[ML] Data Frame HLRC Get API (#40209)

client/rest-high-level/src/main/java/org/elasticsearch/client/DataFrameClient.java

@@ -22,6 +22,8 @@ package org.elasticsearch.client;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.client.core.AcknowledgedResponse;
 import org.elasticsearch.client.dataframe.DeleteDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformResponse;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsRequest;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsResponse;
 import org.elasticsearch.client.dataframe.PreviewDataFrameTransformRequest;
@@ -275,7 +277,7 @@ public final class DataFrameClient {
      * @param listener Listener to be notified upon request completion
      */
     public void stopDataFrameTransformAsync(StopDataFrameTransformRequest request, RequestOptions options,
-                                              ActionListener<StopDataFrameTransformResponse> listener) {
+                                            ActionListener<StopDataFrameTransformResponse> listener) {
         restHighLevelClient.performRequestAsyncAndParseEntity(request,
                 DataFrameRequestConverters::stopDataFrameTransform,
                 options,
@@ -283,4 +285,44 @@ public final class DataFrameClient {
                 listener,
                 Collections.emptySet());
     }
+
+    /**
+     * Get one or more data frame transform configurations
+     * <p>
+     * For additional info
+     * see <a href="https://www.TODO.com">Get Data Frame transform documentation</a>
+     *
+     * @param request The get data frame transform request
+     * @param options Additional request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return An GetDataFrameTransformResponse containing the requested transforms
+     * @throws IOException when there is a serialization issue sending the request or receiving the response
+     */
+    public GetDataFrameTransformResponse getDataFrameTransform(GetDataFrameTransformRequest request, RequestOptions options)
+            throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(request,
+                DataFrameRequestConverters::getDataFrameTransform,
+                options,
+                GetDataFrameTransformResponse::fromXContent,
+                Collections.emptySet());
+    }
+
+    /**
+     * Get one or more data frame transform configurations asynchronously and notifies listener on completion
+     * <p>
+     * For additional info
+     * see <a href="https://www.TODO.com">Get Data Frame transform documentation</a>
+     *
+     * @param request The get data frame transform request
+     * @param options Additional request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @param listener Listener to be notified upon request completion
+     */
+    public void getDataFrameTransformAsync(GetDataFrameTransformRequest request, RequestOptions options,
+                                           ActionListener<GetDataFrameTransformResponse> listener) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(request,
+                DataFrameRequestConverters::getDataFrameTransform,
+                options,
+                GetDataFrameTransformResponse::fromXContent,
+                listener,
+                Collections.emptySet());
+    }
 }

client/rest-high-level/src/main/java/org/elasticsearch/client/DataFrameRequestConverters.java

@@ -24,11 +24,13 @@ import org.apache.http.client.methods.HttpGet;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.client.methods.HttpPut;
 import org.elasticsearch.client.dataframe.DeleteDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformRequest;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsRequest;
 import org.elasticsearch.client.dataframe.PreviewDataFrameTransformRequest;
 import org.elasticsearch.client.dataframe.PutDataFrameTransformRequest;
 import org.elasticsearch.client.dataframe.StartDataFrameTransformRequest;
 import org.elasticsearch.client.dataframe.StopDataFrameTransformRequest;
+import org.elasticsearch.common.Strings;
 
 import java.io.IOException;
 
@@ -49,6 +51,21 @@ final class DataFrameRequestConverters {
         return request;
     }
 
+    static Request getDataFrameTransform(GetDataFrameTransformRequest getRequest) {
+        String endpoint = new RequestConverters.EndpointBuilder()
+                .addPathPartAsIs("_data_frame", "transforms")
+                .addPathPart(Strings.collectionToCommaDelimitedString(getRequest.getId()))
+                .build();
+        Request request = new Request(HttpGet.METHOD_NAME, endpoint);
+        if (getRequest.getFrom() != null) {
+            request.addParameter("from", getRequest.getFrom().toString());
+        }
+        if (getRequest.getSize() != null) {
+            request.addParameter("size", getRequest.getSize().toString());
+        }
+        return request;
+    }
+
     static Request deleteDataFrameTransform(DeleteDataFrameTransformRequest request) {
         String endpoint = new RequestConverters.EndpointBuilder()
                 .addPathPartAsIs("_data_frame", "transforms")

client/rest-high-level/src/main/java/org/elasticsearch/client/dataframe/GetDataFrameTransformRequest.java

