Principle:Helicone Helicone Request Routing and Validation
| Knowledge Sources | |
|---|---|
| Domains | Proxy Architecture, Request Routing, API Gateway |
| Last Updated | 2026-02-14 00:00 GMT |
Overview
Request routing and validation is the process of dispatching an intercepted request to the correct handler based on the type of proxy service being operated, while applying common validation and middleware logic.
Description
In a multi-provider LLM proxy, a single codebase must serve traffic destined for many different providers (OpenAI, Anthropic, Azure, custom gateways, and more). Rather than deploying entirely separate services for each provider, the system uses a routing layer that examines the worker type configured at deployment time and selects the appropriate handler chain.
This routing layer sits between request interception and provider communication. After the raw HTTP request has been parsed and wrapped, the router determines which provider-specific logic to apply. Each provider may have different URL rewriting rules, header transformations, streaming behaviors, and authentication flows. The router encapsulates this divergence behind a common interface so that cross-cutting concerns -- health checks, CORS handling, feedback endpoints -- are defined once and shared across all provider types.
Validation is an integral part of this stage. The router ensures that the worker type is recognized, that required environment variables are present, and that the request matches an expected route pattern before handing off to provider-specific logic. Unrecognized routes or misconfigured workers result in clear error responses.
Usage
Use request routing and validation when operating a polymorphic proxy that must support multiple upstream providers from a single deployment artifact. This pattern is appropriate whenever the choice of downstream handler depends on a deployment-time configuration parameter rather than on the content of the individual request.
Theoretical Basis
The pattern is an application of the Strategy pattern combined with a Front Controller. A front controller receives all inbound requests and delegates to a strategy (provider-specific router) selected at initialization time.
The theoretical process is:
- Read the worker type from the deployment environment.
- Instantiate a base router with shared middleware (health check, CORS, feedback).
- Look up the provider-specific router builder in a dispatch table keyed by worker type.
- Invoke the builder, which registers provider-specific routes on the base router.
- Return the composed router, ready to match incoming request paths to handlers.
This allows new provider support to be added by implementing a new router builder and registering it in the dispatch table, without modifying the shared middleware or the router factory itself.