Application Does Not Return From Call To System.Windows.Forms.Application.DoEvents?
Aug 2, 2011
I have a windows forms application written in VB.NET which scrapes information from serveral web pages (who doesn't right)? Anyway, I am having problem with one particular site where partway through the page navigation my application hangs. When I press pause (or break) in the debugger, it stops on a call to System.Windows.Forms.Application.DoEvents.
Resuming execution shows that it really is stuck on this line (it does not reach the next line of code). It also hangs about the same point each time I run it (at least its consistent). Since System.Windows.Forms.Application.DoEvents yields to other threads on the same processor and then resumes execution of the current thread, I think the problem is that some other thread is not behaving well (not returning from some event handling code). I thought Windows 7 was pre-emptive, which makes me
doubt that theory but I really don't know.
[Code]...
The program scrapes somewhere between 12 and 14 pages before it gets stuck on the call to DoEvents. Does anyone have a clue why this would happen? Why would any call to DoEvents hang?
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Mar 15, 2009
We just spent 300 man-hours fixing a buggy application in the field. It all came down to calling Application.DoEvents (re-entrancy problem).This was not caught in design reviews, code reviews.The code was inserted two years ago with the first version; the application was always "flaky" but recent changes exposed the re-entrancy problems to a greater degree. This incident is the second time in our organization that Application.DoEvents caused failures and multi-man hours of debugging.It was discovered in this case by simply noticing the call,buried way down in a complex event handler for an asynchronous task.What do you suggest to prevent this issue from happening again:
Add checkin gates to source control?
Developer training?
Code Analysis rules (why is this not already a built-in rule?)
How to I enforce a coding practice?
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Jul 18, 2011
i made an application for serial communication. for this application i need to set delay time. during this delay time i m doing some other task. So for those task i need to take back control from delay function, for this purpose i am unsing Doevents() function.Its work fine On other OS (XP, Windows7 32/64-bit). But Application.DoEvents() function halt and crash in windows vista.
Private Sub TimeDelay(ByVal DT As Integer)
Dim StartTick As Integer
StartTick = Environment.TickCount()
[Code].....
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Dec 22, 2010
I am re-posing this question because the prior post has gotten really full of side issues so I fear the main problems has been lost.I have a windows forms application written in VB.NET which scrapes information from serveral web pages? I am having problem with one particular site where partway through the page navigation my application hangs. When I press pause (or break) in the debugger, it stops on a call to System.Windows.Forms.Application.DoEvents.
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Jan 31, 2012
Can I connect phone landline to my computer and when someone call me his information appears by his phone number this information already exist in database.. I want to know is it a service from communication company or can i do it by code just plug the cable into my computer ?
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Mar 4, 2010
I'm running in to a problem that I was able to fix with Application.DoEvents, but don't want to leave that in because it might introduce all sorts of nasty problems. Background: Our app is primarily a desktop app that makes many calls to a web service. We control everything but changes to the overall system design are not going to be seriously considered. One of those calls, Calculate, is used very often, and occasionally can take a few minutes to process all the data to return valid results.
[Code]...
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Jun 3, 2011
I'm trying to use the Shell to have my application call an external application but its not working...I don't understand why. I get the following error: 'System.windows.shell' is a namespace and cannot be used as an expression!
Heres my code....any ideas what I'm doing wrong. Its got to be a simple...stupid error.
Private Sub mnuUpgrade_Click(ByVal Ctrl As Microsoft.Expression.Web.Interop.Legacy.CommandBarButton, ByRef CancelDefault As Boolean) Handles mnuUpgrade.Click
[CODE].....................
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Oct 23, 2010
I am a novice in programming and wrote several simple Windows Forms applications. I need to play mp3 file in Windows 7 x64 application.
Could you, please, explain in simple words, how to call MediaElement.Play() method from Windows Forms?
