When I want to display message I'm calling Message Display sub program(EXE) from my main Program (calling program). I cannot get called exe dialog result to caller.
Dim psiProcessInfo As New ProcessStartInfo
With psiProcessInfo
.FileName = "DisplayMessage"
.Arguments = ("FormName$C$lblMessageLine01$lblMessageLine02$lblMessageLine03")
End With
Process.Start(psiProcessInfo)
above I display calling section.
Private Sub dlgDisplayMessage_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
' Input Parameter Accepted
strInputMessage = Command()
' Composite Parameter Seperator
Dim strParaSeperator As String = "$"
Dim strCompersitePara As String = Microsoft.VisualBasic.Interaction.Command
' Parameter Split & Assign To Array
Dim arParameter() As String = strCompersitePara.Split(strParaSeperator.ToCharArray)
With pbPictureBox
Select Case lblMessageType.Text
Case Is = "C" ' Critical
.Image = My.Resources.Critical
Case Is = "E" ' Exclamation
.Image = My.Resources.Exclamation
Case Is = "Q" ' Question
.Image = My.Resources.Question
End Select
.Visible = True
End With
With txtMessageBody
.Multiline = True
.Size = New Size(386, 215)
.Location = New Point(24, 53)
.ScrollBars = ScrollBars.Vertical
.TextAlign = HorizontalAlignment.Center
.Text = vbCrLf & _
lblMessageLine01.Text.Trim & _
vbCrLf & vbCrLf & _
lblMessageLine02.Text.Trim & _
vbCrLf & vbCrLf & _
lblMessageLine03.Text.Trim
.Visible = True
End With
With cmdCancel
.Focus()
End With
End Sub
Private Sub cmdYes_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdYes.Click
Me.DialogResult = System.Windows.Forms.DialogResult.Yes
End Sub
Private Sub cmdCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCancel.Click
Try
Me.DialogResult = Windows.Forms.DialogResult.No
End Sub
Display message dialog coding I display above. I want to know how I get DialogResult.OK
or DialogResult.No
to calling exe.
Edited
According to the Jimi I change my caller program code. But still it didnt return any value.
Dim p As New Process()
p.StartInfo.UseShellExecute = False
p.StartInfo.ErrorDialog = True
p.StartInfo.RedirectStandardOutput = True
p.StartInfo.UseShellExecute = False
p.StartInfo.Arguments = ("FormName$C$lblMessageLine01$lblMessageLine02$lblMessageLine03")
p.StartInfo.FileName = "DisplayMessage"
p.Start()
Dim output As String = p.StandardOutput.ReadToEnd()
p.WaitForExit()
MessageBox.Show(output)
A few suggestions about the way the dlgDisplayMessage
Form handles the CommandLine arguments:
You should use Environment.GetCommandLineArgs() to get an array of values passed to the command line. These values are meant to be separated by a space.
The first item always represents the executable path. Recommended, it's a .Net method, much easier to translate to another .Net language.
You could also use My.Application.CommandLineArgs, the difference is that the first item is the first parameter of the command line, not the executable path.
Avoid Interaction.Command()
I think that those lblMessageLine01
etc. parts are actually meant to be the content of some Labels. In this case, you should of course use the lblMessageLine01.Text
property. You can use an interpolated string to add these values to the command line. Since these Labels may contain multiple words separated by a space, you need to enclose these values in double quotes. For example:
Dim commandLine = $"FormName C ""{lblMessageLine01.Text}${lblMessageLine02.Text}"""
To return a value from the Dialog, using the Process class, you have a few options:
Console.WriteLine()
/ Console.Out.WriteLine()
StreamWriter.WriteLine()
Of course you could also use some form of Interprocess Communications, but this a different scenario than what described in the OP.
