|
Hi Guys,
I am writing a windows service to start / stop certain utility applications. The utilities are in Vb (Please don't ask me why a background process was programmed in vb, I don't know that myself). I used CreateProcess to start them, that was fine.
Now the problem arises when I want to stop them. I can't use TerminateProcess because the applications may be in the middle of something and I want to wait till they finish the job at hand. So I decided to use messages.
I tried PostThreadMessage. The problem I have was that on the utilities' side, if I used GetMessage then it waits for the message which makes the application hang and if I used PeekMessage then in some cases it was missing the Message altogether.
Finally I thought of using a dummy subclassed form and sending the message to to form. It's working now, but it seems like a mess to me. I'm pretty sure there's a better way. Any suggestions?
thanks.
P
"It was when I found out I could make mistakes that I knew I was on to something."
-Ornette Coleman
|
|
|
|
|
Take a look two or three messages down "how do i Detect if an external program has finished excuting(shellexec)?" and read Rage's and cmk's messages. I think, they apply to you as well.
// Afterall, I realized that even my comment lines have bugs
When one cannot invent, one must at least improve (in bed).-My latest fortune cookie
|
|
|
|
|
I am waiting for them to finish.
Actually, I don't just want to wait for the programs to finish. I actually want to tell them to wrap up whatever they are doing and end.
"It was when I found out I could make mistakes that I knew I was on to something."
-Ornette Coleman
|
|
|
|
|
PostThreadMessage()/PeekMessage() should work. Messages can not get lost if they're being sent to the correct thread, as long as you specify NULL (or 0 in VB) for the HWND parameter, and PM_REMOVE as the flags parameter. My VB is a bit rusty, but:
If PeekMessage(msg, 0, 0, 0, PM_REMOVE) = True Then
If msg.message = MY_MESSAGE Then
ExitProcess 0 ' Exit the process
End If
End IfWhere msg is the MSG structure variable and MY_MESSAGE is the value of the message that you are sending. I can't remember if the PM_REMOVE constant is declared like that, or whether it has a different name. Of course, if a different message is received, then it will need to be processed as well. If PeekMessage() returns False, then a message did not exist.
Hope this helps,
Ryan
Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"
|
|
|
|
|
Thanks a lot. That's exactly what I had done.
But PeekMessage doesn't wait for the next message to arrive.
As a result, if the message arrives when the program might be in the middle of a transaction.
Could it be that by the time I call PeekMessage again the Message get processed (maybe by some default message handler which cannot comprehend the meaning of my user defined message?)
"It was when I found out I could make mistakes that I knew I was on to something."
-Ornette Coleman
|
|
|
|
|
parths wrote:
But PeekMessage doesn't wait for the next message to arrive.
That's correct. If you need this, then you need to use GetMessage().
parths wrote:
Could it be that by the time I call PeekMessage again the Message get processed (maybe by some default message handler which cannot comprehend the meaning of my user defined message?)
Absolutely. If you're using more than one message loop, then you have to make sure all the message loops know about the message. It will probably be easier to code your main message loop similar to this:
Do While GetMessage(msg, 0, 0, 0) = True
If msg.message = MY_MESSAGE Then
ExitProcess 0
Else
TranslateMessage msg
DispatchMessage msg
End If
LoopThis should work (I think  )
Ryan
Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"
|
|
|
|
|
Thanks,
I had tried GetMessage, but then it doesn't return till it gets a message (any message) (right?), and that's a problem too because then I can't continue processing until I get a message. So I'll have to keep sending dummy messages to the app.
I'll look for possible 'hidden' Message handlers, but is it possible that VB has it's own message handler which sort of peeks at all the messages coming into the app before forwarding them to the program message handlers or individual message handlers? I'm guessing that is what calls the VB event handler functions
"It was when I found out I could make mistakes that I knew I was on to something."
-Ornette Coleman
|
|
|
|
|
parths wrote:
I had tried GetMessage, but then it doesn't return till it gets a message (any message) (right?), and that's a problem too because then I can't continue processing until I get a message. So I'll have to keep sending dummy messages to the app.
Not necessarily. Modify the message loop so it uses PeekMessage() instead of GetMessage() and do the processing after the PeekMessage() handling:
Do While True
If PeekMessage(msg, 0, 0, 0, PM_REMOVE) = True Then
If msg.message = MY_MESSAGE Then
ExitProcess 0
Else
TranslateMessage msg
DispatchMessage msg
End If
End If
' Do your processing here
Loop
Ryan
Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"
|
|
|
|
|
In a controller I made I want to catch if user presses alt+return.
and I do it in OnSysKeyDown and everything works. BUT somehow a ‘boing’ sound is getting played.
Like if I pressed some illegal key combo.
How can I Stop it. It gets on my nerves.
