[FEATURE] Enable Generic HTTP Actions in Java Client

Signed-off-by: Andriy Redko <andriy.redko@aiven.io>
Signed-off-by: Andriy Redko <drreta@gmail.com>
Signed-off-by: Andriy Redko <andriy.redko@aiven.io>

CHANGELOG.md

@@ -34,6 +34,7 @@ This section is for maintaining a changelog for all breaking changes for the cli
 ## [Unreleased 2.x]
 
 ### Added
+- [FEATURE] Enable Generic HTTP Actions in Java Client ([#910](https://github.com/opensearch-project/opensearch-java/pull/910))
 
 ### Dependencies
 - Bumps `io.github.classgraph:classgraph` from 4.8.161 to 4.8.165

java-client/src/main/java/org/opensearch/client/opensearch/OpenSearchClient.java

@@ -123,6 +123,7 @@
 import org.opensearch.client.opensearch.core.pit.ListAllPitResponse;
 import org.opensearch.client.opensearch.dangling_indices.OpenSearchDanglingIndicesClient;
 import org.opensearch.client.opensearch.features.OpenSearchFeaturesClient;
+import org.opensearch.client.opensearch.generic.OpenSearchGenericClient;
 import org.opensearch.client.opensearch.indices.OpenSearchIndicesClient;
 import org.opensearch.client.opensearch.ingest.OpenSearchIngestClient;
 import org.opensearch.client.opensearch.nodes.OpenSearchNodesClient;
@@ -155,6 +156,9 @@ public OpenSearchClient withTransportOptions(@Nullable TransportOptions transpor
     }
 
     // ----- Child clients
+    public OpenSearchGenericClient generic() {
+        return new OpenSearchGenericClient(this.transport, this.transportOptions);
+    }
 
     public OpenSearchCatClient cat() {
         return new OpenSearchCatClient(this.transport, this.transportOptions);

java-client/src/main/java/org/opensearch/client/opensearch/generic/Bodies.java

@@ -0,0 +1,48 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.opensearch.generic;
+
+import jakarta.json.stream.JsonGenerator;
+import jakarta.json.stream.JsonParser;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import org.opensearch.client.json.JsonpDeserializer;
+import org.opensearch.client.json.JsonpMapper;
+
+public final class Bodies {
+    private static final String APPLICATION_JSON = "application/json; charset=UTF-8";
+
+    private Bodies() {}
+
+    public static <C> C json(Body body, JsonpDeserializer<C> deserializer, JsonpMapper jsonpMapper) {
+        try (JsonParser parser = jsonpMapper.jsonProvider().createParser(body.body())) {
+            return deserializer.deserialize(parser, jsonpMapper);
+        }
+    }
+
+    public static <C> C json(Body body, Class<C> clazz, JsonpMapper jsonpMapper) {
+        try (JsonParser parser = jsonpMapper.jsonProvider().createParser(body.body())) {
+            return jsonpMapper.deserialize(parser, clazz);
+        }
+    }
+
+    public static <C> Body json(C value, JsonpMapper jsonpMapper) throws IOException {
+        try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+            try (JsonGenerator generator = jsonpMapper.jsonProvider().createGenerator(baos)) {
+                jsonpMapper.serialize(value, generator);
+                return Body.from(baos.toByteArray(), APPLICATION_JSON);
+            }
+        }
+    }
+
+    public static Body json(String str) {
+        return Body.from(str.getBytes(StandardCharsets.UTF_8), APPLICATION_JSON);
+    }
+}

java-client/src/main/java/org/opensearch/client/opensearch/generic/Body.java

@@ -0,0 +1,90 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.opensearch.generic;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import javax.annotation.Nullable;
+
+/**
+ * Generic HTTP request / response body. It is responsibility of the caller to close the body instance
+ * explicitly (or through {@link GenericResponse} instance) to release all associated resources.
+ */
+public interface Body extends AutoCloseable {
+    final int DEFAULT_BUFFER_SIZE = 8192;
+
+    /**
+     * Constructs the generic response body out of {@link InputStream} with assumed content type
+     * @param body response body stream
+     * @param contentType content type
+     * @return generic response body instance
+     */
+    static @Nullable Body from(@Nullable final InputStream body, @Nullable final String contentType) {
+        if (body == null) {
+            return null;
+        } else {
+            return new GenericInputStreamBody(body, contentType);
+        }
+    }
+
+    /**
+     * Constructs the generic response body out of {@link InputStream} with assumed content type
+     * @param body response body stream
+     * @param contentType content type
+     * @return generic response body instance
+     */
+    static @Nullable Body from(@Nullable final byte[] body, @Nullable final String contentType) {
+        if (body == null) {
+            return null;
+        } else {
+            return new GenericByteArrayBody(body, contentType);
+        }
+    }
+
+    /**
+     * Content type of this body
+     * @return content type
+     */
+    String contentType();
+
+    /**
+     * Gets the body as {@link InputStream}
+     * @return body as {@link InputStream}
+     */
+    InputStream body();
+
+    /**
+     * Gets the body as {@link String}
+     * @return body as {@link String}
+     */
+    default String bodyAsString() {
+        try (final ByteArrayOutputStream out = new ByteArrayOutputStream()) {
+            try (final InputStream in = body()) {
+                final byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
+                int read;
+                while ((read = in.read(buffer, 0, DEFAULT_BUFFER_SIZE)) >= 0) {
+                    out.write(buffer, 0, read);
+                }
+            }
+
+            out.flush();
+            return new String(out.toByteArray(), StandardCharsets.UTF_8);
+        } catch (final IOException ex) {
+            throw new UncheckedIOException(ex);
+        }
+    }
+
+    /**
+     * Releases all resources associated with this body stream.
+     */
+    void close() throws IOException;
+}

java-client/src/main/java/org/opensearch/client/opensearch/generic/GenericByteArrayBody.java

@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.opensearch.generic;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import javax.annotation.Nullable;
+
+/**
+ * The HTTP request / response body that uses {@link byte[]}
+ */
+final class GenericByteArrayBody implements Body {
+    private final byte[] bytes;
+    private final String contentType;
+
+    GenericByteArrayBody(final byte[] bytes, @Nullable final String contentType) {
+        this.bytes = bytes;
+        this.contentType = contentType;
+    }
+
+    @Override
+    public String contentType() {
+        return contentType;
+    }
+
+    @Override
+    public InputStream body() {
+        return new ByteArrayInputStream(bytes);
+    }
+
+    @Override
+    public void close() throws IOException {}
+}

java-client/src/main/java/org/opensearch/client/opensearch/generic/GenericInputStreamBody.java

@@ -0,0 +1,41 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.opensearch.generic;
+
+import java.io.IOException;
+import java.io.InputStream;
+import javax.annotation.Nullable;
+
+/**
+ * The HTTP request / response body that uses {@link InputStream}
+ */
+final class GenericInputStreamBody implements Body {
+    private final InputStream in;
+    private final String contentType;
+
+    GenericInputStreamBody(final InputStream in, @Nullable final String contentType) {
+        this.in = in;
+        this.contentType = contentType;
+    }
+
+    @Override
+    public String contentType() {
+        return contentType;
+    }
+
+    @Override
+    public InputStream body() {
+        return in;
+    }
+
+    @Override
+    public void close() throws IOException {
+        in.close();
+    }
+}