C / C++ / MFC Discussion Boards

Re: Calling a COM interface from a worker thread

Stuart Dootson13-Aug-09 6:51

13-Aug-09 6:51

Could you do all of the automation, including creation of the Word object, on the worker thread?

Basically you're running foul of COM single-threaded apartments and things, I think. This article[^] explains them well.

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

Re: Calling a COM interface from a worker thread

sashoalm13-Aug-09 20:48

sashoalm

13-Aug-09 20:48

I read the article about apartments and replaced CoInitialize(NULL); with CoInitializeEx(NULL, COINIT_MULTITHREADED); in both my threads, but it still gives me the exact same error "The application called an interface that was marshalled for a different thread."

It's not really necessary for me to use multiple threads, I'm just doing it because I don't want my UI to block while I'm waiting for the COM method call to return. Do you know if there is some way to make a non-blocking COM method call akin to PostMessage vs SendMessage (I might post this as a new question on the forum btw).

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Re: Calling a COM interface from a worker thread

Stuart Dootson13-Aug-09 21:07

Stuart Dootson

13-Aug-09 21:07

sashoalm wrote:
It's not really necessary for me to use multiple threads, I'm just doing it because I don't want my UI to block while I'm waiting for the COM method call to return

Which is commendable...

sashoalm wrote:
Do you know if there is some way to make a non-blocking COM method call

This[^] is the only thing I remember - and that a) needs support from the COM server (Word doesn't provide it) and b) can't handle automation interfaces (which is probably one reason WHY Word doesn't provide it).

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

Re: Calling a COM interface from a worker thread

Stuart Dootson14-Aug-09 2:08

Stuart Dootson

14-Aug-09 2:08

[I could have sworn I'd posted this message before...]

I've been playing with a little Excel automation sample I've got, adding a) Word automation, and b) multi-threading to it. I've ended up with this code that a) creates a Word instance on the main thread and b) calls that Word instance on a different thread. And the call succeeds, returning the expected value!

#include <boost/thread.hpp>
#import "libid:00020905-0000-0000-C000-000000000046" version("1.6") auto_search no_dual_interfaces rename("RGB", "wordRGB") rename("ReplaceText", "wordReplaceText") rename("FindText", "wordFindText") rename("ExitWindows", "wordExitWindows")

void GetActiveDocName(Word::_ApplicationPtr const& wd, _bstr_t& name)
{
   try
   {
      name = wd->ActiveDocument->Name;
   }
   catch(_com_error& e)
   {
      name = L"No name";
   }
}

int _tmain(int argc, _TCHAR* argv[])
{
   CoInitializeEx(0, COINIT_MULTITHREADED);
   {
      Word::_ApplicationPtr wd;
      if (SUCCEEDED(wd.CreateInstance(__uuidof(Word::Application))))
      {
         // Make sure there's at least one document
         wd->Documents->Add();
         _bstr_t name;
         // Execute GetActiveDocName(wd, name) on a separate thread
         boost::thread getName(GetActiveDocName, boost::cref(wd), boost::ref(name));
         // Wait for the thread to terminate
         getName.join();
         std::cout << (char*)name << std::endl;
      }
   }
   CoUninitialize();
   return 0;
}

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

How to log visited URLs

televes13-Aug-09 5:51

televes

13-Aug-09 5:51

Hello!

I'm trying to make an internet monitoring application to log all the URLs visited by the user. Something like http://www.ematrixsoft.com/website-spy-monitor-software.htm

I tried using a sniffer library as suggested at http://www.codeproject.com/KB/IP/URLLogger.aspx
but had problems with HTTPS URLs because it seems that no only the content of the page is encrypted, but also the URL itself.

Do you have an idea of a "simple" method to catch all the visited URLs from any browser?. I can use a library (Free or not) if necessary.

Thanks.

Re: How to log visited URLs [modified]

Bacon Ultimate Cheeseburger13-Aug-09 12:12

Bacon Ultimate Cheeseburger

13-Aug-09 12:12

televes wrote:
Do you have an idea of a "simple" method to catch all the visited URLs from any browser?