@@ -0,0 +1,96 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.client.dataframe;
+
+import org.elasticsearch.client.Validatable;
+import org.elasticsearch.client.ValidationException;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+
+public class GetDataFrameTransformRequest implements Validatable {
+
+    private final List<String> ids;
+    private Integer from;
+    private Integer size;
+
+    /**
+     * Helper method to create a request that will get ALL Data Frame Transforms
+     * @return new {@link GetDataFrameTransformRequest} object for the id "_all"
+     */
+    public static GetDataFrameTransformRequest getAllDataFrameTransformsRequest() {
+        return new GetDataFrameTransformRequest("_all");
+    }
+
+    public GetDataFrameTransformRequest(String... ids) {
+        this.ids = Arrays.asList(ids);
+    }
+
+    public List<String> getId() {
+        return ids;
+    }
+
+    public Integer getFrom() {
+        return from;
+    }
+
+    public void setFrom(Integer from) {
+        this.from = from;
+    }
+
+    public Integer getSize() {
+        return size;
+    }
+
+    public void setSize(Integer size) {
+        this.size = size;
+    }
+
+    @Override
+    public Optional<ValidationException> validate() {
+        if (ids == null || ids.isEmpty()) {
+            ValidationException validationException = new ValidationException();
+            validationException.addValidationError("data frame transform id must not be null");
+            return Optional.of(validationException);
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(ids);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj == null || getClass() != obj.getClass()) {
+            return false;
+        }
+        GetDataFrameTransformRequest other = (GetDataFrameTransformRequest) obj;
+        return Objects.equals(ids, other.ids);
+    }
+}

client/rest-high-level/src/main/java/org/elasticsearch/client/dataframe/GetDataFrameTransformResponse.java

@@ -0,0 +1,142 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.client.dataframe;
+
+import org.elasticsearch.client.dataframe.transforms.DataFrameTransformConfig;
+import org.elasticsearch.common.Nullable;
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.xcontent.ConstructingObjectParser;
+import org.elasticsearch.common.xcontent.XContentParser;
+
+import java.util.List;
+import java.util.Objects;
+
+import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
+import static org.elasticsearch.common.xcontent.ConstructingObjectParser.optionalConstructorArg;
+
+public class GetDataFrameTransformResponse {
+
+    public static final ParseField TRANSFORMS = new ParseField("transforms");
+    public static final ParseField INVALID_TRANSFORMS = new ParseField("invalid_transforms");
+    public static final ParseField COUNT = new ParseField("count");
+
+    @SuppressWarnings("unchecked")
+    static final ConstructingObjectParser<InvalidTransforms, Void> INVALID_TRANSFORMS_PARSER =
+            new ConstructingObjectParser<>("invalid_transforms", true, args -> new InvalidTransforms((List<String>) args[0]));
+
+    @SuppressWarnings("unchecked")
+    static final ConstructingObjectParser<GetDataFrameTransformResponse, Void> PARSER = new ConstructingObjectParser<>(
+            "get_data_frame_transform", true, args -> new GetDataFrameTransformResponse(
+                    (List<DataFrameTransformConfig>) args[0], (int) args[1], (InvalidTransforms) args[2]));
+    static {
+        // Discard the count field which is the size of the transforms array
+        INVALID_TRANSFORMS_PARSER.declareInt((a, b) -> {}, COUNT);
+        INVALID_TRANSFORMS_PARSER.declareStringArray(constructorArg(), TRANSFORMS);
+
+        PARSER.declareObjectArray(constructorArg(), DataFrameTransformConfig.PARSER::apply, TRANSFORMS);
+        PARSER.declareInt(constructorArg(), COUNT);
+        PARSER.declareObject(optionalConstructorArg(), INVALID_TRANSFORMS_PARSER::apply, INVALID_TRANSFORMS);
+    }
+
+    public static GetDataFrameTransformResponse fromXContent(final XContentParser parser) {
+        return GetDataFrameTransformResponse.PARSER.apply(parser, null);
+    }
+
+    private List<DataFrameTransformConfig> transformConfigurations;
+    private int count;
+    private InvalidTransforms invalidTransforms;
+
+    public GetDataFrameTransformResponse(List<DataFrameTransformConfig> transformConfigurations,
+                                         int count,
+                                         @Nullable InvalidTransforms invalidTransforms) {
+        this.transformConfigurations = transformConfigurations;
+        this.count = count;
+        this.invalidTransforms = invalidTransforms;
+    }
+
+    @Nullable
+    public InvalidTransforms getInvalidTransforms() {
+        return invalidTransforms;
+    }
+
+    public int getCount() {
+        return count;
+    }
+
+    public List<DataFrameTransformConfig> getTransformConfigurations() {
+        return transformConfigurations;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(transformConfigurations, count, invalidTransforms);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+
+        if (other == null || getClass() != other.getClass()) {
+            return false;
+        }
+
+        final GetDataFrameTransformResponse that = (GetDataFrameTransformResponse) other;
+        return Objects.equals(this.transformConfigurations, that.transformConfigurations)
+                && Objects.equals(this.count, that.count)
+                && Objects.equals(this.invalidTransforms, that.invalidTransforms);
+    }
+
+    static class InvalidTransforms {
+        private final List<String> transformIds;
+
+        InvalidTransforms(List<String> transformIds) {
+            this.transformIds = transformIds;
+        }
+
+        public int getCount() {
+            return transformIds.size();
+        }
+
+        public List<String> getTransformIds() {
+            return transformIds;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(transformIds);
+        }
+
+        @Override
+        public boolean equals(Object other) {
+            if (this == other) {
+                return true;
+            }
+
+            if (other == null || getClass() != other.getClass()) {
+                return false;
+            }
+
+            final InvalidTransforms that = (InvalidTransforms) other;
+            return Objects.equals(this.transformIds, that.transformIds);
+        }
+    }
+}

