Write A Thread Into My App Which Basically Does A Loop In The Background Performing Detection?
Mar 15, 2012
I've been able to write a thread into my app which basically does a loop in the background perfroming detection for a device being added or removed.works great!i am trying to implement another thread to check for a file on the found device...but i still haven't figured out threading enough to make this work, the versions i try to implemt are either looping along with the initial loop or cancelling itself because its already running.i've been trying to put a variable in that would switch the thread off, but it doesn't seem to work.
View 2 Replies
ADVERTISEMENT
Jan 15, 2012
I've been reading up on asynchronous function / web pages for ASP.NET 3.5 (we're not using v4 yet) but the ones I've seen all focus on performing a background task but then still coming back to finish up and send the response, after the task is complete.
What I want to do is simply kick off the background task (in this case a call to a web service) but then return a response to the browser immediately - ie. without waiting for the asynchronous task to complete. I don't even need to know if it succeeds or not.What is the best way to do that? I can't seem to find examples of kicking off what you might call an "orphan" background task in ASP.NET.
I thought of doing it via a javascript Ajax call on the page I show to the user, but the information passed to the web service is sensitive, so that's out of the question. But that kind of illustrates what I want to do.
[ed] Another idea: Is there an event in the ASP.NET model I can use which occurs after the response has been sent to the browser and the connection closed? ie. So more processing can occur without the user waiting for it?
View 2 Replies
Aug 26, 2009
I have a spreadsheet that contains details of change requests; one row per request. This information needs to be copied into a Word form for sending off to our customer who then completes the response section. To speed up this process I have written some code that utilises the mail merge feature of Word and merges the relevant info from the spreadsheet into a Word form. This runs from Excel when a button is pressed.The problem comes when I go to save the workbook and exit Excel; it stays running in the background as a process in task manager.
[URL]
I'm fairly sure it has something to do with the merge code itself but my knowledge of VB is enough to grasp what is happening but not why it is happening. If I open the Word doc that has the merge fields in it, then open the spreadsheet that houses the info Excel says the workbook is already open.
View 5 Replies
Mar 27, 2012
I have an asynchronous task that is executing a function. The function does not contains any looping statements, but instead it is executing series of sql commands on sql server. Now, i have a button on my window that can cancel these sql operations. In other words, cancel the whole asynchronous task.
I know that this technique will require CancellationTokenSource and CancellationToken to cancel the task, but i've seen many examples on the internet and all of them are showing that the function that task is executing contains loop statements in which they are checking for IsCancellationRequested boolean property. But in my case, it is not so. My function does not have any loop statements in which i can do a check on this boolean property.
View 3 Replies
Jun 17, 2011
Is it possible to define my list of strings like in 'good old' VB60, to use only on ebyte of memory for each character? .NET always seems to store any string as unicode, which doubles the required memory. The case is that I have a huge list of strings, all of the same size. It is about 50.000.000 items, 12 characters each. You can imagine I am running out of memory in no time. I tried converting them to arrays-of-bytes but in that case I loose the possibility to perform a "LIKE" statement in a FOR-EACH loop to check for a specific item.
View 6 Replies
Aug 27, 2011
I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:
Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())
to call this method:
Private Sub UpdateApplicationDataUI()
...
End Sub
However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").
Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))
View 1 Replies
Dec 4, 2008
A non-UI thread in my prog needs to obtain data from a UI listview control. To prevent cross-thread errors I use the following, but it freezes the prog (probably because the "Else" part is never called).What am I doing wrong?
[Code]...
View 2 Replies
Mar 4, 2009
I'm creating a Client Server application which involves theServer running some scripts in clients and getting back results in an automated way. In Server, other than Main thread, i have 2 worker threads, a) one monitoring response from clients and b) the other scheduling next available job to respective client which executes that job. The issue here is ,I want these worker threads to write the status of their work in the UI(which comes under Main Thread). Also i need to write things in worker thread in a Data table and Rich Text Box in Main thread. But, I can't do so, since it has been blocked to access one thread's function or property directly from others. Is there any work around to do this?
