LLMs som integration Endpoints: Opbygning af Apache Camel Routes med LangChain4j Chat

Opbygning af AI-funktioner er enkel, indtil du har brug for at integrere dem i et produktionssystem. I produktion bliver en simpel 'kald en LLM' ofte: trådløs HTTP/JMS/Kafka/filindtastning at håndhæve timeouts, retries, fallbacks, Stifning af kontekst opnået fra interne datakilder, beskyttelse af hemmeligheder, at gøre det testbart uden at brænde API-kreditter, og sikre, at systemet kan observeres, når problemer opstår natten over. Med Camel 4.5 og nyere kan du håndtere LLM-opkald som standard integration endpoints ved hjælp af camel-langchain4j-chat, der drives af LangChain4j. I denne tutorial vil du opbygge et Java 21 og Gradle-projekt, der demonstrerer: Chat med en enkelt besked (Single Message Chat) Prompt skabeloner + variabler (CHAT_SINGLE_MESSAGE_WITH_PROMPT) Chat historie (CHAT_MULTIPLE_MESSAGES) RAG med Camels Content Enricher (EIP + aggregator strategi) RAG via overskrifter (enkel "inject context" tilgang) En mock mode, så alt udføres i CI uden API-nøgler. Du vil afslutte med et projekt, som du kan genbruge som et fundament for reelle integrationsstrømme, uden at gøre din kodebase til en "hurtig spaghettifabrik". Hvad vi bygger En lille løbende CLI-app, der starter Camel Main (ingen forår kræves) og kører fem demoer: Enlige Hurtigt Historien Ræk-enrik Håndværker Du kan køre dem alle eller én ad gangen fra kommandolinjen. Forudsætninger af Java 21 Grundlæggende kendskab til Apache Camel (ruter, direkte: endpoints, ProducerTemplate) Valgfrit: OpenAI API-nøgle (vejledningen kører fuldt ud uden det) Arkitektur i ét billede Her er den mentale model: For RAG beriger Camel udvekslingen før kald LLM: Projektopbygning Teknisk Stack af Java 21 Anmeldelse af Apache Camel 4.17.0 LangChain4j 1.10.0 Grænseværdi 8.x OpenAI GPT-4o-mini (valgfrit) Folderstruktur camel-langchain4j-chat-demo/ ├── build.gradle ├── settings.gradle ├── src/ │ ├── main/ │ │ ├── java/com/example/langchain4j/ │ │ │ ├── App.java │ │ │ ├── ChatRoutes.java │ │ │ ├── MockChatModel.java │ │ │ └── ModelFactory.java │ │ └── resources/ │ │ ├── application.properties │ │ └── logback.xml │ └── test/ │ └── java/com/example/langchain4j/ │ └── ChatRoutesTest.java └── README.md Trin 1: Grade oprettelse skaber : build.gradle plugins { id 'java' id 'application' }

group = 'com.example' version = '1.0.0'

java { toolchain { languageVersion = JavaLanguageVersion.of(21) } }

application { mainClass = 'com.example.langchain4j.App' }

repositories { mavenCentral() }

dependencies { implementation 'org.apache.camel:camel-core:4.17.0' implementation 'org.apache.camel:camel-main:4.17.0' implementation 'org.apache.camel:camel-langchain4j-chat:4.17.0' implementation 'dev.langchain4j:langchain4j-core:1.10.0' implementation 'dev.langchain4j:langchain4j-open-ai:1.10.0' implementation 'ch.qos.logback:logback-classic:1.5.15' testImplementation 'org.junit.jupiter:junit-jupiter:5.11.4' testImplementation 'org.apache.camel:camel-test-junit5:4.17.0' testImplementation 'org.assertj:assertj-core:3.27.3' }

test { useJUnitPlatform() } og : settings.gradle rootProject.name = 'camel-langchain4j-chat-demo' Trin 2: Konfiguration og logging application.properties # Application Mode (mock or openai) app.mode=openai

# OpenAI Configuration (only used when app.mode=openai) openai.apiKey=sk-***** openai.modelName=gpt-4o-mini openai.temperature=0.3

