I need to create a COM wrapper for a NET API dll, to use it in MS Access.
The NET API DLL I need to create COM wrapper for uses Newtonsoft.Json.dll
So I have he following DLL's
my.dll (COM-enabled DLL exposing few methods to be used in COM Client - MS Access)
api.dll - native NET DLL exposing an api I need to access in MS Access
newtonsoft.json.dll - used by api.dll
When I call from my COM client (MS Access) a method in my.dll (which calls a method in api.dll) I get the error
Could not load file or assembly Newtonsoft.Json.dll (blah blah) or one of its dependences. The system cannot find the file specified
I tried to copy Newtonsoft.dll and api.dll in system.32, in the same folder with my Access MDB, in MS Access folder. Nothing worked.
I tried to add Newtonsoft to GAC using
gacutil /i newtonsoft.json.dll
which apparently worked, response was
Assembly successfully added to the cache
but when I tried to check if it is there with
gacutil /l newtonsoft.json.dll
I got message: Number of items = 0, so apparently it wasn't added to GAC
Anyway, any suggestion to make this work?
Thanks
I found and solved the problem.
When checking the error message more carefully, I noticed it said it cannot load Newtonsoft.Json.dll version 4.5.0
However, in my project I used nuget package for NewtonSoft, which was version 6.0.2
This leaded me to check what actual version of NewtonSoft the api.dll was built against.
Luckily I had access to api dll source, and I noticed it was built against an older version of Newtonsoft, 4.5.0 for NET 3.5
Even if there was the app.config for dll that defined the version redirection, it seems it didn't worked when the COM-enabled DLL was accessed from COM client - MS Access.
But after I rebuilt the api.dll to use the actual current version of NewtonSoft dll, all started to work ok even from COM call
Related
I have an EXE in VB6 that calls a recently upgraded to VB.Net DLL. This part is working fine, but the issue that I am running into is related to locating the interop of another COM DLL the VB.Net DLL references.
An overview: EXE (VB6) calls method A of DLL (VB.Net), no issues. Method A of DLL calls method B of third party DLL (COM), it gets an error of not being able to find the interop file of the COM DLL.
I have tested directly in VB.Net using a test UI to call the same method A in the VB.Net DLL, and everything works fine. I am currently at a loss as to what is causing the issue.
Thanks,
Chris
I have finally found the answer to the issue. All said and done, the issue was that the interop assemblies were framework version 4.0 instead of framework version 2.0. Visual Studio created them this way for some reason, so I had to change them by using Visual Studio 2008 to create new versions of them.
The process to find this out (which most of is already stated above, but repeated here for helpfulness) was to place all my VB.NET dlls and the interop assembly dlls in the directory of the VB6 exe. (I created sub folders for each one for easier cleanup later.) This still resulted in the same error, but the assembly builder log showed a different reason for the error. This time it was able to load the assembly without issue, but was not able to complete the setup of the assembly.
Researching this led me to the idea of checking the framework versions of the interop assemblies using ILSpy to find out they are version 4.0 while my dlls are version 2.0.
Initially I tried recreating them in Visual Studio 2017, since my project uses framework 2.0, but it still created them as framework 4.0 for some reason. I then tried in Visual Studio 2008, and it was able to create the correct framework 2.0 versions of the interop assemblies, and now everything works as expected.
Team,
The following code returns empty/null to myobj, in my classic ASP page while trying to invoke a dll component.
Set myobj = Server.CreateObject("MODULENAME.cCLASSNAME")
This is related to a DLL which is placed alongside this asp page under \Bin. The DLL is an Interop COM dll custom developed by a former colleague and currently there's no access to the code.
The DLL components are appearing in the regEdit under HKEY_LOCAL_MACHINE\SOFTWARE\Classes\ which makes me assume it is registered. However when I try to re-register using regsvr32, it shows that it was loaded but couldn't find DLLRegisterServer method. I use regAsm to register the component.
Any alternate approach that can be done here? Am I missing something?
If the file name starts with "Interop" or "AxInterop", it is likely a wrapper to a COM DLL, not the DLL it's self. The COM DLL must be registered on the system and then a dotNet application will use/create that wrapper so you can make calls to it.
