File System Triggers
A file system trigger enables you to monitor a file or directory for changes such as newly added files or modified files (note that deleted files cannot be monitored). You can configure the polling interval, and you can optionally set the start and expiry date of the trigger. You can also use wildcards to filter specific files of the directory. The screenshot below (with UI opened in Firefox) illustrates how to define the settings of a file system trigger.
The trigger is defined with the help of the following parameters:
•Name: The trigger's name is a string that serves as the trigger's identifier.
•Check Content: Computes and stores a hash code of the specified file or files in the directory. After the polling interval has passed, the hash code is recomputed and compared with the stored value/s. If there is a difference, the trigger fires. (Note that this can place considerable load on the server when a directory is checked.) The trigger also fires if a new file has been added to a directory or if a date has changed.
•Check Modified Date: Checks the last-modified timestamp. If this has changed, then the trigger fires.
•Polling interval: Specifies the frequency, in seconds, with which the file or directory will be polled.
•Wait N seconds to settle: Defines the time in seconds that the server will wait before starting the next service.
•Start, Expires (optional): Defines, respectively, the start and end time of the period within which the service will run.
•Time zone: Specifies the timezone of the values in the Start and Expires fields.
•Enabled: This check box allows you to enable/disable the trigger.