TROUBLE Passing BYTE Array from Client to COM OUTPROC Server [modified]

Stephen Hewitt

I built mine with 2008. What projects are in the workspace? Is there a project to build the proxy-stub (name ends in "PS")?

Steve

K ARUN KUMAR

I have a Project named BytComp and BytCompPS in my workspace. I built the BytCompPS and found ByCompPS.dll and registered it using regsvr32 command. Now, i have added a new interface method as suggested by you but still im not able to access the entire array. :doh:

Stephen Hewitt

Paste the code highlights as I did. Also, building the proxy-stub should have included a post-build step that registered it, so you shouldn't need to do it manually.

Steve

K ARUN KUMAR

Hi Stephen, What do you mean by Code highlights?

Stephen Hewitt

Like this[^].

Steve

K ARUN KUMAR

Ya i did the same way by copying you code.Still not able to access the entire array. Can you send me a working client server codes developed in VC98 or VS2003? My Id: k_arunkumar_1217@yahoo.com

Stephen Hewitt

No, I mean paste in the important sections of your code here (like I did on the post I linked to).

Steve

K ARUN KUMAR

IDL File Entry: [id(5),helpstring("method SetData")] HRESULT SetData([in] ULONG size, [in,size_is(size)] BYTE *pData); Method Override: STDMETHODIMP CDataProvider::SetData(ULONG size, BYTE* bytArray) { // TODO: Add your implementation code here BYTE byt[6]; int i=0; for(;*bytArray!=0;i++) { byt[i]=*bytArray; ::MessageBox(NULL,(LPCTSTR)"he","Msg",MB_OK); bytArray++; } byt[i]=0; return S_OK; } Client: IDataProvider* pServer=NULL; HRESULT hr=::CoCreateInstance(CLSID_CDataProvider,NULL,CLSCTX_LOCAL_SERVER,IID_IDataProvider,(LPVOID*)&pServer); short sSize = 5; BYTE* pBytes; //Allocate the shared Memory pBytes = reinterpret_cast(CoTaskMemAlloc(sSize * sizeof(BYTE))); if(pBytes == NULL) return; ::memset(pBytes, 0, sSize); pBytes[0]='K'; pBytes[1]='K'; pBytes[2]='R'; pBytes[3]='D'; pBytes[4]=NULL; pServer->SetData(5,pBytes); CoTaskMemFree(pBytes); //Free the shared Memory

Stephen Hewitt

There's many problems here. Firstly you haven't escaped the post properly so it's hard to read. For example:

K ARUN KUMAR wrote:

reinterpret_cast(CoTaskMemAlloc(sSize * sizeof(BYTE)));

You didn't escape the < and > so some important code is missing. You didn't bother to point out explicitly which code is in the client and which is in the server. Surrounding code in <pre> and </pre> tags is generally considered polite, not to mention the fact that it makes the code more readable (uses a fixed width font). You also didn't bother to ensure the code was properly indented. In short, if you want help, put some effort in asking for it (at least as much as I do in replying!). Now onto the code....

K ARUN KUMAR wrote:

BYTE byt[6]; int i=0; for(;*bytArray!=0;i++) { byt[i]=*bytArray; ::MessageBox(NULL,(LPCTSTR)"he","Msg",MB_OK); bytArray++; } byt[i]=0;

This doesn't make use of size. Ever heard of buffer overruns? What's with the (LPCTSTR)"he"? Get rid of the cast. If the string is of the wrong type casting just turns what would have been a compiler error into a runtime error and solves nothing.

K ARUN KUMAR wrote:

//Allocate the shared Memory pBytes = reinterpret_cast(CoTaskMemAlloc(sSize * sizeof(BYTE))); if(pBytes == NULL) return;

CoTaskMemAlloc does ***NOT*** allocate shared memory! You don't need to use it in this case (although there is no harm in using it). Can you tell me more about what actually happens when you run it. Does the CDataProvider::SetData function get called? Does it display a MessageBox? How many times?

Steve

K ARUN KUMAR

Sorry Steve. Im new to the message posts. I will follow ur guidelines for sure from next time. Coming to our discussion, iam getting the message box only once, meaning that only one byte is marshalled.

Stephen Hewitt

Post the entire IDL file.