# Apache Camel Configuration camel.main.name=camel-langchain4j-chat-demo camel.main.duration-max-seconds=0 camel.main.shutdown-timeout=30

# Logging Configuration logging.level.root=INFO logging.level.org.apache.camel=INFO logging.level.com.example.langchain4j=DEBUG logback.xml %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n

Trin 3: Produktionsvenlig “Mock Mode” (ingen API-nøgle kræves) Hvis du vil have det til at være mere end en legetøjsdemonstration, har du brug for en måde at køre det på uden eksterne afhængigheder. Derfor implementerer vi en : deterministic MockChatModel MockChatModel.java package com.example.langchain4j;

import dev.langchain4j.data.message.AiMessage; import dev.langchain4j.data.message.ChatMessage; import dev.langchain4j.model.chat.ChatModel; import dev.langchain4j.model.chat.request.ChatRequest; import dev.langchain4j.model.chat.response.ChatResponse;

/** * Mock implementation of ChatModel for testing and demo without API keys. */ public class MockChatModel implements ChatModel {

@Override public ChatResponse chat(ChatRequest request) { StringBuilder response = new StringBuilder("[MOCK] Responding to: "); if (request != null && request.messages() != null && !request.messages().isEmpty()) { ChatMessage lastMessage = request.messages().get(request.messages().size() - 1); // Use text() method which should exist String userText = ""; try { userText = (String) lastMessage.getClass().getMethod("text").invoke(lastMessage); } catch (Exception e) { userText = lastMessage.toString(); } // Generate deterministic response based on content if (userText.contains("recipe") || userText.contains("dish")) { response.append("Here's a delicious recipe with your requested ingredients!"); } else if (userText.contains("Apache Camel")) { response.append("Apache Camel is a powerful integration framework!"); } else if (userText.contains("capital")) { response.append("Paris is the capital of France."); } else { response.append("I understand your question about: ").append(userText.substring(0, Math.min(50, userText.length()))); } } else { response.append("Hello! I'm a mock AI assistant."); } return ChatResponse.builder() .aiMessage(new AiMessage(response.toString())) .build(); } } Hvorfor det er vigtigt i produktionen: CI / CD løber ikke kræver en LLM. Enhedsprøven er stabil. Ingeniører kan arbejde offline. Du kan validere flowlogik (routing, RAG, skabeloner) før du bruger penge. Trin 4: Vælg en model på Runtime (OpenAI eller Mock) ModelFactory.java package com.example.langchain4j;

import dev.langchain4j.model.chat.ChatModel; import dev.langchain4j.model.openai.OpenAiChatModel; import org.slf4j.Logger; import org.slf4j.LoggerFactory;

import java.time.Duration;

/** * Factory to create ChatModel instances based on configuration. */ public class ModelFactory { private static final Logger log = LoggerFactory.getLogger(ModelFactory.class);

public static ChatModel createChatModel(String mode, String apiKey, String modelName, Double temperature) { if ("openai".equalsIgnoreCase(mode) && apiKey != null && !apiKey.isEmpty()) { log.info("Creating OpenAI chat model with model: {}", modelName); return OpenAiChatModel.builder() .apiKey(apiKey) .modelName(modelName) .temperature(temperature) .timeout(Duration.ofSeconds(60)) .build(); } else { log.info("Creating Mock chat model (API key not provided or mode is mock)"); return new MockChatModel(); } } } Trin 5: Camel Routes (Hvor AI bliver “Just Another Endpoint”) Camel-komponenten URI ser ud som: langchain4j-chat:chatId?chatModel=#beanName&chatOperation=OPERATION ChatId er kun en identifikator chatModel=#chatModel refererer til en bean i Camel-registret ChatOperation styrer adfærd ChatRoutes.java package com.example.langchain4j;

import dev.langchain4j.data.message.AiMessage; import dev.langchain4j.data.message.ChatMessage; import dev.langchain4j.data.message.SystemMessage; import dev.langchain4j.data.message.UserMessage; import dev.langchain4j.rag.content.Content; import org.apache.camel.AggregationStrategy; import org.apache.camel.Exchange; import org.apache.camel.builder.RouteBuilder; import org.apache.camel.component.langchain4j.chat.LangChain4jChat;

import java.util.ArrayList; import java.util.List; import java.util.Map;