View 8 Replies
Jan 26, 2010
I have a program that if user presses a key(while the program isn't focused),it presses some keys(some kind of macro to aid gamers).The program works,but I cannot stop the background thread.I use "t.abort()" (t is the name of background thread) but it keeps working(even when I close all forms) and at TaskManager "keypresser.exe" is still there.[code]
View 5 Replies
Oct 4, 2010
I have an application that I need to load data in a background thread and make available to a combobox or list box on my main form or UI Thread. I am really new to threading in VB and how to best accomplish this. Here is some code from a test project:
[Code]...
View 7 Replies
Jun 22, 2010
I have a a main thread and another background thread that does some work (see below).I want to do something within my worker thread and then wait until some other event happens in the main thread before continuing. How do I do this? I thought I could use ManualResetEvent but I can't get it to work properly. I'm a bit confused about the Set, Reset, WaitOne methods and where exactly I should call them from.When the worker thread is suspended it shouldn't affect the main thread.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System. EventArgs) Handles MyBase.Load
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code]....
View 11 Replies
Jun 29, 2011
I am a novice in Threads, but I want to know how to order thread execution in my scenario, and is the following :
UI Thread : Windows Form Background
Thread : Kind of print daemon
implemented with recursive methods
IO Operation : a StreamWriter that do
the job of File.AppendText()
When I execute my main app.exe, sometimes it launches the Windows Forms and the execution process in the task manager (app.exe), in some opportunities its just launches the execution process in background. How can I determine the behavior of launching UI, I have to establish a priority or somewhat else? Code: I'm using framework 2.0 and any answers could be writted in C# or Vb.Net.
View 1 Replies
Apr 7, 2011
I am in the planning stages for developing a VB.Net class (let's call it OpDAq) that is to obtain data via an API provided by a COM object (AxInterop.TWSLib) that makes requests to an Internet server. The API provides data via events. Class OpDAq should do its work on a separate thread; it takes several seconds (sometimes up to ~10) to collect the desired data. One should be able to create several instances of OpDAq in order to collect data in parallel. The class would be given a reference to the TWSLib object when its constructor is called, as well as several parameters. There needs to be a way for the class to provide results, preferably in the form of a generic list.
View 6 Replies
Aug 28, 2011
I'm looking for a configurable way to run some code on a background thread and I'm not too sure what the "best practice" would be. Currently I have something along the lines of:
Dim sendEmails = Sub()
Dim emailToSend As New SendEmailRequest()
TransferCommonValuesTo(emailToSend, request, sendingUser)
usersToSendEmailTo.ForEach(Sub(u)
[Code] .....
Is this a good way of implementing my requirement? This will be called from an ASP.NET front-end (although others are possible) and I am using Framework 3.5.
View 4 Replies
Aug 16, 2011
I've got an application with a ListView and I want to loop through each item in the ListView. But I want to do this in a separate thread.
This is a very simple version of the code - but its error is the same:
Private Sub StartToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles StartToolStripMenuItem.Click
pingThread = New Thread(AddressOf loopingRoutine)
[Code].....
View 2 Replies
Apr 6, 2012
I have a BackgroundWorkerThread which I want to use serially.So some of the code in the UI thread will look like this [code]But of course I can't do the second RunWorkerAsync until the UI thread has seen the RunWorkerCompleted event indicating that the "Sequences" work has been completed (or somehow knows that the "Sequences" work has been completed).So I need some sort of synchronization between the two RunWorkerAsync calls, but whatever I use cannot hang up the UI thread because it has to be able to handle ProgressChanged events.Maybe the RunWorkerCompleted event could make the second call but I really don't like that structure.So how do I delay the second call to RunWorkerAsync (for the "Templates" work) until the background thread has completed the "Sequences" work?
View 6 Replies
Mar 2, 2010
I am running sum of my code in a background worker and I need to show sum tooltip text on a label, but nothing shows up.[code]...
View 1 Replies
Jun 9, 2009
Im trying to run a thread in the background. The sub would take a string as as input and the text to speech object would read the string.
1st problem is: How do I pass my value strIn to my sub SpeekEventWorker when im calling it like this
[code]...
View 10 Replies
Feb 24, 2009
I can't seem to find a good tutorial on how to access uithread components from the background thread.. It seems like there is different means of accomplishing this. I'm not picky about which one I use.