client/rest-high-level/src/main/java/org/elasticsearch/client/dataframe/transforms/DataFrameTransformConfig.java

@@ -46,7 +46,7 @@ public class DataFrameTransformConfig implements ToXContentObject {
     private final DestConfig dest;
     private final PivotConfig pivotConfig;
 
-    public static final ConstructingObjectParser<DataFrameTransformConfig, String> PARSER =
+    public static final ConstructingObjectParser<DataFrameTransformConfig, Void> PARSER =
             new ConstructingObjectParser<>("data_frame_transform", true,
                 (args) -> {
                     String id = (String) args[0];

client/rest-high-level/src/test/java/org/elasticsearch/client/DataFrameRequestConvertersTests.java

@@ -24,6 +24,7 @@ import org.apache.http.client.methods.HttpGet;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.client.methods.HttpPut;
 import org.elasticsearch.client.dataframe.DeleteDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformRequest;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsRequest;
 import org.elasticsearch.client.dataframe.PreviewDataFrameTransformRequest;
 import org.elasticsearch.client.dataframe.PutDataFrameTransformRequest;
@@ -147,4 +148,29 @@ public class DataFrameRequestConvertersTests extends ESTestCase {
         assertEquals(HttpGet.METHOD_NAME, request.getMethod());
         assertThat(request.getEndpoint(), equalTo("/_data_frame/transforms/foo/_stats"));
     }
+
+    public void testGetDataFrameTransform() {
+        GetDataFrameTransformRequest getRequest = new GetDataFrameTransformRequest("bar");
+        Request request = DataFrameRequestConverters.getDataFrameTransform(getRequest);
+
+        assertEquals(HttpGet.METHOD_NAME, request.getMethod());
+        assertThat(request.getEndpoint(), equalTo("/_data_frame/transforms/bar"));
+
+        assertFalse(request.getParameters().containsKey("from"));
+        assertFalse(request.getParameters().containsKey("size"));
+
+        getRequest.setFrom(0);
+        getRequest.setSize(10);
+        request = DataFrameRequestConverters.getDataFrameTransform(getRequest);
+        assertEquals("0", request.getParameters().get("from"));
+        assertEquals("10", request.getParameters().get("size"));
+    }
+
+    public void testGetDataFrameTransform_givenMulitpleIds() {
+        GetDataFrameTransformRequest getRequest = new GetDataFrameTransformRequest("foo", "bar", "baz");
+        Request request = DataFrameRequestConverters.getDataFrameTransform(getRequest);
+
+        assertEquals(HttpGet.METHOD_NAME, request.getMethod());
+        assertThat(request.getEndpoint(), equalTo("/_data_frame/transforms/foo,bar,baz"));
+    }
 }

client/rest-high-level/src/test/java/org/elasticsearch/client/DataFrameTransformIT.java

@@ -27,6 +27,8 @@ import org.elasticsearch.action.support.WriteRequest;
 import org.elasticsearch.client.core.AcknowledgedResponse;
 import org.elasticsearch.client.core.IndexerState;
 import org.elasticsearch.client.dataframe.DeleteDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformResponse;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsRequest;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsResponse;
 import org.elasticsearch.client.dataframe.PreviewDataFrameTransformRequest;
@@ -52,6 +54,7 @@ import org.elasticsearch.client.indices.CreateIndexResponse;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.index.query.MatchAllQueryBuilder;
+import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.search.aggregations.AggregationBuilders;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
 import org.junit.After;
@@ -67,6 +70,7 @@ import java.util.Optional;
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 
@@ -153,16 +157,8 @@ public class DataFrameTransformIT extends ESRestHighLevelClientTestCase {
         String sourceIndex = "transform-source";
         createIndex(sourceIndex);
 