/** * Apache Camel routes demonstrating camel-langchain4j-chat component usage. */ public class ChatRoutes extends RouteBuilder {

@Override public void configure() throws Exception { // Demo 1: CHAT_SINGLE_MESSAGE - Simple question/answer from("direct:single") .log("Demo 1: Single message - Input: ${body}") .to("langchain4j-chat:demo?chatModel=#chatModel&chatOperation=CHAT_SINGLE_MESSAGE") .log("Demo 1: Response: ${body}");

// Demo 2: CHAT_SINGLE_MESSAGE_WITH_PROMPT - Using prompt template with variables from("direct:prompt") .log("Demo 2: Prompt template - Variables: ${body}") .process(exchange -> { // Set the prompt template in header String template = "Create a recipe for a {{dishType}} with these ingredients: {{ingredients}}"; exchange.getIn().setHeader("CamelLangChain4jChatPromptTemplate", template); }) .to("langchain4j-chat:demo?chatModel=#chatModel&chatOperation=CHAT_SINGLE_MESSAGE_WITH_PROMPT") .log("Demo 2: Response: ${body}");

// Demo 3: CHAT_MULTIPLE_MESSAGES - Chat with history/context from("direct:history") .log("Demo 3: Multiple messages with history") .process(exchange -> { // Build a conversation with system message, previous context, and user question List messages = new ArrayList<>(); messages.add(new SystemMessage("You are a helpful AI assistant specialized in Apache Camel.")); messages.add(new UserMessage("What is Apache Camel?")); messages.add(new AiMessage("Apache Camel is an open-source integration framework based on enterprise integration patterns.")); messages.add(new UserMessage("What are some key features?")); exchange.getIn().setBody(messages); }) .to("langchain4j-chat:demo?chatModel=#chatModel&chatOperation=CHAT_MULTIPLE_MESSAGES") .log("Demo 3: Response: ${body}");

// Demo 4: RAG using Content Enricher pattern with LangChain4jRagAggregatorStrategy from("direct:rag-enrich") .log("Demo 4: RAG with Content Enricher - Question: ${body}") .enrich("direct:rag-source", new LangChain4jRagAggregatorStrategy()) .to("langchain4j-chat:demo?chatModel=#chatModel&chatOperation=CHAT_SINGLE_MESSAGE") .log("Demo 4: Response: ${body}");

// RAG knowledge source route from("direct:rag-source") .log("Fetching RAG knowledge...") .process(exchange -> { // Simulate fetching relevant documents/snippets List knowledgeSnippets = new ArrayList<>(); knowledgeSnippets.add("Apache Camel 4.x introduced the concept of lightweight mode for faster startup."); knowledgeSnippets.add("The camel-langchain4j-chat component supports multiple chat operations including single message, prompt templates, and chat history."); knowledgeSnippets.add("LangChain4j integration allows Camel routes to interact with various LLM providers like OpenAI, Azure OpenAI, and more."); exchange.getIn().setBody(knowledgeSnippets); });

// Demo 5: RAG using CamelLangChain4jChatAugmentedData header from("direct:rag-header") .log("Demo 5: RAG with header - Question: ${body}") .process(exchange -> { String question = exchange.getIn().getBody(String.class); // Create augmented data content List augmentedData = new ArrayList<>(); augmentedData.add(Content.from("Apache Camel version 4.0 was released in 2023 with major improvements.")); augmentedData.add(Content.from("The LangChain4j component enables AI-powered integration patterns in Camel routes.")); // Set augmented data in header exchange.getIn().setHeader("CamelLangChain4jChatAugmentedData", augmentedData); // Reset body to the question exchange.getIn().setBody(question); }) .to("langchain4j-chat:demo?chatModel=#chatModel&chatOperation=CHAT_SINGLE_MESSAGE") .log("Demo 5: Response: ${body}"); } /** * Custom aggregation strategy for RAG pattern using Content Enricher. */ private static class LangChain4jRagAggregatorStrategy implements AggregationStrategy { @Override public Exchange aggregate(Exchange original, Exchange resource) { String question = original.getIn().getBody(String.class); List knowledgeSnippets = resource.getIn().getBody(List.class); // Build augmented prompt with context StringBuilder augmentedPrompt = new StringBuilder(); augmentedPrompt.append("Context:\n"); for (String snippet : knowledgeSnippets) { augmentedPrompt.append("- ").append(snippet).append("\n"); } augmentedPrompt.append("\nQuestion: ").append(question); original.getIn().setBody(augmentedPrompt.toString()); return original; } } } Hvorfor Camel's tilgang er nyttig Camilla giver dig (Enterprise Integration Patterns), der gælder smukt for AI: EIPs Indholdsbegrænsning → RAG Circuit breaker → LLM modstandsdygtighed Håndtering af omkostningskontrol Død bogstavskanal → mislykkedes routing Idempotens er ikke at behandle den samme anmodning to gange. Du har ikke brug for en ny arkitektur. Du genbruger bevist integrationsmønstre. Trin 6: Bootstrapping Camel Main + Running Demos App.java package com.example.langchain4j;

