Re: Problem with ATL COM Dll.... Firing event in thread - ATL / WTL / STL Discussion Boards

Problem with ATL COM Dll.... Firing event in thread

chetanjoshi910-Feb-09 20:15

10-Feb-09 20:15

Hi,

I am using the ATL COM DLL. In this I am createng two threads.
I have added new ATL object which supports connceting point, appartment thereaded model,
Dual interface and agregation=yes. While creating thread and passing the interface pointer as this pointer.

hStatusThread = CreateThread(NULL,
o,
LPTHREAD_START_ROUTINE(StatusThread),
(LPVOID)this,
0,
&dwThStId);

::SetThreadPriority(hStatusThread, THREAD_PRIORITY_HIGHEST);

I am accessing the interface pointer in thread and firing the event..

UINT StatusThread(LPVOID param)
{
CMyConnectObj *ptrObj = NULL;
ptrObj = (CMyConnectObj*)param;

if(ptrObj == NULL)
return 0;

if(WaitForSingleObject(g_Mutex,INFINITE) == WAIT_OBJECT_0)
{
ptrObj->Fire_ErrorCode(lErrorCode);
ReleaseMutex(g_Mutex);
}

}

I am using vb6.0 client to use this dll.

but while firing event at line i
ptrObj->Fire_ErrorCode(lErrorCode);

it's giving error as "Unhandled Exception in ConnectProg.exe (MSVBVM60.dll)0x0000005: Access Violation.

But if I tried to fire event for one of the ATL object function there is no problem at all.

Please help me for this with perect solution..
It's very urgent.

Re: Problem with ATL COM Dll.... Firing event in thread

Stuart Dootson10-Feb-09 22:56

Stuart Dootson

10-Feb-09 22:56

chetanjoshi9 wrote:
THREAD_PRIORITY_HIGHEST

That's a bit evil for a start - you really don't want to be altering thread priorities.

chetanjoshi9 wrote:
MSVBVM60

That's likely your problem - your contorl might be thread aware, but I don't think VB6 is...

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Problem with ATL COM Dll.... Firing event in thread

chetanjoshi910-Feb-09 23:06

chetanjoshi9

10-Feb-09 23:06

what is mean by thread aware?

Re: Problem with ATL COM Dll.... Firing event in thread

Stuart Dootson11-Feb-09 0:46

Stuart Dootson

11-Feb-09 0:46

Your control is aware that there can be more more than one thread, and deals with that. Visual Basic doesn't.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Problem with ATL COM Dll.... Firing event in thread

chetanjoshi911-Feb-09 0:52

chetanjoshi9

11-Feb-09 0:52

please tell me the settings required while creating the new ATL object if we want to fire event within the thread....

Re: Problem with ATL COM Dll.... Firing event in thread

Stuart Dootson11-Feb-09 0:59

Stuart Dootson

11-Feb-09 0:59

First thing to try - you need to call CoInitializeEx[^] on the StatusThread, that way your event firing might be marshalled across into the VB thread.

Otherwise...have you thought about firing the event on the other thread, you know, the one VB calls?

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Problem with ATL COM Dll.... Firing event in thread

chetanjoshi911-Feb-09 1:26

chetanjoshi9

11-Feb-09 1:26

hStatusThread = CreateThread(NULL,
0,
LPTHREAD_START_ROUTINE(StatusThread),
(LPVOID)this,
0,
(LPDWORD)&dwStID);

::SetThreadPriority(hStatusThread, THREAD_PRIORITY_HIGHEST);

UINT StatusThread(LPVOID param)
{
MSG msg;

CMyTestObj *ptrObj = (CMyTestObj*)param;

while(1)
{
if(!GetMessage(&msg, NULL, 0, 0))
return 0;

switch(msg.message)
{
case START_COMMAND:

ptrObj->Fire_ErrorCode(123);

break;
}
}
}

This is my code
I am firing event in thread as
PostThreadMessage(dwStID, START_COMMAND, NULL, NULL);

but application crashes at line "ptrObj->Fire_ErrorCode(123);"

But if fire event in any member function (without thread) it works fine..

Please help me for this..
it's very urgent

Thanks.

Re: Problem with ATL COM Dll.... Firing event in thread

Stuart Dootson11-Feb-09 1:56

Stuart Dootson

11-Feb-09 1:56

No, that's not what I said, is it. Did I say something about adding a CoInitializeEx to StatusThread? Yes, I think I did. Try that first, it may enable the COM runtime to marshall the event fire across to the VB thread.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Problem with ATL COM Dll.... Firing event in thread

chetanjoshi911-Feb-09 2:19

chetanjoshi9

11-Feb-09 2:19

please tell me how to use CoInitialzeEx() on StatusThread..
I am not getting....

Please...

Re: Problem with ATL COM Dll.... Firing event in thread

Stuart Dootson11-Feb-09 2:26

Stuart Dootson

11-Feb-09 2:26

Go away and learn about how COM and threads interact[^]. You need to understand this stuff before you try messing with COM and threads.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Help required in writing a class to write/read log data to XML files

Rennie769-Feb-09 0:38

Rennie76

9-Feb-09 0:38

I am relatively new to ATL/WTL. I am writing an application in VC++ using ATL/WTL (not using MFC).

I need to write helper classes for my application that will
- Write all the log information in the form of proper XML files. I need to follow a valid/standard schema with XSLT for writing the XML data.
- Parser to read the XML files using the above schema & iterate through the nodes.

