DevTrain Forum - specific problem: monitoring processes

Forum: VB.NET | Thema: specific problem: monitoring processes | Von: Markus Pöhler ( 03.12.2004 16:24)

		Hi out there,
my specific job is to realize some printing from my Application. It will run on terminal 

servers, so I am sure about the installed local software there. (Acrobat, Office) 
It must do the following:

- allow user to select from pool of documents liested (almost PDF & Excel)
- when pressing print button print all these documents on default printer or (if user selects on 

different one)
- allow the user to continue working with the application while printer is still printing the 

docs

My solution so far:
When firing print button I change the default printer of the user if he selected another 

printer. (this works perfect)
Then I start new processes with "print" verb for every document and load them into the 

associated executable programm (e.g. Acrobat). So the docs should be printed to default printer. 

This also works so far.

BUT: After testing a while I foud some timing problems. If I fire about 7 PDF documents to load, 

print and close again, the number of really sent docs to printer is random. Somtimes 7 are 

printed, somtimes just one, somtimes three...I can watch the opened Acrobat Reader opening not 

all of the documents instances it should do.

Every started process gets a Handler listening for Exited event. So I can make output and see 

when a document is exited. Although the message of exit comes up, the docs are not in printer 

queue. It seems the loading and closing is too fast. Sometimes I get messages about opening a 

document, but the event handler never comes up to close this doc again. 

I defined just one doc to be opened on button press ==> If I pause before repressing the button, 

the doc is always printed. But If I do not pause, there is a delta of #pressed and #printed. It 

chokes on sth.!

Is there a problem with the Eventhandler EXITED?? 
Should I use something else??

Here my code parts:

Dim istarted, iclosed as integer

 Sub startfile(ByVal ffile As String)
        Dim pr As Process = New Process
        istarted += 1
        pr.EnableRaisingEvents = True
        pr.StartInfo.FileName = ffile
        pr.StartInfo.UseShellExecute = True
        pr.StartInfo.Verb = "Print"
        AddHandler pr.Exited, AddressOf ProcessExited
        pr.Start()
        debug("File: " & ffile & " ID: " & pr.Id.ToString & " (" & pr.StartTime.ToString & ") 

startet. No." & iStarted)
    End Sub


 Friend Sub ProcessExited(ByVal sender As Object, ByVal e As System.EventArgs)
       Dim myProcess As Process = DirectCast(sender, Process)
        iClosed += 1    
        debug("The process " & myProcess.StartInfo.FileName & " exited : " & myProcess.ExitTime 

& ". Exit Code: " & myProcess.ExitCode & " ID:" & myProcess.Id.ToString & "(No." & iClosed & 

")")
        myProcess.Close()

        If iStarted = iClosed Then
                debug("all Files printed: " & iClosed & "/" & iStarted)
       End If
    End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles 

Button2.Click
        iStarted = 0
        iClosed = 0
        startfile("C:\1420.html.pdf")
        startfile("C:\1426.html.pdf")
        startfile("C:\1459.html.pdf")
        startfile("C:\1427.html.pdf")
End Sub

Thanks,
MP


	

Betreff Von Datum

Re: specific problem: monitoring processes

Hi Markus, there are two solutions i can offer you: 1. Make your own Threading Model. (not easy) 2. Use MessageQueuing (Its like Bacth Processing) hope that helps Tobi

Tobi Ulm 03.12.2004 17:41

Re: specific problem: monitoring processes

Hi. What I do now is also not easy and it does not work, so I would prefer sth. else not easy and running. How can I build a threading model? I've never heard about that 2nd thing. Could you...

G. Guest 04.12.2004 17:35

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