import dev.langchain4j.model.chat.ChatModel; import org.apache.camel.CamelContext; import org.apache.camel.ProducerTemplate; import org.apache.camel.main.Main; import org.slf4j.Logger; import org.slf4j.LoggerFactory;

import java.util.HashMap; import java.util.Map;

/** * Main application class demonstrating Apache Camel LangChain4j Chat component. */ public class App { private static final Logger log = LoggerFactory.getLogger(App.class);

public static void main(String[] args) throws Exception { Main main = new Main(); // Configure Camel Main main.configure().addRoutesBuilder(new ChatRoutes()); // Initialize Camel context first (without starting routes) main.init(); CamelContext camelContext = main.getCamelContext(); // Read configuration from properties String mode = camelContext.resolvePropertyPlaceholders("{{app.mode}}"); String apiKey = System.getenv("OPENAI_API_KEY"); if (apiKey == null || apiKey.isEmpty()) { apiKey = camelContext.resolvePropertyPlaceholders("{{openai.apiKey}}"); } String modelName = camelContext.resolvePropertyPlaceholders("{{openai.modelName}}"); Double temperature = Double.parseDouble(camelContext.resolvePropertyPlaceholders("{{openai.temperature}}")); // Create and register ChatModel BEFORE starting routes ChatModel chatModel = ModelFactory.createChatModel(mode, apiKey, modelName, temperature); camelContext.getRegistry().bind("chatModel", chatModel); log.info("=".repeat(80)); log.info("Apache Camel LangChain4j Chat Demo"); log.info("Mode: {}", mode); log.info("=".repeat(80)); // Now start Camel main.start(); try { // Determine which demo(s) to run String demoMode = args.length > 0 ? args[0] : "all"; ProducerTemplate template = camelContext.createProducerTemplate(); switch (demoMode.toLowerCase()) { case "single": runSingleMessageDemo(template); break; case "prompt": runPromptTemplateDemo(template); break; case "history": runChatHistoryDemo(template); break; case "rag-enrich": runRagEnrichDemo(template); break; case "rag-header": runRagHeaderDemo(template); break; case "all": default: runAllDemos(template); break; } log.info("=".repeat(80)); log.info("Demo completed! Shutting down..."); log.info("=".repeat(80)); } finally { // Shutdown after demos complete main.stop(); } } private static void runAllDemos(ProducerTemplate template) { runSingleMessageDemo(template); runPromptTemplateDemo(template); runChatHistoryDemo(template); runRagEnrichDemo(template); runRagHeaderDemo(template); } private static void runSingleMessageDemo(ProducerTemplate template) { log.info("\n" + "=".repeat(80)); log.info("DEMO 1: CHAT_SINGLE_MESSAGE"); log.info("=".repeat(80)); String question = "What is the capital of France?"; String response = template.requestBody("direct:single", question, String.class); log.info("Question: {}", question); log.info("Answer: {}", response); } private static void runPromptTemplateDemo(ProducerTemplate template) { log.info("\n" + "=".repeat(80)); log.info("DEMO 2: CHAT_SINGLE_MESSAGE_WITH_PROMPT (Prompt Template)"); log.info("=".repeat(80)); Map variables = new HashMap<>(); variables.put("dishType", "pasta"); variables.put("ingredients", "tomatoes, garlic, basil, olive oil"); String response = template.requestBody("direct:prompt", variables, String.class); log.info("Template: Create a recipe for a {{dishType}} with these ingredients: {{ingredients}}"); log.info("Variables: {}", variables); log.info("Answer: {}", response); } private static void runChatHistoryDemo(ProducerTemplate template) { log.info("\n" + "=".repeat(80)); log.info("DEMO 