Multithreading And Asynchronous Event Raising
Jan 17, 2012
I am developing a form application in VB .Net with a main thread and two other threads that reading values from two serial ports, do some work and raising events to return values when each thread ends.The handlers for the events are in my main thread.Is there any possibility the two threads to raise events the same time or some other event (button click event for example) raised the same time with a thread finished event? What happened then? Is there a way to make asynchronous event raising?
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Jul 8, 2010
Im using Vb.net visual studio 2008. i have got a process(system.diagnostics.process) to be run in background and it updates the Ui thread progressbar and a label and i have worked it using backgroundworker.runworkerAsync. Now the problem is i have to work the same process for a number of time with different inputs.
The code block is :
Private Sub fnStartEvent(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.click
Dim inputFolder = Directory.GetFiles(textboxSourceFolder.text)
Dim currentNumberOfFile As Integer=1
[code]....
The problem in here is the fnStartEvent method once gets started, it calls BackgroundWorker1.runWorkerAsync process and that runs in a seperate thread and does not wait for the thread to complete and it moves to the next line of code i.e loops to the next item and it returns to same BackgroundWorker1.runWorkerAsync line and throws exception that it is already running.
Tried
1.
Private Sub fnStartEvent(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.click
Dim inputFolder = Directory.GetFiles(textboxSourceFolder.text)
Dim currentNumberOfFile As Integer=1
[code]....
But this does not updates the Ui thread used to denote progress.
2.Put the whole process inside the DoWork thread and loop for each file in there itself, but that to returns the cross thread error in progress bar updation.what is the standard procedure in executing a loop for the backgroundworker to wait for finishing as well as update the UI without blocking it.
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Nov 25, 2010
I'm trying to use mockling with VB10(VS2010) to improve my unittesting. I have a C# lamda expression example but I don't know how to implement this in a VB lamda expression? v => v.Load += null The full Moq to raise the load event would be view.Raise(v => v.Load += null, EventArgs.Empty) .Net Developer
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Jul 16, 2009
I am using Visual Basic 2005 Express and have 8 PictureBoxes on the Form.. When the user Double-clicks any of the Picture Boxes, the path of the image needs to be passed to a Subroutine..As of now, I have a different event for each of the PictureBoxes.. I was wondering if there is a way such that I can use a common event. i.e. if a user double-clicks on any of the picture boxes, the same event is raised ?
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Dec 8, 2009
I'm writing a custom textblock control thats populate hyperlinks and raises event when clicked to hyperlink.
I wrote this code but I got stucked.
My code is :
Imports System.Text.RegularExpressions
Public Class CustomTextBlock
Inherits TextBlock
[Code]....
This code gives error at RaiseEvent Klik(sender, EventArgs.Empty)
Error is : Cannot refer to an instance member of a class from within a shared method or shared member initializer without an expliticit instance of the class.
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Feb 12, 2010
I am facing issue in following code syntax...
Protected Overridable Sub OnHeaderClicked(ByVal args As ItemSelectedEventArgs)
If ItemSelected IsNot Nothing Then
RaiseEvent ItemSelected(Me, args)
[CODE]...
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Apr 19, 2012
The MyBase.Shown event only gets raised the first time a form gets shown. How do I make something happen every time the form is shown?
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Jan 7, 2009
As it stands, when I click a button to load the data the application lags and looks as though it has locked up although it has not. There are a lot (10,000) of records to load in some cases.
I thought I could just change my status strip text to dispay "Loading database" while it's loading.
So, I raise an event (dbloading) in the "load db" button.click event before calling the procedure to load the data. When that event is raised, I change the status strip text.... but it does not work.
Here's my
Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click
jnATM = Me.atmJobNum
[Code]....
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Jan 31, 2012
A few weeks ago I wrote a wrapper for the ServiceController control to enhance and streamline the base ServiceController. One of the changes I made was to add a monitoring component using the System.Threading.Timer object. On any change of status, an event is raised to the parent class. The actual monitoring works fine, but when the event is handled in the main form, my program abruptly ends - no exceptions, no warning, it just quits. [code]...
