如何使用COM公开.netstandard2.0库以在VB6中使用？ [英] How do I expose a .netstandard2.0 library with COM for use in VB6?

问题描述

我有一个dotnet核心库，一个框架4.7.2库和一个vb6应用程序。

我想编写一个公共库供所有人访问，因此选择.netstandard2.0

我尝试在.netstandard2.0库和vb6之间的4.7.2框架包装器库中。

但是我遇到了

错误是<$ c之外的程序集版本之间显然不匹配$ c> Project1.exe 文件和所引用程序集的版本（不是您自己创建的引用，而是嵌入在这些程序集中的引用...）。在启动.NET程序时，您看不到它，因为解析是一个非常复杂的过程，它依赖于许多参数（而.NET Core，Framework，Standard，nugets等并没有任何改善）。 / p>

要进一步检查是否存在不匹配错误，您还可以使用 SDK中的Fuslogvw.exe（组件绑定日志查看器）工具。

现在我们知道这是程序集版本不匹配的问题，您可以做的是在 Project1之外创建一个名为 Project1.exe.config 的文件。 exe 并添加程序集绑定将重定向到它。

配置它的最简单方法是将所有可能的版本重定向到包含程序的目录中存在的版本，所以就您而言（从今天开始，所有这些都可以演变...），可能就是这样，可能是您直接或间接引用的每个程序集：

 < configuration> 
< runtime> 
< assemblyBinding xmlns = urn：schemas-microsoft-com：asm.v1> 
 ... 
< dependentAssembly> 
< assemblyIdentity name = Microsoft.Extensions.DependencyInjection.Abstractions publicKeyToken = adb9793829ddae60 /> 
<！-3.1.2.0是您发货的程序集的版本-> 
< bindingRedirect oldVersion = 0.0.0.0-65535.65535.65535.65535 newVersion = 3.1.2.0 /> 
< / dependentAssembly> 
 ... 
< / assemblyBinding> 
< / runtime> 
< / configuration> 
  

不幸的是，有许多附属程序集，创建带有正确信息的所有重定向有点繁琐，因此，我创建了一个工具，该工具可创建 .config 文件，并为给定目录中的所有.NET程序集自动配置了重定向： https://github.com/smourier/BindingRedirectGenerator 。

如果需要的话要同时在VB6 IDE中工作，您必须在 VB6.exe VB6.exe.config 文件中使用相同的过程。

I have a dotnet core library, a framework 4.7.2 library and a vb6 application.

I want to write a common library for them all to access and so choose .netstandard2.0

I tried a the 4.7.2 framework wrapper library between .netstandard2.0 library and vb6.

However I ran into assembly binding problems

Looking at the docs I see

In .NET Core, the process for exposing your .NET objects to COM has been significantly streamlined in comparison to .NET Framework.

However no mention .netstandard2.0

I decided to try following the docs anyway even though my project is using .netstandard2.0

I got up to the instructions on Generating the COM Host in which case the output files ProjectName.dll, ProjectName.deps.json, ProjectName.runtimeconfig.json and ProjectName.comhost.dll should build.

However the ProjectName.comhost.dll and ProjectName.runtimeconfig.json do not create.

I see in this dotnet standard issue that Microsoft plans on having tooling support in "Preview 4"

I am running VS 16.4.5

[Update]

I decided to try making a .net core wrapper library and enabling it for com.

I was able to add my .netstandard to the wrapper library via a nuget package (I build the .netstandard library using azure devops)

When I build my wrapper library the .dll, .deps.json, .pdb, .runtimeconfig.dev.json and .runtimeconfig.json files are created in a bin\Debug\netcoreapp3.1 folder.

However none of the .netstandard library files appear in the bin\debug folder.

I copied the .netstandard library and the .netcore wrapper libraries to the same folder and ran

regsvr32 MyCoreComWrapper.comhost.dll  

However no .tlb file is created which I need to be able to use from VB6

I note the following in the docs

Unlike in .NET Framework, there is no support in .NET Core for generating a COM Type Library (TLB) from a .NET Core assembly. The guidance is to either manually write an IDL file or a C/C++ header for the native declarations of the COM interfaces.

I found some information on github but would love a step by step guide to making the .tlb

I thought about using latebinding instead but am unsure of how to use it with a com library.

[Update]

I put a sample project on GitHub including some VB6 files. With VB6 referencing the .tlb referenced with the framework library.

When I try to run that I get

Could not load file or assembly 'Microsoft.EntityFrameworkCore, Version=3.1.2.0, 
Culture=neutral, PublicKeyToken=adb9793829ddae60' or one of its dependencies. The system cannot find the file specified.

So I copied all the files from my framework test project to my vb6 folder, rebuilt and ran.

Then I got the error

Could not load file or assembly 'Microsoft.Extensions.DependencyInjection.Abstractions, Version=3.1.0.0, 
Culture=neutral, PublicKeyToken=adb9793829ddae60' or one of its dependencies. The system cannot find the file specified.

I see the file Microsoft.Extensions.DependencyInjection.dll is present with File version 3.100.220.6706

解决方案

The issue is due to assembly binding resolution that fails when ran from VB6 (IDE or compiled .exe file).

Here are the steps to solve it:

• Compile the VB project, for example, let's assume the compiled file is Project1.exe.
• Copy all .NET assemblies (including x86 and x64 directories, and languages directory if localized version is important) aside the compiled VB6 file
• Now run Project1.exe, you will get an error like this:

The error is clearly a mismatch between the version of your assemblies aside the Project1.exe file and the version of referenced assemblies (not references you've created yourself but reference embedded in these assemblies... ). You don't see that when you start a .NET program because resolution is a very complex process that depends on a lot of parameters (and it's not getting any better with .NET Core, Framework, Standard, nugets, etc.).

To futher check it's a mismatch error, you can also use the Fuslogvw.exe (Assembly Binding Log Viewer) tool from the SDK.

Now we know it's an assembly version mismatch issue, what you can do is create a file named Project1.exe.config aside Project1.exe and add assembly binding redirects to it.

The easiest way to configure it is to redirect all possible versions to the ones present in the directory that contains your program, so in your case (and as of today, as all these can evolve...), it would be something like this, possibly for every assembly you reference directly or indirectly:

<configuration>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      ...
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Extensions.DependencyInjection.Abstractions" publicKeyToken="adb9793829ddae60" />
        <!-- 3.1.2.0 is the version of the assembly you ship -->
        <bindingRedirect oldVersion="0.0.0.0-65535.65535.65535.65535" newVersion="3.1.2.0" />
      </dependentAssembly>
      ...
    </assemblyBinding>
  </runtime>
</configuration>

Unfortunately, there are many satellite assemblies, and it's a bit tedious to create all redirects with correct information, so I've created a tool that creates a .config file with the redirects configured automatically for all .NET assemblies in a given directory: https://github.com/smourier/BindingRedirectGenerator.

If you want it to work for the VB6 IDE too, you'll have to use the same procedure in a VB6.exe.config file aside VB6.exe.

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