Fraud System Demo

This repository contains two related projects:

1. fraud-service-demo - A gRPC-based service that provides fraud detection data.
2. fraud-client - A client that interacts with the fraud service.

📂 Project Structure

/fraud-system
  /fraud-service  # gRPC service
    build.gradle
    settings.gradle
    Dockerfile
    src/
  /fraud-client   # Client application
    build.gradle
    settings.gradle
    Dockerfile
    src/
  README.md # This file
  docker-compose.yml # Docker Compose file

🏗️ How to Build

Each project can be built independently. Navigate to the respective folder and run:

    ./gradlew clean build

For Windows:

    gradlew.bat build

🚀 Running the Services

Each service can be started independently. Navigate to fraud-service-demo and run:

./gradlew bootRun

To start the client, navigate to fraud-client and run:

./gradlew bootRun

🛠️ Testing with grpcurl

Once the service is running on localhost:9090, you can test it using grpcurl. See the fraud-service/README.md for details.

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Fraud Detection Service

The Fraud Detection Service is a gRPC-based service that provides fraud-related transaction data.

📂 Folder Structure

/fraud-service /src /main /java/com/example/fraudservice # Java code /resources application.yml # Configuration /proto # Protocol Buffers definitions fraud_service.proto build.gradle settings.gradle README.md

🛠️ Setup & Running

1️⃣ Install Dependencies

Make sure you have Java 17+ and Gradle installed.

2️⃣ Build the Project

Run:

./gradlew build

3️⃣ Start the Service

Run:

./gradlew bootRun

The service should start on localhost:9090.

📡 API Endpoints (gRPC)

Once the service is running, you can test it using grpcurl.

List all available services

grpcurl -plaintext localhost:9090 list

List methods in a service

grpcurl -plaintext localhost:9090 list fraudservice.FraudService

Call a method (Get list of countries)

grpcurl -plaintext -d '{}' localhost:9090 fraudservice.FraudService/GetCountries

Call a method with parameters (Get transactions by country)

grpcurl -plaintext -d '{"country_code": "US"}' localhost:9090 fraudservice.FraudService/GetTransactionsByCountry

📝 Proto File (fraud_service.proto)

The service is defined using Protocol Buffers:

syntax = "proto3";

package fraudservice;

service FraudService {
    rpc GetCountries (Empty) returns (CountryList);
    rpc GetTransactionsByCountry (TransactionRequest) returns (TransactionList);
}

message Empty {}

message CountryList {
    repeated string countries = 1;
}

message TransactionRequest {
    string country_code = 1;
}

message TransactionList {
    repeated Transaction transactions = 1;
}

message Transaction {
    string transaction_id = 1;
    double amount = 2;
    string timestamp = 3;
}

🛠️ Logging & Debugging

• Application logs can be found in the console output.
• Use grpcurl to test API responses.

🏗️ Future Improvements

• Add authentication to gRPC calls.
• Implement a database to store transactions.
• Optimize performance for high-load scenarios.