- initial method added to poll server for sensors and retrieve results

Author: jvinall

Example/app/debug/app-debug.apk

@@ -14,6 +14,7 @@
 import android.widget.ArrayAdapter;
 import android.widget.Button;
 import android.widget.CheckBox;
+import android.widget.CompoundButton;
 import android.widget.ImageButton;
 import android.widget.ProgressBar;
 import android.widget.SeekBar;
@@ -48,7 +49,6 @@
 public class PullExampleActivity extends AppCompatActivity implements SosMessageListener {
     private SosService sosService;
     private ArrayList<SosSensor> sensors;
-    private SosSensor currentSensor = null;
 
     @Override
     public void onDestroy() {
@@ -62,14 +62,15 @@ public void onDestroy() {
      */
 
     private TextInputEditText editSosServerUrl, editSosUsername, editSosPassword;
-    private CheckBox checkSendIpc, checkSendNet;
+    private CheckBox checkSendIpc, checkSendNet, checkPoll;
     private TextView textCannotSendWarning, textResult;
     private Button sendButton;
     private View viewMeasurements;
-    private ProgressBar progressBar;
+    private ProgressBar progressBar, progressBarPolling;
     private Spinner spinner;
     private ArrayAdapter spinnerArrayAdapter = null;
     private boolean isWaiting = false;
+    private boolean systemChangingCheckPoll = false;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -86,11 +87,16 @@ protected void onCreate(Bundle savedInstanceState) {
         viewMeasurements = findViewById(R.id.viewMeasurements);
         sendButton.setOnClickListener(v -> sendQuery());
         spinner = findViewById(R.id.spinner);
+        checkPoll = findViewById(R.id.checkPoll);
+        progressBarPolling = findViewById(R.id.progressBarPolling);
         spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
-                if ((sensors != null) && (position < sensors.size()))
-                    currentSensor = sensors.get(position);
+                if ((sensors != null) && (position < sensors.size()) && (sosService != null)) {
+                    sosService.setSensor(sensors.get(position));
+                    if (checkPoll.isChecked())
+                        sosService.startPolling();
+                }
                 updateVisibility();
             }
 
@@ -108,6 +114,15 @@ public void onNothingSelected(AdapterView<?> parent) { }
             if (sosService != null)
                 sosService.setSosServerUrl(isChecked?editSosServerUrl.getText().toString():null);
         });
+        checkPoll.setOnCheckedChangeListener((buttonView, isChecked) -> {
+            if ((!systemChangingCheckPoll) && (sosService != null)) {
+                if (isChecked)
+                    sosService.startPolling();
+                else
+                    sosService.stopPolling();
+                updateVisibility();
+            }
+        });
         textResult.setMovementMethod(new ScrollingMovementMethod());
         loadValuesFromPreferences();
     }
@@ -129,7 +144,7 @@ private void sendQuery() {
         if ((sensors == null) || sensors.isEmpty())
             sosService.broadcast(new OperationGetCapabilities());
         else
-            sosService.broadcast(new OperationGetResults(currentSensor));
+            sosService.broadcast(new OperationGetResults(sosService.getSosSensor()));
     }
 
     private final static String PREFS_SEND_IPC = "ipc";
@@ -184,6 +199,8 @@ private void updateVisibility() {
         progressBar.setVisibility(isWaiting?View.VISIBLE:View.GONE);
         if ((sensors == null) || sensors.isEmpty()) {
             spinner.setVisibility(View.INVISIBLE);
+            checkPoll.setVisibility(View.INVISIBLE);
+            progressBarPolling.setVisibility(View.INVISIBLE);
             sendButton.setText("Request List of Sensors");
         } else {
             if (spinnerArrayAdapter == null) {
@@ -199,9 +216,26 @@ private void updateVisibility() {
                         values);
                 spinner.setAdapter(spinnerArrayAdapter);
                 spinner.setVisibility(View.VISIBLE);
+                checkPoll.setVisibility(View.VISIBLE);
                 spinner.setSelection(0);
             }
-            sendButton.setText("Request Sensor Results");
+            if (sosService != null) {
+                if (sosService.isPollingServer()) {
+                    sendButton.setText("Periodically getting results...");
+                    sendButton.setEnabled(false);
+                    progressBarPolling.setVisibility(View.VISIBLE);
+                } else {
+                    sendButton.setText("Request Sensor Results");
+                    sendButton.setEnabled(true);
+                    progressBarPolling.setVisibility(View.INVISIBLE);
+                }
+            } else
+                sendButton.setEnabled(false);
+        }
+        if (sosService != null) {
+            systemChangingCheckPoll = true;
+            checkPoll.setChecked(sosService.isPollingServer());
+            systemChangingCheckPoll = false;
         }
     }
 
@@ -284,6 +318,8 @@ public void onSosOperationReceived(final AbstractSosOperation operation) {
             runOnUiThread(() -> {
                 updateVisibility();
             });
+            if (checkPoll.isChecked() && (sosService != null))
+                sosService.startPolling();
             if (operation instanceof OperationGetCapabilitiesResponse) {
                 ArrayList<SosSensor> opSensors = ((OperationGetCapabilitiesResponse) operation).getSensors();
                 if ((opSensors != null) && !opSensors.isEmpty()) {
@@ -321,8 +357,10 @@ public void onSosOperationReceived(final AbstractSosOperation operation) {
                 runOnUiThread(() -> {
                     if (received == null)
                         log("GetResults failed to get any sensor information");
-                    else
+                    else {
+                        Toast.makeText(PullExampleActivity.this,received.getId()+" updated",Toast.LENGTH_SHORT).show();
                         log(received.toString());
+                    }
                 });
             }
             runOnUiThread(() -> {

