passing struct to COM objects

[merlinos]

I have some APIs that take one or more struct as input parameters. I need to call these APIs remotely (from a different computer than the one they are sitting on). I figured I could use DCOM. However, how do I call a COM object with a struct as the input? THanks merlinos

[Jorgen Sigvardsson]

You can define structs in MIDL which you can pass over DCOM. The good way to pass the structs to your API would be to repackage the struct in your COM methods. The ugly way would be to just cast and pass the structs to the API functions. Good method

HRESULT COMClass::Method(Struct* pPassedIn)
{
APIStruct s;
s.field = pPassedIn->field;
APICall(&s);
return S_OK;
}

The ugly way

HRESULT COMClass::Method(Struct* pPassedIn)
{
APICall((APIStruct*)pPassedIn);
return S_OK;
}

For the latter case, just make sure the MIDL-struct members are packed and aligned as the API struct. -- Wir müssen leben bis wir sterben.

[sergeyv2002]

Could you please explain in more details what do you mean? I'm not very familiar with all COM/DCOM abbreviations,even thow I have a basic knowledge on the topic, so could you please explain what is APIStruct,APICall and how is it related to MIDL ? Thanks

[Jorgen Sigvardsson]

APIStruct and APICall are just fictious names for the functions he wants to call using DCOM. It is not related to MIDL at all. However, his COM-methods could forward the calls to these APIs, which was the point with my previous message. -- Wir müssen leben bis wir sterben.