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Apr 7, 2010
i'm trying to learn about user controls. I created a user control that has a textbox and a button. What i'd like to be able to do is when i click the button in the user control, populate a label in the aspx page. I understand that i could just have a button on the page that uses some properties on the user control to get that information.. but i'd like to know how to do it with the button the user control.. the reason for this is the button is just an example.. a learning tool. if i can get this working, i'd likely be putting thing in the user control that might require this kind of passing information. Anyway.. i've found some c# examples that i tried to get working as vb.. but once started getting into the delegates and events..
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Dec 5, 2010
i have the following problam: i have a user control which i want to raise an event from to the page that is using that user control (its a button)anyway my problem started when i wanted to put this user control inside a repeater instead of another button (regular asp:button)anyway i needed to support CommandArgument so that page can use the button,so i created a property:
Private m_CommandArgument As Object
Public Property CommandArgument() As Object
Get[code].....
so after i press the button and the postback happen my raised event dosnt have a value..where should this property be saved in order for it to have a value after postback? view state? how do i add to the the viewstate automaticly?
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Apr 27, 2011
I am attempting to test that the event handlers between an interface and controller are wired properly. The system is set up like the example below:
[Code]...
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Mar 30, 2011
Problem that you may have when dealing with two objects that are raising some events. Here, to make it obvious, I am closing the form, but the problem can be experienced with any other 2 classes event. First, what is the problem !
Let suppose that by pressing a button, you want to raise a custom event, then execute a method and then close the form
In that case, you may use a code similar to this
Event BeepIt()
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
RaiseEvent BeepIt()
[CODE]...
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Nov 28, 2009
I was wondering how i would go about threading a paint event. I know the basic multithreading but i cant figure out how i would go about applying this on a paint event. This is the way i know how to go about multithreading.
[Code]...
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Jul 22, 2009
I have a windows application which raises a particular event.I need to create a COM callable class whic will allow VB 6.0 to subscribe to this event.I have done a fair amount of research on this and am confused as hell.
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Mar 8, 2010
figured out a different way to code it that _should_ work around the problems people pointed out before.... but one problem is still the same, the examples I find to code pieces of this are all for old versions of visual basic, and don't workI'm a firefox extension developer. I wrote an extension to allow both private and normal browsing windows simultaneously by having two firefox processes. I figured out a way on the Mac to raise the private browsing process when appropriate... it looks like visual basic is the way to do it on Windows... so I'd like firefox to run a visual basic program that does the following:Look through the process table for all firefox.exe processesFind out the process id of the process that called the visual basic scriptThrow out the process ID of the parent process... now we should just be left with the "private browsing" firefox process
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Aug 15, 2011
can I call shared events contained in one class from another class?
for example:
logonclass.vb : handles login logic and authenticates against database
logonmanager.vb: hold current user reference and some logon and timeout events
Logon.vb: A form with a submit button.
I would like to do something like this but I can't get the compiler to agree with it
If VerifyEntries() Then
Try
privLvl = LoginClass.AttemptLogin(txtUserName.Text, txtPassword.Text)[code].....
If this isn't the proper way to wire things together let me know so I can learn to structure differently. In my planning it seemed like I was raising a lot of extra duplicate events from my logonclass to my loginmanager class. Then the loginmanager had to raise it again for the main form to see the change event. It got me thinking that if I publicly shared the events and could raise them from wherever then it would cut down on the amount of events I needed in code and the amount of them flying around at runtime.
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Jun 28, 2010
I am using the AxWindowsMediaPlayer1 control to play MP3 sound files in my application.
I would like to lower and raise the volume (master) via keypress from my gamepad.
I already have the logic for that established, I just do not see any way to raise and lower the volume within the Windows Media Player control.
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Dec 27, 2010
I am currently trying to make a calendar project it has 2 user controls one is the calendar and the other is the calender day control. When the month changes in the calender control I need to raise an event in daycontrol to update any holidays. In the calendar control I have the following code for the event:
Friend Event MonthChanged()
Public Sub New()
' This call is required by the Windows Form Designer.
[Code].....
