Visual Basic 5.0 introduces the ability to create ActiveX documents (.VBDfiles) for use with Internet browsers. This article will walk youstep-by-step through creating a simple ActiveX document, show you how totest it while within the Visual Basic 5.0 development environment, thentest it outside of the Visual Basic 5.0 development environment.
The power of the Internet is that potential users from all of the worldwill be able to hit and view your page. (The same applies to the Intranet,although on a smaller scale; users all over your corporation may be able tohit and view your web page). With this in mind, different users will havedifferent configurations and different software installed on their PC's.When your ActiveX page is hit by an Internet user, Internet Explorersearches the local PC for all of the files required by the document. If arequired file is present and has a version equal to or greater than theversion you require, it uses it. If a file is missing or is older than theversion required, Internet Explorer prompts the user to install the fileand will proceed to do so.
While testing an ActiveX document, a problem occurs for developers becauseall of the required files are already installed onto the developmentmachine. So how do you simulate a client's machine, one which has not beenexposed to Visual Basic and the components you are using or which you'vecreated? This article will also describe how to simulate such anenvironment.
To begin, you need to create a simple ActiveX document for testingpurposes. If you already have an ActiveX document to test, proceed to thesection "Testing Your Document Using Visual Basic 5.0" later in thisarticle.
Creating a Simple ActiveX Document
- Start Visual Basic 5.0, or select New Project from the File menu if Visual Basic 5.0 is already running. In the New Project dialog, select ActiveX Document EXE and click OK.
- From the Project Window, open the User Documents folder and select UserDocument1. This User Document is created by default. View the properties for UserDocument1, change the (Name) property to MyTestDocument.
- Add some intrinsic controls to MyTestDocument, such as a CommandButton, a Text Box, and a Label. You may modify the properties or add code to these controls as desired. These controls will be used so you can verify that the download of your ActiveX document succeeded.
- From the Project menu, choose Project1 Properties. Change the Project Name to MyActiveXDocument. Click OK.
- Save the Project. Save the user document MyTestDocument.Dob and also save the Project MyActiveXDocument.VBP.
Testing Your Document Using Visual Basic 5.0
The following steps assume you have Microsoft Internet Explorer version3.00 or later installed onto your system. To obtain the latest version ofInternet Explorer be sure to visit the following Web site:
- If you created the simple ActiveX document above, keep the project open. If you are working with your own ActiveX document, open the desired project.
- Click the Start button on the Visual Basic toolbar, or choose Start from the Run menu.
At this point, your document is ready to view with Internet Explorer. For testing purposes, Visual Basic 5.0 has created a .VBD file in the current working directory. This directory is usually where Visual Basic is installed. This file can now be viewed with Internet Explorer.
- Open Internet Explorer.
- In the Address box, type in the path to the .VBD file, which will have the same name as your project. For example, to open the simple ActiveX document created above, type the following:
C:\Program Files\DevStudio\Visual Basic\MyTestDocument.VBD NOTE: Your path to the .VBD file may be different, so modify the line above as appropriate.
The .VBD file should open in Internet Explorer, displaying any controls you added to the document and executing any code you've added to the project, as appropriate.
If this test worked, you can modify the project as desired, adding code, adding controls, etc. You may then continue to test the VBD file with Internet Explorer simply by running the project and viewing the VBD file with Internet Explorer.
NOTE: The VBD file is temporary; Visual Basic will delete the file when the project stops executing.
Creating Your Internet Download Setup
The following steps take you through the creation of your Internet downloadsetup. If you have created your own ActiveX document (rather that using theexample created above), substitute your ActiveX document name wherenecessary.
- From the File menu, choose Make MyActiveXDocument.Exe. Create the executable file in the desired location.
NOTE: The executable file created is designed to execute as an ActiveX document within Internet Explorer. The file cannot be executed successfully by itself.
- Exit Visual Basic 5.0.
- Run the Application Setup Wizard. This Setup Wizard should be available from the Start menu, under Programs\Visual Basic 5.0.
If you are prompted with the "Setup Wizard - Introduction," click Next.
- From the "Select Project and Options" step, click the Browse button to locate your ActiveX document project. If you created the example provided with this article, locate MyActiveXDocument.vbp.
- Under "Options," choose to "Create Internet Download Setup." Click Next.
- On the "Internet Distribution Location" step, select the location where you would like to place the files for Internet download and click Next. For testing purposes, "SWSETUP" may be sufficient.
NOTE: It is important to note that the folder must be accessible, with at least read-only access, from other machines on your network in order to test. In future deployments, you may wish to place the files created onto a web server.
- For the "Internet Package" step, choose "Download from the Microsoft Web site."
NOTE: With this option selected, when a user hits your ActiveX document with Internet Explorer and needs a component installed, IE will go to the Microsoft Web site to install the latest version. If you would like information on how to use an alternate location, refer to the chapter on "Distributing Your Applications" in the Visual Basic 5.0 Programmer's Guide. You may desire to use an alternate location if you are developing an ActiveX document for an intranet where potential users may not have access to the World Wide Web.
