Time slots

As requests are processed from the access log, they are placed into time-slots based upon the reported time of the request. The number of time-slots maintained by alscan varies with the reporting requirements for a specific scan. Each time-slot has four-times associated with it. There are the hard-limits: the start and stop time of the time-slot. There are also two soft-limits: the first and last times. The start time is the earliest time when a request can be included in a particular time-slot. The stop time is the latest time when a request can be included. The first time is the time of the actual first request inside the time-slot. The last time is the latest actual request time in the time-slot.

The duration of the time-slot is defined by a command-line option. There are also two special time-slots. These are used to capture all requests which fall outside of any detailed reporting period. There is a before time-slot which occurs prior to the detailed reporting period, and an after time-slot which follows the detailed reporting period. Depending upon the scan options, these two special time-slots may be empty. The reporting of these time-slots is also optional.

The temporal “width” of the time-slot can be:

• one minute (default for downtime report.)
• one hour (the default for other reports.)
• one day.
• arbitrary number of seconds.
• infinite (only one time-slot).