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Jul 14, 2011
I want to have a collection of a class which inherits picturebox, with a couple of extra properties, so essentially the same. Only I get an error at runtime saying : 'An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.' Here Is my code, I know that the error occurs here :
[Code]...
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Jul 26, 2010
I have a TAPI program that is very similar to [URL] I have a delegate ...
Delegate
Sub TapiEventCallback(ByVal
dwMessage As TapiEvent,
ByVal dwParam1
[code].....
From my program TAPI will call the number. My problem is that its not raising any events. I really need CallStateChange. I raised it from address and moved it up to my TAPI Manager. I put break points everywhere and I can not get anything to raise.
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Mar 16, 2012
I need to raise UAC shield. I found code over net
MyBase.OnLoad(e)
If Not IsAdmin() Then
AddShield(Me.elevateButton)
[code].....
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Aug 17, 2009
I have this code obtaining data from a sensor that is sending a string that contains 4 numbers separated by a tab and terminated by an end of line/ I am trying to use an asynchronous callback to get the data over TCP. That problem is that the callback function is not grabbing the complete string. Sometimes it will, other times it gets half in one retrieve and half in another. I need the callback to hold off until it gets a newline character.
Code:
Public Sub readVaisala()
Dim ip As String = "192.168.1.30"
Dim portNumber As Integer = 23
Dim time As Int32 = Now.Second * 1000 + Now.Millisecond
[code].....
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Feb 18, 2011
How can I set up an asynchronous web service in asp.net?
I want to call a webservice to post some data to a database, but I don't care if the response failed or succeeded.
I can use .net 2.0 or 3.5 only and it can be in vb or c#.
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Jun 4, 2012
I have 3 classes in 3 separate dll.
1) Class "BaseForm" that inherits from System.Windows.Forms.Form with "MyEvent" declared as Public Event ()
2) Class "MyForm" which inherits from "BaseForm"
3) class "MyClass" which has a public property "ExternalObject" of "BaseForm" type (the private variable is declared WithEvents)
I make the following steps:
1) intercept the Form LOAD event in "BaseForm"
- Instance the class "MyClass", Assign public property "ExternalObject" = Me
- I do a RaiseEvent "MyEvent" in "BaseForm"
2) "MyEvent" is triggered BEFORE in "MyForm"
3) AFTER "MyEvent" is triggered in "MyClass".How Can I Raise event Befor in "MyClass" and then in "MyForm"?
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Mar 19, 2012
I am using following code to raise UAC window. It works fine but my form that contains button to raise this window is shown twice. I mean if I put it in CopyFiile Button, when I click this button, it raises UAC windows, copies file, gives success message and then opens another instance of the same form that contains copyfile button.
Dim proc As New ProcessStartInfo
proc.UseShellExecute = True
proc.WorkingDirectory = Environment.CurrentDirectory
[code].....
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Sep 6, 2009
My windows application needs to raise an event in a COM callable assembly so unmanaged code can pick up on the event.I am sick of this. All the crazy tags required for COM callable is doing my head in.
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Mar 15, 2009
I have a small VB.NET application built using VS 2008 and .NET 3.5.Very simply, there is a timer that kicks off every few seconds to download an XML stream from the web. I look at this stream and manipulate it.The problem I am facing is that the remote web server may not respond in a timely fashion to the following line of
[code]...
How can I implement asynchronous calls so that the my application can behave without locking up?
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Feb 1, 2010
I have a class with a mthod which does a a time consuming task. I know how to start the method in a separate thread using the Threading.Thread class. What I want to do is use callback so as to have the method report its result to another method when completed. I chose to use the asynchronous Begin/End call pattern.
Private Function BeginConnect(ByVal URl As String, ByVal callback As AsyncCallback, ByVal state As Object) As IAsyncResult
'Some Code
End Function
[code]....
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Feb 23, 2010
i'm creating an Asynchronous socket programming in vb.net. i've utilised the code from Asynchronous client and server code frtom the following links:m a new user so could post only one link fully)When I try to connect the for more than one client the second client always waits until the first clientcompletes the call. i want the clients to accept calls at the same time
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