I've been able to create a signed CAB file for web deployment containing my control and dll, but my control seems unable to access classes and functions in my dll even though it is listed as a dependency in the CAB's inf file. For all my research, I can't even tell if what I'm trying to do is "allowed". Followup: if it is possible to talk to a non-com dll, is it a security risk?
I'm using msvc 2010. Thanks for your time!
Pretty certain what I was trying to do wasn't possible. Ended up creating a class library instead so that I could reference and include the functions I needed at compile time.
Related
My software is written in VB6. For diagnostic purposes I need to determine the actual DLL / OCX files which are loaded and used by the application on a customer's computer.
Since VB6 DLLs (including OCX files) are COM libraries they are loaded indirectly based on information in the registry. This means it is possible that a different file is being used than what was used in development / testing environments. Sometimes in a client environment this can cause malfunctions which are hard to diagnose without this information.
(My plan is to build a diagnostic readout window in my program that shows the libraries that the program is using at that moment.)
You can use the Dependency Walker to find which DLL your program depend on.
But the OCX are not so easy to find because they are loaded at run-time based on the application dependencies and the registered components through the Windows registry. But you have to already know which OCX components your application references - from the Tools > References and all the places you call CreateObject.
There are many ways in which runtime dependencies on DLLs (or OCX files) can be established. Ideally you would need to account for all of them:
This answer is specific to VB6 but many other programming languages would work similarly.
Mechanisms which establish runtime dependencies:
At Compile time for traditional dynamically-linked libraries (DLLs which are not COM)
Files are (as their name suggests) dynamically loaded at runtime based on the linking process done at the end of compilation
This includes VB6 code which has used a statement like: Declare Function … Lib …
(In .NET this would mean calling out into “native code”)
To identify: Inspect the source code.
To identify without sources: These can be detected by a tool like Dependency Walker
At Compile time for COM DLLs
In VB6 this is known as “early binding”.
This includes VB6 code which has explicitly set a reference to a DLL or OCX.
Note that the dependency is actually on the COM class or interface GUID, and not explicitly on the DLL file itself.
To identify: These are listed in the project VBP.
To identify (alternate): If you don't have the VBP or source code, these dependencies can generally be revealed by by IMPORT statements in OLEView. You might need to look up some GUIDs from there in the registry to see what actual DLL files are used.
At Compile time for statically-linked libraries (not COM, not DLLs)
Library code is included in the EXE or DLL which is being compiled. Therefore there is no runtime dependency to anything external.
As far as I am aware, this is not possible for VB6 programs. Something like a C linker could use libraries like this. A rough equivalent in .NET would be using ILMerge to combine assemblies.
At Runtime for traditional DLLs (not COM)
DLLs can be loaded arbitrarily using Win32 API such as LoadLibrary().
To identify: You have to look at the source to know what might happen.
Alternately if you don't have the source you could use tools like Process Explorer and/or Process Monitor to observe a running instance and see what DLLs actually get loaded.
At Runtime for COM DLLs
Classes can be loaded arbitrarily using eg VB6 CreateObject() calls.
In VB6 this is known as “late binding”
Which DLL will be used to provide the class will be determined by the process’s activation context. The activation context is established by the app manifest file (if there is one) or the Windows registry otherwise (the normal default for VB6 programs).
To identify: You have to look at the source to know what might happen. You also need to know what the configuration state will be on the PC that runs the code - which DLL files are registered, assuming a manifest is not used.
Alternative for no source code: as in the case above
Important: dependencies can be chained. So really you need to "walk the links" of all the dependencies until you build up a complete mapping of what is required. Somewhere in that mapping you can draw a line between what you need to deploy and what the operating system or other runtime environment can be relied on to provide. (IMO for VB6, that line should be drawn rather liberally).
You may be thinking that all this makes the task very difficult or tedious – I totally agree. :)
I have a DLL written in C# and set for COM visibility. I have it setup as a side-by-side assembly and can successfully deploy the application to client PCs registration free. My question is related to the development PC. Is it possible to compile against the DLL in a similar registration-free manner or is registration required on the development machine? I have tried adding the DLL directly though the Project -> References menu and get an error stating "Can't add a reference to the specific file." The DLL is sitting in the same directory as the .vbp file and I have tried adding the DLL both with and without the client app manifest being present.
I have tried adding the DLL directly though the Project -> References menu
That adds a reference to a type library. A type library is a language-independent description of the types in a COM component, VB6 uses it to know how generate efficient code and to provide type checking and auto-completion. A type library is the exact equivalent of metadata in a .NET assembly.
