How does Schedule (Publish/Unpublish) work in the back-end?

I’m sure this has been covered somewhere else in the forum, but I had no success searching.

We have a client’s site with scheduled publish/unpublish issues - previously has been working for a long time, unreliable webhost has changed something(s) and now scheduled events aren’t processed.

My question is how are these schedule events processed by MODx?
Is Cron or some other system-level executable involved?
Or a sneaky PHP library/wrapper? (I have little experience with PHP).
Or are scheduled events simply processed in a queue during hits to the webserver?

It seems like due to the hosts changes, the PHP process now runs as a different user (we’ve had other issues related to filesystem permissions) - Which is why I suspect an issue accessing something like Cron, ie unable to write to a queue file for an external process to read.

EDIT: I don’t imagine there’s significant differences; but the site is running MODx 0.9.6.2 on Apache2, PHP 5.2 & MySQL 4.

Cheers
James

There is a file in the assets/cache folder, sitePublishing.idx.php. The parser check this file on every page request. Based on what it finds in this file, the parser will update the published status and publishedon date of all resources whose pub_date is less than the current date/time (and are unpublished); likewise it will unpublish any documents whose unpub_date is less than the current date/time (and are published).

Does the Reports -> Schedule show the publishing/unpublishing schedule? Is the sitePublishing cache file being written to as documents are saved/edited? Do your error logs or the Reports -> System Events log show anything relevant?

Quote from: sottwell at Jul 26, 2010, 11:31 PM

There is a file in the assets/cache folder, sitePublishing.idx.php. The parser check this file on every page request.

Thanks a lot!
Problem solved.

sitePublishing.idx.php was not writable (0775 to the previous Unix user).
No relevant errors were written to the event log.

I’ll post in ’hosting experience’ regarding the hosting provider.

Thanks again
James

Your site’s PHP error logs should have shown a "permission denied" error.

Quote from: sottwell at Jul 27, 2010, 12:10 AM

Your site’s PHP error logs should have shown a "permission denied" error.

Ooh yes good point thanks.
We don’t have ’easy’ access to log files with this host.
But if we have further problems I’ll try using .htaccess to set the error_log path, to something we can access.

Cheers