Imports System.IO
Public Class dlgDisplayMessage
' For testing. Replace the Bitmaps with anything else
Private images As New Dictionary(Of String, Bitmap) From {
{"C", SystemIcons.Warning.ToBitmap()},
{"E", SystemIcons.Exclamation.ToBitmap()},
{"Q", SystemIcons.Question.ToBitmap()}
}
Protected Overrides Sub OnLoad(e As EventArgs)
' The first item is always the executable path
Dim arParameter = Environment.GetCommandLineArgs()
If arParameter.Count > 1 AndAlso images.ContainsKey(arParameter(1)) Then
pbPictureBox.Image = images(arParameter(1))
End If
If arParameter.Count > 2 Then
txtMessageBody.Visible = True
txtMessageBody.AppendText(String.Join(Environment.NewLine, arParameter(3).Split("$"c)))
End If
MyBase.OnLoad(e)
End Sub
Private Sub btnOK_Click(sender As Object, e As EventArgs) Handles btnOK.Click
Console.WriteLine("Some data to return")
Console.Out.WriteLine("More data")
Environment.Exit(DialogResult.OK)
End Sub
Private Sub btnCancel_Click(sender As Object, e As EventArgs) Handles btnCancel.Click
Using sw = New StreamWriter(Console.OpenStandardOutput())
sw.AutoFlush = True
sw.WriteLine("Other data to return")
End Using
Environment.Exit(DialogResult.Cancel)
End Sub
Private Sub btnAbort_Click(sender As Object, e As EventArgs) Handles btnAbort.Click
Console.Error.WriteLine("Some errors to report")
Environment.Exit(DialogResult.Abort)
End Sub
End Class
The application that starts this executable can get the outcome of the Dialog in different ways: reading the StandardOutput, StandardError or ExitCode of the Process it launched. Or all of them, of course.
I assume the application that creates this Dialog is under your control (you made it).
In any case, the Process StartInfo must set RedirectStandardOutput to True
, optionally RedirectStandardError to True
and UseShellExecute to False
(starting with the System Shell doesn't allow redirections here)
You can then:
Start the Process
Read the StandardOutput and StandardError
Wait synchronously for the Process to exit, using Process.WaitForExit()
Read the Process ExitCode
, e.g.:
[Process].Start()
Dim sOut = [Process].StandardOutput.ReadToEnd()
Dim sErr = [Process].StandardError.ReadToEnd()
[Process].WaitForExit()
Dim exitCode = [Process]?.ExitCode
[Process]?.Dispose()
This procedure is synchronous (blocking). There's a good chance you don't want this when the Process is started and its results waited in a GUI, since it will also block the User Interface.
Of course you could run a Task or start a Thread, then marshal back the results to the UI Thread.
You can also use the asynchronous (event-driven) version, subscribing to the OutputDataReceived, ErrorDataReceived and Exited events.
To enable the Exited
event, you need to set Process.EnableRaisingEvents to True
.
Also setting the Process.SynchronizingObject to the instance of a Control class (usually a Form, but any ISynchronizeInvoke
object would do) that will handle the events. This because the Process' events are raised in ThreadPool Threads. Setting a UI element as the SynchronizingObject
, causes the events to raise in the same Thread where object specified was created (the UI Thread, here).
This can be somewhat obnoxious in existing contexts, because you have to add the event handlers to a Form class, remember to remove them, dispose of the Process asynchronously
etc.
So here's a helper class that transforms the event-driven procedure in an awaitable Task that can be executed from any async method. E.g., it can be called from the Click
event handler of a Button, adding the Async
keyword to the method.
It can be modified and used to test different scenarios and methods to start a Process and get its results in a separate environment.
It uses a TaskCompletionSource + Task.WhenAny().
The Exited
event causes the TaskCompletionSource
to set its result.
The helper class returns the contents of the Process' StandardOutput, StandardError and ExitCode value translated to a DialogResult value.
It can set a Timeout, to stop waiting for the Process to return a result, if specified.
