Tony Leake wrote:
On Thu, 2005-09-29 at 16:15 +0100, Nuno Pereira wrote:
[EMAIL PROTECTED] wrote:
This one is interesting in terms of concurrency...
Is the app2 the one responsable for setting the flag? I supose that it is.
If that happens it's important that app2 doesn't mess with the flag, i
mean, it may lead to problems if app2 sees that app1 writes the sales
data, app2 sees it, starts reading it, app1 writes more data and app2
sets the flag without seeing that app1 have written more data, and sets
the flag without reading the new one.
Make this work without problems can be tricky, and I don't see a good
solution to this in five minutes. When app2 reads data what app does
with it? How app2 sees what was the last data she read?
--
Nuno Pereira
I don't think there is any concurency problem:
App 2 sets the flag and then polls for it to be unset, it is unset by
app 1 when it has written all of the sales data. meanwhile app 2 is
polling for the flag to be unset again and does nothing until it is, if
app 1 dies before unsetting the flag app then app 2 will sit in a loop
forever.
That isn't true if you are using transactions.
when the flag is unset, app 2 reads it, process it and posts it to a
website via xmlrpc
app 2 site in a shell script while loop: (pseudocide)
while (1){
start app 2
sleep (60)
}
so there can never be more than one instance of app 2 running.
tony
You may be right, but app2 is running while app1 is...
You know better if there are problems...
--
Nuno Pereira
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