- For the remaining steps in the Setup Wizard, go with the defaults, clicking Next until you reach the final step.
- On the final step, you may save the template if you prefer. When you are done, click Finish.
The Visual Basic Setup Wizard creates all of the files necessary for anInternet download. The next section of this article describes how to testthe page.
Testing the Internet Download
As a developer, you may want to test the Internet Download from your ownmachine first. Remember, however, that because Visual Basic 5 is alreadyinstalled on your machine, you know all of the necessary files areinstalled and the ActiveX document should load without incident. To testthe document from the development machine, locate the Internet downloadfiles the Setup Wizard created. In the setup folder there will be an HTMfile; if you created the example above this file will be namedMyActiveXDocument.HTM. Simply double-click the file or locate it withInternet Explorer to open it.
The second test you should apply to your ActiveX document is testing itfrom a machine without Visual Basic 5.0 installed. If you do not have sucha machine available to you for testing, refer to the "Simulating a CleanMachine" section of this article.
From a machine that does not have Visual Basic 5.0 installed, use InternetExplorer to locate and open the HTM file created by the Setup Wizard.
IMPORTANT NOTE: Before testing the ActiveX document, be sure the safetylevel in Internet Explorer is set to Medium or None. If the safety level isset to High, the required files will not get downloaded and the ActiveXdocument will not load. To check the security level in Internet Explorer,choose Options from the View menu. From the Options window, select theSecurity tab, and then click the Safety Level button.
If you set the Safety Level to None, all of the missing components willbe installed without warning. If the Safety Level is set to Medium, thefollowing warnings will occur:
First, you will be warned that an attempt to install the CAB file is beingmade if you created the example above you will be prompted to installMyActiveDocument.CAB. If you respond Yes, the MyActiveXDocument.Exe andMyActiveXDocument.INF will be installed onto the client machine in theWindows\OCCache folder.
Second, you will be asked if you wish to install Microsoft Automation. TheAuthenticode screen will display information about this component. If yourespond Yes, a similar screen will warn you that the Microsoft Visual Basic5.0 Run-time Library is going to be installed. Both of these componentswill be installed from the Microsoft Web site into the Windows\Systemfolder (Windows\System32 folder on Windows NT).
Third, a script warning will appear warning the user that the HTM filecontains scripting code. This code is necessary in order to view yourActiveX document.
These warnings are all part of the Internet Explorer's safety mechanisms.If you do not receive all of the above warnings, do not be alarmed. You maynot receive a warning if a necessary component is already installed on theclient machine or a security level option in Internet Explorer is set tosomething other than the defaults.
As part of testing, you may wish to test various Internet Explorer securitysettings to be sure your document loads as expected under varyingcircumstances.
Simulating a Clean Machine
As a developer, you should test your application on various machines withvarying configurations. However, if you do not have a "clean machine" (onethat does not have Visual Basic 5.0 or the Visual Basic 5.0 Run-timeLibrary installed), the steps outlined below describe how to configure adevelopment machine so that it behaves like a clean client. These steps mayalso be taken to clean a client machine that may have been previouslyexposed to your ActiveX document, Visual Basic 5.0, or the Visual Basic 5.0Run-time Library.
WARNING: Before following the steps below to simulate a clean machine, beaware that unregistering, renaming, and deleting any of the following filescould impact other applications installed onto your machine. For moreinformation about undoing the steps provided here, see the "Restoring YourMachine" section of this article.
In order to clean a machine for testing an Internet download, you mustbegin by unregistering the Visual Basic 5.0 Run-time Library. This stepwill require a copy of REGSVR32.EXE. This file may be installed onto yourdevelopment machine; if it is not, it may be found on the Visual Basic 5.0installation CD-ROM.
- From the Start menu, choose Run.
- In the Run dialog, type in the following command;
"<PATH>\REGSVR32.EXE /U <Path to Windows folder>\System\MSVBVM50.DLL" NOTE: If you are running on a Windows NT machine, the MSVBVM50.DLL is installed into the Windows\System32 folder.
- Next, rename or delete the Visual Basic 5.0 Run-time Library.
- From the Start menu, choose Find, and then select Files or Folder.
- In the Find dialog, search the entire hard drive for files named MSVBVM50.DLL.
The file MSVBVM50.DLL may appear in more than one location; if it does, delete or rename the file located in the Windows\System folder (System32 on Windows NT platforms).
- Next, the Microsoft Automation DLL must be deleted or renamed. Follow the steps outlined above for MSVBVM50.DLL, except locate and rename ASYCFILT.DLL, which will also be located in the Windows\System folder (System32 on Windows NT platforms). Do not delete other versions of this file if it is found in alternative locations.
- Next, you must unregister and delete or rename any remaining dependency files installed on the client machine. These files will typically be custom controls that are used in the ActiveX document. For a list of the dependency files used by your ActiveX document, open the INF file created by the Setup Wizard and placed in the Support folder of the Internet Download setup.
