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# Docling in OpenRAG

OpenRAG uses Docling for document ingestion. More specifically, OpenRAG uses Docling Serve, which starts a `docling serve` process on your local machine and runs Docling ingestion through an API service.

Docling ingests documents from your local machine or OAuth connectors, splits them into chunks, and stores them as separate, structured documents in the OpenSearch `documents` index.

OpenRAG chose Docling for its support for a wide variety of file formats, high performance, and advanced understanding of tables and images.

To modify OpenRAG's ingestion settings, including the Docling settings and ingestion flows, click 2" aria-hidden="true"/> Settings.

## Knowledge ingestion settings​

These settings configure the Docling ingestion parameters.

OpenRAG will warn you if `docling serve` is not running. To start or stop `docling serve` or any other native services, in the TUI main menu, click Start Native Services or Stop Native Services.

Embedding model determines which AI model is used to create vector embeddings. The default is the OpenAI `text-embedding-3-small` model.

Chunk size determines how large each text chunk is in number of characters. Larger chunks yield more context per chunk, but may include irrelevant information. Smaller chunks yield more precise semantic search, but may lack context. The default value of `1000` characters provides a good starting point that balances these considerations.

Chunk overlap controls the number of characters that overlap over chunk boundaries. Use larger overlap values for documents where context is most important, and use smaller overlap values for simpler documents, or when optimization is most important. The default value of 200 characters of overlap with a chunk size of 1000 (20% overlap) is suitable for general use cases. Decrease the overlap to 10% for a more efficient pipeline, or increase to 40% for more complex documents.

Table Structure enables Docling's `DocumentConverter` tool for parsing tables. Instead of treating tables as plain text, tables are output as structured table data with preserved relationships and metadata. Table Structure is enabled by default.

OCR enables or disabled OCR processing when extracting text from images and scanned documents. OCR is disabled by default. This setting is best suited for processing text-based documents as quickly as possible with Docling's `DocumentConverter`. Images are ignored and not processed.

Enable OCR when you are processing documents containing images with text that requires extraction, or for scanned documents. Enabling OCR can slow ingestion performance.

If OpenRAG detects that the local machine is running on macOS, OpenRAG uses the ocrmac OCR engine. Other platforms use easyocr.

Picture descriptions adds image descriptions generated by the SmolVLM-256M-Instruct model to OCR processing. Enabling picture descriptions can slow ingestion performance.

## Knowledge ingestion flows​

Flows in Langflow are functional representations of application workflows, with multiple component nodes connected as single steps in a workflow.

The OpenSearch Ingestion flow is the default knowledge ingestion flow in OpenRAG: when you Add Knowledge in OpenRAG, you run the OpenSearch Ingestion flow in the background. The flow ingests documents using Docling Serve to import and process documents.

This flow contains ten components connected together to process and store documents in your knowledge base.

- The Docling Serve component processes input documents by connecting to your instance of Docling Serve.
- The Export DoclingDocument component exports the processed DoclingDocument to markdown format with image export mode set to placeholder. This conversion makes the structured document data into a standardized format for further processing.
- Three DataFrame Operations components sequentially add metadata columns to the document data of `filename`, `file_size`, and `mimetype`.
- The Split Text component splits the processed text into chunks with a chunk size of 1000 characters and an overlap of 200 characters.
- Four Secret Input components provide secure access to configuration variables: `CONNECTOR_TYPE`, `OWNER`, `OWNER_EMAIL`, and `OWNER_NAME`. These are runtime variables populated from OAuth login.
- The Create Data component combines the secret inputs into a structured data object that will be associated with the document embeddings.
- The Embedding Model component generates vector embeddings using OpenAI's `text-embedding-3-small` model. The embedding model is selected at [Application onboarding] and cannot be changed.
- The OpenSearch component stores the processed documents and their embeddings in the `documents` index at `https://opensearch:9200`. By default, the component is authenticated with a JWT token, but you can also select `basic` auth mode, and enter your OpenSearch admin username and password.

All flows included with OpenRAG are designed to be modular, performant, and provider-agnostic. To modify a flow, click
Settings, and click Edit in Langflow. OpenRAG's visual editor is based on the Langflow visual editor, so you can edit your flows to match your specific use case.

### OpenSearch URL Ingestion flow​

An additional knowledge ingestion flow is included in OpenRAG, where it is used as an MCP tool by the Open Search Agent flow. The agent calls this component to fetch web content, and the results are ingested into OpenSearch.

For more on using MCP clients in Langflow, see MCP clients.
To connect additional MCP servers to the MCP client, see Connect to MCP servers from your application.

## Use OpenRAG default ingestion instead of Docling serve​

If you want to use OpenRAG's built-in pipeline instead of Docling serve, set `DISABLE_INGEST_WITH_LANGFLOW=true` in Environment variables.

The built-in pipeline still uses the Docling processor, but uses it directly without the Docling Serve API.

For more information, see `processors.py` in the OpenRAG repository.