3: CHAT_MULTIPLE_MESSAGES (Chat History)"); log.info("=".repeat(80)); log.info("Building conversation with context..."); String response = template.requestBody("direct:history", null, String.class); log.info("Final Answer: {}", response); } private static void runRagEnrichDemo(ProducerTemplate template) { log.info("\n" + "=".repeat(80)); log.info("DEMO 4: RAG with Content Enricher Pattern"); log.info("=".repeat(80)); String question = "What's new in Apache Camel 4.x?"; String response = template.requestBody("direct:rag-enrich", question, String.class); log.info("Question: {}", question); log.info("Answer (with RAG context): {}", response); } private static void runRagHeaderDemo(ProducerTemplate template) { log.info("\n" + "=".repeat(80)); log.info("DEMO 5: RAG with CamelLangChain4jChatAugmentedData Header"); log.info("=".repeat(80)); String question = "Tell me about the LangChain4j integration in Camel"; String response = template.requestBody("direct:rag-header", question, String.class); log.info("Question: {}", question); log.info("Answer (with augmented data): {}", response); } } Løber det Byg + kør alle demos (mock mode) ./gradlew clean test ./gradlew run Kør en demo ./gradlew run --args="prompt" ./gradlew run --args="rag-enrich" Sådan aktiveres OpenAI mode Valgmulighed A (Egenskaber): app.mode=openai openai.apiKey=sk-... Alternativ B (anbefales): miljøvariabel Windows (PowerShell) setx OPENAI_API_KEY "sk-..." Derefter i Du kan bruge en pladsholder: application.properties openai.apiKey=${OPENAI_API_KEY:} Eksempel på output (Mock Mode) Du vil se logs som: === DEMO 1: CHAT_SINGLE_MESSAGE === Q: What is the capital of France? A: [MOCK] The capital of France is Paris. Bedste praksis (Det du vil sætte pris på senere) 1) Aldrig harde API-nøgler Brug miljøvariabler eller en hemmeligholdere. Selv i demoer, indstille mønsteret. openai.apiKey=${OPENAI_API_KEY:} 2) Tilføj tid og modstandsdygtighed tidligt LLM'er er netværksopkald. Behandle dem som enhver afhængighed: timeouts, retries, fallback. I Camel bliver dette typisk: timeout() / kredsløbBreaker() (Resilience4j) onException() for kontrollerede fejlveje throttle() for at beskytte budget og opstrømsgrænser 3) Hold prompts versioneret og outsourcet Prompts er "business logic". begrave dem ikke som strenge i tilfældige metoder. I det mindste: butikker templates i og indlæse dem eller administrere dem som versionerede aktiver. resources/ 4) Brug mock mode + tests til at beskytte din rørledning Din LLM-kode skal være testbar uden netværksopkald. Giver dig . MockChatModel Enheden tester ruterne ChatRoutesTest.java package com.example.langchain4j;

import dev.langchain4j.data.message.UserMessage; import dev.langchain4j.model.chat.request.ChatRequest; import dev.langchain4j.model.chat.response.ChatResponse; import org.apache.camel.CamelContext; import org.apache.camel.ProducerTemplate; import org.apache.camel.builder.RouteBuilder; import org.apache.camel.test.junit5.CamelTestSupport; import org.junit.jupiter.api.Test;

import java.util.HashMap; import java.util.List; import java.util.Map;

import static org.assertj.core.api.Assertions.assertThat;

/** * Unit tests for ChatRoutes using MockChatModel. */ public class ChatRoutesTest extends CamelTestSupport {

@Override protected CamelContext createCamelContext() throws Exception { CamelContext context = super.createCamelContext(); // Register MockChatModel for testing context.getRegistry().bind("chatModel", new MockChatModel()); return context; }