No. Encryption is used to prevent exactly what you are trying to do. Since the URL may contain arguments for a GET operation the request and response headers are also encrypted. Attempting to subvert this is typically frowned upon as it becomes a potential exploit for use by Spyware.

I am a lean mean ground beef machine!!!

modified on Thursday, August 13, 2009 6:40 PM

Re: How to log visited URLs

Moak13-Aug-09 13:43

Moak

13-Aug-09 13:43

Are you the "man in the middle"? Big Grin | :-D

My webchat in Europe Java | [Coffee]

(in 4K)

Re: How to log visited URLs

televes14-Aug-09 10:51

televes

14-Aug-09 10:51

No, not in the middle, in the client machine. In fact, I have discovered a library to do this:
http://www.komodia.com/index.php?page=interceptor.html

Re: How to log visited URLs

kilt17-Aug-09 3:36

kilt

17-Aug-09 3:36

You don't need any library.
Just use COM (Notifications)

MSI installation: problem when Norton Antivirus is active

VictorSotnikov13-Aug-09 5:47

VictorSotnikov

13-Aug-09 5:47

I have created MSI package of my product - using Install Shield 12. The package contains several redistributable files included - partially, Visual Studio 2005 ones.

A customer sent me the following complaint:

"We use corporate version of Norton Antivurus. After installation of your product, any right click on any folder in Windows explorer and many other interactions with Windows cause a prompt of installing missing Norton Antivirus components."

Does someone have any idea what is reason of the problem?

Re: MSI installation: problem when Norton Antivirus is active

Bacon Ultimate Cheeseburger13-Aug-09 16:11

Bacon Ultimate Cheeseburger

13-Aug-09 16:11

Sounds like you may be installing older versions of a redistributable file that Norton relies on. The first thing I would check is the file versions and then move to make sure that any files you are installing into the System32 folder actually belong there.

I am a lean mean ground beef machine!!!

rand() causing unresolved external symbol

Member 321680813-Aug-09 5:05

Member 3216808

13-Aug-09 5:05

Hi! I am using Visual Studio 2008, and am trying to put some custom code into a DLL whose source code is supplied by a third party. The third party code compiles fine, and everything is fine until I write a piece of code that calls rand(). At that point, when I compile, I get the error message:
error LNK2019: unresolved external symbol _main referenced in function __tMainCRTStartup (file is LIBCMT.lib).

I tried excluding that lib from the link, but that caused a bunch of other errors. Does anyone know how to resolve this problem?

Re: rand() causing unresolved external symbol

Stuart Dootson13-Aug-09 5:17

Stuart Dootson

13-Aug-09 5:17

The only reason that the C runtime should look for 'main' is if it thinks you're building an EXE. Make sure your project properties do actually say your building a DLL...

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

Re: rand() causing unresolved external symbol

Member 321680813-Aug-09 5:25

Member 3216808

13-Aug-09 5:25

I checked that; it does indeed think it is a DLL, and in fact it makes a DLL quite happily when I comment out the lines that call rand().

Re: rand() causing unresolved external symbol

Randor 13-Aug-09 12:56

Randor

13-Aug-09 12:56

Hi,

Do you have /GS (Buffer Security Check)[^] enabled? Can you disable this setting and let me know if your problem is fixed?

Thanks,
-David Delaune

Re: rand() causing unresolved external symbol

Member 321680814-Aug-09 3:27

Member 3216808

14-Aug-09 3:27

I disabled it; that didn't help.

Word automation question

sashoalm13-Aug-09 4:54

sashoalm

13-Aug-09 4:54

I create an instance of Word by

app.CreateDispatch("Word.Application");

In task manager I can see this has started winword.exe with these command arguments:
WINWORD /Automation -Embedding

But I want it to start with
WINWORD /a /Automation -Embedding

Is there any way to make CreateDispatch start word with: "WINWORD /a /Automation -Embedding" ?

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Re: Word automation question

Stuart Dootson13-Aug-09 5:11

Stuart Dootson

13-Aug-09 5:11

Doubt it - I think those arguments are probably stored in the registry, under the registration information for Word as a local COM server. I guess if you wanted to hack the registry...but that's a bad idea, I think.