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May 18, 2010
i Have a programa that has starts in a main sub, it executes some code and after that code it opens a form using
System.Windows.Forms.Application.Run(General)
General is a form but also a class, so I wonder what it the pros or cons of using :
System.Windows.Forms.Application.Run(General)
vs
Dim gen as general
System.Windows.Forms.Application.Run(gen)
In the first I am opening a form using the name of the class, and I read that it is best to declare the instance as an object variable.
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Jun 12, 2011
i have one window application developed in VS 2005 which is running successfully on client side,My question is that now i want to convert this window application in WPF browser based application, so what should i keep in mind to convert this application to wpf applicaton, One more thing that in Window Application i have used one mdb file which contain database login detail, so on application startup this file is accessed using System.Windows.Forms.Application.StartupPath+@"/filename.mdb", now im just want to test only whether can i login to my application using WPF or not this time it give me this error "Request for the permission of type 'System.Security. Permissions. RegistryPermission, mscorlib, Version=2.0.0.0, Culture=neutral".
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Sep 28, 2010
I grabbed an example program to modify for my needs to grab data from a Word doc and transform to XML. Right off the bat I get multiple errors. [Code] I am getting Error Type 'System.Windows.Forms.Application' has no constructors.
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Aug 23, 2010
I am adapting this code from excel vba to a Visual Studio program I am writing that will list files that are relevant to given information. I keep getting an error about filesearch not being a memeber of 'system.windows.forms.application' on line fs = Application.FileSearch, I have read and saw that I should be using the DIR function...
Sub SearchForForms()
Dim fs As FileSearch ', ws As Worksheet, i As Long
Dim SearchFileName As String
fs = Application.FileSearch <~~~ ERROR[code]....
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Aug 17, 2011
I Have one Windows Application in which i have one MDI Form (Say App1). And I too have another Windows Application in which I have a Child Form (Say App2). So now i want to Call App2 from App1 .. And want to Display App2 form As MDIChild in App1 MDI Form . I am Able to open the Form of App2 , But how to set It As App1' Child .
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Mar 25, 2012
I am trying to return two menu tabs using System.Windows.Forms. I have tried using an array and tried using control.add but I cant seem to get this working. What am I doing wrong?
Public Function MonitorsInit() As System.Windows.Forms.TabPage Implements LabTech.Interfaces.ITabs.MonitorsInit
Dim TP As New Windows.Forms.TabPage("Ticket")
Dim TP1 As New Windows.Forms.TabPage("Ticket1")
TP.Controls.Add(TP1)
Return TP
End Function
[Code]...
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Sep 14, 2010
I am trying to use the System.Diagnostics.Process class.I have the following Windows Forms application. It consists of 1 Button and 1 TextBox. The only code is for the button click event as follows.
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim myProcess As New Process()
[code]....
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Feb 7, 2010
I have a fully functional multi-threaded VB2008 console application that I need to convert to a windows forms application. I am doing this to add additional functionality at a later time. How would I go about doing this?
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Jun 23, 2010
My boss gave me an MS Access application that was developed by our former colleague. He wants me to convert that application to VB.Net Windows form application. I went through the MS Access Application. It contains tables, queries, forms, reports and macros. I could not find the programming (Where is the code written in MS Access?). My boss wants the windows application to be same as the MS Access Application (both in design and logic). I don't how will i develop the windows form. How can I achieve this?
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Jun 23, 2010
My boss gave me an MS Access application that was developed by our former colleague. He wants me to convert that application to VB.Net Windows form application. I went through the MS Access Application. It contains tables, queries, forms, reports and macros. I could not find the programming (Where is the code written in MS Access?). My boss wants the windows application to be same as the MS Access Application (both in design and logic). I don't how will i develop the windows form.
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Dec 28, 2010
Imagine that I have a System.Windows.Forms.Timer with 1000 ms interval. If I call Timer.Start() method and after 500 ms I call again Timer.Start() what happens? The second Start call will reset the interval or not? Are there any side effects?
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Nov 25, 2009
I have an application in VB.NET. I want to call that application from a remote system by using Java servlets. Can anybody tell me the methods for that?