What you need to do is find the DLL, not the Interop because you are not using dotNet in Classic ASP. Make sure it is registered on that computer (using regsvr32 without error) and then this should work.
Last note/hint, that dll created by ex-coworker was done in C or VB (not dotNet) right? If done in dotNet, it is not COM and you need to research "How to call a managed DLL from unmanaged code".
I have downloaded a .exe file that when executed (in wine) it puts two dll's in the system32 folder and a dll in the "Common files/App-name/" folder.
In theory, the installing of this file creates a tab in Visual Studio that appears when referencing and it is a COM library.
I have tried to reference these dll's in my console project but I get a message of "Is not a valid .Net assembly".
Is there something I can do?
MonoDevelop does not have support for adding COM references directly. You will have to use tlbimp.exe to generate a wrapper dll, then reference that. This is essentially what VS does transparently when you reference a native COM dll.
I have one problem in vb6. I created a .tlb file in VB.net 2005 by adding Com class to project. I built the project, I got .tlb file and .dll files while building project, i selected "Register for Com interop" from project properties and built. It registered autometically and I can use created .tlb file in that PC in Vb6 working fine. if I deploy application to another PC and run I am getting "Error 429 ActiveX Component Can't create object" run time error. What I need to do? Please help me as soon as possible. I can't deploy the application to client due to above error.
one possible solution is to install .net frame work on client pc i never want to install .net framework any other solution will be most appreciatable.
If you've created a DLL in a .NET language (such as VB.NET), the target computer must have the .NET Framework installed in order to use the DLL.
This a hard and fast requirement, irrelevant of how you're utilizing the DLL, whether from a VB 6 application through COM interop or otherwise. It is also a hurdle you'll have to jump over first, before you worry about things like registering COM components, as Uday's answer suggests.
If you don't want a dependency on .NET, you need to use another environment to create the ActiveX DLL; either C++ or VB 6 are possible choices.
One option may be that, while deployment, you need to register that .tlb file in System Registry using regsvr32 command in command-prompt. Generally static libraries does not work until they are registered with System Registry.
You might have seen many programs register components during installation like 'Registering Type Components' or 'Registering COM Components' (for those who do networking especially). Those components are nothing but native COM dlls and tlbs.
so when creating deployment project, add some scripting login to register thode dlls and tlb to System registry using:
regsvr32 <path to tlb/dll>
you have to recursivey call this command for every dll/tlb you want to register with system. For example, if you have 4 dlls and 2 tlbs then you have to call it 6 times providing the path of dll and tlb one at a time.
I have a C++ DLL project which is created in VS 2010. It is exposed as COM(ATL). I used this dll to another .NET Project as reference. C++ Project linker settings are set as follows:
"Register Output" = Yes
"Per-user Redirection = Yes
I created a build definition to build these two projects in tfs 2010. C++ Project builds fine, but .NET project fails because the output dll of C++ project is not registered. Setting to "Per-User redirection" = false does not work. I also tried using WF activity 'InvokeProecss' to register the c++ dll using Regsrv32/batch file/my own exe etc, but I get exit code of 5. My TFS 2010 is in Windows 2008 Server R2. And I think, it's not running the process as admin.
If I generate a interop dll using tlbimp, and then I refer that interop in my .NET proejct, it works fine(oviously in tfs build, I need to add InvokeProecss to call tlb). But this is not acceptable as our general practice is to refer a COM dll directly from .NET proejct.
Can anybody please help about this?
Is there a way to run the tfs automated build activity 'InvokeProcess' as Administrator without prompting for user name/password?
By default, the TFS Build Service runs as the "Network Service" account which is a relatively low-privilege account. Alternatively, you can configure it to run as any domain account you like. I wouldn't recommend that as a solution to the problem you described, however. I would agree with Hans that, in this case, it would be better to use the type library importer (TlbImp.exe) to "reference" your COM server from your managed assembly.
If the COM object isn't changing, you can just use the type library importer to generate an interop assembly, check that in and reference it from your .NET project. If it is changing, you can add a post-build step to generate the interop assembly rather than using the InvokeProcess activity. As Hans pointed out, you can't actually reference a COM object directly from a managed assembly. Your reference is actually causing an interop assembly to get generated at build time after resolving the reference to the registered COM server.