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AllJoyn™ Control Panel Framework API Guide – Java

Reference code

Control Panel service framework packages

Package Description
ControlPanelService.jar The service layer does all the work against the AllJoyn™ framework.
ControlPanelAdapter.jar Creates Android-specific user interface views.

Reference Java application code

Application Description
ControlPanelBrowser.apk Sample application that uses the service framework and adapter APIs.

Obtain the Control Panel service framework

See the Building Android section for instructions on obtaining the Control Panel service framework.

Build a Controller

The following steps provide the high-level process to build a Controller.

  1. Create the base for the AllJoyn application.
  2. Start the AboutClient.
  3. Listen for the announcement to find Controllee devices on the network.
  4. Choose a control panel from the collection that was received in the announcement in your preferred language.
  5. Establish a session with the Controllee device that you would like to interact with.
  6. Get the device's control panel widgets to pass to the Adapter. The Adapter converts these widgets to Android UI elements.
  7. Get the Android UI elements from the Adapter to be displayed in the application. These elements are combined to create the graphical control panel that is displayed by the Controller application for the end user to interact with.

Setting up the AllJoyn framework and About feature

The steps required for this service are universal to all applications that use the AllJoyn framework and for any application using one or more AllJoyn services. Prior to use of the Control Panel service framework, the About feature must be implemented and the AllJoyn framework set up.

Complete the procedures in the following sections to guide you in this process:

Implementing a Controller

Initialize the AllJoyn framework

See the About API Guide for instructions to set up the AllJoyn framework.

Start the AboutService in client mode

The Control Panel service framework depends on the About feature.

For more information about the About feature, see the About API Guide.

Initialize the About feature

aboutClient = AboutServiceImpl.getInstance();
aboutClient.startAboutClient(bus);

Listen for announcements from Controllee devices

Register an announcement handler to receive announcements from the About feature.

aboutClient.addAnnouncementHandler(announcementHandler,
new String[] { "org.alljoyn.ControlPanel.*" });

For each announcement that is received, check if it implements the ControlPanel interface. If it does, save it as a controllable device for later use.

@Override
public void onAnnouncement(String busName, short port, BusObjectDescription[]
objectDescriptions, Map<String, Variant> aboutMap) {
   Variant varDeviceId = aboutMap.get(AboutKeys.ABOUT_DEVICE_ID);
   String devIdSig    = VariantUtil.getSignature(varDeviceId);
   if ( !devIdSig.equals("s") ) {
      return;
   }
   deviceId = varDeviceId.getObject(String.class);
   // get the device name from the annoucement just as the device id above

   for(int i = 0; i < objectDescriptions.length; ++i){
      BusObjectDescription description = objectDescriptions[i];
      String[] supportedInterfaces    = description.getInterfaces();
      for(int j = 0; j < supportedInterfaces.length; ++j){
      if(supportedInterfaces[j].startsWith
         ("org.alljoyn.ControlPanel")){
         // found a control panel interface
         if (deviceContext == null) {
            deviceContext = new DeviceContext
         (deviceId, busName, deviceName);
}     deviceContext.addObjectInterfaces
(description.getPath(), supportedInterfaces);
         }
      }
   }
}

Get the controllable device

Once a controllable device is detected via the announcement, get its ControllableDevice proxy object.

The ControllableDevice is used to later create a session with the Controllee.

controllableDevice = ControlPanelService.getInstance()
   .getControllableDevice(deviceContext.deviceId, deviceContext.busName);

Start a session with the Controllee

To get the control panels of a Controllee, you must create a session with it. This is an asynchronous call and requires a DeviceEventsListener as a callback.

controllableDevice.startSession(DeviceEventsListener);

Listen for a sessionEstablished event to verify the session was established successfully. When a session is established, a collection of control panel containers is received.

NOTE: There may be more than one control panel container, each intended for a different use. For example, one for the home user and another for a technician. Each element of the container is a DeviceControlPanel and provided per language.

@Override
public void sessionEstablished(ControllableDevice device,
   Collection<ControlPanelCollection> controlPanelContainer)
{
   //At this point the session was established
}

Implement the DeviceEventsListeners

There are other methods of the DeviceEventsListener (besides for sessionEstablished) that should be implemented to receive session-related events from the Control Panel service framework.

public void sessionLost(ControllableDevice device);

public void errorOccured(ControllableDevice device, String reason);

For more information, refer to the API documentation.

Get a device control panel

Get a collection of device control panels and select the one with the desired language.

Collection<DeviceControlPanel> controlPanels =
    controlPanelCollection.getControlPanels();

for(DeviceControlPanel controlPanel : controlPanels) {
   String cpLanguage = controlPanel.getLanguage();
   if (cpLanguage.equalsIgnoreCase(desired_language)) {
      //found the desired device control panel
      DeviceControlPanel deviceControlPanel = controlPanel;
   }
}

Get the root container

Once the DeviceControlPanel is selected, get its root container element.

The root container element is the top-level UI element that contains all the child UI elements of the selected DeviceControlPanel.

Detect the type of the root container. It may be either a ContainerWidget or an AlertDialogWidget (mostly used for notification with action).

UIElement rootContainerElement =
   deviceControlPanel.getRootElement(ControlPanelEventsListener);
UIElementType elementType = rootContainerElement.getElementType();

Implement the ControlPanelEventsListener

The ControlPanelEventsListener interface should be implemented to receive changes that occurred in the control panel on the Controllee and should be reflected on the UI accordingly.

public void valueChanged(DeviceControlPanel panel, UIElement uielement, Object newValue);

public void metadataChanged(DeviceControlPanel panel, UIElement uielement);

public void notificationActionDismiss(DeviceControlPanel panel);

public void errorOccured(DeviceControlPanel panel, String reason);

For more information, refer to the API documentation.

Build the Android UI elements

The Adapter loops through the UI elements list, received from the root container, and builds a linear layout with all the contained Android views.

The application can embed this inside an activity.

ControlPanelAdapter  controlPanelAdapter =
new ControlPanelAdapter(Context, ControlPanelExceptionHandler);

// create an android view for the abstract container
final View adapterView = controlPanelAdapter.createContainerView(container);

ControlPanelExceptionHandler

When an error occurs while retrieving any of the widgets, the Adapter throws an exception to the application to better handle the error. The application can decide how to display this error to the user. A typical method is to show a toast to the user that an error occurred.

Compile the code

See the Building Android section for instructions on how to compile the application with this service framework.

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