Adding sourcecode for reference in the article tracked under BAEL-6970.

libraries-llms/README.md

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+## Language Model Integration Libraries
+
+This module contains articles about libraries for language model integration in Java.
+
+### Relevant articles
+- [Introduction to LangChain](https://www.baeldung.com/langchain)

libraries-llms/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>libraries-llms</artifactId>
+    <name>libraries-llms</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- dependencies for langchain4j -->
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-embeddings</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-open-ai</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-embeddings-all-minilm-l6-v2</artifactId>
+            <version>${langchain4j.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <langchain4j.version>0.23.0</langchain4j.version>
+    </properties>
+
+</project>

libraries-llms/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT"
+        class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} -
+                %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+    <logger name="io.ebean.DDL" level="TRACE" />
+    <logger name="io.ebean.SQL" level="TRACE" />
+    <logger name="io.ebean.TXN" level="TRACE" />
+    <root level="WARN">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

libraries-llms/src/test/java/com/baeldung/langchain/ChainWithDocumentLiveTests.java

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+package com.baeldung.langchain;
+
+import static dev.langchain4j.data.document.FileSystemDocumentLoader.loadDocument;
+import static dev.langchain4j.model.openai.OpenAiModelName.GPT_3_5_TURBO;
+import static java.time.Duration.ofSeconds;
+import static java.util.stream.Collectors.joining;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Logger;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import dev.langchain4j.data.document.Document;
+import dev.langchain4j.data.document.DocumentSplitter;
+import dev.langchain4j.data.document.splitter.DocumentSplitters;
+import dev.langchain4j.data.embedding.Embedding;
+import dev.langchain4j.data.message.AiMessage;
+import dev.langchain4j.data.segment.TextSegment;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.embedding.AllMiniLmL6V2EmbeddingModel;
+import dev.langchain4j.model.embedding.EmbeddingModel;
+import dev.langchain4j.model.input.Prompt;
+import dev.langchain4j.model.input.PromptTemplate;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.model.openai.OpenAiTokenizer;
+import dev.langchain4j.store.embedding.EmbeddingMatch;
+import dev.langchain4j.store.embedding.EmbeddingStore;
+import dev.langchain4j.store.embedding.inmemory.InMemoryEmbeddingStore;
+
+public class ChainWithDocumentLiveTests {
+
+    @Test
+    public void givenChainWithDocument_whenPrompted_thenValidResponse() {
+
+        Document document = loadDocument(toPath("src/test/resources/example-files/simpson's_adventures.txt"));
+        DocumentSplitter splitter = DocumentSplitters.recursive(100, 0, new OpenAiTokenizer(GPT_3_5_TURBO));
+        List<TextSegment> segments = splitter.split(document);
+
+        EmbeddingModel embeddingModel = new AllMiniLmL6V2EmbeddingModel();
+        List<Embedding> embeddings = embeddingModel.embedAll(segments)
+            .content();
+        EmbeddingStore<TextSegment> embeddingStore = new InMemoryEmbeddingStore<>();
+        embeddingStore.addAll(embeddings, segments);
+
+        String question = "Who is Simpson?";
+        Embedding questionEmbedding = embeddingModel.embed(question)
+            .content();
+        int maxResults = 3;
+        double minScore = 0.7;
+        List<EmbeddingMatch<TextSegment>> relevantEmbeddings = embeddingStore.findRelevant(questionEmbedding, maxResults, minScore);
+
+        PromptTemplate promptTemplate = PromptTemplate.from("Answer the following question to the best of your ability:\n" + "\n" + "Question:\n" + "{{question}}\n" + "\n" + "Base your answer on the following information:\n" + "{{information}}");
+
+        String information = relevantEmbeddings.stream()
+            .map(match -> match.embedded()
+                .text())
+            .collect(joining("\n\n"));
+
+        Map<String, Object> variables = new HashMap<>();
+        variables.put("question", question);
+        variables.put("information", information);
+
+        Prompt prompt = promptTemplate.apply(variables);
+        ChatLanguageModel chatModel = OpenAiChatModel.builder()
+            .apiKey(Constants.OPEN_API_KEY)
+            .timeout(ofSeconds(60))
+            .build();
+        AiMessage aiMessage = chatModel.generate(prompt.toUserMessage())
+            .content();
+
+        Logger.getGlobal()
+            .info(aiMessage.text());
+        Assert.assertNotNull(aiMessage.text());
+
+    }
+
+    private static Path toPath(String fileName) {
+        try {
+            URL fileUrl = new File(fileName).toURI()
+                .toURL();
+            System.out.println(new File(fileName).toURI()
+                .toURL());
+            return Paths.get(fileUrl.toURI());
+        } catch (URISyntaxException | MalformedURLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/ChatWithDocumentLiveTests.java