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Jun 6, 2011
Any good alternative to using DoEvents in VB.NET
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Apr 18, 2006
Can somebody tell me the steps to follow so that i can call my windows application (.exe) file from my windows service in C# (.Net 2003
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Mar 26, 2009
I have a simple program made in VB .NET 2003 with a few functions. I want to call these function from another application with automation.How can i do this?
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Dec 15, 2009
how to exit out of the Application.Do() as i am hanging in that .Here is a sample of my code.
Imports PDFCreator
Imports System.Windows.Forms
Public Class Form1
[Code]....
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Jul 25, 2009
I am not very familiar with VB.NET so I don't know if this is possible.Some code I am working on is setting the properties of a very large class. In the setter of each property an event is raised to indicate that the class data has changed. An event handler then serializes the instance of the class to a database.Obviously I do not want this to happen after each property is set, so I need to either have a delay before saving, or something else.I am keeping a large list of instances in a cache implementation already, so one option would be to only process the cache every now and then and save all unsaved instances in cache to the database.So I tried to see if I could derive a class from Application (and override DoEvents), but it is NotInheritable, so no luck there.
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Mar 8, 2009
My mdi VB.Net application performs a long operation on some data. Ideally I should use a separate thread to prevent the dreaded "Not Responding" message.My problem is if I use a separate thread users then have the ability to click on other controls in the application which can directly affect the operation my background thread is working on, creating an error.
Is there any way to prevent all the mdi windows, toolbars and other controls from receiving mouse clicks and keyboard input during my background thread's operation?
Or is there a way to clear the message que before performing a Application.DoEvents?
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Dec 11, 2009
I have a unique situation in that I've developed a VB.NET application for AutoCAD. The way this works, you build your project into a dll and utilize AutoCAD API references when designing the project. From AutoCAD, a "Netload" command will load your dll into it's namespace to run. AutoCAD then essentially takes ownership of your application from here on out. The application is ran using a command defined in a method's attribute:
<CommandMethod("CommandNameForApp")>Public Sub MyCommand()
'Code Here
End Sub
Due to the heavy load of processing loops as it evaluates AutoCAD drawing data, processes this data, and generates many, many Excel reports, I've added a boolean property called Cancelled to my Progress class. When the user cancel's the process, this is seen by the process and further evaluation is ended and everything is cleaned up nicely. In order for this to work though, I have to implement Application.DoEvents. Without it, the Cancel feature will not work at all. With it, now instead of allowing the application to stay loaded, the Command method is fully closed.I have added a go-to point and simply verify that the application isn't closing because of a user-cancellation event. Here's what it looks like now:
<CommandMethod("WireShop")> Public Sub WireShopApplication()
'Initialize Configuration File Data
'Initializes ValidBlocks, MarginDistance, WindowDistance, and HelpFileName Properties
If ConfigurationFileInitialization() = False Then Exit Sub
[code].....
In my opinion, this seems a little hokey. However, I'm not that familiar with exactly what Application.DoEvents is doing in the background to understand how to "head it off at the pass".
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Sep 8, 2006
I have written a windows service to do some operation (in .net), im calling the same in .net it works quite fine without any issues. Now my problem is i need to call the same service which is written in .net from an VB application.
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Nov 9, 2009
I'm trying to automate the process of logging into twitterfeed.com, and filling in the information (the feed url and twitter username are pulled from textboxes). I had it mostly working the other day, even if it is a bit sloppy (the only way I could get one button to click is to send 50-some tabs). However, lately it seems to enter in a sort of loop. When I pause the program, Visual Studio indicates that it is the Application.DoEvents in the Private Sub "wait" that is still running even after it should be.
Public Class Form1
Private feed, username, temp As String
' Code stolen off of a website as an alternative to sleeping, or trying to do a timer + while combo like I had been doing
[Code].....
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Jul 9, 2010
I have a basic three form application. It doesn't seem to close after navigating through forms. If I were to open the application, and the main form is displayed. If I press the X button, the application closes fine(Goes from processes) If I were to open the application, and then navigate from the main form to another form using me.hide & form1.show, and press the red X on Form1, the application again, closes fine.
[Code]...
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