# API Gateway

## Overview
The API Gateway service will provide a unified entry point for all external API requests to the stock-bot platform. It will handle request routing, composition, protocol translation, authentication, and other cross-cutting concerns, providing a simplified interface for clients while abstracting the internal microservice architecture.

## Planned Features

### Request Management
- **Routing**: Direct requests to appropriate backend services
- **Aggregation**: Combine results from multiple microservices
- **Transformation**: Convert between different data formats and protocols
- **Parameter Validation**: Validate request parameters before forwarding
- **Service Discovery**: Dynamically locate service instances

### Security Features
- **Authentication**: Centralized authentication for all API requests
- **Authorization**: Role-based access control for API endpoints
- **API Keys**: Management of client API keys and quotas
- **JWT Validation**: Token-based authentication handling
- **OAuth Integration**: Support for OAuth 2.0 flows

### Traffic Management
- **Rate Limiting**: Protect services from excessive requests
- **Throttling**: Client-specific request throttling
- **Circuit Breaking**: Prevent cascading failures
- **Load Balancing**: Distribute requests among service instances
- **Retries**: Automatic retry of failed requests

### Operational Features
- **Request Logging**: Comprehensive logging of API activity
- **Metrics Collection**: Performance and usage metrics
- **Caching**: Response caching for improved performance
- **Documentation**: Auto-generated API documentation
- **Versioning**: Support for multiple API versions

## Planned Integration Points

### Frontend Connections
- Trading Dashboard (web client)
- Mobile applications
- Third-party integrations
- Partner systems

### Backend Services
- All platform microservices
- Authentication services
- Monitoring and logging systems

## Planned Technical Implementation

### Technology Stack
- **API Gateway**: Kong, AWS API Gateway, or custom solution
- **Runtime**: Node.js with TypeScript
- **Documentation**: OpenAPI/Swagger
- **Cache**: Redis for response caching
- **Storage**: Database for API configurations

### Architecture Pattern
- Backend for Frontend (BFF) pattern
- API Gateway pattern
- Circuit breaker pattern
- Bulkhead pattern for isolation

## Development Guidelines

### API Design
- RESTful API design standards
- Error response format
- Versioning strategy
- Resource naming conventions

### Security Implementation
- Authentication requirements
- Authorization approach
- API key management
- Rate limit configuration

### Performance Optimization
- Caching strategies
- Request batching techniques
- Response compression
- Timeout configurations

## Implementation Roadmap
1. Core routing and basic security features
2. Traffic management and monitoring
3. Request aggregation and transformation
4. Advanced security features
5. Developer portal and documentation