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All IP-packets are sent with a CRC32 checksum that the receiver recalculates to validate the data. If the checksum is incorrect, the packet is discarded.
This happens regardless of what you do, it's how the IP-protocol works.
If you're using an UDP ports, the sender will never be informed whether the receiver got the packet or not, at any OSI level, since UDP traffic is connectionless.
If you're using TCP ports, the sender will be sent an ACK for each packet. Whether the packet is to be resent or not is depending on a configurable threshold in the registry found at HKEY_LOCAL_MACHINE/SYSTEM/currentcontrolset/services/tcpip/parameters.
This means that the sender cannot be informed if the receiver got a corrupt packet since the receiving application will never get the packet since it's been discarded.
I suggest you implement a small protocol of your own at the OSI application level that send ACKs to the sender's application. You will then be informed if the receiver never got the packet by the absence of an ACK.
Hope this helps
--
Roger
It's supposed to be hard, otherwise anybody could do it!
Regarding CodeProject: "resistance is pointless; you will be assimilated"
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sivaprakashshanmugam wrote: e. Meaning i need acknowledge from server side. How can i do it?.
Send a ACK Packet back to client simple
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You
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Hi friends,
I have an application that was designed in VS2002(VC 7).
Now when i tried 2 run the same in VS 2003, i am getting an error,
fatal error LNK1104: cannot open file 'mfc70.lib'
what might be the wrong with it ??
Appu..
"If you judge people, you have no time to love them."
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Hi thank u so much for the response,
But i could not able to find out mfc70.lib in the settings.
Can u tell me where i can find mfc70.lib ??
Thanks again
Appu..
"If you judge people, you have no time to love them."
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No ,
No where i could able to find any .lib file in Linker Settings.
Had it been, VC6 i could have easily done this.But i am not able to find it in VC7 IDE.
Appu..
"If you judge people, you have no time to love them."
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Project Settings -> Linker -> Input -> Additional Dependencies
SaRath
"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"
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Hi,
these are the steps i have done
1.Copy and Paste mfc70.lib,mfc70.dll,mfc70d.dll to the corresponding folders.
2.Under project->properties->Linker->input->Additional Dependencies, i have added mfc71.lib and build the application.
No i am getting
LNK2022 metadata operation failed (80131195)
What does this mean??
Thanks
Appu..
"If you judge people, you have no time to love them."
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Hey I could able to Run it successfully.
I just deleteed the Release folder and Rebuild the application.
Thanks u guys, for u r help.
Appu..
"If you judge people, you have no time to love them."
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NiceNaiduCan u tell me where i can find mfc70.lib ??
If you have it, it's most likely in the c:\windows\system32\ folder. Have you checked there?
"The largest fire starts but with the smallest spark." - David Crow
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Hi,
I have record a video avi, but some time I get a blank frame at first. I need to remove this but I don't know how to check if bitmap frame is blank or not. Please help me with checking for this.
Thanks in advance!
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Hi all,
As developing an NT service I've come across a little problem that I'm no able to sort it out. The problem is as follows:
My service is running on local system account (as it is natural) and one of its chores is to launch a particular process in a particular session and with the privileges of a particular user(impersonation). I think I do everything I am supposed to:
- Retrieve environment block of the user.
- Retrieve access token of the user we try to impersonate.
- Convert the token into a primary one.
- Stablish the session for the token.
- Fill in STARTUPINFO structure with the window station and desktop information
.
.
.
-Finally I call CreateProcessAsUserW this way:
CreateProcessAsUserW(hToken,
NULL,
wszCommand,
NULL,
NULL,FALSE,
NORMAL_PRIORITY_CLASS|CREATE_UNICODE_ENVIRONMENT,
Environment,
NULL,
&si,
&pi);
Well, the code I have in my service works perfectly well in any platform save for the case when I try to create a new process in a terminal session of windows 2003 Server (64 bits) where I get error code 6 (Handle not valid). Any suggestion? Thanks in advance.
Regards,
Alvaro
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Hi,
I have a class which encapsulates a window. This class has all the Message handlers and stuff. Lets say this class is CMainFrame.
Now, I am creating CMainFrame from another class....
CMainFrame* cMainFrame = new CMainFrame() ;<br />
cMainFrame->CreateWindow() ;
Now when I destory the window does the object tha cMainFrame is pointing to also get deleted from memory or do we have to do it explicitly? What I did was
cMainFrame->DestroyWindow() ;<br />
delete cMainFrame ;<br />
cMainFrame = NULL ;
Is this destruction of the Window and object the correct way to do it?
