Re: Problem marshalling interface pointer into local server

Hi,

I found some sources regarding this issue. As most of the interfaces in
my common IDL is not oleautomation or dispatch interfaces, I think what
my local servers need is what we call "standard mashalling", mashall via
a proxy/stub dll instead of mashalling via TypLib. Furthermore, the
parameter types used by the interfaces are also not ole-compatible.

But when I read the book about creating of the proxy/stub dll, they
mention something about using MIDL to compile the IDL file, creating a
DLL project and adding the generated _p.c,_i.c,dlldata.c and .DEF file
into the project and build the project to get the proxy/stub dll. I am
not sure whether the book mentions this method because it uses VC6 to
compile. I believe that in VC7, I can use the common IDL file (below) as
the main project IDL file. By building the project, it will auto
generate the typeLib, _p.c, _i.c and dlldata.c. In fact, when I create a
COM dll project, there is a default PS project generated. So in this
case, can I just compile the main DLL project and then the PS project,
and use the PS project binary as the common proxy/stub dll for all the
local servers?

IDL file:

import "oaidl.idl";
import "ocidl.idl";

typedef enum abc_TYPE
{
   abc= 0,
   def,
   ghi
} abc_UNION_TYPE;

..... //other enum structure info

[
   object,
   uuid(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx),
   helpstring("IFaceB Interface"),
   pointer_default(unique)
]
interface IFaceB : IUnknown{
   [helpstring("method GetStatusB")] HRESULT GetStatusB([out] DWORD*
pStatus);
};
typedef IFaceB* PFaceB;

[
   object,
   uuid(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx),
   helpstring("IFaceD Interface"),
   pointer_default(unique)
]
interface IFaceD : IUnknown{
   [helpstring("method GetStatusD")] HRESULT GetStatusD([out] DWORD*
pStatus);
};
typedef IFaceD* PFaceD;

...... //other interface info
......

[
   uuid(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx),
   version(1.0),
   helpstring("CommonInterface 1.0 Type Library")
]
library CommonInterfaceLib
{
   importlib("stdole2.tlb");

   interface IFaceB;
   interface IFaceD;
}

Further to this, I had an issue where I have a in-proc server (server
A), that uses the merged proxy/stub, and a local out-proc server(server
B) both running on 1 system. Both servers implements IFace and register
their own proxy/stub for IFace. Server A was regsvr after server B, and
from what I saw in the registry, the proxy that was registered for IFace
is server A's proxy.

So during one of the use, I had an application that is trying to access
IFace on server B, but as the proxy is pointing to server A, server A's
proxy is used to call to server B. The application then called
CoFreeUnusedLibrary(), which triggers the DLLCanUnloadNow() call in both
server A's proxy and server B. Server B returns FALSE since it's CoClass
is in used, but server A's proxy actually return TRUE. So after 10 mins,
which the default delay before libraries deems unused by the system is
unloaded, server A's proxy got unloaded as a result. When that happen,
and the application tries to use IFace on server B which it previously
obtained before the CoFreeUnusedLibrary() call, an ACCESS_VIOLATION
error was triggered since the proxy is no longer loaded.

I would like to know would the current method to create a common
proxy/stub dll face the same issue as what I describe above?

Thank you very much.
Angela

"Angela Yan" <yanyan9@hotmail.com> wrote in message
news:OiucGLiqGHA.1976@TK2MSFTNGP04.phx.gbl...