VS 2010 Async Sockets Causing UI Update?
Apr 9, 2011
I'm using .BeginConnect with an AsyncCallBack and for some odd reason when I try to add a string to a textbox using the sub below, from a routine within the socket, it just does not work. It's not stating an invoke is required either.Private Delegate Sub DelegateAddText(ByRef theText As String, ByRef AddReturn As Boolean, ByRef AddPrefix As Boolean) Public Sub AddText(ByRef theText As String, ByRef AddReturn As Boolean, ByRef AddPrefix As Boolean)
[Code]...
as a side note which would be more efficient ... Indexing sockets and passing indexes through routines, or spawning classes. I realize spawning may use more memory but is it faster than indexing?
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Jul 25, 2011
I'm using vb .net 2008 with 3.5 framework. (the following 2 classes are put in a DLL that i import in a main application)
Server class:
Code:
Imports System.Xml
Imports System.Net.Sockets
Imports System.Text
Imports System.Net
[code]....
Basically in my main application i am instantiating the client class from this dll, as well as the server one. On the client form i got a "send data" (SendFISA sub) and a "connect" button. After connecting the client and clicking on the "send data" i am sending to the server a string formed of some information created when instantiating the client class from the dll (i can't make that type of data public, but i'm just using a constructor to assign values to a class object, nothing special).
Now, when the server receives the data sent by "send data" button click it responds with "PKG_SENT" corresponding to the "FISASENT" string terminator(in the module) of the string that was sent. The "WRONG_MSG" constant is for when the string terminator is different from the 2 from above.
On the local disk, if the server cannot be reached, the client saves an xml file with this data. In the dll i made a timer that ticks every 5 seconds and checks to see if there is any xml file on the disk and sends it to the server if the connection is ok (trimiteXML sub). The server would respond with "XML_SENT" corresponding to the string terminator "XMLSENT"(in the module) appended to the read string from the xml file. After the file is sent it is deleted from the local dir.
The problem occurs when i click "send data" AND there are XML files to be sent from the disk. I believe they are interpreted by the server somehow at the same time because the message is neither "PKG_SENT" nor "XML_SENT", but it becomes a combination of the "WRONG_MSG_TYPE" and "XML_SENT", "XML_SENTG_TYPE". I have no idea why this is happening and i basically want the socket to wait with sending the files from the disks until the "send data" finishes.
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Jun 16, 2009
I'm trying to setup an asynchronous client and I can send/receive one command and response, but when I try to send the second command, the command is sent (I verified by code inspection), but I am getting no response.
Heres the code, a majority of it is from the Microsoft example.
Option Explicit On
Imports System
Imports System.Net
[Code].....
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Dec 17, 2008
Alright Simple question I got my main thread running Form Load and I make a socket then called BeginAcceptthen I pass AR to a Function that handles the Accept and creates a whole another sockets out of it and then loops for recv then when it gets everything closes then exits the functionbut how do I make the Socket from Form_Load run BeginAccept again to wait for another connection.. Do I call that command and Point it to the same Block thats Currently running, The block that Handles the AR Param??
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Oct 27, 2009
Here's the code on the sending side of my sockets:
Private Sub Send(ByRef Buffer() As Byte)
Dim obj_StateObject As New StateObject
obj_StateObject.WorkSocket = m_tmpSocket
[code].....
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Dec 18, 2009
I have been developing an async socket connection server and client program. I have been testing it, and noticed that if I connect to the server from my client and then disconnect. Upon reconnecting I am on a different port(local IP still). This is fine, however when I go to send a message, and the server trys to update all the clients, it eventually hits clients that do not exist anymore. I get the SocketException 10054, and upon connecting/disconnecting enough, it no longer works at all. My question is how do I clear out these no longer useful sockets from the server? I am doing currentsocket.Shutdown(SocketShutDown.Both); and then a currentsocket.Close(); after that. When a user disconnects.
[Code]...