Sample calling procedure:
Private Async Sub SomeButton_Click(sender As Object, e As EventArgs) Handles SomeButton.Click
Dim exePath = "[The Executable Path]"
Dim cmdLine = $"FormName C ""{lblMessageLine01.Text}${lblMessageLine02.Text}${lblMessageLine03.Text}"""
Dim dlgResponse = New DialogResponseHelper(exePath, cmdLine)
' This call returns when the Dialog is closed or a Timeout occurs
Dim exitCode = Await dlgResponse.Start()
' Read the StandardOutput results
If dlgResponse.DialogData.Count > 0 Then
For Each dataItem In dlgResponse.DialogData
Console.WriteLine(dataItem)
Next
End If
' See whether errors are signaled
Console.WriteLine(dlgResponse.DialogErrors.Count)
If dlgResponse.ExitCode = DialogResult.OK Then
' Do something
End If
End Sub
If the Interpolated Strings feature is not available, use String.Format()
instead:
Dim dataOut = {lblMessageLine01.Text, lblMessageLine02.Text, lblMessageLine03.Text}
Dim cmdLine = String.Format("FormName C ""{0}${1}${2}""", dataOut)
DialogResponseHelper
class:
Imports System.Collections.Concurrent
Imports System.Collections.Generic
Imports System.Diagnostics
Imports System.IO
Imports System.Linq
Imports System.Threading
Imports System.Threading.Tasks
Imports System.Windows.Forms
Public Class DialogResponseHelper
Private exitedTcs As TaskCompletionSource(Of Integer) = Nothing
Private dlgData As New ConcurrentBag(Of String)()
Private dlgErrors As New ConcurrentBag(Of String)()
Private mExitCode As DialogResult = DialogResult.None
Private proc As Process = Nothing
Public Sub New(exePath As String, cmdLine As String, Optional timeout As Integer = Timeout.Infinite)
ExecutablePath = exePath
CommandLine = cmdLine
WaitTimeout = timeout
End Sub
Public ReadOnly Property ExecutablePath As String
Public ReadOnly Property CommandLine As String
Public ReadOnly Property WaitTimeout As Integer
Public ReadOnly Property ExitCode As DialogResult
Get
Return mExitCode
End Get
End Property
Public ReadOnly Property DialogData As List(Of String)
Get
Return dlgData.ToList()
End Get
End Property
Public ReadOnly Property DialogErrors As List(Of String)
Get
Return dlgErrors.ToList()
End Get
End Property
Public Async Function Start() As Task(Of Integer)
exitedTcs = New TaskCompletionSource(Of Integer)()
proc = New Process()
Dim psi = New ProcessStartInfo(ExecutablePath, CommandLine) With {
.RedirectStandardError = True,
.RedirectStandardOutput = True,
.UseShellExecute = False,
.WorkingDirectory = Path.GetDirectoryName(ExecutablePath)
}
proc.StartInfo = psi
AddHandler proc.OutputDataReceived, AddressOf DataReceived
AddHandler proc.ErrorDataReceived, AddressOf ErrorReceived
AddHandler proc.Exited, AddressOf ProcessExited
proc.EnableRaisingEvents = True
proc.Start()
proc.BeginErrorReadLine()
proc.BeginOutputReadLine()
Await Task.WhenAny(exitedTcs.Task, Task.Delay(WaitTimeout))
If proc IsNot Nothing Then
RemoveHandler proc.Exited, AddressOf ProcessExited
RemoveHandler proc.ErrorDataReceived, AddressOf ErrorReceived
RemoveHandler proc.OutputDataReceived, AddressOf DataReceived
proc.Dispose()
proc = Nothing
End If
Return exitedTcs.Task.Result
End Function
Private Sub DataReceived(sender As Object, e As DataReceivedEventArgs)
If String.IsNullOrEmpty(e.Data) Then Return
dlgData.Add(e.Data)
End Sub
Private Sub ErrorReceived(sender As Object, e As DataReceivedEventArgs)
If String.IsNullOrEmpty(e.Data) Then Return
dlgErrors.Add(e.Data)
End Sub
Private Sub ProcessExited(sender As Object, e As EventArgs)
Dim exitId = (proc?.ExitCode).Value
mExitCode = CType(exitId, DialogResult)
exitedTcs.TrySetResult(exitId)
End Sub
End Class