Scheduled tasks upon Joomla systems usually make use of an operating daemon named 'cron'. This is because most are based upon UNIX operating systems, although a number do make use of Windows based operating systems. Since they are so common we have concentrated upon enabling the use of a cron based scheduling ability within the component.
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The Issue Tracker Design Guide contains more information upon the scheduling design and the interested reader is referred to that documents for more information. |
Cron is basically a time-based job scheduler that runs in the background on UNIX systems. Typically a task requiring repetitive actions to be carried out on a regular (pre-determined) basis would be ideal candidates for using cron.
Joomla systems can offer a number of different mechanisms to perform repetitive actions, of which the one to be used is very dependant upon the facilities offered by the hosting supplier.
It is possible to make use of a ‘bespoke’ plugin which can be invoked when someone accesses one or more pages upon a site and performs some predefined tasks. This is really a 'real' cron since there is no real way in which one can guarantee that there would be a site visitor at any predetermine time, and has an unavoidable side effect of slowing the site access for the specific visitor that happen to visit the site at or immediately after the desired time. For this reason we have not implemented such a mechanism, however for some other ‘short’ running tasks it might be suitable, so although not suitable for our implementation can in some circumstances provide a reasonable solution.