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+package com.baeldung.langchain;
+
+import static dev.langchain4j.data.document.FileSystemDocumentLoader.loadDocument;
+import static java.time.Duration.ofSeconds;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.logging.Logger;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import dev.langchain4j.chain.ConversationalRetrievalChain;
+import dev.langchain4j.data.document.Document;
+import dev.langchain4j.data.document.splitter.DocumentSplitters;
+import dev.langchain4j.data.segment.TextSegment;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.embedding.AllMiniLmL6V2EmbeddingModel;
+import dev.langchain4j.model.embedding.EmbeddingModel;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.retriever.EmbeddingStoreRetriever;
+import dev.langchain4j.store.embedding.EmbeddingStore;
+import dev.langchain4j.store.embedding.EmbeddingStoreIngestor;
+import dev.langchain4j.store.embedding.inmemory.InMemoryEmbeddingStore;
+
+public class ChatWithDocumentLiveTests {
+
+    @Test
+    public void givenDocument_whenPrompted_thenValidResponse() {
+
+        EmbeddingModel embeddingModel = new AllMiniLmL6V2EmbeddingModel();
+
+        EmbeddingStore<TextSegment> embeddingStore = new InMemoryEmbeddingStore<>();
+
+        EmbeddingStoreIngestor ingestor = EmbeddingStoreIngestor.builder()
+            .documentSplitter(DocumentSplitters.recursive(500, 0))
+            .embeddingModel(embeddingModel)
+            .embeddingStore(embeddingStore)
+            .build();
+
+        Document document = loadDocument(toPath("src/test/resources/example-files/simpson's_adventures.txt"));
+        ingestor.ingest(document);
+
+        ChatLanguageModel chatModel = OpenAiChatModel.builder()
+            .apiKey(Constants.OPEN_API_KEY)
+            .timeout(ofSeconds(60))
+            .build();
+
+        ConversationalRetrievalChain chain = ConversationalRetrievalChain.builder()
+            .chatLanguageModel(chatModel)
+            .retriever(EmbeddingStoreRetriever.from(embeddingStore, embeddingModel))
+            // .chatMemory() // you can override default chat memory
+            // .promptTemplate() // you can override default prompt template
+            .build();
+
+        String answer = chain.execute("Who is Simpson?");
+
+        Logger.getGlobal()
+            .info(answer);
+        Assert.assertNotNull(answer);
+
+    }
+
+    private static Path toPath(String fileName) {
+        try {
+            URL fileUrl = new File(fileName).toURI()
+                .toURL();
+            System.out.println(new File(fileName).toURI()
+                .toURL());
+            return Paths.get(fileUrl.toURI());
+        } catch (URISyntaxException | MalformedURLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/ChatWithMemoryLiveTests.java

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+package com.baeldung.langchain;
+
+import dev.langchain4j.data.message.AiMessage;
+import dev.langchain4j.memory.ChatMemory;
+import dev.langchain4j.memory.chat.TokenWindowChatMemory;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.model.openai.OpenAiTokenizer;
+
+import static dev.langchain4j.data.message.UserMessage.userMessage;
+import static dev.langchain4j.model.openai.OpenAiModelName.GPT_3_5_TURBO;
+
+import java.util.logging.Logger;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class ChatWithMemoryLiveTests {
+
+    @Test
+    public void givenMemory_whenPrompted_thenValidResponse() {
+
+        ChatLanguageModel model = OpenAiChatModel.withApiKey(Constants.OPEN_API_KEY);
+        ChatMemory chatMemory = TokenWindowChatMemory.withMaxTokens(300, new OpenAiTokenizer(GPT_3_5_TURBO));
+
+        chatMemory.add(userMessage("Hello, my name is Kumar"));
+        AiMessage answer = model.generate(chatMemory.messages())
+            .content();
+        Logger.getGlobal()
+            .info(answer.text());
+        Assert.assertNotNull(answer.text());
+        chatMemory.add(answer);
+
+        chatMemory.add(userMessage("What is my name?"));
+        AiMessage answerWithName = model.generate(chatMemory.messages())
+            .content();
+        Logger.getGlobal()
+            .info(answerWithName.text());
+        Assert.assertTrue(answerWithName.text()
+            .contains("Kumar"));
+        chatMemory.add(answerWithName);
+
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/Constants.java

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+package com.baeldung.langchain;
+
+public class Constants {
+    
+    public static String OPEN_API_KEY = "demo";
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/PromptTemplatesLiveTests.java