-        QueryConfig queryConfig = new QueryConfig(new MatchAllQueryBuilder());
-        GroupConfig groupConfig = new GroupConfig(Collections.singletonMap("reviewer", new TermsGroupSource("user_id")));
-        AggregatorFactories.Builder aggBuilder = new AggregatorFactories.Builder();
-        aggBuilder.addAggregator(AggregationBuilders.avg("avg_rating").field("stars"));
-        AggregationConfig aggConfig = new AggregationConfig(aggBuilder);
-        PivotConfig pivotConfig = new PivotConfig(groupConfig, aggConfig);
-
         String id = "test-crud";
-        DataFrameTransformConfig transform = new DataFrameTransformConfig(id,
-            new SourceConfig(new String[]{sourceIndex}, queryConfig), new DestConfig("pivot-dest"), pivotConfig);
+        DataFrameTransformConfig transform = validDataFrameTransformConfig(id, sourceIndex, "pivot-dest");
 
         DataFrameClient client = highLevelClient().dataFrame();
         AcknowledgedResponse ack = execute(new PutDataFrameTransformRequest(transform), client::putDataFrameTransform,
@@ -180,20 +176,78 @@ public class DataFrameTransformIT extends ESRestHighLevelClientTestCase {
         assertThat(deleteError.getMessage(), containsString("Transform with id [test-crud] could not be found"));
     }
 
-    public void testStartStop() throws IOException {
+    public void testGetTransform() throws IOException {
         String sourceIndex = "transform-source";
         createIndex(sourceIndex);
 
-        QueryConfig queryConfig = new QueryConfig(new MatchAllQueryBuilder());
-        GroupConfig groupConfig = new GroupConfig(Collections.singletonMap("reviewer", new TermsGroupSource("user_id")));
-        AggregatorFactories.Builder aggBuilder = new AggregatorFactories.Builder();
-        aggBuilder.addAggregator(AggregationBuilders.avg("avg_rating").field("stars"));
-        AggregationConfig aggConfig = new AggregationConfig(aggBuilder);
-        PivotConfig pivotConfig = new PivotConfig(groupConfig, aggConfig);
+        String id = "test-get";
+        DataFrameTransformConfig transform = validDataFrameTransformConfig(id, sourceIndex, "pivot-dest");
+
+        DataFrameClient client = highLevelClient().dataFrame();
+        AcknowledgedResponse ack = execute(new PutDataFrameTransformRequest(transform), client::putDataFrameTransform,
+                client::putDataFrameTransformAsync);
+        assertTrue(ack.isAcknowledged());
+
+        GetDataFrameTransformRequest getRequest = new GetDataFrameTransformRequest(id);
+        GetDataFrameTransformResponse getResponse = execute(getRequest, client::getDataFrameTransform,
+                client::getDataFrameTransformAsync);
+        assertNull(getResponse.getInvalidTransforms());
+        assertThat(getResponse.getTransformConfigurations(), hasSize(1));
+        assertEquals(transform, getResponse.getTransformConfigurations().get(0));
+    }
+
+    public void testGetAllAndPageTransforms() throws IOException {
+        String sourceIndex = "transform-source";
+        createIndex(sourceIndex);
+
+        DataFrameClient client = highLevelClient().dataFrame();
+
+        DataFrameTransformConfig transform = validDataFrameTransformConfig("test-get-all-1", sourceIndex, "pivot-dest-1");
+        AcknowledgedResponse ack = execute(new PutDataFrameTransformRequest(transform), client::putDataFrameTransform,
+                client::putDataFrameTransformAsync);
+        assertTrue(ack.isAcknowledged());
+
+        transform = validDataFrameTransformConfig("test-get-all-2", sourceIndex, "pivot-dest-2");
+        ack = execute(new PutDataFrameTransformRequest(transform), client::putDataFrameTransform,
+                client::putDataFrameTransformAsync);
+        assertTrue(ack.isAcknowledged());
+
+        GetDataFrameTransformRequest getRequest = new GetDataFrameTransformRequest("_all");
+        GetDataFrameTransformResponse getResponse = execute(getRequest, client::getDataFrameTransform,
+                client::getDataFrameTransformAsync);
+        assertNull(getResponse.getInvalidTransforms());
+        assertThat(getResponse.getTransformConfigurations(), hasSize(2));
+        assertEquals(transform, getResponse.getTransformConfigurations().get(1));
+
+        getRequest.setFrom(0);
+        getRequest.setSize(1);
+        getResponse = execute(getRequest, client::getDataFrameTransform,
+                client::getDataFrameTransformAsync);
+        assertNull(getResponse.getInvalidTransforms());
+        assertThat(getResponse.getTransformConfigurations(), hasSize(1));
+
+        GetDataFrameTransformRequest getMulitple = new GetDataFrameTransformRequest("test-get-all-1", "test-get-all-2");
+        getResponse = execute(getMulitple, client::getDataFrameTransform,
+                client::getDataFrameTransformAsync);
+        assertNull(getResponse.getInvalidTransforms());
+        assertThat(getResponse.getTransformConfigurations(), hasSize(2));
+    }
+
+    public void testGetMissingTransform() {
+        DataFrameClient client = highLevelClient().dataFrame();
+
+        ElasticsearchStatusException missingError = expectThrows(ElasticsearchStatusException.class,
+                () -> execute(new GetDataFrameTransformRequest("unknown"), client::getDataFrameTransform,
+                        client::getDataFrameTransformAsync));
+        assertThat(missingError.status(), equalTo(RestStatus.NOT_FOUND));
+    }
+
+    public void testStartStop() throws IOException {
+        String sourceIndex = "transform-source";
+        createIndex(sourceIndex);
 
