Re: DLL COM Problems - COM Discussion Boards

nebbish6-Nov-02 10:14

6-Nov-02 10:14

I'm looking for an explanation for why this syntax works, or what ATL macros or declarations is being referenced to make it work:

'SAFEARRAY(VARIANT)'

I've only been able to find 'SAFEARRAY' typedef'd as a struct and not a macro like I was expecting.

So as an experiment I put these two properties in an IDL file:

[propget] HRESULT Prop1([out, retval] SAFEARRAY(VARIANT) *pVal);
[propput] HRESULT Prop1([in] SAFEARRAY(VARIANT) newVal);
[propget] HRESULT Prop2([out, retval] SAFEARRAY *pVal);
[propput] HRESULT Prop2([in] SAFEARRAY newVal);

Then I referenced the type library from within a VB project and brought up the object browser to see how they were interpreted. After finding them and highlighting them, the information at the bottom of the screen looked like this:

<br />
Property Prop1 As Variant()<br />
Property Prop2 As tagSAFEARRAY<br />

HOW can this be???? how the heck does the SAFEARRAY(VARIANT) syntax work? is it spawning a constructor, or is it some hidden macro? is there a way to view the IDL file after pre-processing to see how this is expanded (again this assumes a macro i've not been able to find), or is IDL even pre-processed. I'm lost as to how the type information in the type library for these two parameters differs.

Can anybody shed some light? I'll make my project work regardless, but I feel incomplete without my having an understanding of what I'm doing.

thanks,
nebbish

Smart, Sexy, Sane. Pick two.

Re: IDL syntax for SAFEARRAY parameters

Steve S7-Nov-02 21:31

Steve S

7-Nov-02 21:31

Get yourself a copy of Essential IDL by Martin Gudgin.
Yes, IDL is preprocessed (in a similar way to C/C++), and if you have MIDL 6.0.0.x (platform SDK version) rather than the VC++ supplied version, then it supports /savePP to save the preprocessed version.

It's just a syntax thing, no constructor, since IDL is purely a description language. Although hints about the SAFEARRAY type are put in the type library, I don't believe they are checked or enforced by any marshalling.

Steve S
[This signature space available for rent]

Apps hangs in memory..

LukeV6-Nov-02 4:07

LukeV

6-Nov-02 4:07

Hello,

My app remains in memory for 2-3 seconds when I close it (as I can see in the process viewer). I guess that it's because some COM objects are unreleased but all seems in order in my app.

Is there a way to know what causes this hang?

Thanks!

---------------
Concentrating on Ideas
http://www.edovia.com

When a WebBrowser2 control navigate a Web Page,how to drop selected range's html source to a EditBox control?

ChengMing Liu6-Nov-02 1:59

ChengMing Liu

6-Nov-02 1:59

In my program, have a EditBox and a WebBrowser2 control,I want to drop a select range's html source to the EditBox control,when I use WebBrowser2 control to navigate a Web page.
My original way is,when a event(mouse dorp) coming , I send a copy(Ctrl + C) event,
then paste the content in the clipboard,but I think is effect on the other program.
So I want other way for resolute this problem.
Very thanks.

DLL COM Problems

simwiz6-Nov-02 0:40

simwiz

6-Nov-02 0:40

Can anybody help me please? I had an error for 3 days and i don´t know where really is the problem.

I have created a dll, which has its interface declaration (with IID) and the class declaration (*.h + CLSID + interface inheritance) and the functions definitions (*.cpp). The registration of the dll was ok.

In another program, I want to create an instance to this dll, and threfore i call the functions of DirectX

CODE
________________________________________________

CoInitialize(0);

CoCreateInstance(CLSID_Something, NULL, CLSCTX_INPROC_SERVER, IID_ISomething, (void**)&m_pSomething );

-----------------------------------------------------------------------------

The compiler and linker give no error, but when runnig the application it breaks because the instance was not created (NULL pointer returned, E_NOINTERFACE).

Re: DLL COM Problems

Stephane Rodriguez.6-Nov-02 1:01

Stephane Rodriguez.

6-Nov-02 1:01

What about naming that interface in your post ?

Back to real work : D-24.