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+package com.baeldung.langchain;
+
+import static dev.langchain4j.model.openai.OpenAiModelName.GPT_3_5_TURBO;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.logging.Logger;
+
+import org.junit.Test;
+
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.input.Prompt;
+import dev.langchain4j.model.input.PromptTemplate;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+
+import org.junit.Assert;
+
+public class PromptTemplatesLiveTests {
+
+    @Test
+    public void givenPromptTemplate_whenSuppliedInput_thenValidResponse() {
+
+        PromptTemplate promptTemplate = PromptTemplate.from("Tell me a {{adjective}} joke about {{content}}..");
+        Map<String, Object> variables = new HashMap<>();
+        variables.put("adjective", "funny");
+        variables.put("content", "humans");
+        Prompt prompt = promptTemplate.apply(variables);
+
+        ChatLanguageModel model = OpenAiChatModel.builder()
+            .apiKey(Constants.OPEN_API_KEY)
+            .modelName(GPT_3_5_TURBO)
+            .temperature(0.3)
+            .build();
+
+        String response = model.generate(prompt.text());
+        Logger.getGlobal()
+            .info(response);
+        Assert.assertNotNull(response);
+
+    }
+
+}

libraries-llms/src/test/java/com/baeldung/langchain/ServiceWithToolsLiveTests.java

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+package com.baeldung.langchain;
+
+import java.util.logging.Logger;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import dev.langchain4j.agent.tool.Tool;
+import dev.langchain4j.memory.chat.MessageWindowChatMemory;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.service.AiServices;
+
+public class ServiceWithToolsLiveTests {
+
+    static class Calculator {
+
+        @Tool("Calculates the length of a string")
+        int stringLength(String s) {
+            return s.length();
+        }
+
+        @Tool("Calculates the sum of two numbers")
+        int add(int a, int b) {
+            return a + b;
+        }
+
+    }
+
+    interface Assistant {
+
+        String chat(String userMessage);
+    }
+
+    @Test
+    public void givenServiceWithTools_whenPrompted_thenValidResponse() {
+
+        Assistant assistant = AiServices.builder(Assistant.class)
+            .chatLanguageModel(OpenAiChatModel.withApiKey(Constants.OPEN_API_KEY))
+            .tools(new Calculator())
+            .chatMemory(MessageWindowChatMemory.withMaxMessages(10))
+            .build();
+
+        String question = "What is the sum of the numbers of letters in the words \"language\" and \"model\"?";
+        String answer = assistant.chat(question);
+
+        Logger.getGlobal()
+            .info(answer);
+        Assert.assertNotNull(answer);
+
+    }
+
+}

libraries-llms/src/test/resources/example-files/simpson's_adventures.txt

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+Once upon a time in the town of VeggieVille, there lived a cheerful carrot named Simpson.
+Simpson was a radiant carrot, always beaming with joy and positivity.
+His vibrant orange skin and lush green top were a sight to behold, but it was his infectious laughter and warm personality that really set him apart.
+
+Simpson had a diverse group of friends, each a vegetable with their own unique characteristics.
+There was Bella the blushing beetroot, always ready with a riddle or two; Timmy the timid tomato, a gentle soul with a heart of gold; and Percy the prankster potato, whose jokes always brought a smile to everyone's faces.
+Despite their differences, they shared a close bond, their friendship as robust as their natural goodness.
+
+Their lives were filled with delightful adventures, from playing hide-and-seek amidst the leafy lettuce to swimming in the dewy droplets that pooled on the cabbage leaves.
+Their favorite place, though, was the sunlit corner of the vegetable patch, where they would bask in the warmth of the sun, share stories, and have hearty laughs.
+
+One day, a bunch of pesky caterpillars invaded VeggieVille.
+The vegetables were terrified, fearing they would be nibbled to nothingness.
+But Simpson, with his usual sunny disposition, had an idea.
+He proposed they host a grand feast for the caterpillars, with the juiciest leaves from the outskirts of the town.
+Simpson's optimism was contagious, and his friends eagerly joined in to prepare the feast.
+
+When the caterpillars arrived, they were pleasantly surprised.
+They enjoyed the feast and were so impressed with the vegetables' hospitality that they promised not to trouble VeggieVille again.
+In return, they agreed to help pollinate the flowers, contributing to a more lush and vibrant VeggieVille.
+
+Simpson's idea had saved the day, but he humbly attributed the success to their teamwork and friendship.
+They celebrated their victory with a grand party, filled with laughter, dance, and merry games.
+That night, under the twinkling stars, they made a pact to always stand by each other, come what may.
+
+From then on, the story of the happy carrot and his friends spread far and wide, a tale of friendship, unity, and positivity.
+Simpson, Bella, Timmy, and Percy continued to live their joyful lives, their laughter echoing through VeggieVille.
+And so, the tale of the happy carrot and his friends serves as a reminder that no matter the challenge, with optimism, teamwork, and a bit of creativity, anything is possible.

pom.xml

@@ -936,6 +936,7 @@
                 <module>spring-di-4</module>
                 <module>spring-kafka-2</module>
                 <!--<module>java-panama</module> Java-19 module-->
+				<module>libraries-llms</module>
             </modules>
 
             <properties>
@@ -1223,6 +1224,7 @@
                 <module>spring-di-4</module>
                 <module>spring-kafka-2</module>
                 <!--<module>java-panama</module> Java-19 module-->
+				<module>libraries-llms</module>
             </modules>
 
             <properties>