Prompt

Implement API gateway pattern for microservices.

<backend_services>
{list of backend APIs}
</backend_services>

<client_needs>
{different client requirements}
</client_needs>

<cross_cutting_concerns>
{auth, rate limiting, etc}
</cross_cutting_concerns>

Implement:
1. Gateway technology choice
2. Request routing logic
3. Authentication/authorization
4. Rate limiting strategy
5. Response aggregation
6. Caching approach