         String id = "test-stop-start";
-        DataFrameTransformConfig transform = new DataFrameTransformConfig(id,
-            new SourceConfig(new String[]{sourceIndex}, queryConfig), new DestConfig("pivot-dest"), pivotConfig);
+        DataFrameTransformConfig transform = validDataFrameTransformConfig(id, sourceIndex, "pivot-dest");
 
         DataFrameClient client = highLevelClient().dataFrame();
         AcknowledgedResponse ack = execute(new PutDataFrameTransformRequest(transform), client::putDataFrameTransform,
@@ -226,15 +280,7 @@ public class DataFrameTransformIT extends ESRestHighLevelClientTestCase {
         createIndex(sourceIndex);
         indexData(sourceIndex);
 
-        QueryConfig queryConfig = new QueryConfig(new MatchAllQueryBuilder());
-        GroupConfig groupConfig = new GroupConfig(Collections.singletonMap("reviewer", new TermsGroupSource("user_id")));
-        AggregatorFactories.Builder aggBuilder = new AggregatorFactories.Builder();
-        aggBuilder.addAggregator(AggregationBuilders.avg("avg_rating").field("stars"));
-        AggregationConfig aggConfig = new AggregationConfig(aggBuilder);
-        PivotConfig pivotConfig = new PivotConfig(groupConfig, aggConfig);
-
-        DataFrameTransformConfig transform = new DataFrameTransformConfig("test-preview",
-            new SourceConfig(new String[]{sourceIndex}, queryConfig), null, pivotConfig);
+        DataFrameTransformConfig transform = validDataFrameTransformConfig("test-preview", sourceIndex, null);
 
         DataFrameClient client = highLevelClient().dataFrame();
         PreviewDataFrameTransformResponse preview = execute(new PreviewDataFrameTransformRequest(transform),
@@ -245,11 +291,27 @@ public class DataFrameTransformIT extends ESRestHighLevelClientTestCase {
         assertThat(docs, hasSize(2));
         Optional<Map<String, Object>> theresa = docs.stream().filter(doc -> "theresa".equals(doc.get("reviewer"))).findFirst();
         assertTrue(theresa.isPresent());
-        assertEquals(2.5d, (double)theresa.get().get("avg_rating"), 0.01d);
+        assertEquals(2.5d, (double) theresa.get().get("avg_rating"), 0.01d);
 
         Optional<Map<String, Object>> michel = docs.stream().filter(doc -> "michel".equals(doc.get("reviewer"))).findFirst();
         assertTrue(michel.isPresent());
-        assertEquals(3.6d, (double)michel.get().get("avg_rating"), 0.1d);
+        assertEquals(3.6d, (double) michel.get().get("avg_rating"), 0.1d);
+    }
+
+    private DataFrameTransformConfig validDataFrameTransformConfig(String id, String source, String destination) {
+        QueryConfig queryConfig = new QueryConfig(new MatchAllQueryBuilder());
+        GroupConfig groupConfig = new GroupConfig(Collections.singletonMap("reviewer", new TermsGroupSource("user_id")));
+        AggregatorFactories.Builder aggBuilder = new AggregatorFactories.Builder();
+        aggBuilder.addAggregator(AggregationBuilders.avg("avg_rating").field("stars"));
+        AggregationConfig aggConfig = new AggregationConfig(aggBuilder);
+        PivotConfig pivotConfig = new PivotConfig(groupConfig, aggConfig);
+
+        DestConfig destConfig = (destination != null) ? new DestConfig(destination) : null;
+
+        return new DataFrameTransformConfig(id,
+                new SourceConfig(new String[]{source}, queryConfig),
+                destConfig,
+                pivotConfig);
     }
 
     public void testGetStats() throws Exception {

client/rest-high-level/src/test/java/org/elasticsearch/client/ESRestHighLevelClientTestCase.java

