When using Clireg32.exe to register the type library (.tlb file) of a DCOM
server, the type library entries are not entered in the registry. This
problem also occurs during the Internet download of usercontrols that
reference DCOM servers. When this problem occurs, you will receive one of
the following error messages while trying to run the DCOM client
application:
The instruction at '0x00000000' referenced memory at '0x00000000'. The
memory could not be 'read'
-or-
An application error has occurred and an application error log is being
generated. '<Client.exe>' Exception: access violation (0xc0000005),
address: 0x00000000
To resolve this issue, modify the DCOM Server .vbr file, and then use CliReg32.Exe to reregister the DCOM Server, first as a remote
automation component, then as a DCOM component, as detailed below.
Open the DCOM Server .vbr file in Notepad or any text editor.
Both the ProxyStubClsid and ProxyStubClsid32 keys for the DCOM Server ClassId must modified. (In the sample below, the underscore character (_) is used as a line-continuation character; the line does not appear in this way in your .vbr file.)
NOTE: In the above command, "DCOMSERVER" is the name of your DCOM
server, and "SERVERMACHINENAME" is the name of the server where the DCOM
component will reside. Choose Remote Automation from Remote Transport options.
NOTE: This article assumes that you are familiar with creating and
deploying DCOM client and server applications.
Create the DCOM Server
Create a new ActiveX EXE project in Visual Basic 5; Class1 is created by default.
Rename Class1 to "CDCOMServer".
On the Project menu, click Project Properties, and rename the project to DCOMServer.
Click the Component tab, and then click Remote Server Files.
Add the following code to the CDCOMServer class module:
Private mName As String
Public Property Let sName(str As String)
mName = str
End Property
Public Property Get sName() As String
sName = mName
End Property
Private Sub Class_Initialize()
mName = "DCOM Server"
End Sub
Create the ActiveX EXE.
Create the Client
Create a new ActiveX Control project in Visual Basic 5.0; UserControl1 is created by default.
Rename UserControl1 to "CtlDownload" (without the quotation marks).
Add a TextBox, a CommandButton, and a Label to the control.
On the Project menu, click References, and then click DCOMServer.
Place the following code in the user control's code pane:
Private Sub Command1_Click()
Dim svr As New DCOMServer.CDCOMServer
svr.sName = Text1.Text
Label1.Caption = svr.sName
End Sub
[Optional] For testing, create a Standard EXE project to test the
ActiveX control. Whenever you enter something in the TextBox and click
Command1, the same text should be displayed on the Label.
Create the CtlDownload OCX.
Create Installation Programs for the Client and the Server
Use the Application Setup Wizard to create a setup program for
DCOMServer project.
Create an Internet Component Download Setup for the client
(CtlDownload). Be sure to add the DCOMServer.vbr file.
NOTE: To have a successful download, please refer to the following
Microsoft Knowledge Base article:
168429
(http://support.microsoft.com/kb/168429/EN-US/
)
PRB: Component Download Fails for DCOM Projects
Install the Server and Test the Client
Install the DCOMServer on a Windows 2000 (Professional or Server) or Windows NT 4.0 (workstation or server) with Service Pack 3 installed.
From a client computer, open the CtlDownLoad.htm file in the control's setup folder.
Click the CommandButton on the control to reproduce one of the above-mentioned errors.
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.