Jina AI Embedding model integration (langchain4j#997)

## Context
This pr is for integration of jina ai embedding model which is mentioned
in the issue
[973](langchain4j#973)

## Change
1. Since no jina sdk was available for java hence built client for the
same .
2. Added method of embedding generation for both single input and
multiple inputs
3. Default model used _jina-embeddings-v2-base-en_

## Checklist
Before submitting this PR, please check the following points:
- [x] I have added unit and integration tests for my change
- [x] All unit and integration tests in the module I have added/changed
are green
- [x] All unit and integration tests in the
[core](https://github.com/langchain4j/langchain4j/tree/main/langchain4j-core)
and
[main](https://github.com/langchain4j/langchain4j/tree/main/langchain4j)
modules are green
- [ ] I have added/updated the
[documentation](https://github.com/langchain4j/langchain4j/tree/main/docs/docs)
- [ ] I have added an example in the [examples
repo](https://github.com/langchain4j/langchain4j-examples) (only for
"big" features)
- [ ] I have added my new module in the
[BOM](https://github.com/langchain4j/langchain4j/blob/main/langchain4j-bom/pom.xml)
(only when a new module is added)

## Checklist for adding new embedding store integration
- [ ] I have added a {NameOfIntegration}EmbeddingStoreIT that extends
from either EmbeddingStoreIT or EmbeddingStoreWithFilteringIT

langchain4j-jina/pom.xml

@@ -0,0 +1,60 @@
+<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/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>dev.langchain4j</groupId>
+        <artifactId>langchain4j-parent</artifactId>
+        <version>0.31.0-SNAPSHOT</version>
+        <relativePath>../langchain4j-parent/pom.xml</relativePath>
+    </parent>
+
+    <artifactId>langchain4j-jina</artifactId>
+    <name>LangChain4j :: Integration :: Jina</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.squareup.retrofit2</groupId>
+            <artifactId>retrofit</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.squareup.retrofit2</groupId>
+            <artifactId>converter-gson</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.tinylog</groupId>
+            <artifactId>tinylog-impl</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.tinylog</groupId>
+            <artifactId>slf4j-tinylog</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/EmbeddingRequest.java

@@ -0,0 +1,10 @@
+package dev.langchain4j.model.jina;
+
+import lombok.Builder;
+
+import java.util.List;
+@Builder
+public class EmbeddingRequest {
+    String model;
+    List<String> input;
+}

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/EmbeddingResponse.java

@@ -0,0 +1,10 @@
+package dev.langchain4j.model.jina;
+
+import lombok.Data;
+
+import java.util.List;
+@Data
+public class EmbeddingResponse {
+    Usage usage;
+    List<JinaEmbedding> data;
+}

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/JinaApi.java

@@ -0,0 +1,14 @@
+package dev.langchain4j.model.jina;
+
+import retrofit2.Call;
+import retrofit2.http.Body;
+import retrofit2.http.Header;
+import retrofit2.http.Headers;
+import retrofit2.http.POST;
+
+public interface JinaApi {
+    @POST("v1/embeddings")
+    @Headers({"Content-Type: application/json"})
+    Call<EmbeddingResponse> embed(@Body EmbeddingRequest request, @Header("Authorization") String authorizationHeader);
+
+}

