I had thought of something just like this, having something in the data being
what B looks for and acts on, otherwise sleeps. However this makes it disk
based, and B has to poll. I was hoping something simple in memory could wake
up B rather than referring to the filesystem.
The main disadvantage of using one of the approaches mentioned is that there is
two things that have to work right for the communication, two things could
break.
Slight aside:
You know there is one really cunning way to get A to signal to B that I have
used in the past that involves sending nothing at all:
B in a timer monitors the foreground window title bar of A
P:array[0..256] of Char;
GetWindowText(GetForeGroundWindow,p,256);
ATNowNewTitle := p;
then searches for certain text in it, if its there its a signal to do
something. This assumes A has focus which worked fine in my case. I used
it to automatically suspend an automated time logging whenever the reporting
program for said logging was in focus, as it was likely to be searching the
same data file. It was spooky how well that worked! (Every time the report
program lost focus or closed the time logging resumed.)
John
From: Graham Marsden
Sent: Wednesday, August 18, 2010 7:54 PM
To: delphi@delphi.org.nz
Subject: [DUG] Sending notification between programs
Keep it simple .....
...... 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.
Why not use the exis the very existance of the data transfer file as the
trigger.
Program A creates the file(s) with the data and then goes on with whatever else
it needs to do. Perhaps even creating another data file or appending to an
existing one.
Program B sleeps on a timer, wakes up, checks for the existance of a/the data
file(s). If one/some exist then process, if not then sleep another cycle.
I have use this method to pass both fax and email files and other messages to a
"server". Naming conventions, folder locations etc can all be used to do any
segregation of users/purposes as required.
Using this method A and B don't even have to be on the same machine.
Hope this helps.
Graham Marsden
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