Payment-Gateway

About the Project

The goal is to demonstrate the construction of a modern distributed system with separation of concerns, asynchronous communication, and real-time fraud analysis.

Architecture

View the complete architecture here

System Components

• Frontend (Next.js)

  • User interface for account management and payment processing
  • Built with Next.js to ensure performance and a good user experience

• Gateway (Go)

  • Main system for payment processing
  • Manages accounts, transactions, and coordinates the payment flow
  • Publishes transaction events to Kafka for fraud analysis

• Apache Kafka

  • Responsible for asynchronous communication between the API Gateway and the Anti-fraud service
  • Ensures reliable message exchange between services
  • Specific topics for transactions and analysis results

• Anti-fraud Service (Nest.js)

  • Consumes transaction events from Kafka
  • Performs real-time analysis to detect potential fraud
  • Publishes analysis results back to Kafka

Communication Flow

1. The frontend sends REST requests to the API Gateway
2. The Gateway processes the requests and publishes transaction events to Kafka
3. The Anti-fraud service consumes the events and performs real-time analysis
4. The analysis results are published back to Kafka
5. The Gateway consumes the results and finalizes the transaction processing

Service Startup Order

To run the complete project, services must be started in the following order:

1. API Gateway (Go) – Should be started first as it sets up the Docker network
2. Anti-fraud Service (Nest.js) – Depends on Kafka, which is configured by the Gateway
3. Frontend (Next.js) – The user interface that communicates with the API Gateway

Detailed Instructions

Each system component contains specific setup and configuration instructions in its respective folder:

• API Gateway: See the README in the /go-gateway-api folder
• Anti-fraud Service: See the README in the /nestjs-anti-fraud folder
• Frontend: See the README in the /gateway-fe folder

Important: It's crucial to follow the startup order above, as each service depends on the previous ones to function correctly.

General Prerequisites

To run all components of the project, you’ll need:

• Docker
• Docker Compose
• Git

Key Business Rules

• Transactions over R$ 10,000 are automatically sent for analysis and marked as "pending"
• Smaller transactions are processed immediately
• The interface displays different statuses using colors: green (approved), yellow (pending), red (rejected)