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Nov 3, 2011
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In my scenario the Button_Click is a command delegate in the VM, and the Thread.Sleep is some long-running process (about 2-10 seconds). I want, that when the user calls the command, it should immediately update the UI disabling the button so the user cannot execute it while it's running, then execute that operation, then, when operation completed, unblock the button.
[Code]...
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Dec 7, 2011
I am having an issue with the SQLCommand query update handling apostrophes. I have a gridview that accepts edited text which might have apostrophes and other such accent characters.The UPDATE keeps throwing errors on the apostrophes in the text entered causing the SQL UPDATE to fail.
Here is the code:
Dim lbl1 As Label = GridView3.Rows(e.RowIndex).Cells(0).FindControl("Label1")
IDVal = lbl1.Text
[code].....
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Jul 22, 2010
I have a very simple StopWatch application in Silverlight. I have the following private properties in my MainPage class: _StopPressed (bool), _TimeStart, _Elapsed (string). I also have a "Start" and "Stop" button. The "Start" button calls a method called UpdateTime that constantly updates _ElapsedTime until _StopPressed is true. When I originally wrote it, UpdateTime would block the UI so I couldn't press the Stop button, so I updated my code to use System.Threading.ThreadPool.QueueUserWorkItem with my UpdateTime method so that it updates _Elapsed on a background thread. That works great at updating the value.However, if I try to set the .Text value of my TextBlock from within UpdateTime(), I get an UnauthorizedAccessException that has to do with one thread accessing the data in another thread.What do I need to do to avoid getting this exception and appropriately update the UI without blocking it?
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Sep 15, 2009
I am doing some graphics work like Paint event, but I found a problem that the form will flash again and again whenever I call the method IRefresh() or Invalidate(). What can I do if I want to update a graph continuously but not causing the form to flash?
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Jun 3, 2010
I'm trying to write a 'developer friendly' wrapper for the Windows API EnumWindows - the problem is that the API uses a callback function that gets invoked on another thread, where as I want my wrapper function to simplify this and make it more useful by working like any other normal synchronous function and just returning a value.
Now if the API just called the callback once that would be fine, as I would just call the API and make the wrapper function wait until it got a signal from the callback function telling it to continue... but the API calls the callback function over 100 times (once for every window handle that exists). The biggest problem is that there is nothing that indicates that any particular call to this callback function is the last one, so my wrapper function has no idea when it is safe to continue and return the list of window handles to the caller.
The only solution I could think of is to do this:
1. The wrapper function calls the API and starts a timer that waits 2 seconds before it raises the Elapsed event. The wrapper function then pauses until it receives a signal (ManualResetEvent)
2. Each time the callback function is raised by the API on a different thread, it stops the timer (so this is before the 2 seconds have elapsed), adds the current window handle that was passed in by the API to the list of handles, then starts the timer again.
3. If the timer reaches its 2 second interval then it is assumed that we are at the end of the windows because otherwise the callback would have stopped the timer. So the timer's Elapsed event handler is what signals the original thread (that the wrapper function is executing on) to continue as we now have a complete list of windows to return.
This works fine and does exactly what I want... but I dont like it.
I dont like forcing the caller to wait an extra 2 seconds after the API has done its last callback but more importantly I dont like assuming that the API will never take longer than 2 seconds between callbacks. In reality on my PC it is never anywhere near that long between callbacks, it is something like 200 miliseconds, but I have no idea how long it would be on a slower PC and I want this to be completely reliable.
[URL]
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Dec 1, 2011
I am trying to get my program to read async so it doesn't just freeze up while it fetches the data. I have:
SR = New StreamReader(WC.OpenReadAsync(New Uri(url)))
Dim html = SR.ReadToEnd.ToString
It keeps throwing the error "does not produce an expression". I remember trying this in the past, only to have the same error.