@@ -34,6 +34,7 @@ import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.core.internal.io.IOUtils;
 import org.elasticsearch.ingest.Pipeline;
 import org.elasticsearch.search.SearchHit;
+import org.elasticsearch.search.SearchModule;
 import org.elasticsearch.test.rest.ESRestTestCase;
 import org.junit.AfterClass;
 import org.junit.Before;
@@ -130,7 +131,7 @@ public abstract class ESRestHighLevelClientTestCase extends ESRestTestCase {
 
     private static class HighLevelClient extends RestHighLevelClient {
         private HighLevelClient(RestClient restClient) {
-            super(restClient, (client) -> {}, Collections.emptyList());
+            super(restClient, (client) -> {}, new SearchModule(Settings.EMPTY, false, Collections.emptyList()).getNamedXContents());
         }
     }
 

client/rest-high-level/src/test/java/org/elasticsearch/client/dataframe/GetDataFrameTransformRequestTests.java

@@ -0,0 +1,32 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.client.dataframe;
+
+import org.elasticsearch.test.ESTestCase;
+
+import static org.hamcrest.Matchers.containsString;
+
+public class GetDataFrameTransformRequestTests extends ESTestCase {
+    public void testValidate() {
+        assertFalse(new GetDataFrameTransformRequest("valid-id").validate().isPresent());
+        assertThat(new GetDataFrameTransformRequest(new String[0]).validate().get().getMessage(),
+                containsString("data frame transform id must not be null"));
+    }
+}

client/rest-high-level/src/test/java/org/elasticsearch/client/dataframe/GetDataFrameTransformResponseTests.java

@@ -0,0 +1,84 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.client.dataframe;
+
+import org.elasticsearch.client.dataframe.transforms.DataFrameTransformConfig;
+import org.elasticsearch.client.dataframe.transforms.DataFrameTransformConfigTests;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.xcontent.NamedXContentRegistry;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.search.SearchModule;
+import org.elasticsearch.test.ESTestCase;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.elasticsearch.test.AbstractXContentTestCase.xContentTester;
+
+
+public class GetDataFrameTransformResponseTests extends ESTestCase {
+
+    public void testXContentParser() throws IOException {
+        xContentTester(this::createParser,
+                GetDataFrameTransformResponseTests::createTestInstance,
+                GetDataFrameTransformResponseTests::toXContent,
+                GetDataFrameTransformResponse::fromXContent)
+                .supportsUnknownFields(false)
+                .test();
+    }
+
+    private static GetDataFrameTransformResponse createTestInstance() {
+        int numTransforms = randomIntBetween(0, 3);
+        List<DataFrameTransformConfig> transforms = new ArrayList<>();
+        for (int i=0; i<numTransforms; i++) {
+            transforms.add(DataFrameTransformConfigTests.randomDataFrameTransformConfig());
+        }
+        GetDataFrameTransformResponse.InvalidTransforms invalidTransforms = null;
+        if (randomBoolean()) {
+            List<String> invalidIds = Arrays.asList(generateRandomStringArray(5, 6, false, false));
+            invalidTransforms = new GetDataFrameTransformResponse.InvalidTransforms(invalidIds);
+        }
+        return new GetDataFrameTransformResponse(transforms, transforms.size() + 10, invalidTransforms);
+    }
+
+    private static void toXContent(GetDataFrameTransformResponse response, XContentBuilder builder) throws IOException {
+        builder.startObject();
+        {
+            builder.field("count", response.getCount());
+            builder.field("transforms", response.getTransformConfigurations());
+            if (response.getInvalidTransforms() != null) {
+                builder.startObject("invalid_transforms");
+                builder.field("count", response.getInvalidTransforms().getCount());
+                builder.field("transforms", response.getInvalidTransforms().getTransformIds());
+                builder.endObject();
+            }
+        }
+        builder.endObject();
+    }
+
+    @Override
+    protected NamedXContentRegistry xContentRegistry() {
+        SearchModule searchModule = new SearchModule(Settings.EMPTY, false, Collections.emptyList());
+        return new NamedXContentRegistry(searchModule.getNamedXContents());
+    }
+}

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/DataFrameTransformDocumentationIT.java

@@ -27,6 +27,8 @@ import org.elasticsearch.client.RestHighLevelClient;
 import org.elasticsearch.client.core.AcknowledgedResponse;
 import org.elasticsearch.client.core.IndexerState;
 import org.elasticsearch.client.dataframe.DeleteDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformRequest;
+import org.elasticsearch.client.dataframe.GetDataFrameTransformResponse;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsRequest;
 import org.elasticsearch.client.dataframe.GetDataFrameTransformStatsResponse;
 import org.elasticsearch.client.dataframe.PreviewDataFrameTransformRequest;
@@ -178,7 +180,6 @@ public class DataFrameTransformDocumentationIT extends ESRestHighLevelClientTest
 