Re: DLL COM Problems

simwiz6-Nov-02 3:32

simwiz

6-Nov-02 3:32

Ok, here it goes Wink | ;)

The next code is the declaration of the interface:

CODE
_____________________________________________________________________________

static const GUID IID_ISomething =
{ 0x5a9fc16e, 0x69b0, 0x4092,{0x9b, 0x17, 0x0e, 0xae, 0x91, 0x9c, 0x61, 0x2d}};

DECLARE_INTERFACE_(ISomething, IUnknown)
{
STDMETHOD (func1) (THIS_
unsigned char* Data, int width, int height
) PURE;
STDMETHOD (func2) (THIS_
int* MyFeature
) PURE;
STDMETHOD (func3) (THIS_
int Feature1, int Feature2, float *Distance
) PURE;
};

_____________________________________________________________________________

And the class is declared as follows:

CODE
_____________________________________________________________________________

static const GUID CLSID_Something =
{0x5b4f902f, 0x0d14, 0x44df, {0x99, 0x51, 0x1a, 0x18, 0x70, 0x4f, 0x3c, 0x21}};

class CSomething : public ISomething
{
public:

//IUnknown interface
HRESULT __stdcall QueryInterface(REFIID riid , void **ppObj);
ULONG __stdcall AddRef();
ULONG __stdcall Release();

//ISomething interface
STDMETHODIMP func1( unsigned char* Data, int width, int height);
STDMETHODIMP func2( int *MyFeature);
STDMETHODIMP func3( int Feature1, int Feature2, float *Distance);

};

Re: DLL COM Problems

Stephane Rodriguez.6-Nov-02 3:46

Stephane Rodriguez.

6-Nov-02 3:46

This code looks pretty much ok, but there are many things to figure out :
- if you try dumpbin /exports, do you see 4 exported function names ?
- do you have an IDL file ?
- do you use ATL for the registration ? and regarding this, what is the implementation of DllRegisterServer() and DllGetClassObject() ?

I guess that, instead you start zipping the whole stuff and upload it somewhere, you could get a bit further by putting a breakpoint in DllRegisterServer() (I assume your component is a DLL, not a .exe). At least if this gets called when you do regsvr32, that's because things are about right.
Then, put a breakpoint in DllGetClassObject(), there you should see somehow a class factory create for you an instance of CSomething. If you are using ATL, you'll have to put a breakpoint in the plain ATL code.

Back to real work : D-24.

Re: DLL COM Problems

simwiz6-Nov-02 5:40

simwiz

6-Nov-02 5:40

Yes, I have my exports, declared in exports.def and defined in exports.cpp (where I have my DllGetClassObject() which creates an instance to the Factory class).
Inside Createinstance() of the Factory, a new object of my dll is created. Later, it goes inside the QueryInterface() of me Object dll. The next interfaces are called: ISomething, IMarshall, IUnknown, and more.... y only have implemented the handling for IUnknown and ISomething, therefore, the rest of them are returned as E_NOINTERFACE. What should i do?

I am not using IDL file.
I have bebugged also the registration of the DLL and everything seems ok, the DllRegisterServer() seems to work.

IStream Interface, How to Update data ?

sajal5-Nov-02 3:21

sajal

5-Nov-02 3:21

Hello,

I am using IStream interface to read and write data objects into a structured storage file.

pOrderInfo->Write(&cust1, sizeof(cust1), NULL);
pOrderInfo->Read(&cust2,sizeof(cust2),NULL);

Can some one tell me what should I do if I want to update information in cust1 structure and save it back to file ?

Say, I want to change cust1.Name = "new name".

thanks,
Confused | :confused:

How Can I Export a CMDIChildFrame from a COM?

IMiracle4-Nov-02 0:48

IMiracle

4-Nov-02 0:48

I want a COM control held a FormView and CMDIChildFrame. And the control provides a interface, the container App(a MDI App) can use the interface gain the pointer to the CMDIChildFrame from the control. Then the container App can use the CMDIChildFrame as its own child frame.

??? documentation or SDK for MS-Word 97 and 2000 DOC-file format ???

maksym_from_odessa3-Nov-02 6:04

maksym_from_odessa

3-Nov-02 6:04

Please, suggest me where I can find or purchase documentation or SDK for MS-Word 97 and 2000 DOC-file format. May be you can also suggest me where I can find or purchase any component, which can write data directly into DOC-file without using MS-Word OLE Automation Server functions, or which can directly convert MS-Word RTF-file into MS-Word DOC-file without using MS-Word OLE Automation Server functions.

