add documentation & TaskWorker interface

Signed-off-by: Varun Bansal <bansvaru@amazon.com>

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/TaskClient.java

@@ -9,6 +9,8 @@
 package org.opensearch.offline_tasks;
 
 import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.offline_tasks.task.Task;
+import org.opensearch.offline_tasks.task.TaskId;
 
 import java.util.List;
 
@@ -21,37 +23,37 @@
 public interface TaskClient {
 
     /**
-     * Submit a new task to Task Store/Queue
+     * Submit a new task to TaskStore/Queue
      *
      * @param task
      */
     void submitTask(Task task);
 
     /**
-     * Claim task from Task Store/Queue. This ensure no 2 nodes work on the same task.
+     * Claim task from TaskStore/Queue. This ensures no 2 Offline Nodes work on the same task.
      *
      * @param taskId
      */
     void claimTask(TaskId taskId);
 
     /**
-     * Get task from Task Store/Queue
+     * Get task from TaskStore/Queue
      *
      * @param taskId
-     * @return
+     * @return Task corresponding to TaskId
      */
     Task getTask(TaskId taskId);
 
     /**
-     * Update task in Task Store/Queue
+     * Update task in TaskStore/Queue
      *
      * @param task
-     * @return
      */
-    Task updateTask(Task task);
+    void updateTask(Task task);
 
     /**
-     * Mark task as cancelled
+     * Mark task as cancelled.
+     * Ongoing Tasks can be cancelled as well if the corresponding worker supports cancellation
      *
      * @param taskId
      */

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/Task.java → libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/task/Task.java

@@ -6,11 +6,14 @@
  * compatible open source license.
  */
 
-package org.opensearch.offline_tasks;
+package org.opensearch.offline_tasks.task;
+
+import org.opensearch.common.annotation.ExperimentalApi;
 
 /**
  * A Background Task to be run on Offline Node.
  */
+@ExperimentalApi
 public class Task {
 
     /**

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/TaskId.java → libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/task/TaskId.java

@@ -6,18 +6,25 @@
  * compatible open source license.
  */
 
-package org.opensearch.offline_tasks;
+package org.opensearch.offline_tasks.task;
+
+import org.opensearch.common.annotation.ExperimentalApi;
 
 /**
- * Class encapsulating Task id
+ * Class encapsulating Task identifier
  */
+@ExperimentalApi
 public class TaskId {
 
     /**
-     * Id of the Task
+     * Identified of the Task
      */
     String id;
 
+    /**
+     * Constructor to initialize TaskId
+     * @param id
+     */
     public TaskId(String id) {
         this.id = id;
     }

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/task/TaskParams.java

@@ -0,0 +1,23 @@
+/*
+ * 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.offline_tasks.task;
+
+import org.opensearch.common.annotation.ExperimentalApi;
+
+/**
+ * Base class for all TaskParams implementation of various TaskTypes
+ */
+@ExperimentalApi
+public abstract class TaskParams {
+
+    /**
+     * Default constructor
+     */
+    public TaskParams() {}
+}

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/TaskType.java → libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/task/TaskType.java

@@ -6,7 +6,7 @@
  * compatible open source license.
  */
 
-package org.opensearch.offline_tasks;
+package org.opensearch.offline_tasks.task;
 
 /**
  * Enum for task type

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/package-info.java → libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/task/package-info.java

@@ -7,6 +7,6 @@
  */
 
 /**
- * Contains telemetry related classes
+ * Contains tasks related classes
  */
 package org.opensearch.offline_tasks;

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/worker/TaskWorker.java

@@ -0,0 +1,31 @@
+/*
+ * 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.offline_tasks.worker;
+
+import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.offline_tasks.task.Task;
+import org.opensearch.offline_tasks.task.TaskParams;
+
+/**
+ * Task Worker that executes the Task
+ *
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public interface TaskWorker {
+
+    /**
+     * Execute the Task
+     *
+     * @param task Task to be execute
+     * @param taskParams TaskParams to be used while executing the task
+     */
+    void executeTask(Task task, TaskParams taskParams);
+
+}

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/worker/package-info.java

@@ -0,0 +1,12 @@
+/*
+ * 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.
+ */
+
+/**
+ * Contains task worker related classes
+ */
+package org.opensearch.offline_tasks.worker;

libs/offline-tasks/src/main/java/org/opensearch/offline_tasks/TaskParams.java → libs/offline-tasks/src/test/java/org/opensearch/offline_tasks/TaskClientTest.java

@@ -8,8 +8,6 @@
 
 package org.opensearch.offline_tasks;
 
-/**
- * Base class for all TaskParams implementation of various TaskTypes
- */
-public abstract class TaskParams {
+public class TaskClientTest {
+    public TaskClientTest() {}
 }