[DUG] Sending data between process on same computer on windows

[Myles Penlington]

There are limits on the #msgs per thread etc, security issues eg Vista,
System shutdown, system message hooks (which may throw messages away -
and you have no way of knowing if this happens - e.g desktop/video
managers), Journal hooks, Message deadlocks (have to be unlucky to get
these).

 

Mind you some of these only apply to PostMessage.

 

In essence, you do not have full control over SendMessage - lots of
things can get in the way. 

I would always use a system wide Mutex/Semaphore etc in preference and
WaitForMultipleObjectsEx.

 

Myles

 

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz]
On Behalf Of Leigh Wanstead
Sent: Tuesday, 8 May 2007 10:46
To: NZ Borland Developers Group - Delphi List
Subject: RE: [DUG] Sending data between process on same computer on
windows

 

May I ask why sendmessage is not reliable? In what situation will cause
sendmessage fail to break the communication?

 

TIA

 

Leigh

	-----Original Message-----
	From: delphi-bounces at delphi.org.nz
[mailto:delphi-bounces at delphi.org.nz]On Behalf Of Myles Penlington
	Sent: Tuesday, 8 May 2007 10:29 a.m.
	To: NZ Borland Developers Group - Delphi List
	Subject: RE: [DUG] Sending data between process on same computer
on windows

	The devil is in the detail in this kind of stuff, and your
actual implementation can have a great effect.

	As implied, the best method will be to develop 2 or 3 different
methods, test and compare the results.

	 

	Myles.

	 

	 

	From: delphi-bounces at delphi.org.nz
[mailto:delphi-bounces at delphi.org.nz] On Behalf Of Conor Boyd
	Sent: Tuesday, 8 May 2007 10:19
	To: NZ Borland Developers Group - Delphi List
	Subject: RE: [DUG] Sending data between process on same computer
on windows

	 

	Sorry Leigh, I haven't done enough testing with big volume
messages to be able to answer that for you.

	 

	I was more interested in something that worked and was reliable.

	 

	Cheers,

	 

	Conor

	 

	
________________________________


	From: delphi-bounces at delphi.org.nz
[mailto:delphi-bounces at delphi.org.nz] On Behalf Of Leigh Wanstead
	 

	May I ask which is faster, ipc or sendmessage?

		-----Original Message-----
		From: delphi-bounces at delphi.org.nz
[mailto:delphi-bounces at delphi.org.nz]On Behalf Of Conor Boyd
		 

		I found the IPC functionality from madshi.net
(http://help.madshi.net/IPC.htm <http://help.madshi.net/IPC.htm> ) to
work very nicely.

		 

		I needed a way to send messages from a screensaver I was
writing to another process on the same box, and SendMessage didn't seem
to work when a screensaver was active (which I found strange, but
anyway...), and the IPC stuff from madshi works flawlessly.

		 

		
________________________________


		From: delphi-bounces at delphi.org.nz
[mailto:delphi-bounces at delphi.org.nz] On Behalf Of Leigh Wanstead
		 

		May I ask what is the fastest way to send data between
process on same computer on windows? I assume sendmessage api faster
than semaphore waiting, of course faster than TCP/IP which will go
through huge amounts of tcp/ip stack. I just want lowest overhead on per
call. Anyone have any experiences on that?

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