Method: SetArgument for LocalWorker

Method: SetArgument for LocalWorker

Sets the transfer parameter of the LocalWorker object which you can read in the master with GetArgument for Worker. Exchange data as an Array between master and worker. Use the commands ChannelsToArray and ArrayToChannels to exchange channel data. If you want to exchange large amounts of data, you can save them in a file. Do not use class or object references because in that case the associated code is executed in the master.

Object.SetArgument(Value)

The following example starts five Worker objects. The Worker objects execute the WorkerScript.vbs on the current path. After a Worker object has executed the script, it executes the CallbackFct user command in the master.

The Worker objects receive an array as transfer parameter. The content of the first array element is an array, which contains the values of a channel. The second array element contains the ID of the Worker object and the third array element contains the interval width for an RMS calculation.

As soon as a Worker object changes its status, DIAdem executes the CheckState user command. In this user command, you can check, for example, whether an error has occurred. The user commands are defined in the registered Callback.vbs file.

If none of the Workers are executing a script, DIAdem deletes all Worker objects. As soon as a worker has completed the WorkerScript.vbs script, DIAdem executes the user command CallbackFct in the master.

Dim i, oMyWorker, MyArgArray(2)
Call Data.Root.Clear()
Call DataFileLoad("Example.tdm","TDM","")
Call ScriptCmdAdd(CurrentScriptPath & "Callback.vbs")
ParallelProcessControl.OnWorkerStateChange = "CheckState"
For i= 1 to Data.Root.ChannelGroups(2).Channels.Count
  Set oMyWorker = ParallelProcessControl.Workers.Add(i,true,"")
  MyArgArray(0) = ChannelsToArray("[2]/[" & i & "]")
  MyArgArray(1) = i
  MyArgArray(2) = 50
  oMyWorker.SetArgument(MyArgArray)
  Call oMyWorker.Run(CurrentScriptPath & "WorkerScript.vbs","CallbackFct")
Next
Do
  Call Pause(0.1)
Loop Until ParallelProcessControl.Workers.RunningWorkersCount < 1
Call ParallelProcessControl.Workers.RemoveAll()

The following script displays the WorkerScript.vbs script mentioned above. The LocalWorker object converts the contents of the first array element back into a channel. The script uses the third argument as the parameter for an RMS calculation. The LocalWorker object transfers the calculation result through the SetArgument for LocalWorker method to the master and the CallbackFct user command evaluates the result. The algorithm is not optimized but is only used as an example for the calculation.

Dim oTempChannel, i, aInputArg, aResults(1)
Call DBM ("Worker " & LocalWorker.ID)
Call Data.Root.Clear()
aInputArg = LocalWorker.GetArgument

Call ArrayToChannels(aInputArg(0), Array("tempChannel"))
set oTempChannel = Data.GetChannel("/tempChannel")

Call RMS(oTempChannel,aInputArg(2))  ' Do some analysis

aResults(0) = ChannelsToArray("/tempChannel")
aResults(1) = aInputArg(1)
Call LocalWorker.SetArgument(aResults)

Sub RMS(Channel, Width)
Dim i, Sum, j
  For i = 1 + Width to Channel.Size - Width
    Sum = 0
    For j = i - Width to i
      Sum = Sum + Channel(j) * Channel(j)
    Next
    Channel(i-Width) = Sqr(Sum/Width)
  Next
End Sub

The following script displays the Callback.vbs script mentioned above. The user command CallbackFct displays the ID of the requesting Worker object and evaluates the transfer parameter. In this example the user command replaces the input channels with the calculation results. If the master executes user command instructions, you must ensure that the DIAdem environment matches because, for example, data might have been deleted, layouts changed, or a different panel used after you called the Worker object.

The CheckState user command checks whether an error occurs in the Worker object. If an error occurs, the user command instruction DBM outputs the error description as a debug message and resets the error status.

Sub CallbackFct(oWorker)
Dim aResults
  aResults = oWorker.GetArgument
  Call DBM("Worker ID: " & oWorker.ID & " Result#: " & aResults(1))
  Call ArrayToChannels(aResults(0),array("[2]/[" & aResults(1) & "]"),true)
End Sub
 
Sub CheckState(oWorker,iState)
  ' The following statement is not executed. It is only used for autocompletion.
  If False Then Set oWorker = ParallelProcessControl.Workers.Add(i,true,"")

  If oWorker.GetErrorFlag Then
    Call DBM ("Error: " & oWorker.GetErrorText)
    oWorker.ResetError
  End If  
  Select Case iState 
  Case eWorkerCreated
    Call DBM ("Status "& oWorker.ID & " Created")
  Case eWorkerScriptStarting
    Call DBM ("Status "& oWorker.ID & " Starting")
  Case eWorkerScriptFinished
    Call DBM ("Status "& oWorker.ID & " Finished")
  Case eWorkerRemoving
    Call DBM ("Status "& oWorker.ID & " Removing")
  End Select
End Sub