(You get the same sound if you stand in IE and press alt+return )
|
|
|
|
|
Hello,
i must read values from an Excel sheet, which becomes updated by another program. So i tried to open the Excel-File with CDaoDatabase and open a CDaoRecordset with the OpenType "dbOpenDynaset".
I can reed the values from the sheet, but the recordset wasn´t updated, if the values from the sheet have changed. I must open and close the recordset again.
Another thing is, that i get the message, that the Excel-File is blocked by another user", when i try to open the Excel-File.
But the attribut bExclusive from the CDaoDatabase::Open is set to FALSE.
Thanks
Andy
|
|
|
|
|
Hi Andy!
Thought I should take a short look for the news...
Andy@ wrote:
Another thing is, that i get the message, that the Excel-File is blocked by another user", when i try to open the Excel-File.
I think you should open it as a snapshot, but then you don't have an actual update...
Did you check that xt54 stuff??
There was a good class for that...
Hope it helps a little...
Greetings from a strange world!
Olli!
Olli
"Ooooooh, they have the internet on computers now!"
Homer Simpson
![Beer | [beer]](https://www.codeproject.com/script/Forums/Images/beer.gif) + ![Java | [Coffee]](https://www.codeproject.com/script/Forums/Images/coffee.gif) = NULL :=> 
|
|
|
|
|
Hi Olli!
Nice to hear about you.
I use the xt54 stuff, it´s good to create a snapshot.
So i can get a actual update when i open and close the recordset cyclically. But this only works when i first open the file with excel and then change the values.
But when i create a test app which use a dynaset recordset for writing data and another dynaset recordset for reading data, i get the actual update.
So i must find out, how exactly the datas become changed in the excel sheet.
Greetings
Andy
|
|
|
|
|
I want to execute several external programs in a que. I have to execute one program and wait for it to finish and excute another. Is there a way to detect if a external running program has finished?
Thanks
|
|
|
|
|
Now this might sound way off because I don't know what you're trying to do, but you could write a batch file "somefile.bat" and there you can put the names of your programs. I don't know if you're familiar with batch files so for example to execute notepad, paint, and minesweeper one after the other you could just write
c:\windows\notepad
c:\windows\paint
c:\windows\winmine
paint won't start until notepad closes and so on. So you can just try to execute this batch file from your program and you won't have to worry about the checking them (unless you want the opposite).
// Afterall, I realized that even my comment lines have bugs
When one cannot invent, one must at least improve (in bed).-My latest fortune cookie
|
|
|
|
|
Use CreateProcess instead of ShellExecute, and use WaitForSingleObject like this :
STARTUPINFO lpsi;
lpsi.cb=sizeof(STARTUPINFO);
lpsi.cbReserved2=0;
lpsi.lpReserved2=0;
lpsi.lpReserved=0;
lpsi.lpDesktop=NULL;
lpsi.lpTitle="Doing something ...";
lpsi.dwFlags=STARTF_USESHOWWINDOW;
lpsi.wShowWindow=SW_SHOWMAXIMIZED;
PROCESS_INFORMATION lppi;
if (CreateProcess(NULL,(LPTSTR)path.operator LPCTSTR), NULL, NULL, FALSE, NORMAL_PRIORITY_CLASS, NULL, m_TotalCompPath.operator LPCTSTR(),&lpsi,&lppi)==0)
else
{
WaitForSingleObject(lppi.hProcess,INFINITE);
}
~RaGE();
|
|
|
|
|
WaitForSingleObject() will allow you to wait on a process handle.
It uses the handle from CreateProcess() or OpenProcess().
The handle is signaled when the process terminates and is non-signaled while running.
...cmk
|
|
|
|
|
I know how to make a checksum and the other day I was wondering if it is possible to have an exe perform a checksum on itself. I know that it is possible but, there is a catch to it. I realize that you could use a dll function to find the checksum of the exe, or you can put it in the registry, or who knows what other methods you could use. My question is the following:
Let's say that you have a single executable file. Is it possible to have this file perform a checksum on itself but without geting the checksum number from external sources (i.e. files, registry, dlls, etc.)? I was thinking that you cannot hardcode it in the source code because you don't know what the checksum would be until you compile the code, but then again, after you compile it, you can't change the exe because the checksum would change as well. It seems impossible to me to perform a checksum check without any help from external resources. As I came up with this problem in my head a couple of days ago I realized that I should stop thinking (and hopefully reach nirvana) because this problem is driving me crazy.
// Afterall, I realized that even my comment lines have bugs
When one cannot invent, one must at least improve (in bed).-My latest fortune cookie
|
|
|
|
|
A common method is to store the checksum in an unused field in the EXE header. To calculate the checksum, you either ignore the EXE header entirely, or start calculating it at the byte following that field.