@Override protected RouteBuilder createRouteBuilder() { return new ChatRoutes(); }

@Test public void testSingleMessage() { ProducerTemplate template = context.createProducerTemplate(); String question = "What is the capital of France?"; String response = template.requestBody("direct:single", question, String.class); assertThat(response) .isNotNull() .isNotEmpty() .contains("MOCK") .contains("capital"); }

@Test public void testPromptTemplate() { ProducerTemplate template = context.createProducerTemplate(); Map variables = new HashMap<>(); variables.put("dishType", "pasta"); variables.put("ingredients", "tomatoes, garlic, basil"); String response = template.requestBody("direct:prompt", variables, String.class); assertThat(response) .isNotNull() .isNotEmpty() .contains("MOCK") .containsAnyOf("recipe", "dish"); }

@Test public void testChatHistory() { ProducerTemplate template = context.createProducerTemplate(); String response = template.requestBody("direct:history", null, String.class); assertThat(response) .isNotNull() .isNotEmpty() .contains("MOCK"); }

@Test public void testRagEnrich() { ProducerTemplate template = context.createProducerTemplate(); String question = "What's new in Apache Camel 4.x?"; String response = template.requestBody("direct:rag-enrich", question, String.class); assertThat(response) .isNotNull() .isNotEmpty() .contains("MOCK") .containsAnyOf("Camel", "Apache"); }

@Test public void testRagHeader() { ProducerTemplate template = context.createProducerTemplate(); String question = "Tell me about LangChain4j in Camel"; String response = template.requestBody("direct:rag-header", question, String.class); assertThat(response) .isNotNull() .isNotEmpty() .contains("MOCK"); }

@Test public void testMockChatModel() { MockChatModel mockModel = new MockChatModel(); ChatRequest request = ChatRequest.builder() .messages(List.of(new UserMessage("What is Apache Camel?"))) .build(); ChatResponse response = mockModel.chat(request); assertThat(response).isNotNull(); assertThat(response.aiMessage()).isNotNull(); assertThat(response.aiMessage().text()) .contains("MOCK") .contains("Apache Camel"); } } RAG: To tilgange (når du skal bruge hvilken) Approach How it works Best for Tradeoff ( ) Content Enricher enrich Camel pulls context from one or more routes and merges it Dynamic retrieval, multiple sources Slightly more code (strategy) ( ) Header-based AUGMENTED_DATA You directly attach known context as structured content Simple static context or already-retrieved context Less flexible for complex retrieval logic (Det er ) Content Enricher enrich Camel trækker kontekst fra en eller flere ruter og fusionerer det Dynamisk retrieval, flere kilder Lidt mere kode (strategi) (Det er ) Header-based AUGMENTED_DATA Du vedhæfter kendt kontekst direkte som struktureret indhold Enkel statisk kontekst eller allerede genvundet kontekst Mindre fleksibel til kompleks retrieval logik I virkelige projekter udvikler RAG sig ofte sådan her: Start med header-baseret (hurtig, let, forudsigelig) Flyt til enrich() når indhentning bliver en arbejdsproces (vektor DB, tilladelser, omrangering) Real World Use Cases (Hvor dette mønster passer) Når du er komfortabel med De samme kompetencer: camel-langchain4j-chat Routing af kundesupport (billetter → kontekst → svar) Dokumentrørledninger (ekstrakt → sammenfatning → klassificering → rute) Data berigelse (indkommende begivenheder → forklar/label → vedblive) Ops assistenter (logs/metrikker → RAG → afhjælpningstrin) Nøglen er Camel: det ved allerede, hvordan man forbinder og orkestrerer alt omkring AI-opkaldet. Konklusion: Behandle LLM kalder som integrationer, ikke "Special Snowflakes" Den største mindset skift er dette: En LLM er ikke en app. Det er en afhængighed - som en database, en kø eller en API. En LLM er ikke en app. Det er en afhængighed - som en database, en kø eller en API. Og hvis du behandler det på den måde, vil du naturligt opbygge: Hurtigere og sikrere bedre håndtering af fejl, afprøvning af, og integrationsstrømme, der kan udvide sig ud over demos.