如何从进程外服务器实现自定义编组接口的 IMarshal
我试图弄清楚如何在进程外 COM 服务器触发事件时实现自定义编组。服务器实现 IConnectionPoint 接口。它调用以发出事件信号的接口上的方法之一采用指向接口的指针（将其称为 IMyEventData。）。服务器中实现 IMyEventData 的类也实现 IMarshal。当我的服务器触发该事件时，我会收到预期的 IMarshal 调用，包括 GetMarshalSizeMax、GetUnmarshalClass 和 MarshalInterface。到目前为止，一切都很好。
我已经在系统上注册的单独 DLL 中实现了解组器。在服务器处理 MarshalInterface 调用之后，我的解组器 DLL 立即加载到客户端中，但我在其 IMarshal 接口上收到的调用不是我所期望的。这些调用是对 GetUnmarshalClass、GetMarshalSizeMax 和 MarshalInterface 的调用。在所有这些调用中，上下文都是进程内的，显然是试图跨单元而不是进程边界进行编组。我从未收到对 UnmarshalInterface 的预期调用。当我在调试器下运行客户端和服务器时，在调用解组器的 IMarshal 接口后，每个客户端和服务器都会在输出窗口中显示异常，表明发生了不正确的参数错误 (0x80070057)。
谁能告诉我我做错了什么？我原本期望我的解组器能够调用 IMarshal::UnmarshalInterface，以便它可以访问服务器在调用 IMarshal::MarshalInterface 时提供的数据。我一定在这里遗漏了一些基本的东西。
谢谢。
韦恩
I am trying to figure out how to implement custom marshalling for an out-of-proc COM server when it fires an event. The server implements the IConnectionPoint interface. One of the methods on the interface that it calls to signal an event takes a pointer to an interface (Call it IMyEventData.). The class that implements IMyEventData in the server also implements IMarshal. When my server fires the event, I get the calls to IMarshal that I expect, including GetMarshalSizeMax, GetUnmarshalClass, and MarshalInterface. So far, so good.
I have implemented the unmarshaller in a separate DLL that is registered on the system. Right after the server handles the MarshalInterface call, my unmarshaller DLL gets loaded into the client, but the calls that I get on its IMarshal interface are not what I expect. The calls are to GetUnmarshalClass, GetMarshalSizeMax, and MarshalInterface. In all of these calls, the context is in-proc, apparently attempting to marshal across apartments rather than process boundaries. I never get the expected call to UnmarshalInterface. When I run both client and server under the debugger, each displays an exception in the output window right after the calls to my unmarshaller's IMarshal interface are made, indicating that an incorrect parameter error (0x80070057) occurred.
Can anyone tell me what I am doing wrong? I had expected my unmarshaller to get a call to IMarshal::UnmarshalInterface so that it would get access to the data that the server supplied in the call to IMarshal::MarshalInterface. I must be missing something basic here.
Thanks.
Wayne
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这个问题有点不具体，所以答案将概述发生的主要步骤。
给定的是服务器端的接口指针，该指针需要被编组到外部单元中。服务器 COM 对象实现了应该被拾取的自定义封送拆收器。客户端期望通过自定义封送获得指向代理的接口指针。
服务器端
IMarshal接口 - 这成功了，我们的对象确实实现了它IMarshal::GetUnmarshalClass来获取CLSID> 负责客户端解组的类；这可能与服务器对象的 CLSID 相同，这可能是代理类CLSID或代理工厂类CLSID- 这个想法是 COM 通过方法调用请求它，所以对象可以自由地返回任何看起来合适的内容IMarshal::GetMarshalSizeMax来准备用于封送数据的缓冲区IMarshal::MarshalInterfacemarhsal 数据客户端
CLSID<解组器类的 /code> 和来自编组器的数据CLSID实例化一个类IMarhsal::UnmarshalInterface并提供IID它最终想要获得请注意，在上面的最后一步，COM 具有以下内容：
CLSID，以从请求接口指针所请求的接口指针的 IID对于所有这些输入，解组器类预计会返回一个有效的指针，该指针可能是也可能不是解组器本身的接口。因此，您可以自由选择是否需要专门的“工厂”解组器类来创建客户端对象，或者您只想创建一个新实例并从封送数据初始化它。
The question is a bit not specific, so the answer will outline the main steps taking place.
Given is an interface pointer on the server side and the pointer needs to get marshaled into foreign apartment. The server COM object implements custom marshaler supposed to be picked up. The client expects the interface pointer to a proxy obtained through custom marshaling.
Server Side
IMarshalinterface - this succeeds, our object indeed implements itIMarshal::GetUnmarshalClassto getCLSIDof the class responsible for unmarshaling on client side; this might be the same CLSID of the server object , this could be proxy classCLSID, or proxy factory classCLSID- the idea is that COM requests this via method call, so object is free to return whatever seems appropriateIMarshal::GetMarshalSizeMaxto prepare a buffer for marshaling dataIMarshal::MarshalInterfaceto marhsal the dataClient Side
CLSIDof the unmarshaler class and data from the marshalerCLSIDIMarhsal::UnmarshalInterfaceon the created class and providesIIDit eventually wants to obtainNote that on the last step above COM has the following:
CLSIDof the class to instantiate to request interface pointer fromIIDof the interface pointer requestedWith all these inputs, the unmarshaler class is expected to return a valid pointer, which might be or might be not the interface of the unmarshaler itself. So you are free to choose whether you want a specialized "factory" unmarshaler class to do create client side object, or you want simply create a new instance and initialize it from marshaling data.