Architecture & Core Pipeline

langchain-openapi processes raw OpenAPI specs into native LangChain tools using a clean, modular pipeline.

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Execution Pipeline

OpenAPI Spec (JSON / YAML / Dict)
              │
              ▼
       OpenAPILoader
              │
              ▼
        OpenAPIParser
              │
              ▼
      SchemaConverter ────► Pydantic Dynamic Models
              │
              ▼
    LangChainToolFactory
              │
              ▼
      AsyncHTTPExecutor
              │
              ▼
     Middleware Pipeline (Retry, Cache, RateLimit, Logging, Pagination)
              │
              ▼
      Request Providers (Authentication & Header Mutations)
              │
              ▼
         httpx.AsyncClient (Target HTTP API)

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Pipeline Components

1. OpenAPILoader

In-gests raw JSON/YAML specifications from local disk files, remote HTTP endpoints, or in-memory dictionaries. Normalizes encoding and format.

2. OpenAPIParser

Translates raw specification dictionaries into strongly-typed internal data models (Operation, Parameter, RequestBody, Response, Schema). Resolves internal $ref pointers using ReferenceResolver.

3. SchemaConverter & PydanticFactory

Converts JSON Schema representations into dynamic Pydantic models at runtime using pydantic.create_model(). Ensures incoming LLM function call arguments adhere to strict type schemas.

4. LangChainToolFactory

Translates parsed Operation models into executable LangChain StructuredTool instances.

5. AsyncHTTPExecutor

Orchestrates request building, middleware execution, provider transformations, and asynchronous network transport.

6. Middleware Pipeline

Intercepts outgoing requests and incoming responses to apply retries, rate limiting, caching, result aggregation, and sanitized telemetry.

7. Request Providers

Applies authentication schemes (Bearer tokens, API Keys, Basic Auth) and static headers before network transport.