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Apr 23, 2012
I am creating xml files that contain chinese posts and it seemed to be working but I started getting an error:This page contains the following errors:error on line 4165 at column 25: Input is not proper UTF-8, indicate encoding !Bytes: 0x0B 0xC3 0xA5 0xC2
Below is a rendering of the page up to the first error.When trying to open some of the resulting files.The line it references contains chinese characters and the error occurs only for some posts and my guess is that the text has some encoding issues.
Public Shared xwriter As XmlTextWriter = New XmlTextWriter(xmlfile, Encoding.UTF8)
I make sure the xmltextwriter is properly declared and set the encoding and from what I understand is that vb.net encodes everything in utf-16. My code works well with streams I get from another source that sometime contains chinese characters and it never invalidates the xml. I tried cleaning the text using the following functions and the xml is now valid but when viewing the xml in the browser the characters are not chinese but junk.
Private Shared Sub replaceIllegalXMLChars(ByRef tempstring As String)
'remove any hexdecimal characters like and �
tempstring = Regex.Replace(tempstring, "&#x([0-9A-F]{1}[0-9A-F]{0,1});", " ")
[code]....
so if I need to fix my data, my question is how can I detect what encoding is used for a specific text and how do I convert it into utf8 format that can be viewed in an xml file and make the file valid.
EDIT: I messed around with converting from one type to another, first ASCII to UTF8, then Unicode to UTF-8. did not work. The only time the xml is valid is when characters display as such:
油价，老百姓心�*永远的痛！ � 民生、控物价一边说，油价一边涨，国家真得是为了老百姓的民生� �？
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Dec 5, 2011
I managed to get a program I made up and running fine, but i noticed it has a small memory leak somewhere. I looked through the code and I think its coming from somewhere in this
vb
Private Sub Button4_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
[code].....
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Jul 3, 2011
I have a Socket application that, when data is received (on the Server side) and the client is recognized, the data is passed onto its own socket and stream, and the previous socket and stream is discarded.
The data is serialized with a binary formatter before sending and deserialized on receiving the data.
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Oct 11, 2011
I have installed VB Studio 2010 Express this week and have began working through the tutorials that are built in to the program to familiarise myself with using VB (I have zero previous knowledge).
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Feb 14, 2012
I'm creating a web browser and I was wondering how I could make a button click cause the enter key to be pressed after without having to do it yourself on the keyboard.
Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
End Sub
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Jul 13, 2011
I'm having an issue with a program. It seems to run (continuously) any amount of time from a few days to about a week.Eventually, and seemingly randomly I get the following Errror. None of the users see a consistent item that is causing the hang, and sometimes it's even just running with no interaction with the user.I just get long signature alpha numerics as a debugging tool.Is there any way to
a) force my program to kick out of the hang if it detects one, (and I guess, how could I write a separate thread to detect a hang?)
b) find out where my program is hanging?
c) if none of these options are viable, some coding practices I might be doing wrong that I could change to help avoid this?
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Apr 9, 2012
I have a small problem with sockets (I'm new to sockets). Below is the code I'm using. The problem is that when the client closes, the server closes aswell. How do I stop it from doing that?
[Code]...
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Jul 15, 2010
I have two methods on the page. One AddMessageToInboxOutbox(params[]) and other one SendNewMessageMail(params[]).
Once user sends an message to other other first message is added to DB and then sent to recipient's email. Sometimes SMTP is heavy loaded and it takes up to 5 seconds to get answer from it. I want to enclose SendNewMessageMail(params[]) with async call using other thread or something. I have never done that.
How do i perform this action right in ASP.NET?
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Jun 12, 2009
I have a bunch of operations that need to be executed simultaneously. For this I'm using the thread pool to execute the tasks. I'd like to know if it's possible to consume some sort of Async Callback (similar to BackgroundWorker.DoWorkComplete) when each thread is finished. The reasoning behind this is that I have a windows service running that uses IPC to update a GUI and I need to know the time at which each specific thread finishes I've used background workers to do a set of tasks and they work perfectly, however, they take longer than I would like. I've timed the execution on my BGW method for a designated number of said tasks and it took 27 seconds, and the same set of tasks takes 4 seconds using the threadpool method. I've also tried using managed threads, to the same effect as the background workers.