Steve

K ARUN KUMAR

ENTIRE IDL File:

import "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\include\prsht.idl";
import "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\include\mshtml.idl";
import "c:\program files\microsoft visual studio .net 2003\vc7\platformsdk\include\dimm.idl";
import "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\include\mshtmhst.idl";
import "c:\program files\microsoft visual studio .net 2003\vc7\platformsdk\include\docobj.idl";
import "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\include\exdisp.idl";
import "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\include\objsafe.idl";

[
object,
uuid(A12EAEC2-2B64-470B-93AF-EFE0855DD3AC),
dual,
helpstring("IDataProvider Interface"),
pointer_default(unique)
]
#line 14 "d:\\vc++\\sample applications\\bytcomp\\dataprovider.h"
interface IDataProvider : IDispatch {
#line 16 "d:\\vc++\\sample applications\\bytcomp\\dataprovider.h"
[id(1),helpstring("method GetSafeArray")] HRESULT GetSafeArray([out,retval] VARIANT *vtSafeArray);
[id(2),helpstring("method SetByteData")] HRESULT SetByteData([in] BYTE *bytArray);
[id(3),helpstring("method SetArray")] HRESULT SetArray([in]BSTR bstrArray);
[id(4),helpstring("method SetThings")] HRESULT SetThings([in]BYTE **ppThings );
[id(5),helpstring("method SetData")] HRESULT SetData([in] ULONG size, [in,size_is(size)] BYTE *pData);
};

[ version(1.0), uuid(0381FBF3-32C1-4AF1-B6DD-EFB51815DD72), helpstring("BytComp 1.0 Type Library") ]
library BytComp
{
importlib("stdole2.tlb");
importlib("olepro32.dll");

\[
	version(1.0),
	uuid(8816EAAA-91D5-4DCF-BA1A-DD699529D099),
	helpstring("DataProvider Class")
\]

#line 36 "d:\\vc++\\sample applications\\bytcomp\\dataprovider.h"
coclass CDataProvider {
interface IDataProvider;
};

}

Stephen Hewitt

Ok. Open the registry editor and search for the following key: {A12EAEC2-2B64-470B-93AF-EFE0855DD3AC} If you find if right click on it and select "Export". Post the contents of the file this generates.

Steve

K ARUN KUMAR

Hi Steve, i found two registry entries.. 1st Entry

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}]
@="IDataProvider"

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\NumMethods]
@="12"

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\ProxyStubClsid]
@="{00020424-0000-0000-C000-000000000046}"

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\ProxyStubClsid32]
@="{00020424-0000-0000-C000-000000000046}"

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\TypeLib]
@="{0381FBF3-32C1-4AF1-B6DD-EFB51815DD72}"
"Version"="1.0"

2nd Registry Entry:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\CLSID\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}]
@="PSFactoryBuffer"

[HKEY_CLASSES_ROOT\CLSID\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\InProcServer32]
@="D:\\VC++\\Sample Applications\\BytComp\\DebugPS\\BytCompPS.dll"
"ThreadingModel"="Both"

Stephen Hewitt

First note that the proxy-stub you built is creatable:

K ARUN KUMAR wrote:

[HKEY_CLASSES_ROOT\CLSID\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\InProcServer32] @="D:\\VC++\\Sample Applications\\BytComp\\DebugPS\\BytCompPS.dll" "ThreadingModel"="Both"

But your interface isn't using it:

K ARUN KUMAR wrote:

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\ProxyStubClsid32] @="{00020424-0000-0000-C000-000000000046}"

{00020424-0000-0000-C000-000000000046} is the universal marshaller, not your proxy-stub ({A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}). Also I notice your interface is marked with [dual]. This means the interface has to be automation compatible and should only use a limited number of types (which doesn't include BYTE arrays). Do you get warnings when you compile the IDL file? Did you ignore them? Since you exported these keys you're free to tinker with them as they can easily be restored using the exported files. Change this key:

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\ProxyStubClsid32]
@="{00020424-0000-0000-C000-000000000046}"

So that it looks like this:

[HKEY_CLASSES_ROOT\Interface\{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}\ProxyStubClsid32]
@="{A12EAEC2-2B64-470B-93AF-EFE0855DD3AC}"

NOTE: Don't alter the exported files, make the changes in the registry. Alternatively copy the exported file, make the change in the copy, then double click the copy.

Steve

K ARUN KUMAR

Hi Steve, You are amazing. The change worked. But when iam building the server, it again modifying the registry setting to default Marshaller GUID. How to set my ProxtStub GUID as default?

Stephen Hewitt

The problem is your interface is marked as an automation interface but it uses types that are not automation compatible. As I said, I'm sure the MIDL compiler would have warned you about this, and you should always investigate compiler warnings. The are a number of ways to fix this:

Don't use an automation compatible interface. Remove the dual and all the [id] attributes, and derive from IUnknown instead of IDispatch. You will not need the IDispatchImp base class in you server implementation either.
Add another interface to the object (which isn't dual and derives from IUnknown, as described above) to contain the non-automation compatible methods.
Manually make the changes I described after RegisterTypeLib[^] makes the "wrong" ones. This is a hack though: why use an automation-compatible interface that automation clients will not be able to call?
Give my posts good marks ;)

Steve

K ARUN KUMAR

Thanks a lot buddy. Sure.. Arun