DOCUMENT:Q161837 22-MAY-1997 [vbwin] TITLE :HOWTO: Create a DCOM Client/Server Application PRODUCT :Microsoft Visual Basic for Windows PROD/VER:5.0 OPER/SYS:WINDOWS KEYWORDS:kbtool kbusage vb5all vb5howto VBKBAutomation VBKBAX VBKBComp kbhowto ====================================================================== ------------------------------------------------------------------------- The information in this article applies to: - Enterprise Edition of Microsoft Visual Basic, for Windows, version 5.0 ------------------------------------------------------------------------- SUMMARY ======= In the Enterprise Edition of Visual Basic for Windows version 5.0, you can use the Distributed Component Object Model (DCOM) to perform client/server operations. This article shows you how to create a client/server application that uses DCOM to retrieve the name of the server. WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN RISK. Microsoft provides this code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. MORE INFORMATION ================ System Requirements ------------------- The following operating systems may be used for DCOM applications: Operating System Server Client ---------------- ------ ------ WinNT 4.0 Server YES YES WinNT 4.0 Workstation YES YES Windows 95 YES: YES: See Q165101 with DCOM for Win95 files Prepare the Computer -------------------- (While this step is not required, it keeps your project in order.) Create the following directories on your computer: C:\DCOMDemo C:\DCOMDemo\Server C:\DCOMDemo\Server\Setup C:\DCOMDemo\Client C:\DCOMDemo\Client\Setup Create the Server ----------------- 1. Start a new Visual Basic Project. In the New Project dialog box, select "ActiveX EXE" and click Open. 2. Set the following properties: Control Name Property Value ------------------------------------------------------------------ Class Module Class1 (Name) clsDCOMDemoServer Instancing 5 - MultiUse 3. Copy the following code to the Class Module clsDCOMDemoServer: Option Explicit Public Function ServerTime() 'Retrieves the time from the server. ServerTime = Time End Function Public Function AddNumbers(x As Integer, y As Integer) As Integer 'Receives two integers and adds them together. AddNumbers = x + y End Function Public Function SubtractNumbers(x As Integer, y As Integer) _ As Integer 'Receives two integers and subtracts the second from the first. SubtractNumbers = x - y End Function 4. On the Project menu, click "Project1 Properties..." NOTE: If you saved the project previously or have another project open, the menu item may not be called "Project1." Select the menu item for "Properties." 5. Click the General tab and set the following properties: Project Type: ActiveX EXE (Create out-of-process ActiveX component) Startup Object: (None) (None required) Project Name: proDCOMDemoServer (Will be used in client code to define the project to be used) Help File Name: Project Help Context ID: 0 Project Description: DCOM Demo Project - Server Unattended Execution: Upgrade ActiveX Controls: (Enables upgrading of ActiveX controls) 6. Click the Make tab and set the following properties: Auto Increment: (Useful for version comparison.) Application Title: proDCOMDemoServer (Name of the EXE that will be compiled.) Version Information: Command Line Arguments: Conditional Compilation Arguments: 7. Click the Compile tab and set the following properties: Compile to P-Code: Compile to Native Code: The rest of the options should be unavailable. 8. Click the Component tab and set the following options: Start Mode: ActiveX Component Remote Server Files: (Creates TLB and VBR files) Version Compatibility: Project Compatibility (Keeps GUIDs updated) Click OK. 9. On the File menu, click Save Project As. Save the following files as described: Directory File Filename Extension --------------------------------------------------------------------- C:\DCOMDemo\Server Class Module clsDCOMDemoServer .cls Project proDCOMDemoServer .vbp 10. Select File from the menu, and choose "Make proDCOMDemoServer.exe." 11. In the Make Project dialog box, save the executable to the \DCOMDemo\Server directory. 12. Select Project from the menu and choose "proDCOMDemoServer Properties." 13. Click the Component tab and confirm that Version Compatibility is still set to Project Compatibility. 14. The file proDCOMDemo.exe appears in the text box at the bottom of the Version Compatibility group. If it is not there, click on the button with the three ellipses (...) and go to step 16. If the file is already in the text box, go to step 17. 15. In the Compatible ActiveX Component dialog box, select the file that you just compiled (C:\DCOMDemo\Server\proDCOMDemoServer.exe). 16. Click OK to close the "proDCOMDemoServer" - Project Properties dialog box. 17. Open a new project ("File... New Project") and save the changes in the server project. Create the Client ----------------- 1. In the New Project dialog box, select "Standard EXE" and click OK. 2. On the Project menu, click References. 3. Scroll down in the Available References text box until you see "DCOM Project - Server." Select the box on the left and click OK. Note that the component automatically appears in the "Available References" text box. In Remote OLE Automation, you have to double-click the server executable to register it. In DCOM, the server component is automatically registered. 