Add batch direct get (#1229)

README.md

@@ -980,6 +980,8 @@ You can however set the deliver policy which will be used to start the subscript
 | JsConsumerCreate290NotAvailable              | CON-90301 | Name field not valid when v2.9.0 consumer create api is not available.                                         |
 | JsConsumerNameDurableMismatch                | CON-90302 | Name must match durable if both are supplied.                                                                  |
 | JsMultipleFilterSubjects210NotAvailable      | CON-90303 | Multiple filter subjects not available until server version 2.10.0.                                            |
+| JsAllowDirectRequired                        | CON-90304 | Stream must have allow direct set.                                                                             |
+| JsDirectBatchGet211NotAvailable              | CON-90305 | Batch direct get not available until server version 2.11.0.                                                    |
 | OsObjectNotFound                             | OS-90201  | The object was not found.                                                                                      |
 | OsObjectIsDeleted                            | OS-90202  | The object is deleted.                                                                                         |
 | OsObjectAlreadyExists                        | OS-90203  | An object with that name already exists.                                                                       |

src/main/java/io/nats/client/JetStreamManagement.java

@@ -17,6 +17,7 @@
 import java.io.IOException;
 import java.time.ZonedDateTime;
 import java.util.List;
+import java.util.concurrent.LinkedBlockingQueue;
 
 /**
  * JetStream Management context for creation and access to streams and consumers in NATS.
@@ -324,6 +325,48 @@ public interface JetStreamManagement {
      */
     MessageInfo getNextMessage(String streamName, long seq, String subject) throws IOException, JetStreamApiException;
 
+    /**
+     * Request a batch of messages using a {@link MessageBatchGetRequest}.
+     * <p>
+     * This API is currently EXPERIMENTAL and is subject to change.
+     *
+     * @param streamName the name of the stream
+     * @param messageBatchGetRequest the request details
+     * @return a list containing {@link MessageInfo}
+     * @throws IOException covers various communication issues with the NATS
+     *         server such as timeout or interruption
+     * @throws JetStreamApiException the request had an error related to the data
+     */
+    List<MessageInfo> fetchMessageBatch(String streamName, MessageBatchGetRequest messageBatchGetRequest) throws IOException, JetStreamApiException;
+
+    /**
+     * Request a batch of messages using a {@link MessageBatchGetRequest}.
+     * <p>
+     * This API is currently EXPERIMENTAL and is subject to change.
+     *
+     * @param streamName the name of the stream
+     * @param messageBatchGetRequest the request details
+     * @return a queue used to asynchronously receive {@link MessageInfo}
+     * @throws IOException covers various communication issues with the NATS
+     *         server such as timeout or interruption
+     * @throws JetStreamApiException the request had an error related to the data
+     */
+    LinkedBlockingQueue<MessageInfo> queueMessageBatch(String streamName, MessageBatchGetRequest messageBatchGetRequest) throws IOException, JetStreamApiException;
+
+    /**
+     * Request a batch of messages using a {@link MessageBatchGetRequest}.
+     * <p>
+     * This API is currently EXPERIMENTAL and is subject to change.
+     *
+     * @param streamName the name of the stream
+     * @param messageBatchGetRequest the request details
+     * @param handler the handler used for receiving {@link MessageInfo}
+     * @throws IOException covers various communication issues with the NATS
+     *         server such as timeout or interruption
+     * @throws JetStreamApiException the request had an error related to the data
+     */
+    void requestMessageBatch(String streamName, MessageBatchGetRequest messageBatchGetRequest, MessageInfoHandler handler) throws IOException, JetStreamApiException;
+
     /**
      * Deletes a message, overwriting the message data with garbage
      * This can be considered an expensive (time-consuming) operation, but is more secure.

src/main/java/io/nats/client/MessageInfoHandler.java

@@ -0,0 +1,29 @@
+// Copyright 2024 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package io.nats.client;
+
+import io.nats.client.api.MessageInfo;
+
+/**
+ * Handler for {@link MessageInfo}.
+ */
+public interface MessageInfoHandler {
+    /**
+     * Called to deliver a {@link MessageInfo} to the handler.
+     *
+     * @param messageInfo the received {@link MessageInfo}
+     * @throws InterruptedException if the thread for this handler is interrupted
+     */
+    void onMessageInfo(MessageInfo messageInfo) throws InterruptedException;
+}

src/main/java/io/nats/client/api/ApiResponse.java

@@ -76,6 +76,12 @@ public ApiResponse() {
         type = NO_TYPE;
     }
 
+    public ApiResponse(Error error) {
+        jv = null;
+        this.error = error;
+        type = NO_TYPE;
+    }
+
     @SuppressWarnings("unchecked")
     public T throwOnHasError() throws JetStreamApiException {
         if (hasError()) {