---
With best regards,
A Manchester United Fan
The Genius of a true fool is that he can mess up a foolproof plan!
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TechyMaila wrote: Now when I destory the window does the object tha cMainFrame is pointing to also get deleted from memory or do we have to do it explicitly? What I did was
cMainFrame->DestroyWindow() ;
delete cMainFrame ;
cMainFrame = NULL ;
Is this destruction of the Window and object the correct way to do it?
From MSDN:
About DestroyWindow:
Destroys the Windows window attached to the CWnd object. The DestroyWindow member function sends appropriate messages to the window to deactivate it and remove the input focus. It also destroys the window’s menu, flushes the application queue, destroys outstanding timers, removes Clipboard ownership, and breaks the Clipboard-viewer chain if CWnd is at the top of the viewer chain. It sends WM_DESTROY and WM_NCDESTROY messages to the window. It does not destroy the CWnd object.
Nibu thomas
A Developer
Programming tips[^] My site[^]
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Thanks Nibu.
So whatever I am doing is correct. I have one question though. As you can see from my example above, I have created a cMainFrame Pointer to the CMainFrame class. Now, lets say that cMainFrame is a private data member of class A. So, it is a who is creating cMainFrame and calling cMainFrame->CreateWindow().
Now my question is, if a user closes the window from the close button on the Window Title bar, I would have to notify class A so that it may do the required cleaning up like delete cMainFrame and stuff. So, when do I notify A then the window is destroyed? Lets say, that I am notifying A during WM_DESTROY. The implementation in A would be as follows:
void A::OnFrameDestroy()<br />
{<br />
delete cMainFrame ;<br />
cMainFrame = NULL ;<br />
}
But the fact is, when I do this, the teh control passes back to the window's WM_DESTROY message handler after notifying A which results in an error. Any suggestions....???? 
---
With best regards,
A Manchester United Fan
The Genius of a true fool is that he can mess up a foolproof plan!
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Nibu thomas wrote: Delete the pointer in CWnd::PostNcDestroy.
I am using the Win32API. No MFC. Could you tell me which Windows message is equivalent to CWnd::PostNcDestroy?
---
With best regards,
A Manchester United Fan
The Genius of a true fool is that he can mess up a foolproof plan!
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TechyMaila wrote: I am using the Win32API. No MFC. Could you tell me which Windows message is equivalent to CWnd::PostNcDestroy?
WM_NCDESTROY is the last message for a window.
The MFC implementation goes like this. MFC does some clean up in OnNcDestroy and then calls PostNcDestroy. The default implementation does nothing. So you will have to implement something like this.
From MSDN about PostNcDestroy:
The default implementation of CWnd::PostNcDestroy does nothing which is appropriate for window objects allocated on the stack frame or embedded in other objects. This is not appropriate for window objects that are designed to be allocated by themselves on the heap (not embedded in other C++ object).
Those classes that are designed to be allocated by themselves on the heap override the PostNcDestroy member function to perform a "delete this". This statement will free any C++ memory associated with the C++ object. Even though the default CWnd destructor calls DestroyWindow if m_hWnd is non-NULL, this does not lead to infinite recursion since the handle will be detached and NULL during the cleanup phase.
Nibu thomas
A Developer
Programming tips[^] My site[^]
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TechyMaila wrote: cMainFrame->DestroyWindow() ;
delete cMainFrame ;
I think it is ok.
if some OnClose operations mapped in the class, it is better to Send WM_CLOSE command using "SendMessage" function
cMainFrame->SendMessage(WM_CLOSE) ;<br />
delete cMainFrame ;<br />
cMainFrame = NULL ;
SaRath
"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"
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Hello Comunity,
i have two questions about Programs, first is:
How to change the Text in the Titlebar when the program is minimized SW_MINIMIZE!
and second is:
How to make an TrayIcon, i want to show my application as TryIcon on the right side from the taskbar,
for example right from the clock in the task bar!?  confused:
thanx for any help!
break;
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For placing icon in System tray :
http://www.codeproject.com/shell/trayicons.asp
For changing text in Titlebar:
void CMainFrame::OnSysCommand(UINT nID, LPARAM lParam)
{
// TODO: Add your message handler code here and/or call default
if(nID == SC_MINIMIZE)
{
SetWindowText(_T("Minize"));
}
else
{
SetWindowText(_T("Maximize"));// Original
}
CFrameWnd::OnSysCommand(nID, lParam);
}
 Amar
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