4. Insert a Module. Place two command buttons, two text boxes, and three labels on Form1. Set the following properties: Control Name Property Value ------------------------------------------------------------------ Module Module1 Name modDCOMDemoClient Form Form1 Name frmDCOMDemoClient Caption DCOM Demo - Client Command Button Command1 Name cmdServerTime Caption &Get Server Time Command2 Name cmdComputeNumbers Caption &Compute Numbers Text Box Text1 Name txtX TabStop True TabIndex 0 Text2 Name txtY TabStop True TabIndex 1 Label Label1 Name lblAnswerAdd Label2 Name lblAnswerSubtract Label3 Name lblServerTime You may want to add additional labels to the form to serve as captions for these labels. 5. Copy the following code to the Module: Option Explicit Public oServer As New proDCOMDemoServer.clsDCOMDemoServer 6. Copy the following code to the frmDCOMDemoClient code window: Option Explicit Private Sub Form_Load() 'Set initial values for text boxes. txtX.Text = "1" txtY.Text = "2" End Sub Private Sub txtX_GotFocus() 'Select all the text when the text box gets focus. 'This makes it easier to change the values. txtX.SelStart = 0 txtX.SelLength = Len(txtX.Text) End Sub Private Sub txtY_GotFocus() 'Select all the text when the text box gets focus. 'This makes it easier to change the values. txtY.SelStart = 0 txtY.SelLength = Len(txtY.Text) End Sub Private Sub cmdServerTime_Click() 'Get the time from the server and put it in the 'lblServerTime label. lblServerTime.Caption = oServer.ServerTime End Sub Private Sub cmdComputeNumbers_Click() 'Passes the integers to the server and puts the answers in the 'appropriate labels. The "CInt" is to ensure that you are 'passing integers, which is what the server is expecting. lblAnswerAdd.Caption = oServer.AddNumbers _ (CInt(txtX.Text), CInt(txtY.Text)) lblAnswerSubtract.Caption = oServer.SubtractNumbers _ (CInt(txtX.Text), CInt(txtY.Text)) End Sub Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As _ Integer) 'Closes the object when the form unloads. Set oServer = Nothing End Sub 7. On the Project menu, click "Project1 Properties..." NOTE: If you saved the project previously or have another project open, the menu item may not be called "Project1." Select the menu item for "Properties. " 8. Click the General tab and set the following properties: Project Type: Standard EXE (Client is a Standalone executable) Startup Object: frmDCOMDemoClient (frmDCOMDemoClient and the code behind the form run upon execution) Project Name: proDCOMDemoClient (Will be the name of the client executable) Help File Name: Project Help Context ID: 0 Project Description: DCOM Demo Project - Client Unattended Execution: Upgrade ActiveX Controls: (Enables upgrading of ActiveX controls) 9. Click the Make tab and set the following properties: Auto Increment: (Useful for Version checking) Application Title: proDCOMDemoClient Version Information: Command Line Arguments: Conditional Compilation Arguments: 10. Click the Compile tab and set the following properties: Compile to P-Code: Compile to Native Code: The rest of the options should be unavailable. 11. Click the Component tab and ensure that all options are disabled. Click OK. 12. On the File menu, click Save Project As. Save the following files as described: Directory File Filename Extension ---------------------------------------------------------------- C:\DCOMDemo\Client Module modDCOMDemoClient .bas Form1 frmDCOMDemoClient .frm Project proDCOMDemoClient .vbp 13. Test the client by clicking Run or pressing the F5 key. When you click Get Server Time, the current system time appears in the label. When you click Compute Numbers, the sum and the difference between the numbers appear in the appropriate labels. Stop the project. 14. On the File menu, click "Make proDCOMDemoClient.exe". 15. In the Make Project dialog box, save the executable to the C:\DCOMDemo\Client directory. 16. Close your project, and save the changes. Distribute the Server --------------------- You can use the same computer that you developed the application on as your server. However, if you want to distribute your server to another computer, follow these instructions: 1. Start the Application Setup Wizard by clicking "Start... Programs... Visual Basic 5.0... Application Setup Wizard". (If the "Introduction" dialog box appears, click Next.) 2. In the Select Project and Options dialog box, click Browse. In the "Locate VB application's .VBP file" dialog box, select C:\DCOMDemo\Server\proDCOMDemoServer.VBP. 3. Click Open and set the following options: Rebuild the Project: Options: Create a Setup Program Click Next. 4. In the Distribution Method dialog box, select "Single Directory" and click Next. 5. In the Single Directory dialog box, select the C:\DCOMDemo\Server\Setup directory. Click Next. 6. In the ActiveX Components dialog box, click Next. (Do not select any components. They are not needed for this project.) 7. In the Confirm Dependencies dialog box, make sure that the Stdole2.tlb file is listed. (If it is not listed, you will have to add it later. It is located in your \Windows\System directory.) Click Next. 8. In the Shared ActiveX Application dialog box, select "Install as a shared component" and "No" since we are installing this as a DCOM application. Click Next. 9. In the File Summary dialog box, the Setup Wizard processes your files. When it is finished you will see a list of files that will be included in your project. If the Stdole2.tlb file is not listed, click Add. In the Add Files dialog box, select the file from your system directory. Click Next. 10. Save the template if desired, and then click Finish. 