Traditionally, and the way VB6 did it, the type library was embedded as a resource in a DLL. So you are probably used to picking a DLL in the dialog. That however doesn't work so well when the DLL is generated by C#, the type library can only be generated after the C# code is compiled. You have to pick the .tlb file in the VB6 dialog. The traditional way starts with the COM component being described in the IDL language, the type library can be generated before the code is compiled so can easily be embedded in the final DLL. It is technically possible to do it in C# as well, but the build steps are very laborious and painful, you essentially have to build the DLL twice with different build commands.
The type library for a C# library is normally generated in one of three ways:
Using Project + Properties, Build tab, "Register for COM interop" option. This requires VS to run elevated so it can write to the registry. You start VS elevated by right-clicking its shortcut and picking "Run as Administrator"
By running Regasm.exe, using the /tlb:filename option. An alternative for the 1st bullet and necessary if you don't want to run VS elevated for some reason. Using the /codebase option on your dev machine is also wise to make it work exactly like the 1st bullet and not require putting the DLL into the GAC with gacutil.exe
By running the Tlbexp.exe utility, the type library exporter for .NET assemblies. No registration is done, it only generates the .tlb file.
The first bullet is the normal choice and very desirable because you can never forget to update the type library this way. It is perfectly fine on a dev machine since you only really care about reg-free deployment on the user's machine. You probably got into trouble by not doing this anymore.
Using the 3rd choice is okay and more compatible with your goals, run Tlbexp from the Visual Studio Command Prompt. Just keep in mind that you have to do it again when you make changes to your C# code. Forgetting this once and losing clumps of head-hair trying to figure out why your C# changes don't seem to be effective or getting hard-to-diagnose error codes gives you lots of reasons to consider the 1st bullet again :) You can emulate the reg-free scenario by running Regasm.exe with the /uninstall option.
I have an environment where there is a combination of managed and non-managed executables being run for a particular suite.
I have a scenario where the only reason I have a managed assembly (in this case) is because code was easier to write in C# than in VB6.
My 'main' application, written in VB6, needs to make a call to this assembly. So I create the TLB file, so its COM callable.
Now for deployment, is it better practice to place the managed assembly 'with' the tlb in the windows system directory? to have them both in the same place? Seems to me a bit easier to manage that way.
Or the managed assembly (not-signed since it isn't to be shared among diff apps) should just go to the BIN of the application dir, and the TLB moved to the windows\system32 and registered there.
Overall it seems more straight forward to keep them together, but it doesn't seem to be the correct way to do things.
Thx for any tips.
None of the above. You only need the type library when you compile your VB6 program. It does not need to and should not be deployed on the user's machine. There's a small corner case where a type library can help with marshaling an interface across an apartment or process. That won't be the case in a VB6 app.
Personally, I'd put both of them in your application's installation folder or under the Common Files structure.
The System32 folders are ideally just for the system files. (Ignoring history for the moment :)
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.
We have a Powerbuilder 10 application that is using .Net COM assemblies. We are trying to embed the manifest in the PB application (to invoke COM assemblies without registration). The merged manifest file has added sections for dependecies on the .Net COM assemblies. We have tries various tools to inject the new manifest with different results
- using GenMan32 to inject truncates the application from 6MB to 45KB.
- using ResourceTuner, the file size looks okay, but trying to launch application gives "Fatal Disk Error".
Any suggestions on invoked .Net ComEnabled assembly from PB without registration?
Have you tried it with an external manifest and ensured that works? If an external manifest doesn't work, then the manifest information isn't correct.
Once you have a valid external manifest, you might try the Manifest Tool (MT.EXE) from the .Net SDK. It works well with true EXE files. As Terry noted though, the PB generated executable contains additional information that tools that manipulate the EXE need to respect or they will break it.
http://blogs.msdn.com/patricka/archive/2009/12/09/answers-to-several-application-manifest-mysteries-and-questions.aspx
This is more a redirection than an answer. One thing you need to be aware of is that PowerBuilder produces executables that do not follow standards for Windows executable files. Essentially they are a bootstrap routine to load the PowerBuilder virtual machine, plus a collection of class definitions (objects). The cases you've brought up are not the first I've heard of where utilities meant to modify executables don't work on PowerBuilder executables.
As for a positive contribution on what other directions to follow, I don't really know enough to give qualified advice. If it were me, I'd try to register the COM object if ConnectToNewObject() fails, but I've got no idea if that possible or if that route is a dead end.
Good luck,
Terry.