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

Re: Word automation question

sashoalm13-Aug-09 5:35

sashoalm

13-Aug-09 5:35

Well, I actually might have considered it (changing the registry before making the call to CreateDispatch and changing it back immediately after), but I think I can't do it as a limited user, because the key is in CLASSES_ROOT. I'm going to check on that. Anyway, thanks.

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Re: Word automation question

Stuart Dootson13-Aug-09 22:17

Stuart Dootson

13-Aug-09 22:17

Further to my previous answer...

It just so happens that I have a little sample app that automates Excel, so I modified it slightly to a) automate Word as well, and b) call a method on a thread (I use Boost.Threads for this because it makes it so much easier than raw Win32 threads). This app is quite happy to make Excel or Word method calls on a thread other than the one that created the Word/Excel instance - here's the code (missing some #includes, but you get the drift):

#include <boost/thread.hpp>
#import "libid:00020813-0000-0000-C000-000000000046" version("1.6") auto_search no_dual_interfaces rename("DialogBox", "excelDialogBox") rename("RGB", "excelRGB") rename("DocumentProperties", "excelDocumentProperties") rename("SearchPath", "excelSearchPath") rename("CopyFile", "excelCopyFile") rename("ReplaceText", "excelReplaceText")
#import "libid:00020905-0000-0000-C000-000000000046" version("1.6") auto_search no_dual_interfaces rename("RGB", "wordRGB") rename("ReplaceText", "wordReplaceText") rename("FindText", "wordFindText") rename("ExitWindows", "wordExitWindows")

void GetActiveDocName(Word::_ApplicationPtr const& wd, _bstr_t& name)
{
   try
   {
      name = wd->ActiveDocument->Name;
   }
   catch(_com_error& e)
   {
      name = L"No name";
   }
}

void GetActiveWorkbookName(Excel::_ApplicationPtr const& xl, _bstr_t& bs)
{
   if (Excel::_WorkbookPtr wb = xl->ActiveWorkbook)
   {
      try
      {
         bs = wb->FullName;
      }
      catch(_com_error& e)
      {
         bs = L"No name";
      }
   }
}

int _tmain(int argc, _TCHAR* argv[])
{
   CoInitializeEx(0, COINIT_MULTITHREADED);
   {
      Excel::_ApplicationPtr xl;
      if (SUCCEEDED(xl.CreateInstance(__uuidof(Excel::Application))))
      {
         // Make sure there's at least one workbook
         xl->Workbooks->Add();
         _bstr_t name;
         // Execute GetActiveWorkbookName(xl, name) on a separate thread
         boost::thread getName(GetActiveWorkbookName, boost::cref(xl), boost::ref(name));
         // Wait for the thread to terminate
         getName.join();
         std::cout << (char*)name << std::endl;
      }
      Word::_ApplicationPtr wd;
      if (SUCCEEDED(wd.CreateInstance(__uuidof(Word::Application))))
      {
         // Make sure there's at least one document
         wd->Documents->Add();
         _bstr_t name;
         // Execute GetActiveDocName(wd, name) on a separate thread
         boost::thread getName(GetActiveDocName, boost::cref(wd), boost::ref(name));
         // Wait for the thread to terminate
         getName.join();
         std::cout << (char*)name << std::endl;
      }
   }
   CoUninitialize();
   return 0;
}

This code, when run, displays correct names. So - it IS possible to call Word on a thread other than the one that instantiated it...

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

Static pointer

kumar sanghvi13-Aug-09 4:22

kumar sanghvi

13-Aug-09 4:22

Hi,
I have a static pointer in a class and im allocating memory in heap in a static function..and that function returns the same pointer...

then im using that function in some other class...now when should i deallocate the memory in heap....in the destructor of the class where the static pointer belongs to...?

Please correct me if im wrong..

Re: Static pointer

Cedric Moonen13-Aug-09 4:29

Cedric Moonen

13-Aug-09 4:29

The first thing which is important to understand here is that the static member of a class is shared across all instances of that class. It means that if you destroy your pointer inside the desctrutor of your class, as soon as one instance gets destroyed, then you end up with an invalid pointers for all other instances.