View 1 Replies
Apr 6, 2011
I have searched the forum and found several forums related to the backgroundworker thread but have been unsuccessful in finding my answer.My objective is to display an animated gif or progress bar while the program is executing a particular method which can take upwards of several minutes to complete. I cannot get the second thread to run the progress bar while the main progrem is executing the time consuming method. I have created a demo based on another thread and can't seem to get it to create two threads. I was attempting to get the backgroundworker to execute the progress bar while my main code runs on UI thread.
[Code]...
View 10 Replies
Jul 8, 2011
I'm using the code below in a separate (background) thread, in order to read parts from a file, so they can be uploaded.
The problem is that when the user stops the upload, the thread is sometimes aborted while it's still reading from the file. This keeps the file locked and when the user starts the upload again, the following message appears.[code]...
View 4 Replies
Jul 2, 2011
My application has a total of 1 form. I have several modules, one of which is a module that handles a background worker dynamically. But what I need to be able to do is update a textbox from the background worker thread. Again, this code is contained within a module, not directly on the main form, so I am totally clueless as to how to make a reference to it. It's easy in WinForms, but I can't for the life of me figure out how to do it in WPF...
View 4 Replies
Jun 14, 2010
Currently I have a background worker doing a bunch of stuff and if a condition is met, it throws up a MessageBox for the user to pick from an the background thread pauses like I need it to, however most of the time the Messagebox shows up behind the main form (which is on the primary app thread, the UI thread) and I'd like the BW code to pause until it's acknowlegded and I also want the MessageBox to be owned by the main form (so it's always displayed in front and you can't get to the main form until you acknowledge the MessageBox. Later I'll be changing the MessageBox to be a modal form that matches the app's theme (I'll be opening this form using .ShowDialog()) should I go ahead and make that form now?
View 20 Replies
Apr 25, 2012
I have a application which processes 1000's datas.. for each processing it needs to update gui and db and many variables in my application. So what i have planned is to use 50~90 background worker with my own algorithm of thread pool, synchronization and thread close.So here is it efficient in terms of memory and performance. just confused what to use.. backgroundworker componenet or standard thread.
View 11 Replies
Feb 24, 2009
I'm using the webbrowser control in VB.net. I want to click a button and have the webbrowser go to a certain website (done). Then I want it to wait a period of time and then do something on the page its on. The part I'm having a problem with is the waiting period. In the main form I have no problem manipulating controls or anything like that.
One solution would be to use thread.sleep() but that locks the ui and I don't like that. What I am trying to do is have a backgroundworker do the waiting then perform the necessary actions on the webpage, but the backgroundworker isn't able to access that thread, makes sense. I've explored delegates but that doesn't seem to do what I want as it doesn't allow me to put the background thread to sleep before it does its work.
View 2 Replies
May 30, 2011
I am testing a background workder. I am running the following code for the test.
Private Sub bgwTest_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwTest.DoWork
Dim a As Integer = 0
Do While a < 10 'Infinite loop
ComboBox1.Items.Add(1)
[Code] .....
But this code generates the following error:
"Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on."
View 2 Replies
May 19, 2010
Can someone tell me how to get the selected text in the combo as it encountered cross-thread in the following code:
[Code]...
View 5 Replies
Sep 23, 2009
Is it possible to create a WebBrowser control in a background thread in BackgroundWorker?
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Using web1 As New WebBrowser[code].....
Does anyone know a way to create a background WebBrowser? I would like to do it to extract info from websites then spit out the various HTML DOM arrays
View 4 Replies
Mar 15, 2010
I was looking for a solution to run a lengthy job (looking for files on the fixed drives) withouth freezing the UI, and saw that using a BackGroundWorker control is the recommended solution.
Problem is, I don't see its ProgressChange event being triggered:
Imports System.IO Imports System.Text.RegularExpressions
Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Button1.Enabled = False
[Code]...
View 6 Replies
Oct 4, 2010
What is the Invoke syntax to marshall data from a background thread receive callback method to a function on the UI Thread?(Form1).
Public Class Form1
MyDelegate = New DisplayData(AddressOf DisplayData)
Private Sub Form1_Load()
MyDelegate = New DisplayData(AddressOf DisplayData)
[code]....
View 12 Replies
