Service feature table (no cache)

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Display a feature layer from a service using the no cache feature request mode.

Image of service feature table no cache

Use case

Service feature tables support 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 no cache in scenarios where you always want the freshest data. See Table performance concepts in the ArcGIS Runtime SDK for Android guide to learn more.

How to use the sample

Run the sample and pan and zoom around the map. With each interaction, new features will be requested from the service and displayed on the map.

How it works

  1. Set the ServiceFeatureTable.setFeatureRequestMode(...) property of the service feature table to ON_INTERACTION_NO_CACHE before the table is loaded.
  2. Add the table to the map using a FeatureLayer; features will be requested for the visible extent as the user pans and zooms.

Relevant API

  • FeatureLayer
  • FeatureRequestMode.ONINTERACTIONNO_CACHE
  • ServiceFeatureTable
  • ServiceFeatureTable.setFeatureRequestMode

About the data

The sample opens with an initial visible extent centered over pool permit statuses in California.

Additional information

In no cache mode, features are automatically populated from the service for the visible extent. Each time the user pans and zooms, features are downloaded for the visible extent. Features are still cached in a local geodatabase for display, but the cache will always be populated with the latest data after navigation.

NOTE: No cache does not guarantee that features won't be cached locally; feature request mode is a performance concept unrelated to data security.

Tags

cache, feature request mode, performance

Sample Code

MainActivity.java
                                                                                             
/* Copyright 2016 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.arcgisruntime.samples.servicefeaturetablenocache;

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.data.ServiceFeatureTable;
import com.esri.arcgisruntime.geometry.Envelope;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.layers.FeatureLayer;
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 MainActivity extends AppCompatActivity {

  private MapView mMapView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // authentication with an API key or named user is required to access basemaps and other
    // location services
    ArcGISRuntimeEnvironment.setApiKey(BuildConfig.API_KEY);

    // inflate MapView from layout
    mMapView = findViewById(R.id.mapView);

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

    // create feature layer with its service feature table
    // create the service feature table
    ServiceFeatureTable serviceFeatureTable = new ServiceFeatureTable(getString(R.string.sample_service_url));

    // explicitly set the mode to on interaction no cache (every interaction (pan, query etc) new features will be
    // requested
    serviceFeatureTable.setFeatureRequestMode(ServiceFeatureTable.FeatureRequestMode.ON_INTERACTION_NO_CACHE);

    // create the feature layer using the service feature table
    FeatureLayer featureLayer = new FeatureLayer(serviceFeatureTable);

    // add the layer to the map
    map.getOperationalLayers().add(featureLayer);

    // set the map to be displayed in the map view
    mMapView.setMap(map);

    // set an initial viewpoint
    mMapView.setViewpoint(new Viewpoint(
        new Envelope(-1.30758164047166E7, 4014771.46954516, -1.30730056797177E7, 4016869.78617381,
            SpatialReferences.getWebMercator())));
  }

  @Override
  protected void onPause() {
    super.onPause();
    // pause MapView
    mMapView.pause();
  }

  @Override
  protected void onResume() {
    super.onResume();
    // resume MapView
    mMapView.resume();
  }

  @Override
  protected void onDestroy() {
    super.onDestroy();
    // dispose MapView
    mMapView.dispose();
  }
}