             // Replace the empty listener by a blocking listener in test
             final CountDownLatch latch = new CountDownLatch(1);
-            ActionListener<AcknowledgedResponse> ackListener = listener;
             listener = new LatchedActionListener<>(listener, latch);
 
             // tag::put-data-frame-transform-execute-async
@@ -264,7 +265,6 @@ public class DataFrameTransformDocumentationIT extends ESRestHighLevelClientTest
 
             // Replace the empty listener by a blocking listener in test
             final CountDownLatch latch = new CountDownLatch(1);
-            ActionListener<StartDataFrameTransformResponse> ackListener = listener;
             listener = new LatchedActionListener<>(listener, latch);
 
             StartDataFrameTransformRequest request = new StartDataFrameTransformRequest("mega-transform");
@@ -294,7 +294,6 @@ public class DataFrameTransformDocumentationIT extends ESRestHighLevelClientTest
 
             // Replace the empty listener by a blocking listener in test
             final CountDownLatch latch = new CountDownLatch(1);
-            ActionListener<StopDataFrameTransformResponse> ackListener = listener;
             listener = new LatchedActionListener<>(listener, latch);
 
             StopDataFrameTransformRequest request = new StopDataFrameTransformRequest("mega-transform");
@@ -392,14 +391,14 @@ public class DataFrameTransformDocumentationIT extends ESRestHighLevelClientTest
                 pivotConfig);
 
         PreviewDataFrameTransformRequest request =
-            new PreviewDataFrameTransformRequest(transformConfig); // <3>
+                new PreviewDataFrameTransformRequest(transformConfig); // <3>
         // end::preview-data-frame-transform-request
 
         {
             // tag::preview-data-frame-transform-execute
             PreviewDataFrameTransformResponse response =
-                    client.dataFrame()
-                            .previewDataFrameTransform(request, RequestOptions.DEFAULT);
+                client.dataFrame()
+                    .previewDataFrameTransform(request, RequestOptions.DEFAULT);
             // end::preview-data-frame-transform-execute
 
             assertNotNull(response.getDocs());
@@ -482,10 +481,83 @@ public class DataFrameTransformDocumentationIT extends ESRestHighLevelClientTest
         {
             // tag::get-data-frame-transform-stats-execute-listener
             ActionListener<GetDataFrameTransformStatsResponse> listener =
-                new ActionListener<GetDataFrameTransformStatsResponse>() {
+                    new ActionListener<GetDataFrameTransformStatsResponse>() {
+                        @Override
+                        public void onResponse(
+                                GetDataFrameTransformStatsResponse response) {
+                            // <1>
+                        }
+
+                        @Override
+                        public void onFailure(Exception e) {
+                            // <2>
+                        }
+                    };
+            // end::get-data-frame-transform-stats-execute-listener
+
+            // Replace the empty listener by a blocking listener in test
+            final CountDownLatch latch = new CountDownLatch(1);
+            listener = new LatchedActionListener<>(listener, latch);
+
+            // tag::get-data-frame-transform-stats-execute-async
+            client.dataFrame().getDataFrameTransformStatsAsync(
+                    request, RequestOptions.DEFAULT, listener);  // <1>
+            // end::get-data-frame-transform-stats-execute-async
+
+            assertTrue(latch.await(30L, TimeUnit.SECONDS));
+        }
+    }
+
+
+    public void testGetDataFrameTransform() throws IOException, InterruptedException {
+        createIndex("source-data");
+        
+        QueryConfig queryConfig = new QueryConfig(new MatchAllQueryBuilder());
+        GroupConfig groupConfig = new GroupConfig(Collections.singletonMap("reviewer", new TermsGroupSource("user_id")));
+        AggregatorFactories.Builder aggBuilder = new AggregatorFactories.Builder();
+        aggBuilder.addAggregator(AggregationBuilders.avg("avg_rating").field("stars"));
+        AggregationConfig aggConfig = new AggregationConfig(aggBuilder);
+        PivotConfig pivotConfig = new PivotConfig(groupConfig, aggConfig);
+
+        
+        DataFrameTransformConfig putTransformConfig = new DataFrameTransformConfig("mega-transform",
+                new SourceConfig(new String[]{"source-data"}, queryConfig),
+                new DestConfig("pivot-dest"), pivotConfig);
+
+        RestHighLevelClient client = highLevelClient();
+        client.dataFrame().putDataFrameTransform(new PutDataFrameTransformRequest(putTransformConfig), RequestOptions.DEFAULT);
+        transformsToClean.add(putTransformConfig.getId());
+
+        {
+            // tag::get-data-frame-transform-request
+            GetDataFrameTransformRequest request =
+                    new GetDataFrameTransformRequest("mega-transform"); // <1>
+            // end::get-data-frame-transform-request
+
+            // tag::get-data-frame-transform-request-options
+            request.setFrom(0);     // <1>
+            request.setSize(100);   // <2>
+            // end::get-data-frame-transform-request-options
+
+            // tag::get-data-frame-transform-execute
+            GetDataFrameTransformResponse response =
+                client.dataFrame()
+                    .getDataFrameTransform(request, RequestOptions.DEFAULT);
+            // end::get-data-frame-transform-execute
+
+            // tag::get-data-frame-transform-response
+            List<DataFrameTransformConfig> transformConfigs =
+                    response.getTransformConfigurations();
+            // end::get-data-frame-transform-response
+
+            assertEquals(1, transformConfigs.size());
+        }
+        {
+            // tag::get-data-frame-transform-execute-listener
+            ActionListener<GetDataFrameTransformResponse> listener =
+                new ActionListener<GetDataFrameTransformResponse>() {
                     @Override
-                    public void onResponse(
-                            GetDataFrameTransformStatsResponse response) {
+                    public void onResponse(GetDataFrameTransformResponse response) {
                         // <1>
                     }
 
