Service feature table (manual cache)

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Display a feature layer from a service using the manual cache feature request mode.

Image of service feature table manual cache

Use case

ServiceFeatureTable supports three request modes, which define how features are requested from the service and stored in the local table. The feature request modes have different performance characteristics. Use manual cache in scenarios where you want to explicitly control requests for features.

How to use the sample

Run the sample and pan and zoom around the map. No features will be requested and displayed automatically. Press the "Request Cache" button to have features and a count of features display.

Note: Maximum of Features returned is set to 1000.

How it works

  1. Set the ServiceFeatureTable.FeatureRequestMode property of the service feature table to MANUAL_CACHE before the table is loaded.
  2. Load the table.
  3. Call populateFromServiceAsync() on the table to request features.

Relevant API

  • FeatureLayer
  • ServiceFeatureTable
  • ServiceFeatureTable.FeatureRequestMode

About the data

The samples uses an incident feature layer queried to show tree maintenance or damage. The sample opens with an initial visible extent centered over San Francisco.

Additional information

In manual cache mode, features are never automatically populated from the service. All features are loaded manually using calls to PopulateFromServiceAsync.

Tags

cache, feature request mode, performance

Sample Code

ServiceFeatureTableManualCacheSample.java
                                                                                                                                                                                                      
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/*
 * Copyright 2017 Esri.
 *
 * 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 com.esri.samples.service_feature_table_manual_cache;

import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

import javafx.application.Application;
import javafx.application.Platform;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Paint;
import javafx.stage.Stage;

import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.concurrent.ListenableFuture;
import com.esri.arcgisruntime.data.FeatureQueryResult;
import com.esri.arcgisruntime.data.QueryParameters;
import com.esri.arcgisruntime.data.ServiceFeatureTable;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.layers.FeatureLayer;
import com.esri.arcgisruntime.loadable.LoadStatus;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.BasemapStyle;
import com.esri.arcgisruntime.mapping.Viewpoint;
import com.esri.arcgisruntime.mapping.view.MapView;

public class ServiceFeatureTableManualCacheSample extends Application {

  private MapView mapView;
  private FeatureLayer featureLayer; // keep loadable in scope to avoid garbage collection
  private Label featuresReturnLabel;
  private ServiceFeatureTable featureTable;
  private ListenableFuture<FeatureQueryResult> tableResult;

  private static final String SERVICE_FEATURE_URL =
      "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/0";

  @Override
  public void start(Stage stage) {

    try {
      // create stack pane and application scene
      StackPane stackPane = new StackPane();
      Scene scene = new Scene(stackPane);
      scene.getStylesheets().add(getClass().getResource("/service_feature_table_manual_cache/style.css").toExternalForm());

      // set title, size, and add scene to stage
      stage.setTitle("Service Feature Table Manual Cache Sample");
      stage.setWidth(800);
      stage.setHeight(700);
      stage.setScene(scene);
      stage.show();

      // authentication with an API key or named user is required to access basemaps and other location services
      String yourAPIKey = System.getProperty("apiKey");
      ArcGISRuntimeEnvironment.setApiKey(yourAPIKey);

      // create a control panel
      VBox controlsVBox = new VBox(6);
      controlsVBox.setBackground(new Background(new BackgroundFill(Paint.valueOf("rgba(0,0,0,0.3)"), CornerRadii.EMPTY,
          Insets.EMPTY)));
      controlsVBox.setPadding(new Insets(10.0));
      controlsVBox.setMaxSize(200, 80);
      controlsVBox.getStyleClass().add("panel-region");

      // create button to request the service table's cache
      Button requestCacheButton = new Button("Request Cache");
      requestCacheButton.setMaxWidth(Double.MAX_VALUE);
      requestCacheButton.setDisable(true);

      requestCacheButton.setOnAction(e -> fetchCacheManually());

      // create a label to display number of features returned
      featuresReturnLabel = new Label("Features Returned: ");
      featuresReturnLabel.getStyleClass().add("panel-label");

      // add label and button to the control panel
      controlsVBox.getChildren().addAll(featuresReturnLabel, requestCacheButton);

      // create service feature table from a url
      featureTable = new ServiceFeatureTable(SERVICE_FEATURE_URL);

      // set request mode of service feature table to manual cache
      featureTable.setFeatureRequestMode(ServiceFeatureTable.FeatureRequestMode.MANUAL_CACHE);

      // create a feature layer from the service feature table
      featureLayer = new FeatureLayer(featureTable);

      // enable button when feature layer is done loading
      featureLayer.addDoneLoadingListener(() -> {
        if (featureLayer.getLoadStatus() == LoadStatus.LOADED) {
          requestCacheButton.setDisable(false);
        } else {
          Alert alert = new Alert(Alert.AlertType.ERROR, "Feature Layer Failed to Load!");
          alert.show();
        }
      });

      // create a map with the topographic basemap style
      ArcGISMap map = new ArcGISMap(BasemapStyle.ARCGIS_TOPOGRAPHIC);

      // create a map view and set the map to it
      mapView = new MapView();
      mapView.setMap(map);

      // add the feature layer to the map's operational layers
      map.getOperationalLayers().add(featureLayer);

      // set the starting viewpoint for the map view
      mapView.setViewpoint(new Viewpoint(new Point(-13630484, 4545415, SpatialReferences.getWebMercator()), 150000));

      // add the map view and control panel to stack pane
      stackPane.getChildren().addAll(mapView, controlsVBox);
      StackPane.setAlignment(controlsVBox, Pos.TOP_LEFT);
      StackPane.setMargin(controlsVBox, new Insets(10, 0, 0, 10));
    } catch (Exception e) {
      // on any error, display the stack trace
      e.printStackTrace();
    }
  }

  /**
   * Fetches the cache from a Service Feature Table manually.
   */
  private void fetchCacheManually() {

    // create query to select all tree or damage features
    QueryParameters queryParams = new QueryParameters();
    queryParams.setWhereClause("req_type = 'Tree Maintenance or Damage'");

    // * means all features
    List<String> outfields = Collections.singletonList("*");
    // get queried features from service feature table and clear previous cache
    tableResult = featureTable.populateFromServiceAsync(queryParams, true, outfields);

    tableResult.addDoneListener(() -> {
      try {
        // find the number of features returned from query
        AtomicInteger featuresReturned = new AtomicInteger();
        tableResult.get().forEach(feature -> featuresReturned.getAndIncrement());

        // display to user how many features where returned
        Platform.runLater(() -> featuresReturnLabel.setText("Features Returned: " + featuresReturned));
      } catch (Exception e) {
        // on any error, display the stack trace
        e.printStackTrace();
      }
    });
  }

  /**
   * Stops and releases all resources used in application.
   */
  @Override
  public void stop() {

    if (mapView != null) {
      mapView.dispose();
    }
  }

  /**
   * Opens and runs application.
   *
   * @param args arguments passed to this application
   */
  public static void main(String[] args) {

    Application.launch(args);
  }

}

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