11. Connect to the distribution directory from your server and run the Setup.exe file that the Setup Wizard generated. 12. After the server setup is complete, start the "Dcom Configuration" application by clicking "Start... Run" and type Dcomcnfg.exe in the Run dialog box. If you do not configure the server class that was just installed, the default configuration is used. For this example, select proDCOMDemoServer.clsDCOMDemoServer and click Properties. 13. Click the General tab. This tab lists the following information about the application, it's name, type, and where it is stored: Application Name: proDCOMDemoServer.clsDCOMDemoServer Application Type: Local Server Local Path: C:\WINNT\system32\proDCOMDemoServer.exe 14. Click the Location tab to choose where you want the application to run from. Set the following properties: Run application on the computer where the data is located Run application on this computer Run application on the following computer 15. Click the Security tab to set application security. You set Access, Launch, and Configuration permissions from this tab. 16. Select "Use custom access permissions." Click "Edit," which just became available. In the Registry Value Permissions dialog box, click "Add." 17. In the Add Users and Groups dialog box, select Everyone, and then click Add. The Add Users and Groups dialog box enables you to allow or deny access to the class to certain individuals or groups. 18. In Type of Access box, select Allow Access and click OK. The Registry Value Permissions dialog box now reflects that you are allowing access to this class to Everyone. Click OK. 19. On the Security tab, select "Use custom launch permissions." Click "Edit..." which just became available. In the Registry Value Permissions dialog box, click "Add." 20. In the Add Users and Groups dialog box, select Everyone and then click Add. The Add Users and Groups dialog box enables you to allow or deny certain individuals or groups to launch the class. 21. In the Type of Access box, select Allow Launch and click OK. The Registry Value Permissions dialog box now reflects that you are allowing Everyone to launch this class. Click OK. 22. Leave Configure Permissions in the Custom selection. 23. Click the Identity tab to set the user account that you want to use to run the application. Set the following properties: The Interactive User The Launching User This User 24. Click OK. When you get back to "Distributed COM Configuration Properties," click OK. The following message should appear: "The operation completed successfully." Click OK. Distribute the Client --------------------- 1. Start the Application Setup Wizard by clicking "Start... Programs... Visual Basic 5.0... Application Setup Wizard." (If the Introduction dialog box appears, click Next.) 2. In the Select Project and Options dialog box, click Browse. In the "Locate VB application's .VBP file" dialog box, select C:\DCOMDemo\Client\proDCOMDemoClient.VBP. 3. Click Open and set the following options: Rebuild the Project: Options: Create a Setup Program Click Next. 4. In the Missing Dependencies dialog box, click Next. Dependency files are not required for this project. In the Confirm Missing Dependencies dialog box, click Yes. 5. In the Distribution Method dialog box, select Single Directory and then click Next. 6. In the Single Directory dialog box, select the C:\DCOMDemo\Client\Setup directory. Click Next. 7. In the ActiveX Components dialog box, deselect proDCOMDemoServer.exe. You do not need to distribute it with the client. 8. Click Add Remote. In the Add ActiveX Components dialog box, select C:\DCOMDemo\Server\proDCOMDemoServer.VBR. This file was created when you compiled the server executable. It was created because you checked the Remote Server Files option on the Server's "Properties Component" tab. 9. Click Open. The Remote Connection Details dialog box appears. Set the following options: Remote Transport: Distributed COM (DCOM) Network Address: Click OK. Click Next. 10. In the Confirm Dependencies dialog box, make sure that the Stdole2.tlb file is listed. (If it is not listed, you will have to add it later. It is located in your \Windows\System directory.) Click Next. 11. The File Summary dialog box appears and the Setup Wizard processes your files. When it is finished you will see a list of files that will be included in your project. If the Stdole2.tlb file is not listed, click Add. In the Add Files dialog box, select the file from your system directory. Click Next. 12. Save the template if desired, and then click Finish. 13. Connect to the distribution directory from your client and run the Setup.exe file that the Setup Wizard generated. When you run the application from the client, it returns the time of the computer that the server component is on. When you click Compute Numbers, the result of the addition and subtraction of the numbers appears in the text boxes. Try changing the numbers to confirm that everything works, but don't use a very large number because you told that class that you are passing integers. ====================================================================== Keywords : kbtool kbusage vb5all vb5howto VBKBAutomation VBKBAX VBKBComp kbhowto Technology : kbole Version : 5.0 Platform : WINDOWS Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1997.