@@ -494,16 +566,18 @@ public class DataFrameTransformDocumentationIT extends ESRestHighLevelClientTest
                         // <2>
                     }
                 };
-            // end::get-data-frame-transform-stats-execute-listener
+            // end::get-data-frame-transform-execute-listener
 
             // Replace the empty listener by a blocking listener in test
             final CountDownLatch latch = new CountDownLatch(1);
             listener = new LatchedActionListener<>(listener, latch);
 
-            // tag::get-data-frame-transform-stats-execute-async
-            client.dataFrame().getDataFrameTransformStatsAsync(
+            GetDataFrameTransformRequest request = new GetDataFrameTransformRequest("mega-transform");
+
+            // tag::get-data-frame-transform-execute-async
+            client.dataFrame().getDataFrameTransformAsync(
                     request, RequestOptions.DEFAULT, listener);  // <1>
-            // end::get-data-frame-transform-stats-execute-async
+            // end::get-data-frame-transform-execute-async
 
             assertTrue(latch.await(30L, TimeUnit.SECONDS));
         }

docs/java-rest/high-level/dataframe/get_data_frame.asciidoc

@@ -0,0 +1,45 @@
+--
+:api: get-data-frame-transform
+:request: GetDataFrameTransformRequest
+:response: GetDataFrameTransformResponse
+--
+[id="{upid}-{api}"]
+=== Get Data Frame Transform API
+
+The Get Data Frame Transform API is used get one or more {dataframe-transform}.
+The API accepts a +{request}+ object and returns a +{response}+.
+
+[id="{upid}-{api}-request"]
+==== Get Data Frame Request
+
+A +{request}+ requires either a data frame transform id, a comma separated list of ids or
+the special wildcard `_all` to get all {dataframe-transform}s
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-request]
+--------------------------------------------------
+<1> Constructing a new GET request referencing an existing {dataframe-transform}
+
+==== Optional Arguments
+
+The following arguments are optional.
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-request-options]
+--------------------------------------------------
+<1> Page {dataframe-transform}s starting from this value
+<2> Return at most `size` {dataframe-transform}s
+
+include::../execution.asciidoc[]
+
+[id="{upid}-{api}-response"]
+==== Response
+
+The returned +{response}+ contains the requested {dataframe-transform}s.
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-response]
+--------------------------------------------------

docs/java-rest/high-level/supported-apis.asciidoc

@@ -554,6 +554,7 @@ include::ilm/remove_lifecycle_policy_from_index.asciidoc[]
 
 The Java High Level REST Client supports the following Data Frame APIs:
 
+* <<{upid}-get-data-frame-transform>>
 * <<{upid}-get-data-frame-transform-stats>>
 * <<{upid}-put-data-frame-transform>>
 * <<{upid}-delete-data-frame-transform>>
@@ -561,6 +562,7 @@ The Java High Level REST Client supports the following Data Frame APIs:
 * <<{upid}-start-data-frame-transform>>
 * <<{upid}-stop-data-frame-transform>>
 
+include::dataframe/get_data_frame.asciidoc[]
 include::dataframe/get_data_frame_stats.asciidoc[]
 include::dataframe/put_data_frame.asciidoc[]
 include::dataframe/delete_data_frame.asciidoc[]