FMX.Remote Service Demo Sample

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This demo shows two Android applications that use a remote Android service to present a message in the screen. The Android service works as a background task.

The service presents the text in the Android device, after the application binds to the service, and clicking Get Data. Data is only accessible while the application is bound to the service.

Location

You can find the Remote Service sample project at:

Description

This sample demonstrates how to use remote Android services from local and remote applications, to present a message in the screen. We understand local application as the application that contains the service, and remote application as the application that access a service hosted in a different application.

The Remote Service demo consists of one remote service and two applications, the app that contains the service and an external application:

  • Remote Service: This is a remote Android service project. It consists of a Data Module without visual components, the functionality for this demo is included in the code.
  • App Remote Host: This is a Multi-Device application that contains the service. The application provides three buttons:
    • Bind: To bind to the service. After binding to the service, the Get Data button is enabled.
    • UnBind: To unbind to the service. After unbinding from the service, the Get Data button is disabled.
    • Get Data: To get data from the service hosted in the application.
  • App Remote External: This is a Multi-Device application that uses a remote service connection to bind to the service included in the App Remote Host application. The application provides three buttons:
    • Bind: To bind to the remote service. After binding to the service, the Get Data button is enabled.
    • UnBind: To unbind to the remote service. After unbinding from the service, the Get Data button is disabled.
    • Get Data: To get data from the remote service.

How to Use the Sample

To open the projects:

  1. Navigate to the location given above.
  2. Open the sample application group project file: RemoteDemo.groupproj.
    Note: The RemoteService is already attached to the App Remote Host application. The service comes by default selected in Project Dependencies, which means that you do not need to compile the project after it changes.
  3. In the Project Manager, select AppRemoteHost.
    1. Press F9 or choose Run > Run to deploy the application to an Android device.
  4. In the Project Manager, select AppRemoteExternal.
    1. Press F9 or choose Run > Run to deploy the application to the same Android device.

In the AppRemoteHost:

  1. Click Bind to bind to the local service.
    Note: You can bind to the service from the application that hosts the service and by the external application.
  2. Click Get Data to show the message in the screen.
    Note: Get Data only appears enabled while the application is bound to the service.
  3. Click UnBind to unbind from the service.

In the AppRemoteExternal:

  1. Click Bind to bind to the remote service hosted in AppRemoteHost.
    Note: You can bind to the service from the application that hosts the service and by the external application.
  2. Click Get Data to show the message in the screen.
    Note: Get Data only appears enabled while the application is bound to the service.
  3. Click UnBind to unbind from the service.

Implementation

Remote Service

The Remote Service is an Android service project. The type of the service is remote.

This option includes the following line in the Android Manifest file of the AppRemoteHost, after compiling:

<service android:exported="true" android:name="com.embarcadero.services.RemoteService" /> //RemoteService is the name of the service. Exported means that can be accessed by an external application.

The OnHandleMessage event of the Data Module triggers a handler instance that presents a string in the Android application.

Two codes are defined in the service:

  GET_STRING = 123;
  SERVICE_STRING = 321;

App Remote Host

AppRemoteHost is a Multi-Device application project that hosts the service.

A specific line included in the Android Manifest file allows external applications to use RemoteService.

<service android:exported="true" android:name="com.embarcadero.services.RemoteService" /> //RemoteService is the name of the service. Exported means that can be accessed by an external application.
  • The OnCreate event from the TForm creates the remote service connection.
  • The OnConnected event of the TRemoteServiceConnection is associated to the OnServiceConnected procedure.
  • The OnHandleMessage event of the TRemoteServiceConnection is associated to the OnHandleMessage procedure.

Bind Button

It stablishes the connection to RemoteService with TRemoteServiceConnection.BindService('APackageName', AServiceName). If the service is not started, it also starts it.

procedure TForm1.Button3Click(Sender: TObject);
begin
  FServiceConnection.BindService('com.embarcadero.AppRemoteHost',
    'com.embarcadero.services.RemoteService');
end;

The OnConnected event fires when you are connected to the service.

The OnConnected calls the OnServiceConnected procedure with the Service Messenger (JMessenger), and enables the Get Data button.

UnBind Button

It unbinds from the service with TRemoteServiceConnection.UnbindService. It does not stop the service when it is bound to other applications.

procedure TForm1.Button4Click(Sender: TObject);
begin
  FServiceConnection.UnbindService;
end;

Get Data

Get Data establishes the connection with the service messenger. The local messenger and the service messenger establishes the interaction using a verification code GET_STRING = 123.

procedure TForm1.Button2Click(Sender: TObject);
var
  LMessage: JMessage;
const
  GET_STRING = 123;
begin
  LMessage := TJMessage.JavaClass.obtain(nil, GET_STRING);
  LMessage.replyTo := FServiceConnection.LocalMessenger;
  FServiceConnection.ServiceMessenger.send(LMessage);
end;

When the service receives the right code, replies sending the message.

The OnHandleMessage event fires when the message arrives to the local messenger. It handles the answer from the service using a verification code SERVICE_STRING = 321.

The OnHandleMessage procedure presents the message from the service in the screen.

App Remote External

AppRemoteExternal is a Multi-Device application project that connects to RemoteService hosted in AppRemoteHost.

Bind Button

It stablishes the connection to RemoteService with TRemoteServiceConnection.BindService('APackageName', AServiceName). If the service is not started, it also starts it.

procedure TForm1.Button3Click(Sender: TObject);
begin
  FServiceConnection.BindService('com.embarcadero.AppRemoteHost',
    'com.embarcadero.services.RemoteService');
end;

The OnConnected event fires when you are connected to the service.

The OnConnected calls the OnServiceConnected procedure with the Service Messenger (JMessenger), and enables the Get Data button.

UnBind Button

It unbinds from the service with TRemoteServiceConnection.UnbindService. It does not stop the service when it is bound to other applications.

procedure TForm1.Button4Click(Sender: TObject);
begin
  FServiceConnection.UnbindService;
end;

Get Data

Get Data establishes the connection with the service messenger. The local messenger and the service messenger establishes the interaction using a verification code GET_STRING = 123.

procedure TForm1.Button2Click(Sender: TObject);
var
  LMessage: JMessage;
const
  GET_STRING = 123;
begin
  LMessage := TJMessage.JavaClass.obtain(nil, GET_STRING);
  LMessage.replyTo := FServiceConnection.LocalMessenger;
  FServiceConnection.ServiceMessenger.send(LMessage);
end;

When the service recives the right code, replies sending the message.

The OnHandleMessage event fires when the message arrives to the local messenger. It handles the answer from the service using a verification code SERVICE_STRING = 321.

The OnHandleMessage procedure presents the message from the service in the screen.

Uses

  • System.Android.Service
  • System.Android.ServiceApplication

The sample uses Built-in Java libraries for Android.

  • Androidapi.Helpers
  • AndroidApi.JNI.GraphicsContentViewText
  • Androidapi.JNI.Os
  • Androidapi.JNI.JavaTypes
  • Androidapi.JNI.Widget

See Also

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