The INF file will have a [Add.Code] section, listing the dependency files used by your ActiveX document. For example, the MyActiveXDocument.INF file created for the example in this article appears as follows:
The dependency files must be unregistered, if necessary, and deleted or renamed. The MyActiveXDocument.Exe file does not need to be unregistered. However, it will need to be deleted or renamed. Internet Explorer 3.x places this file into the \Windows\OCCache folder. Internet Explorer 4.0 places this file into the "\Windows\Downloaded Program Files" directory. If you are uncertain whether a file needs to be unregistered or not, you can run REGSVR32.EXE with the /U switch to determine whether or not it can be unregistered. If you receive an error, the file does not need to be unregistered.
[Add.Code] MYACTIVEXDOCUMENT.EXE=MYACTIVEXDOCUMENT.EXE ASYCFILT.DLL=ASYCFILT.DLL MSVBVM50.DLL=MSVBVM50.DLL
NOTE: One file installed that is not listed in the [Add.Code] section is the INF file which is installed into the Windows\OCCache folder for each ActiveX document. This file will have the same name as the ActiveX EXE with an INF extension; for example, MyActiveDocument.INF. For a truly clean machine, this file would need to be deleted as well. However, not deleting the file will not have any adverse affects on the setup.
Other dependency files may include OCX files for custom controls or DLLs for various components. For example, if you used any of the Windows Common Controls in your application ,the Add.Code section of your INF file may appear as follows;
In order to remove the COMCTL32.OCX file from the system, run:
[Add.Code] MYACTIVEXDOCUMENT.EXE=MYACTIVEXDOCUMENT.EXE ASYCFILT.DLL=ASYCFILT.DLL MSVBVM50.DLL=MSVBVM50.DLL COMCTL32.OCX=COMCTL32.OCX
REGSVR32.EXE /U <PATH>\System\COMCTL32.OCX This will unregister the control, then locate the file and either delete or rename it. Most of the custom controls that ship with Visual Basic 5.0 will install themselves into the Windows\System folder. Internet Explorer, however, will install some custom controls into the Windows\OCCache folder. You will need to be sure the path to the desired OCX is correct when using REGSVR32.EXE or else an error will occur.
This same procedure must be followed for every dependency file used by your ActiveX document.
Once all of the dependency files have been unregistered and renamed or deleted, open Internet Explorer and view your HTM page. When you view the HTM page, all of the missing components will automatically be downloaded and installed onto the user's machine.
Restoring Your Machine
Opening the HTM file as described in the last step of the previous sectionof this article will restore your machine to its original configuration.Internet Explorer will download and register each required file for you.However, if something should go wrong during the Internet download setup,you can reverse the changes made by restoring all of the original files andregistering the necessary components.
Any file deleted or renamed would need to be renamed back to its originalname or restored from the Windows Recycle Bin. If a file cannot be restoredfrom the Windows Recycle Bin, an original may be found on the Visual Basic5.0 CD-ROM (unless the file was provided by a third party, in which caseyou will need to restore the file from the appropriate location). Once thenecessary files have been restored, you can run REGSVR32.EXE to registerthose files that were initially unregistered. For example, to register theVisual Basic 5.0 Run-time Library, execute the following command from therun dialog:
REGSVR32 <Path to Windows>\System\MSVBVM32.DLL
This section addresses some of the problems you might encounter during theInternet Download setup.
You receive one of the following error messages when you try to delete orrename the Visual Basic 5.0 Run-time Library:
Cannot delete MSVBVM50.DLL: Access is denied.
Cannot rename MSVBVM50.DLL: Access is denied.
You cannot delete a file while it is in use because Visual Basic 5.0 usesthis file while it is running. Be sure Visual Basic 5.0 is not running whenyou attempt to delete this file. This error may also occur if InternetExplorer is currently or has recently viewed a Visual Basic 5.0 ActiveXDocument. In this case, close Internet Explorer before attempting to deletethe file.
You receive the following error message:
The dynamic link library could not be found in the specified path...
The ActiveX document file is still present on the machine. Delete or renamethe ActiveX document file found in the Windows\OCCache folder and refreshthe page. If you built the ActiveX document example in this article, thefile would be named MyActiveXDocument.Exe.
You receive the following error message:
An error has occurred copying MSVBVM50.DLL. Ensure the location
specified below is correct...C:\TEMP\ICD10E.TMP
The exact file names and paths may vary.
There is insufficient disk space on the target machine. Free up some diskspace on the target machine and refresh the page.
A dialog box with the following messages appear in Internet Explorer:
Opening file <ActiveX Document>.VBD
What would you like to do with this file?
Open it or Save it to disk.
This error occurs because the Visual Basic 5.0 Run-time Library(MSVBVM50.DLL) is not installed. This will most likely occur if theInternet Explorer safety level is set to High. Set the Internet Explorersafety level to Medium or None.