Example/app/release/app-release.apk

@@ -138,6 +138,19 @@
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content" />
 
+            <CheckBox
+                android:id="@+id/checkPoll"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="Periodically poll server for results" />
+
+            <ProgressBar
+                android:id="@+id/progressBarPolling"
+                style="?android:attr/progressBarStyleHorizontal"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:indeterminate="true" />
+
             <Button
                 android:id="@+id/send"
                 android:layout_width="match_parent"

Example/app/src/main/java/org/sofwerx/swe/example/PullExampleActivity.java

@@ -11,6 +11,7 @@ A quick way to send sensor data to an OGC Sensor Observation Service - Transacti
 1. [What is SOS-T](#what-is)
 1. [How SOS-T Works](#brief-sos)
 1. [How to Send Sensor Data](#how-to)
+1. [How to Get Sensor Data](#how-to-receive)
 
 <h2 id="quick-start">Quick Start</h2>
 
@@ -120,3 +121,8 @@ When you are finally done communicating with the server, clean up the server con
 ```java
 sosService.shutdown();
 ```
+
+<h2 id="how-to-receive">How to Get Sensor Data</h2>
+
+Although outside of the original scope of this library, you can also use swe-android to pull data from an **SOS 2.0** compatible server. swe-library will retrieve a list of sensors and will allow you to get the latest sensor data for a particular sensor to include automatically polling the server to regularly get sensor data. To see how this is implemented, check out the PullExampleActivity in the Example app.<br/>
+swe-android will also except a limited number of **SOS-T** commands to allow one app running swe-android to share OGS SOS data with another app running swe-android. This is mostly a temporary work around to provide interim connectivity while more robust solutions like **Open Sensor Hub** become fully integrated.

Example/app/src/main/res/layout/activity_pull.xml

@@ -38,6 +38,8 @@ public class SosService implements SosMessageListener {
     private boolean ipcBroadcast;
     private boolean sosHttpBroadcast;
     private boolean sensorMode = true;
+    private AtomicBoolean shouldPollServer = new AtomicBoolean(false);
+    private long pollInterval = 1000l * 15l; //default server polling interval
 
     /**
      * Creates a new SosService
@@ -81,6 +83,45 @@ public SosService(Context context, SosSensor sosSensor, String sosServerURL, fin
         this(context, sosSensor, sosServerURL, null, null, turnOn, enableIpcBroadcast);
     }
 
+    public boolean startPolling() {
+        if (!shouldPollServer.get()) {
+            if (handler == null) {
+                Log.d(SosIpcTransceiver.TAG,"cannot setup regular server polling as handler is not yet assigned");
+                return false;
+            }
+            shouldPollServer.set(true);
+            handler.post(repeatPollServer);
+            return true;
+        }
+        return true;
+    }
+
+    public void stopPolling() {
+        shouldPollServer.set(false);
+    }
+
+    /**
+     * TIme between polling of the SOS server for sensor data
+     * @param interval time (in ms)
+     */
+    public void setPollingInterval(long interval) { pollInterval = interval; }
+    public boolean isPollingServer() { return shouldPollServer.get(); }
+
+    private Runnable repeatPollServer = new Runnable() {
+        @Override
+        public void run() {
+            if (shouldPollServer.get()) {
+                if (sosSensor != null) {
+                    OperationGetResults op = new OperationGetResults(sosSensor);
+                    if (op.isValid())
+                        broadcast(op);
+                }
+                if (handler != null)
+                    handler.postDelayed(repeatPollServer, pollInterval);
+            }
+        }
+    };
+
     /**
      * Toggles between on (active/running/transmitting and receiving) and off (paused)
      * @param on true = on/active/transmitting and receiving
@@ -95,6 +136,8 @@ public void setOn(boolean on) {
                     context.registerReceiver(transceiver, intentFilter);
                     if (sensorMode)
                         broadcastSensorReadings();
+                    else
+                        startPolling();
                 }
             } else {
                 Log.i(SosIpcTransceiver.TAG,"SosService turned OFF");
@@ -209,6 +252,7 @@ public void broadcast(AbstractSosOperation operation) {
 
     public void shutdown() {
         Log.i(SosIpcTransceiver.TAG,"Shutting down SosServer");
+        stopPolling();
         setOn(false);
         if (sosThread != null) {
             if (handler != null)
@@ -251,6 +295,7 @@ public void registerSensor() {
     public SosMessageListener getListener() { return listener; }
     public void setListener(SosMessageListener listener) { this.listener = listener; }
     public SosSensor getSosSensor() { return sosSensor; }
+    public void setSensor(SosSensor sensor) { this.sosSensor = sensor; }
     public void setSosServerUrl(String serverUrl) { this.serverURL = serverUrl; }
     public String getSosServerUrl() { return serverURL; }
     public void setSosServerUsername(String username) {