Implementation Guide › Case Study Examples › Writing Effective Business Logic Examples › Case Study 17: Built-in Functionality

Case Study 17: Built-in Functionality

ACE has built-in functionality and tools for various purposes. Using this built-in functionality is preferable to writing it in VBS. Since VBS is an interpreted language, reproducing it in VBS damages performance.

Here is a list of the built-in functions and the appropriate way to use them:

IsWithinTimeslot

This is the simplest of the built-in functions. Its purpose is to enable the business logic to tell whether the system is currently within a timeslot or not. This removes the need to manage a variable in the timeslot enter and timeslot exit functions in order to do the same thing. For example, instead of running the following code:

Dim amIWithinATimeslot
Sub OnTimeslotEnter(time)
     amIWithinATimeslot = 1
End sub
Sub OnTimeslotExit(time)
     amIWithinATimeslot = 0
End sub
Sub OnEvent(eventDetails)
     If amIWithinATimeslot = 1 Then
           count = count + 1
     End if
End sub

You can run this much simpler code, instead:

Sub OnEvent(eventDetails)
     If context.IsWithinTimeslot Then
          count = count + 1
     End if
End sub

If you want to use or keep information about the timestamp of the timeslot enter and exit, this functionality would not cover your needs. But normally this is not needed, and this code is sufficient.

TimeOfLastEvent

This function gives you the timestamp of the last raw data or intermediate data event that was handled. This means you do not need to save this information in the event handler, as it is directly available through this function. For example:

Function result
     Dim LastEventTimestamp
     LastEventTimestamp = Context.TimeOfLastEvent
End function

TimeOfLastEventHandler

This function returns the timestamp of the last event handler called by ace. This includes not only raw and intermediate data event handlers, but also any system events that were called as well. This is especially useful in event handlers that do not receive the time to e.g. the result function. For example:

Function result
     Dim LastEventHandlerTimestamp
     LastEventHandlerTimestamp= Context.TimeOfLastEventHandler
End function

NetTime

This function allows you to specify two timestamps and to receive the net time (in seconds) that the system was within timeslot for the current rule, between those two timestamps. This especially is a cumbersome functionality and should not be implemented in VBS. Implementing this in VBS would entail keeping a list of all the timeslot enters and exits or calculating the difference between each time of entering timeslot exit directly, in order to figure out the time span between them. Under extreme conditions, this might happen a large number of times and this would not be good for calculation performance. The internal function does the same after significant optimization, and so does it much efficiently. For example:

Function result
     Dim MyNetTime
     MyNetTime = Tools.NetTime(MyBeginTimestamp, MyEndTimestamp)
End function

The context object

The context object has a variety of parameters that supply information about:

• The current metric.
• The contract it's in.
• The current calculation state.
• Service domain, Domain category and their related values (e.g. threshold).
• Clustering information – The cluster in general and the specific cluster item being handled.
• Functions that return lists of resources based on user requirements.
• Functions that allow you to convert resource names to resource IDs and back.

Accessing this information directly from the database using Safe ODBC is extremely inefficient and makes no sense as the information is readily available from the context object. If possible, always use the built in functionality is a way to get information.