• Maven Coordinates

• In-Process Embedding Model

• Additional Information

In addition to the LangChain4j integration core dependencies, add:

<dependency>
    <groupId>io.helidon.integrations.langchain4j.providers</groupId>
    <artifactId>helidon-integrations-langchain4j-providers-lc4j-in-process</artifactId>
</dependency>

Depending on configured model type, add model artifact dependencies as follows:

• For type: all_minilm_l6_v2, add:

  <dependency>
      <groupId>dev.langchain4j</groupId>
      <artifactId>langchain4j-embeddings-all-minilm-l6-v2</artifactId>
  </dependency>

  content_copy Copied

• For type: all_minilm_l6_v2_q, add:

  <dependency>
      <groupId>dev.langchain4j</groupId>
      <artifactId>langchain4j-embeddings-all-minilm-l6-v2-q</artifactId>
  </dependency>

  content_copy Copied

• For type: custom, no additional model-specific dependency is required. Configure path-to-model, path-to-tokenizer, and pooling-mode.

Provider key: lc4j-in-process.

LangChain4j in-process embedding models run ONNX embedding inference locally in your process (see LangChain4j documentation).

In Helidon, a named entry under langchain4j.models with provider: lc4j-in-process is created as a named singleton declarative service bean in the Helidon service registry. This is how foo-bar-embedding-model becomes available for content retrievers and direct injection.

langchain4j:

  models:
    foo-bar-embedding-model: 
      provider: lc4j-in-process
      type: all_minilm_l6_v2_q 

  content-retrievers:
    foo-bar-content-retriever:
      provider: lc4j-content-retriever
      embedding-model: foo-bar-embedding-model 
      embedding-store: foo-bar-inmemory-embedding-store

• Creates a named embedding model singleton bean (foo-bar-embedding-model) in Helidon.
• Sets provider defaults for in-process embedding model creation.
• Uses the named in-process embedding model from the service registry.

For type: custom, configure model and tokenizer paths and pooling mode:

langchain4j:
  models:
    foo-bar-content-retriever:
      provider: lc4j-in-process
      type: custom 
      path-to-model: "/models/custom-embeddings/model.onnx" 
      path-to-tokenizer: "/models/custom-embeddings/tokenizer.json" 
      pooling-mode: mean 

• Uses user-provided ONNX model.
• Required for custom type.
• Required for custom type.
• Required for custom type; maps to LangChain4j pooling mode.

If type: custom is selected but any of path-to-model, path-to-tokenizer, or pooling-mode is missing, Helidon fails startup with a configuration exception.

@Service.Singleton
public class EmbeddingModelConsumer {
    EmbeddingModelConsumer(@Service.Named("foo-bar-embedding-model") EmbeddingModel embeddingModel) { 
    }
}

• Injects the named in-process embedding model bean directly into another Helidon declarative service.

Configuration properties:

Configuration options

• LangChain4j Integration

• Lc4j Built-in Providers

• Retrieval-Augmented Generation (RAG)