COM Local Security

thowra31-Oct-02 4:29

thowra

31-Oct-02 4:29

I need to write an extensible app. My app uses services provided by one or more plug-ins written as COM components. Users can write a plug-in and then install it. That's going pretty well so far but it suddenly struck me that I'm not doing any real verification. In other words, if one of the user-written COM plug-ins wasn't a "genuine" one, how would my application know? Further, if I provided one or two COM objects that offered services to plug-ins and to the application I need to ensure plug-ins haven't got access to certain methods/objects that the application has access to.

It seems that COM offers excellent security for distributed object requests but local security only consists of ensuring the user has access to a particular COM object.

To summarise then:

1. How do I verify a COM component's source? In other words, how do I verify that a COM component which has been "discovered" by my application on initialisation, is geuine?

2. How do I allow one COM object to access another COM object's services, and denying it other services?

Thanks for reading and any input gratefully accepted Smile | :)

"The folly of man is that he dreams of what he can never achieve rather than dream of what he can."

Re: COM Local Security

Stephane Rodriguez.31-Oct-02 5:44

Stephane Rodriguez.

31-Oct-02 5:44

1. A COM interface is a contract between a client and a server. You have to trust it somehow. If you want to make sure people use badly the plugin architecture you provide them, force them to sign (public keys, etc.). You have docs on MSDN for that.

2. Use DCOMCNFG.EXE to create interactively the proper RunAs registry keys so certain COM services are run with degraded priviledges.

How low can you go ?
(MS rant)

HELPPPP

Renjith Ramachandran29-Oct-02 16:33

Renjith Ramachandran

29-Oct-02 16:33

I am newbie to COM, What i want to Do.?

in Msn Messenger : renji12renji@hotmail.com

Re: HELPPPP

Christian Graus29-Oct-02 16:47

Christian Graus

29-Oct-02 16:47

Renjith r wrote:
What i want to Do.?

Wow - there's a question. You should buy a good book, I recommend 'creating lightweight components with ATL' by Jonothan Bates. ATL is a template library, it's the ONLY way to be creating COM components.

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002

During last 10 years, with invention of VB and similar programming environments, every ill-educated moron became able to develop software. - Alex E. - 12-Sept-2002

Re: HELPPPP

Stephane Rodriguez.31-Oct-02 5:38

Stephane Rodriguez.

31-Oct-02 5:38

Christian Graus wrote:
it's the ONLY way to be creating COM components.

Ain't that a tease to hell! OMG | :OMG:

How low can you go ?
(MS rant)

Re: HELPPPP

Christian Graus31-Oct-02 9:43

Christian Graus

31-Oct-02 9:43

*grin* A general question demands a vague answer.

Christian

No offense, but I don't really want to encourage the creation of another VB developer. - Larry Antram 22 Oct 2002

Hey, at least Logo had, at it's inception, a mechanical turtle. VB has always lacked even that... - Shog9 04-09-2002

During last 10 years, with invention of VB and similar programming environments, every ill-educated moron became able to develop software. - Alex E. - 12-Sept-2002

Re: HELPPPP

Renjith Ramachandran1-Nov-02 6:45

Renjith Ramachandran

1-Nov-02 6:45

AnyWay Thanks For Ur Kindly info..
Thank you

in Msn Messenger : renji12renji@hotmail.com

Problem using IStorage::CreateStream()

Xeena28-Oct-02 2:09

Xeena

28-Oct-02 2:09

Hello All,

In my project, I am using IStorage::CreateStream(). What I am doing is creating storage, and adding a file into the stream. For that I am using CreateStream, but the problem is, if the file name is large my program is crashing. I read MSDN, that CreateStream can't handle large filename (more than 31 characters.) Its giving me an error invalid pwcsName.Is there anyway to handle this problem???
Or is there any alternative which can solve this problem. Please, help.

