Federation & Service
What Federation and Service are in Downcity's AI infrastructure
Federation & Service
Federation is the model abstraction layer in City. It provides a unified interface over multiple AI providers (OpenAI, Anthropic, Google, local models, etc.) so that Agents do not need to hardcode provider-specific APIs.
Federation AIService
The Federation AIService is a City component that:
- Registers model providers and their capabilities
- Exposes a unified model API regardless of the backend
- Tracks usage and routes requests to the appropriate provider
- Handles failover and rate limiting
An Agent binds to a model through an ID like "default" or "quality". The Federation AIService resolves this ID to a live model instance at runtime.
Service / Action infrastructure
City also provides a general-purpose Service and Action layer for building backend capabilities that Agents can call:
- Service — a long-running backend capability (e.g., a knowledge base, a search engine, a database)
- Action — a discrete operation that an Agent can invoke (e.g., send an email, query a database, call an external API)
Services and Actions are registered with City and can be discovered and called by any connected Agent.
Relationship to City
Federation is a subsystem of City. When you use the City SDK, you are interacting with:
- City identity and auth
- Federation AIService (model catalog and routing)
- Service/Action infrastructure (backend capabilities)
- Usage, balance, and billing (City Services)