Adding MLTask

plugin/src/main/java/org/opensearch/ml/model/MLTask.java

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+/*
+ * 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.
+ *
+ * Modifications Copyright OpenSearch Contributors. See
+ * GitHub history for details.
+ *
+ */
+
+package org.opensearch.ml.model;
+
+import lombok.Builder;
+import lombok.Data;
+import org.opensearch.common.io.stream.StreamInput;
+import org.opensearch.common.io.stream.StreamOutput;
+import org.opensearch.common.io.stream.Writeable;
+
+import java.io.IOException;
+import java.time.Instant;
+
+@Data
+public class MLTask implements Writeable {
+    private final String taskId;
+    private final String taskType;
+    private String state;
+    private final Instant createTime;
+    private final String modelId;
+
+    @Builder
+    public MLTask(String taskId, String taskType, String state, Instant createTime, String modelId) {
+        this.taskId = taskId;
+        this.taskType = taskType;
+        this.state = state;
+        this.createTime = createTime;
+        this.modelId = modelId;
+    }
+
+    public MLTask(StreamInput input) throws IOException {
+        this.taskId = input.readOptionalString();
+        this.taskType = input.readOptionalString();
+        this.state = input.readOptionalString();
+        this.createTime = input.readOptionalInstant();
+        this.modelId = input.readOptionalString();
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        out.writeOptionalString(taskId);
+        out.writeOptionalString(taskType);
+        out.writeOptionalString(state);
+        out.writeOptionalInstant(createTime);
+        out.writeOptionalString(modelId);
+    }
+}

plugin/src/main/java/org/opensearch/ml/model/MLTaskState.java

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+/*
+ * 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.
+ *
+ * Modifications Copyright OpenSearch Contributors. See
+ * GitHub history for details.
+ *
+ */
+
+package org.opensearch.ml.model;
+
+/**
+ * ML task states.
+ * <ul>
+ * <li><code>CREATED</code>:
+ *     When user send a machine-learning(ML) request(training/inference), we will create one task to track
+ *     ML task execution and set its state as CREATED
+ *
+ * <li><code>RUNNING</code>:
+ *     Once MLTask is dispatched to work node and start to run corresponding ML algorithm, we will set the task state as RUNNING
+ *
+ * <li><code>COMPLETED</code>:
+ *     When all training/inference completed, we will set task state as COMPLETED
+ *
+ * <li><code>FAILED</code>:
+ *     If any exception happen, we will set task state as FAILED
+ * </ul>
+ */
+public enum MLTaskState {
+    CREATED,
+    RUNNING,
+    COMPLETED,
+    FAILED
+}

plugin/src/main/java/org/opensearch/ml/model/MLTaskType.java

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+/*
+ * 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.
+ *
+ * Modifications Copyright OpenSearch Contributors. See
+ * GitHub history for details.
+ *
+ */
+
+package org.opensearch.ml.model;
+
+public enum MLTaskType {
+    TRAINING,
+    PREDICTION
+}

plugin/src/test/java/org/opensearch/ml/model/MLTaskTests.java

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+/*
+ * 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.
+ *
+ * Modifications Copyright OpenSearch Contributors. See
+ * GitHub history for details.
+ *
+ */
+
+package org.opensearch.ml.model;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.opensearch.common.io.stream.BytesStreamOutput;
+
+import java.io.IOException;
+import java.time.Instant;
+
+public class MLTaskTests {
+    @Test
+    public void testWriteTo() throws IOException {
+        BytesStreamOutput output = new BytesStreamOutput();
+        Instant now = Instant.now();
+        MLTask task1 = MLTask.builder()
+                .taskId("dummy taskId")
+                .taskType(MLTaskType.PREDICTION.name())
+                .modelId(null)
+                .createTime(now)
+                .state(MLTaskState.RUNNING.name())
+                .build();
+        task1.writeTo(output);
+        MLTask task2 = new MLTask(output.bytes().streamInput());
+        Assert.assertEquals(task1, task2);
+    }
+}