Claus Ibsen created CAMEL-24820:
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Summary: Make LangChain4j models easy to declare in YAML and
properties: builder inference, component-level model, validator hints
Key: CAMEL-24820
URL: https://issues.apache.org/jira/browse/CAMEL-24820
Project: Camel
Issue Type: Improvement
Components: camel-jbang, camel-yaml-dsl, camel-ai
Reporter: Claus Ibsen
Using camel-langchain4j-chat from the YAML DSL is harder than it should be. A
LangChain4j model has no public constructor; it is built through a nested
builder, so the only way to declare one today without Java is:
{code:yaml}
- beans:
- name: chatModel
type: dev.langchain4j.model.ollama.OllamaChatModel
builderClass:
dev.langchain4j.model.ollama.OllamaChatModel$OllamaChatModelBuilder
builderMethod: build
properties:
baseUrl: "{{ollama.base.url}}"
modelName: "{{ollama.model}}"
{code}
A user has to know that LangChain4j models come from builders, the exact name
of a nested builder class with a $ in it, and that the method is called build.
None of that is Camel knowledge, and when they get it wrong the error is a
reflection exception rather than a hint. This came up while writing the
langchain4j-chat example for camel-jbang-examples (CAMEL-24808).
Proposal, cheapest first:
# *Builder inference in bean declarations.* When a bean type has no usable
public constructor but a public static builder() method, call it and use
build() as the default builder method. Then the declaration is type plus
properties; builderClass and builderMethod stay as overrides for the odd cases.
This is generic and helps every builder-style library, not only LangChain4j.
# *Validator hint.* The source validator (camel validate, the MCP server
validate tool) should recognise a bean type without a public constructor and
say: this class is built through a builder, add builderClass and builderMethod
(or, once 1 exists, that the builder is inferred and which properties the
builder accepts).
# *Component-level model.* Let camel.component.langchain4j-chat.chat-model
accept the #class: syntax like any other bean property, with the builder
inference behind it, so application.properties alone configures the model and
the route is just langchain4j-chat:chatId. Same for langchain4j-embeddings,
langchain4j-agent and the other langchain4j components that take a model bean.
# *Provider shortcuts.* camel.langchain4j.chat.provider=ollama with base-url
and model keys, mapping to the right builder for the common providers (ollama,
openai, anthropic, ...). This also gives Camel JBang a way to add the right
langchain4j-* dependency from the provider name instead of from a class name.
1 and 2 remove most of the pain without new configuration surface; 3 and 4 are
the follow-ups.
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