Thanks,

Re: Problem using IStorage::CreateStream()

ian mariano29-Oct-02 2:37

ian mariano

29-Oct-02 2:37

I answered this in the C++ section: here

"The greatest danger to humanity is humanity without an open mind."
- Ian Mariano

http://www.ian-space.com/

Re: Problem using IStorage::CreateStream()

sajal5-Nov-02 3:24

sajal

5-Nov-02 3:24

Note :

Storage and stream names cannot contain the characters /,\,:, or !. If the first character has an ASCII value of the less than 32, the element is marked as managed by some agent other than the owner.;P

How to build CCommand from IRowset*

Rohit27-Oct-02 20:18

Rohit

27-Oct-02 20:18

Hi All,

I was trying to write component in which I perform database access only once and return the IRowset* to client. In subsequent client requests, CCommand is built using client given IRowset* without making d/b connection again.

Here is how it goes.
I built CCommand<Accessor<CMyAccessor> > and Opened it using a CSession-obj and extracted IRowset* and other public members from CCommand. I closed CDataSource,CSession not CCommand.
Later I want to build CCommand<> again by assigning IRowset* etc to it.
The problem is I am able to iterate CCommand but CMyAccessor-members the current record holds are garbage values.

Does anyone know the missing steps? Please let me know!

Here goes the code.. (VC++/ATL/SQL Server OLEDB Driver)
//--------------------------------------------------------
// CCommand members to be used in 2nd section
ICommand *pCommand=0;
IRowset *pRowset=0;
_ATL_ACCESSOR_INFO AccInfo={0};

//---------------------------------------------------
//1st Section opens CCommand using session
//---------------------------------------------------
CDataSource connection;
CSession session;
CCommand<CAccessor<CMyAccessor> > cmd;

// establish connection and session

// command opened successfully
cmd.Open(session,"select * from tab1");

//Extract members
pCommand = cmd.m_spCommand.Detach();
pRowset = cmd.m_spRowset.Detach();
AccInfo.bAutoAccessor =
cmdCalDefault.m_pAccessorInfo->bAutoAccessor;
AccInfo.hAccessor = cmdCalDefault.m_pAccessorInfo->
hAccessor;

cmd.Close(); // do nothing as such
session.Close();
connection.Close();

//---------------------------------------------------
//2nd Section builds CCommand using IRowset*
//---------------------------------------------------
CCommand<CAccessor<CMyAccessor> > cmd2;

//Assign to CCommand
cmd2.m_spCommand = pCommand;
cmd2.m_spRowset = pRowset;
cmd2.m_pAccessorInfo = &AccInfo;
cmd2.m_nAccessors = 1;

// Iteration of cmd2 gives garbage values

//--------------------------------------------------------

Regards
Rohit Arora
VC++ Team Member
rohita@dsrsolutions.com

COM freezed

Ph@ntom25-Oct-02 21:05

Ph@ntom

25-Oct-02 21:05

I was developing a COM. It's a DLL. Also I include MFC support.

I've choosen Apartment threading model. Dual Interface support. And no Aggregation support.

The business logic is written with the help of CInternetSession class. Actually I was trying to get the source of a URL.

Now after implement the business logic. I build the COM DLL.

After building the the COM DLL successfully. I used the COM with VB. The VB program has a GUI.

I don't know why it freezes the GUI when it start retreiving the source of the URL. As the COM Framework covers the threading detail itself.

Any body has the answer Cry | :((

Dammy More

Design Question

Simon Steele25-Oct-02 0:02

Simon Steele

25-Oct-02 0:02

Hi, I want to create an application which will have three "services" (not necessarily NT services). I need fast and frequent IPC calls, and think that COM is probably the way forward for this.

One of these services will need to communicate with the two others, and those two others will need to know about the first.

When defining the interfaces for these services, should I create a single IDL that defines all three? Surely this will reduce include complexity? Am I correct in thinking that the best way to do so is to derive from IUnknown - or should I be aiming at IDispatch?

Having defined that IDL, is the best way to attempt to compile that into a .tlb and import it in the other projects?

I'm relatively new to COM so please excuse my lack of knowledge...

Thanks in advance for any advice or suggestions you can give me. I am trying to work my way through Essential COM while programming with ATL7 - something which doesn't exactly ease the process of getting into COM Smile | :)

--
Simon Steele
Programmers Notepad - http://www.pnotepad.org/

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.