Reverse Proxy
Acts as a single point of contact for clients, forwarding requests to appropriate backend servers. It offers features like SSL termination, caching, and security filtering.
Key Functions:
- Forwarding: Directs client requests to backend servers.
- SSL Termination: Handles HTTPS encryption/decryption.
- Caching: Stores frequently accessed responses to speed up delivery.
- Security: Filters web traffic, masks IP addresses.
- General-purpose for websites, APIs, WebSockets.
Load Balancer
A specialized reverse proxy designed to distribute incoming network traffic across multiple backend servers, enhancing availability and scalability.
Key Functions:
- Traffic Distribution: Spreads requests across multiple servers.
- Scalability: Handles more traffic by using multiple servers.
- Availability: Routes traffic away from unhealthy servers.
- Algorithms: Round Robin, Least Connections, IP Hash, Weighted.
- Operates at Layer 4 (Transport Layer).
API Gateway
An API-aware reverse proxy that manages, secures, and monitors your APIs, essential for microservices architectures to handle cross-cutting concerns.
Key Functions:
- Authentication & Authorization: Manages client access.
- Rate Limiting: Enforces request limits per tier.
- Request/Response Transformation: Modifies data formats.
- API Versioning: Routes requests to specific service versions.
- Analytics & Monitoring: Tracks API usage and performance.
Choosing the Right Tool
The choice between these intermediaries depends on your specific architectural needs. Often, they are used in combination:
- Need multiple instances of a service for high availability? Consider a Load Balancer.
- Exposing APIs to external consumers with security, rate limiting, or transformation needs? An API Gateway is crucial.
- Simply need SSL termination and caching for a single web server? A Reverse Proxy might be sufficient.
In microservices, an API Gateway often sits at the edge, routing to internal load balancers, which then distribute traffic to individual services.