

Development

To run with hot reloading (automatically restarts on file changes):

./gradlew bootRun --continuous