And also, if you allocate that pointer inside a static function, each time the function is called, the pointer will be recreated (which will lead to memory leak), unless you check if it has already been created.

Is there a valid reason why you need to have this static pointer ? If yes, then you will need to destroy that pointer when you don't have any class instances anymore.

Could you please explain the scenario here ?

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

Re: Static pointer

kumar sanghvi13-Aug-09 5:03

kumar sanghvi

13-Aug-09 5:03

ya ill explain....

i have function which calculates the font ie...

CFont* Temp::m_newFont=NULL;
void Temp::init(CDC*pDc)
{
NONCLIENTMETRICS ncmet;
ncmet.cbSize = sizeof(ncmet);
SystemParametersInfo(SPI_GETNONCLIENTMETRICS, sizeof(ncmet), &ncmet, 0);
m_newFont=new CFont;
LOGFONT lf;
HDC hDC=pDc->GetSafeHdc();
SecureZeroMemory(&lf, sizeof(lf));
lf.lfHeight = -MulDiv(20, GetDeviceCaps(hDC, LOGPIXELSY), 72);
lf.lfWeight = FW_MEDIUM;
lstrcpy(lf.lfFaceName,ncmet.lfMenuFont.lfFaceName);
m_newFont->CreateFontIndirect(&lf);

}

and other function which returns pointer..

CFont* Temp::getFont()
{
return m_newFont;
}

where as the above 2 functions are static functions and m_newFont(member varibale) is a static CFont*...

and now im exporting this class using _declspec(dllexport)

and im using this class in some other process..as below...

where pDc is a CDC pointer..
Temp::init(pDC);

and when im trying to use

LOGFONT lf;
CFont* pFont=Temp::getFont();
pFont->GetLogFont(&lf);

lf.lfHeight value is garbage value.....instead of correct value
and when i used Quickwatch and see pFont i see m_hObject as 0x00000000

im not able to understand why it"s getting null..

and even i tried like instead of creating a static pointer i created static CFont object and in getFont() i returned address of the object ...but even that doesn"t help...

pls let me know..

Re: Static pointer

sashoalm13-Aug-09 21:00

sashoalm

13-Aug-09 21:00

Cedric Moonen wrote:
The first thing which is important to understand here is that the static member of a class is shared across all instances of that class

I've always thought that this is a bit misleading, it's really just a global variable/function, and the class acts only as a namespace. I've read that explanation about being "shared across all instances of that class" and I think it confuses people rather that give them an accurate idea of what a static member is.

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Sequencing or queuing parallel process [modified]

s v joshi13-Aug-09 3:36

s v joshi

13-Aug-09 3:36

Please help to solve these scenario of process waiting for execution in C++
Scenario is as follows
There is one parent process say P1 and 4 child processes say A B C D
Process A starts at 3:00 pm
Process B starts at 3:15 pm
Process C starts at 3:30 pm
Process D starts at 3:45 pm

Process A take 1 hour for completion and process B,C,D takes
10 mins for completion
At a time only one process is allowed to execute since
these process shared some common resources so at any point of time
only one process is allowed to execute. but these are scheduled job so
process B, C, and D must wait till process A get completes

so process B must wait till 4:00 PM for execution
and starts at 4:00 PM
process C must start at 4:10 PM after completion of process A and B
process D must start at 4:20 PM after completion of process A and B and C
so these sequencing also should maintained

B, C and D cannot start unless and until A is get completed and user dose not know how much time A will take so B,C and D must wait for completion of A and after A completes then and then only B,C and D execute in a same order

so how to implement wait mechanism for this scenario ?

Currently i have implemented a lock mechanism where first process A will create a lock file and process B,C and D will continuously poll this lock file and as soon as process A finishes it will release a lock on and whichever process acquires a lock first will get executed first but here sequencing is not maintained and process executes randomly

so what kernel objects like event, semaphore are needed to solve this scenario.
Where to store data (simple command line) when this process are waiting ?
How to maintain a sequence for excutation ?

please help to solve this scenario of process waiting for execution

-Thanks

modified on Thursday, August 13, 2009 9:46 AM

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