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/JinaClient.java

@@ -0,0 +1,67 @@
+package dev.langchain4j.model.jina;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import lombok.Builder;
+import okhttp3.OkHttpClient;
+import retrofit2.Retrofit;
+import retrofit2.converter.gson.GsonConverterFactory;
+
+import java.io.IOException;
+import java.time.Duration;
+
+import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES;
+import static dev.langchain4j.internal.ValidationUtils.ensureNotBlank;
+
+public class JinaClient {
+    private static final Gson GSON = new GsonBuilder()
+            .setFieldNamingPolicy(LOWER_CASE_WITH_UNDERSCORES)
+            .setPrettyPrinting()
+            .create();
+
+    private final JinaApi jinaApi;
+    private final String authorizationHeader;
+
+    @Builder
+    JinaClient(String baseUrl, String apiKey, Duration timeout){
+        OkHttpClient.Builder okHttpClientBuilder = new OkHttpClient.Builder()
+                .callTimeout(timeout)
+                .connectTimeout(timeout)
+                .readTimeout(timeout)
+                .writeTimeout(timeout);
+        Retrofit retrofit = new Retrofit.Builder()
+                .baseUrl(baseUrl)
+                .client(okHttpClientBuilder.build())
+                .addConverterFactory(GsonConverterFactory.create(GSON))
+                .build();
+
+
+        this.jinaApi = retrofit.create(JinaApi.class);
+        this.authorizationHeader = "Bearer " + ensureNotBlank(apiKey, "apiKey");
+    }
+
+    public EmbeddingResponse embed(EmbeddingRequest request) {
+        try {
+            retrofit2.Response<EmbeddingResponse> retrofitResponse
+                    = jinaApi.embed(request, authorizationHeader).execute();
+
+            if (retrofitResponse.isSuccessful()) {
+                return retrofitResponse.body();
+            } else {
+                throw toException(retrofitResponse);
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+
+
+    private static RuntimeException toException(retrofit2.Response<?> response) throws IOException {
+        int code = response.code();
+        String body = response.errorBody().string();
+        String errorMessage = String.format("status code: %s; body: %s", code, body);
+        return new RuntimeException(errorMessage);
+    }
+
+}

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/JinaEmbedding.java

@@ -0,0 +1,13 @@
+package dev.langchain4j.model.jina;
+
+import dev.langchain4j.data.embedding.Embedding;
+
+public class JinaEmbedding {
+    long index;
+    float[] embedding;
+    String object;
+
+    public Embedding toEmbedding(){
+        return Embedding.from(embedding);
+    }
+}

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/JinaEmbeddingModel.java

@@ -0,0 +1,68 @@
+package dev.langchain4j.model.jina;
+
+import dev.langchain4j.data.embedding.Embedding;
+import dev.langchain4j.data.segment.TextSegment;
+import dev.langchain4j.model.embedding.EmbeddingModel;
+import dev.langchain4j.model.output.Response;
+import dev.langchain4j.model.output.TokenUsage;
+import lombok.Builder;
+
+import java.time.Duration;
+import java.util.List;
+
+import static dev.langchain4j.internal.RetryUtils.withRetry;
+import static dev.langchain4j.internal.Utils.getOrDefault;
+import static java.time.Duration.ofSeconds;
+import static java.util.stream.Collectors.toList;
+
+/**
+ * An integration with Nomic Atlas's Text Embeddings API.
+ * See more details <a href="https://api.jina.ai/redoc#tag/embeddings">Jina API reference</a>
+ */
+
+public class JinaEmbeddingModel implements EmbeddingModel {
+
+
+    private static final String DEFAULT_BASE_URL = "https://api.jina.ai/";
+
+    private final JinaClient client;
+    private final String modelName;
+    private final Integer maxRetries;
+
+    @Builder
+    public JinaEmbeddingModel(String baseUrl,
+                              String apiKey,
+                              String modelName,
+                              Duration timeout,
+                              Integer maxRetries) {
+        this.client = JinaClient.builder()
+                .baseUrl(getOrDefault(baseUrl,DEFAULT_BASE_URL))
+                .apiKey(apiKey)
+                .timeout(getOrDefault(timeout, ofSeconds(60)))
+                .build();
+        this.modelName = getOrDefault(modelName, "jina-embeddings-v2-base-en");
+        this.maxRetries = getOrDefault(maxRetries, 3);
+    }
+
+    public static JinaEmbeddingModel withApiKey(String apiKey) {
+        return JinaEmbeddingModel.builder().apiKey(apiKey).build();
+    }
+
+
+    @Override
+    public Response<List<Embedding>> embedAll(List<TextSegment> textSegments) {
+        EmbeddingRequest request = EmbeddingRequest.builder()
+                .model(modelName)
+                .input(textSegments.stream().map(TextSegment::text).collect(toList()))
+                .build();
+
+        EmbeddingResponse response = withRetry(() -> client.embed(request), maxRetries);
+
+        List<Embedding> embeddings = response.getData().stream()
+                .map(JinaEmbedding::toEmbedding).collect(toList());
+
+        TokenUsage tokenUsage = new TokenUsage(response.getUsage().getPromptTokens(),0 );
+        return Response.from(embeddings,tokenUsage);
+    }
+
+}