I have never worked with XML before and I am only trying to use ATL/WTL with VC++, so I would greatly appreciate if anyone can instruct me on how I can go about implementing this, for example - point me to the right classes for implementing a XML wrapper for writing data in XML files & for parsing the XML files and iterating through the nodal data. Some sample code would also be very helpful for me in this regard.

modified on Monday, February 9, 2009 8:21 AM

Re: Help required in writing a class to write/read log data to XML files

Stuart Dootson9-Feb-09 2:33

Stuart Dootson

9-Feb-09 2:33

ATL's not going to help you much - it doesn't have any XML classes. I would use MSXML[^], I guess. You could use ATL smart pointer and BSTR wrapper classes.

Rennie76 wrote:
I need to follow a valid/standard schema with XSLT for writing the XML data

XML Schemas are XSD, not XSLT - XSLT is for transforming XML from one format to another.

Re: Help required in writing a class to write/read log data to XML files

led mike10-Feb-09 5:28

led mike

10-Feb-09 5:28

Stuart Dootson wrote:
I guess. You could use ATL smart pointer and BSTR wrapper classes.

Yes, I would not use MSXML without the ATL #import code. Also _com_error, _bstr_t, _variant_t

Re: Help required in writing a class to write/read log data to XML files

Rennie7610-Feb-09 21:38

Rennie76

10-Feb-09 21:38

Thanks for the pointers!

Re: Help required in writing a class to write/read log data to XML files

led mike10-Feb-09 5:31

led mike

10-Feb-09 5:31

As already mentioned there is MSXML and also XMLLite.

Rennie76 wrote:
Some sample code would also be very helpful for me in this regard.

Both are documented on the msdn web site and I imagine sample code is available there as well.

Re: Help required in writing a class to write/read log data to XML files

Stuart Dootson10-Feb-09 6:37

Stuart Dootson

10-Feb-09 6:37

led mike wrote:
XMLLite

Ooooh - I'd forgotten about that one. Nice reminder.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Help required in writing a class to write/read log data to XML files

Rennie7610-Feb-09 22:00

Rennie76

10-Feb-09 22:00

Thanks!

ATL Simple Object Methods and retval [modified]

bob169725-Feb-09 8:32

bob16972

5-Feb-09 8:32

When creating an ATL COM project and adding an ATL Simple Object, if I create a method for that class that has one [in] BSTR parameter and one [out,retval] BSTR* parameter...

What can I assume or assert about the retval in this circumstance? In other words, do I need to check the BSTR to ensure that it does not already point to something and deallocate it if I decide to set the value? Is it mandatory to set the BSTR's value to something?

STDMETHODIMP CSomeATLClass::SomeATLClassMethod(BSTR bstrIn, BSTR* retVal)
{
	// Is retVal guaranteed to be pointing to a NULL BSTR at this point?

	/*
	Am I required to set the BSTR that retVal points to to something other than NULL
	before the method returns?
	*/

	return S_OK;
}

modified on Thursday, February 5, 2009 3:04 PM

Re: ATL Simple Object Methods and retval

Jonathan Davies5-Feb-09 9:23

Jonathan Davies

5-Feb-09 9:23

An [out] BSTR* will not point to a valid BSTR when your method is entered; it will not be set to NULL either so will contain some invalid value.
Setting it to NULL on entering the method I would consider good practice - at least you know what its set to at that point. Your interface definition will say a BSTR is returned so a caller using it might not be too happy to have NULL returned where a string is expected. Using an assert to check its not null in the calling code would be a good idea.
Personally I like code to be simple in that if a BSTR is expected that's what I get, conveying some deeper meaning by setting the pointer to NULL, complicates things as far as I'm concerned. If you decide for some reason you can't return a BSTR why not use the HRESULT to convey this information?

Re: ATL Simple Object Methods and retval

bob169725-Feb-09 9:48

bob16972

5-Feb-09 9:48

I'm currently setting the BSTR to an empty string on error but with try/catch blocks in there, I was questioning myself if all the hoopla was really needed.

Thanks for taking the time out to assist me. I will keep the code that ensures an empty BSTR is returned.

Take care. Smile | :)

Sinking IE printpreview toolbar events

TClarke5-Feb-09 0:46

TClarke

5-Feb-09 0:46

Hi All,

Is there an interface in IE I can get hold of to sink the event of someone clicking the print button on the print preview window in IE?

Thanks for any help or ideas

Cheers
Tom

Philosophy: The art of never getting beyond the concept of life.
Religion: Morality taking credit for the work of luck.

Re: Sinking IE printpreview toolbar events

Stuart Dootson5-Feb-09 6:29

Stuart Dootson

5-Feb-09 6:29

The only thing I can see are the PrintTemplateTeardown[^] and PrintTemplateInstantiation[^] events on the InternetExplorer object[^]?

I can't tell what they do, but they may be of use.

Re: Sinking IE printpreview toolbar events

TClarke6-Feb-09 0:22

TClarke

6-Feb-09 0:22

Thanks for the reply. I'll look into it.

Cheers
Tom

Philosophy: The art of never getting beyond the concept of life.
Religion: Morality taking credit for the work of luck.

WTL 8.0 tabbrowser sample crash

Babil_JR3-Feb-09 4:40

Babil_JR

3-Feb-09 4:40

Hi all again, i'm developing an application based on the tabbrowser sample. I added some event handling
and other operations but when i try to open a pdf file from a link the app crash (c000005).
This happens only with acrobat reader installed, if i use something else (like the freeware foxit reader)
it runs properly.
Any idea?

Re: WTL 8.0 tabbrowser sample crash

Jonathan Davies3-Feb-09 5:23

Jonathan Davies

3-Feb-09 5:23

I've just built the sample with VS2005. Running the browser (on XP) I just typed a link to a local pdf file. I saw the Adobe Reader 6.0 splash screen start up and the file was opened in the browser with no problems. But maybe you're using different version of something to me.

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