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How To Use a Satellite DLL for Localization Purposes

This article was previously published under Q188659
This article demonstrates how to use a satellite DLL to provide dynamiclocalization for a Visual Basic 6.0 application.
Visual Basic allows you to use resource files to help you localize anapplication. Localization is the process of adapting a program for aspecific international market, which includes customizing the userinterface and features of the application. While it is possible to useseparate resource files within an application, it is not recommendedbecause resource files are compiled into an application and you will needto create and redistribute a new executable with each change to theresource file.

With the use of a satellite DLL, an application can easily target manylanguages. For this to occur, you need to place all resources that areunique to the language into a separate DLL. When the application isstarted, the application will detect which regional setting is currentlybeing used by the computer and will then load the appropriate DLL. Bysimply compiling and distributing an additional DLL, which contains its ownunique resource file, it is much easier to support additional languages.

How a Satellite DLL Works

To make a satellite DLL work properly, the application must determine thelocale (regional setting) of the computer that it is running on. When theapplication first starts, it determines the locale ID from the operatingsystem by calling GetUserDefaultLCID. The application uses this locale IDto load a DLL that contains the specific locale ID number as part of itsname. If the application locates the DLL, the application will use theresources contained within the DLL. If the application does not find theDLL, the application defaults to whatever language it was compiled with.

The difference between the DLLs is in the unique resource files that areused for the specific language being targeted. By containing the same codeand the same basic interface, the main application can use any of the DLLs.Each satellite DLL should be named in a similar and standard way. For thesample below, "TestSat" + LocaleID of the region is used, where twoLocaleID's are shown as follows:
   409 : LocaleID for English (United States)   40C : LocaleID for French (Standard)				
The English Satellite DLL in the sample below will be named"TestSat409.DLL", and the French Satellite DLL will be named"TestSat40C.DLL". The test application contains the necessary code todetermine which locale it is running in and how to load the appropriatesatellite DLL.

The sample steps below show how to create a simple satellite DLL, how todetermine which locale an application is running in, and how to create andload the proper resources.

Steps to Create the Test Application

  1. Create a new Standard EXE project in Visual basic 6.0. Form1 is created by default.
  2. Add a Standard Module to the project by selecting Add Module from the Project menu.
  3. Add a Command Button to Form1.
  4. Add the following code to the Declarations section of Form1:
          Private Sub Command1_Click()         MsgBox "Command Button was Clicked", vbOKOnly, "Satellite Test"      End Sub      Private Sub Form_Load()      ' When this application launches, the code attempts      ' to find a local satellite DLL that will contain all the      ' resources.         If (LoadLocalizedResources) Then            ' Pull a string resource out of a local resource            ' object for demonstration purposes.            Command1.Caption = GetString(101)         End If     End Sub					
  5. Add the following code to Module1:
          Option Explicit      ' This module contains all the code necessary for the application      ' to use a satellite DLL for localization purposes.      ' Please refer to the MSDN for more information regarding the APIs      ' used in this example.      Public Declare Function GetUserDefaultLCID Lib "kernel32" () As Long      ' Object reference to the DLL that contains the resources      ' to be loaded.      Private clsSatellite As Object      Public Function LoadLocalizedResources() As Boolean         Dim lLocalID As String         ' Find the LocalID.         lLocalID = Hex(GetUserDefaultLCID)         ' Load the Satellite DLL that contains the local         ' resource object to be used. If CreateObject         ' fails, there is no local version of the         ' resources.         On Error GoTo NoLocalResource         ' Create a local object containing resources.         Set clsSatellite = CreateObject("TestSat" & lLocalID & _            ".clsResources")         ' Return true, then read local resources.         LoadLocalizedResources = True      Exit Function      NoLocalResource:         ' There is no local satellite DLL. As a result, false is returned.         LoadLocalizedResources = False      End Function      ' GetString will access the object and return the string      ' resources specific to the region. For this example, only      ' basic error handling is implemented.      Public Function GetString(StringIndex As Long) As String       ' Make sure there is a resource object.         If Not (clsSatellite Is Nothing) Then            ' Get the resource from the resource object.            GetString = clsSatellite.GetResourceString(StringIndex)         Else           ' For this example, if there is no resource           ' object something is still returned.           GetString = "Error : No Local Data"         End If      End Function					
  6. Save and compile the project (Project1.Exe).

Steps to Create Satellite DLLs

  1. Create a new ActiveX DLL project in Visual Basic 6.0. Class1 is created by default.
  2. From the Project menu, select Project1 Properties. Set the Project Name to "TestSat409."
  3. Rename Class1 to clsResources.
  4. Paste the following code into clsResources:
          Public Function GetResourceString(ResourceIndex As Long) As String         GetResourceString = LoadResData(ResourceIndex, 6)      End Function					
  5. Start the Visual Basic 6.0 Resource Editor Add-In.
  6. In the Resource Editor, select "Edit String Tables."
  7. A new string table will be created, with a blank resource (101). Enter some sample text into the resource (for example, "English Language").
  8. Close the String editor, and save the resource file as "TestSat409.Res".
  9. Save the Project, and make the ActiveX DLL.
  10. Perform Steps 1-9 again, but this time change the project name to "TestSat40C", save the resource file as "TestSat40C.Res", and modify the string contained in Step 7 to "French Language". For this particular test, keep each satellite DLL in its own folder by placing the ActiveX DLL and resource file into its own folder.

Steps To Test Satellite DLLs

  1. From the Windows Control Panel, select Regional Settings.
  2. Select "English (United States)." The system might prompt you to reboot if another region was originally selected.
  3. Run the test project (Project1.exe). The command button caption should have the "English" resource string you used for the first ActiveX DLL.
  4. From the Windows Control Panel, select Regional Settings again.
  5. Select French (Standard). If you are using Windows 95 or Windows 98 you have to reboot.
  6. Run the test project (Project1.exe). The command button caption should have the "French" resource string you used for the second ActiveX DLL.
  7. For testing purposes, rename the Test40C.dll. Re-run the test project (Project1.Exe). The command button should have the default caption "Command1". This is the case because the application could not find a localized satellite DLL to use. As a result, the application used the default caption of the command button.

Article ID: 188659 - Last Review: 07/13/2004 14:57:00 - Revision: 1.1

  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 6.0 Enterprise Edition
  • kbhowto KB188659