I can't remember where the field is off the top of my head, but it shouldn't be too hard to find with Google
--Mike--
"So where does that leave us? Well, it leaves us right back where we started, only more confused than before." -- Matt Gullett
Ericahist | Homepage | RightClick-Encrypt | 1ClickPicGrabber
|
|
|
|
|
So simple and so amazing. Thank you very much for your reply. I never thought about the fact that I can start reading the exe at any location.
// Afterall, I realized that even my comment lines have bugs
When one cannot invent, one must at least improve (in bed).-My latest fortune cookie
|
|
|
|
|
The "normal" way to do it is this:
1.
Write your program, which includes your checksum algorithm.
2.
Put in a constant string of a known length. This string must have an unique identifier (which can later be found, browsing through the exe file).
I.e. "____xyz____zyx____AAAA".
(This string is 22 bytes long + the null, making it 23.)
The "AAAA"-part is later gonna be replaced with the real checksum code (assuming that the checksum will be 4 bytes long).
3.
Write the check code (still in your program), working like this:
Open the exe file, read through it and calculate the checksum, but DON'T count the constant string! Instead, when the string is found, read the "AAAA"-part and interpret it as an integer (likely an unsigned int, depending on the checksum algorithm). Close the exe-file.
4.
Compare the calculated checksum with the checksum from the "AAAA"-part. If a match, the it is OK.
5.
Write another program, a;) checksum generator (re-use the code in step 3), but this time, when the ID is found, save the file offset to the "AAAA"-part. (Remember, don't count the ID-string!)
When the checksum is calculated, seek to the saved offset to the "AAAA"-part, convert the checksum to a string, and write it to the exe-file.
Of course, you must recalculate the checksum every time you compile your program.
Good luck.
kakan
|
|
|
|
|
Wow! That is a brilliant idea. Now, why couldn't I think of that? Thank you very much for your reply.
// Afterall, I realized that even my comment lines have bugs
When one cannot invent, one must at least improve (in bed).-My latest fortune cookie
|
|
|
|
|
Your'e welcome. One advantage with this approach is that it works in any operating system, environment, and for all types of progs.
Good luck. Kakan.
|
|
|
|
|
The doc's for AcceptEx() state that :
On _WindowsXP_ or later, once the AcceptEx function completes and the SO_UPDATE_ACCEPT_CONTEXT option is set on the accepted socket, the local address associated with the accepted socket can also be retrieved using the getsockname function. Likewise, the remote address associated with the accepted socket can be retrieved using the getpeername function.
Great, but what do i do on Win2K ?
After setting SO_UPDATE_ACCEPT_CONTEXT getsockname() works but getpeername() doesn't - in fact it doesn't even give an error, just acts as a no-op.
I don't want to save the remote address from GetAcceptExSockaddrs() as state if i can get/set it in the socket.
I would like to be able to do one of the following :
1. Be able to set the peer address in the accepted socket to the remote address obtained from GetAcceptExSockaddrs() - is there a low-level way to do this ?
2. Use a function(s) other than getpeername() that will also give me the peer address.
3. Give up programming and find a remote tropical island where the most advanced piece of technology i have to deal with is the ice-cooler that's keeping my beer cold.
Any suggestions ?
...cmk
|
|
|
|
|
cmk wrote:
3. Give up programming and find a remote tropical island where the most advanced piece of technology i have to deal with is the ice-cooler that's keeping my beer cold.
That sounds like the best one 
Seriously, getpeername() should work, unless there's some obscure reason why it doesn't. Does it work if you don't set SO_UPDATE_ACCEPT_CONTEXT? It only mentions this flag for WinXP, so perhaps it's not necessary for pre-WinXP machines. Certainly, I've used getpeername() successfully on pre-WinXP machines, although I've generally used accept(), not AcceptEx()
Ryan
Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"
|
|
|
|
|
>>Does it work if you don't set SO_UPDATE_ACCEPT_CONTEXT?
No, if i don't set SO_UPDATE_ACCEPT_CONTEXT then even getsockname() won't work.
I think they mention XP because they finally got around to fixing it there. 
The problem is only with AcceptEx(), not accept() or WSAAccept().
Part of the problem is that accept() and WSAAccept() are sync calls that block until a connection is available and then they create the socket and establish the connection in one shot.
AcceptEx() is async and requires the socket to be created, then an AcceptEx() request posted. When a connection is available the winsock lib (?) attaches the connection to the pre-created socket but does not set any other state information. Setting SO_UPDATE_ACCEPT_CONTEXT copies the state info from the listening socket to the accepted socket (or is supposed to anyways).
It looks like it doesn't do a complete job in Win2K, so i was hoping to find a low-level way of setting it myself, or find another way of obtaining the peer address from the handle (there has to be a way as netstat shows both sides of the connection).
...cmk
|
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
