Visual Basic

23-Mar-07 6:25

Thanks for any guidance.

I am working in a gray area that I am not familiar with.

I have a DLL by a third party supplier. It has a .H file
and a .LIB File. So they have been created in C I am guessing.

How do I wrap this DLL so that I call its functions from
within VB.NET

This is the C# lines from thier example:

#ifdef SPOEM_EXPORTS
#define SPOEM_API __declspec(dllexport)
#else
#define SPOEM_API __declspec(dllimport)
#pragma message("automatic link to spoem.lib") ' <== add this line
#pragma comment(lib, "spoem.lib") ' <== add this line
#endif

Christian Graus23-Mar-07 6:34

23-Mar-07 6:34

mlauahi wrote:
So they have been created in C I am guessing.

Or C++

mlauahi wrote:
This is the C# lines from thier example:

Are you sure ? That looks like C to me.

p/invoke is how you'd call your dll in C# or VB.NET.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

mlauahi23-Mar-07 6:37

23-Mar-07 6:37

Thanks for your fast reply:

I have tried:

<dllimport("spoem")> _
Public Shared Function InitParameter(ByVal chSPDir As char)
End Function

<dllimport("spoem")> _
Public Shared Function ExitSpDll()
End Function

<dllimport("spoem")> _
Public Shared Function USBCommunication() As BOOLEAN
End Function

etc.....

It says that it cannot find the DLL. I have Spoem.dll, spoem.h, and spoem.lib in the project
directory. How do I point this class to the DLL.

mlauahi23-Mar-07 6:39

23-Mar-07 6:39

I am using <dllimport("spoem")> _

This line did not appear on the last post

mlauahi23-Mar-07 6:54

23-Mar-07 6:54

Hello Christain

I cannot add a reference to the DLL, it says that it is invalid.

I have tried both the DLLIMPORT,and then a simpe Declare

It says that it cannot locate the DLL. Where does the DLL need
to reside, and how do I tell my class where it is??

Thanks

Christian Graus23-Mar-07 7:20

23-Mar-07 7:20

You have a dll, or not ? A h and a lib is useless to you in this instance. You'd have to write C++/CLI code that imports those files and exposes a managed class.

If you have a dll, you can't add a reference, that's for COM only.

mlauahi23-Mar-07 7:23

23-Mar-07 7:23

I copied the SPOEM.DLL to my System32 directory,

It now finds the DLL, but it cannot locate the designated
Entry Point.

One of the function calls is SPOEM.USBCommunication(). When
I call this is says:

Unable to find an entry point named 'USBCommunication' in DLL 'Spoem'

ANy suggestions at this point???

Christian Graus23-Mar-07 7:46

23-Mar-07 7:46

Perhaps the DLL is not exporting it properly. But, if it can be called from C++, it would be usable with p/invoke.

You should NEVER copy stuff to System32. Just put it in the directory with the exe.

mlauahi23-Mar-07 7:52

23-Mar-07 7:52

Im am stuck right now.

The example code that they give you with this is indeed a C++ 6.0
MFC wizard application.

They company supplys the .H, .LIB, and the .dll files.

The example just shows those original #DEFINE statements, and there
is the exported class for the DLL. I am trying to make the DLL wotk in
VB.NET. I am not sure why I am getting an:

Unable to find an entry point named 'USBCommunication' in DLL 'Spoem.Dll'.

If I am understanding you at this point. I do not use the .H or the .LIB.

I should only use the

Christian Graus23-Mar-07 9:22

23-Mar-07 9:22

Did you look into how to do pinvoke in VB.NET ? I have no idea, but I'm pretty sure none of your code has tried it, as none has specified the dll name, that I can recall seeing.

Here is an example I found online:

Public Declare Function BitBlt Lib "gdi32.dll" (hdc As IntPtr , nXDest As Integer, nYDest As integer, nWidth As Integer, nHeight As Integer, hdcSrc As IntPtr, nXSrc As Integer, nYSrc As Integer, dwRop As TernaryRasterOperations) As Boolean

Note the Lib "gdi32.dll", that's how to tell VB to load this function from a dll.

mlauahi23-Mar-07 9:32

23-Mar-07 9:32

Thats exactly what I did, and it complained about not finding
the entry point in the DLL. The example I had was "USBComunication",
it said that it could not locate the entry point in the DLL

Christian Graus23-Mar-07 9:58

23-Mar-07 9:58

OK, perhaps the DLL doesn't expose the entry point. To build a DLL with entry points, you need a seperate text file that defines them.

System.Net.WebException

snema8323-Mar-07 4:31

23-Mar-07 4:31

I'm developing a application that consumes a webservice on my local
machine. The problem is that when I call the method of webservice I instantly get a WebException with no further information. The method can be called from IE. How can I find out the reason and solution for the exception?

Shashank Nema

Christian Graus23-Mar-07 4:59

23-Mar-07 4:59

I assume the web service doesn't require you to log on ? The odds are, it's a problem with your code that's connecting, or your connection.

Have you checked the InnerException ?

snema8323-Mar-07 5:15

23-Mar-07 5:15

Exception.InnerException object is Nothing and webservice is using windows authentication.

Christian Graus23-Mar-07 5:32

23-Mar-07 5:32

Do you have any access to the webservice ? What happens if you step into the code to see what line of the generated code is blowing up ?

snema8323-Mar-07 5:39

23-Mar-07 5:39

I have access to webservice and it is embedded into my application however when I debug I am unable to hit webservice. It trhows me error before going to web service.

Christian Graus23-Mar-07 7:20

23-Mar-07 7:20

Then it's a connection issue. Firewall ?

snema8323-Mar-07 7:24

23-Mar-07 7:24

No firewall everything is on same local machine.....

Christian Graus23-Mar-07 7:46

23-Mar-07 7:46

What line of code blows up ? Is the webservice published and IIS running ?

snema8323-Mar-07 7:52

23-Mar-07 7:52

Line of code is:

NotificationObject.ProcessRatingStatus(AppId, ObjProgressionEnum, ObjProcessStatusEnum, Message, RunLength, UserId)

ProcessRatingStatus is the function in Webservice which I want to call from my application. Also webservice and my application are both authenticated through windows authentication.

Christian Graus23-Mar-07 9:23

23-Mar-07 9:23

OK, so it is indeed the webservice call that fails, you said it was before. Attach a debugger to the aspnet process, with the webservice project open, run the app, and see if a breakpoint at the start of this function will trigger.

snema8326-Mar-07 3:20