The property FILE_NOTIFY_CHANGE_LAST_WRITE looks like a possibility, as if structured data has just been written to a file this event should be triggered. The only gotcha seems to be that the better the caching is the less likely the event will fire - according to the help. Tricky.
John > > John, > > Hi. What you want to use is WinAPI: FindFirstChangeNotification, > FindNextChangeNotification and FindCloseChangeNotification in program B. > Essentially, A writes to a file, and renames it. This causes the handle > returned by FindFirstChangeNotification to be signaled. You can test for > this using a loop and WaitForSingleObject / WaitForMulitipleObjects. You > can even specify a timeout in the WaitXXX calls so that B wakes > periodically, even if there are nothing signaled. When the WaitXXX > function > returns, you can check for the existence of the file. > > Regards, > Dennis. > > -------------------------------------------------- > From: "John Bird" <johnkb...@paradise.net.nz> > Sent: Wednesday, August 18, 2010 4:43 PM > To: "NZ Borland Developers Group - Delphi List" <delphi@delphi.org.nz> > Subject: [DUG] Sending notification between programs > >> Which way would you favour to do the following ? >> >> I have two Delphi programs (A and B) that I will pass data from A to B - >> I >> will probably use a file to put the data in because its quite >> structured. >> B will sleep on a timer loop until this something is triggered. >> >> What I want to do is send a simple notification from program A to B that >> there is something to do - i.e. trigger an event in B to wake and do >> something to process this. >> >> There are various ways I could communicate this notification >> >> 1 - Has to add minimal overhead of size and processing to programs A and >> B >> 2 - A can tolerate B not responding immediately without freezing but >> preferably will know >> >> The ways I have considered to be candidates are >> >> a - Windows messaging >> b - TCP/IP Indy (which could send the data too. (adds complexity of >> needs to be done in a thread to not affect the main program A) >> c - make program B a DLL >> d - Roll my own - make a timer in B which polls for for some condition >> and >> otherwise continues to sleep >> e - something else. >> >> Kindly share your favoured options how you might do this. >> >> John > > > >> _______________________________________________ >> NZ Borland Developers Group - Delphi mailing list >> Post: delphi@delphi.org.nz >> Admin: http://delphi.org.nz/mailman/listinfo/delphi >> Unsubscribe: send an email to delphi-requ...@delphi.org.nz with Subject: >> unsubscribe > > _______________________________________________ > NZ Borland Developers Group - Delphi mailing list > Post: delphi@delphi.org.nz > Admin: http://delphi.org.nz/mailman/listinfo/delphi > Unsubscribe: send an email to delphi-requ...@delphi.org.nz with Subject: > unsubscribe _______________________________________________ NZ Borland Developers Group - Delphi mailing list Post: delphi@delphi.org.nz Admin: http://delphi.org.nz/mailman/listinfo/delphi Unsubscribe: send an email to delphi-requ...@delphi.org.nz with Subject: unsubscribe