langchain4j-jina/src/main/java/dev/langchain4j/model/jina/Usage.java

@@ -0,0 +1,12 @@
+package dev.langchain4j.model.jina;
+
+import com.google.gson.annotations.SerializedName;
+import lombok.Getter;
+
+@Getter
+class Usage {
+    @SerializedName("total_tokens")
+    private Integer totalTokens;
+    @SerializedName("prompt_tokens")
+    private Integer promptTokens;
+}

langchain4j-jina/src/test/java/dev/langchain4j/model/jina/JinaEmbeddingModelIT.java

@@ -0,0 +1,71 @@
+package dev.langchain4j.model.jina;
+
+import dev.langchain4j.data.embedding.Embedding;
+import dev.langchain4j.data.segment.TextSegment;
+import dev.langchain4j.model.embedding.EmbeddingModel;
+import dev.langchain4j.model.output.Response;
+import dev.langchain4j.store.embedding.CosineSimilarity;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static java.time.Duration.ofSeconds;
+import static java.util.Arrays.asList;
+import static org.assertj.core.api.Assertions.assertThat;
+
+
+
+public class JinaEmbeddingModelIT {
+    @Test
+    public void should_embed_single_text() {
+
+        // given
+        EmbeddingModel model = JinaEmbeddingModel.withApiKey(System.getenv("JINA_AI_API_KEY"));
+
+        String text = "hello";
+
+        // when
+        Response<Embedding> response = model.embed(text);
+
+        // then
+        assertThat(response.content().dimension()).isEqualTo(768);
+
+        assertThat(response.tokenUsage().inputTokenCount()).isEqualTo(3);
+        assertThat(response.tokenUsage().outputTokenCount()).isEqualTo(0);
+        assertThat(response.tokenUsage().totalTokenCount()).isEqualTo(3);
+    }
+
+    @Test
+    public void should_embed_multiple_segments() {
+
+        // given
+        EmbeddingModel model = JinaEmbeddingModel.builder()
+                .baseUrl("https://api.jina.ai/")
+                .apiKey(System.getenv("JINA_AI_API_KEY"))
+                .modelName("jina-embeddings-v2-base-en")
+                .timeout(ofSeconds(10))
+                .maxRetries(2)
+                .build();
+
+        TextSegment segment1 = TextSegment.from("hello");
+        TextSegment segment2 = TextSegment.from("hi");
+
+        // when
+        Response<List<Embedding>> response = model.embedAll(asList(segment1, segment2));
+
+        // then
+        assertThat(response.content()).hasSize(2);
+
+        Embedding embedding1 = response.content().get(0);
+        assertThat(embedding1.dimension()).isEqualTo(768);
+
+        Embedding embedding2 = response.content().get(1);
+        assertThat(embedding2.dimension()).isEqualTo(768);
+
+        assertThat(CosineSimilarity.between(embedding1, embedding2)).isGreaterThan(0.9);
+
+        assertThat(response.tokenUsage().inputTokenCount()).isEqualTo(6);
+        assertThat(response.tokenUsage().outputTokenCount()).isEqualTo(0);
+        assertThat(response.tokenUsage().totalTokenCount()).isEqualTo(6);
+    }
+}

pom.xml

@@ -37,6 +37,7 @@
         <module>langchain4j-vertex-ai</module>
         <module>langchain4j-vertex-ai-gemini</module>
         <module>langchain4j-zhipu-ai</module>
+        <module>langchain4j-jina</module>
 
         <!-- embedding stores -->
         <module>langchain4j-azure-ai-search</module>