AI Services

AI services are the primary integration point between LangChain4j and CDI. You declare a Java interface annotated with @RegisterAIService, and the CDI extension creates a proxy implementation that delegates to LangChain4j's AiServices builder.

Declaring an AI Service

@RegisterAIService(
    chatModelName = "#default",
    toolProviderName = "myTools",
    chatMemoryName = "chat-memory",
    contentRetrieverName = "retriever"
)
public interface ChatAiService {
    String chat(String userMessage);
}

The proxy is registered as a CDI bean and can be injected into any CDI-managed bean.

Annotation Attributes

Attribute	Description
chatModelName	Name of the ChatLanguageModel CDI bean
streamingChatModelName	Name of the StreamingChatLanguageModel CDI bean
toolProviderName	Name of the ToolProvider CDI bean
tools	Array of tool classes (alternative to toolProviderName)
chatMemoryName	Name of the ChatMemory CDI bean
chatMemoryProviderName	Name of the ChatMemoryProvider CDI bean
contentRetrieverName	Name of the ContentRetriever CDI bean
retrievalAugmentorName	Name of the RetrievalAugmentor CDI bean

Name Resolution

Attribute values are resolved using these patterns:

• "#default" -- Use the default CDI bean of that type
• "" (empty) -- Ignore this dependency
• "myBean" -- Use the CDI bean named myBean
• "${property.key}" -- Resolved via MicroProfile Config (requires langchain4j-cdi-config)
• "#{el.expression}" -- Evaluated as Jakarta EL (requires langchain4j-cdi-el)

Component Priority

When multiple component sources are specified:

• RetrievalAugmentor takes precedence over ContentRetriever
• ToolProvider is preferred over the tools array

Configuration-Based Creation

Components can also be created from configuration properties:

dev.langchain4j.cdi.plugin.my-model.class=dev.langchain4j.model.openai.OpenAiChatModel
dev.langchain4j.cdi.plugin.my-model.scope=jakarta.enterprise.context.ApplicationScoped
dev.langchain4j.cdi.plugin.my-model.config.apiKey=${OPENAI_API_KEY}
dev.langchain4j.cdi.plugin.my-model.config.modelName=gpt-4o

Special Lookup Values

• lookup:@default -- Select the default CDI bean
• lookup:@all -- All beans of this type as a list
• lookup:<name> -- Named bean lookup