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Apr 20, 2012
Async Sub like this: Dim f As Func(Of Task) = Async Sub() End Sub Produces compiler error: error BC36670: Nested sub does not have a signature that is compatible with delegate 'System.Func(Of System.Threading.Tasks.Task)'.Equivalent C# code compiles fine:
Func<Task> f = async () => { };Rewriting Async Sub into Async Function make code works.
Why does Async Sub() is not convertible to delegate types with return value of type Task?
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Oct 1, 2011
I think this is a simple question for you, but I don't understand other cases of webRequests, so I asked here: How can I make this webRequest asynchronous?
Dim sBuffer As String
Dim oRequest As WebRequest = WebRequest.Create(url)
oRequest.Method = "GET"
Dim oResponse As WebResponse = oRequest.GetResponse()
Dim oStream As New StreamReader(oResponse.GetResponseStream())
[Code] .....
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Jul 15, 2011
Relevant to Silverlight 5 / Async CTP
I want to create an asynchronous function that initiates a layout update and then Awaits for the layout update to complete. Something like:
Private Async Function UpdateLayoutRoot() As Task
LayoutRoot.UpdateLayout()
Await LayoutRoot.LayoutUpdated <--- (NOT valid but shows desired outcome)
End Function
How can this be done? More generally, how can you use Await to wait for existing events?
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Mar 31, 2011
I have some code that iterates a few 100 urls and requests the data from the web.It looks something like this
for each url in urls
Dim hwr = CType(WebRequest.Create(url), HttpWebRequest)
Dim rq = New ReqArgs
[code]....
How come the BeginGetresponse line takes about 2-3 seconds to complete before going to dim a=1?. Actually I debugged and I see that the FinishWebRequest procedure runs completely before the Dim a=1 is reached.So is this async?I'm not earning any time by using the async. am I? Or is there a different way to do this?The point is that the main sub should fire off 300 requests and return control to the UI, then the FinishWebRequest should process them slowly on its own thread and own time , as the requests come in.How do I do that?Btw, the main sub is running in a BackgroundWorker, but I checked with out the BackgroundWorker and the problem is the same?
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Jun 14, 2012
I have a WPF application in which i have to do a long running task (basically reading from network). Just to give you a snapshot I am doing the following thing on button click
Dim t As Task(Of String) = Task.Factory.StartNew(Of String)(Function()
'Thread.sleep is simulating long running task that will make UI unresponsive
Thread.Sleep(10000)
[Code].....
I cannot use Event based async methodology because the reading API actually exist in a dll which i refer in my program, that contains a function Public function ReadFromNetwork() as String. This API is making an async call to network to read a long string and return to UI. So, in short i m doing TextBlock1.Text = ExternalDll.ReadFromNetwork().
but the problem is that even if i use Task asynchrony, the UI is still unresponsive.
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Nov 24, 2011
I've run into a bit of a problem using Async ping. Basically, I want to ping computers in the list before I run the next bit of my program. The computers who I can ping are added to a list and that is used in a background worker. Trouble is can't seem to work out how to wait until after pinging ALL computers in the list, either successful or timed-out. Is there something a long the lines of 'If Async Ping is running'?
Private Sub pingCompleted(ByVal sender As Object, ByVal e As System.Net.NetworkInformation.PingCompletedEventArgs)
If e.Reply.Status = Net.NetworkInformation.IPStatus.Success Then
complist.Add(e.UserState)
Else
'do nothing
End If
End Sub
I need the next bit to wait because if 'complist' is changed while it's being used I get collection errors.
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Dec 21, 2009
I am working on moving a project from VB6 to VB 2008 Express. [Code] When I connect to mysql db in VB6, I connect using adAsynConnect. This way, I have a "Loading..." animation display while a connection is attempted. Is there a way to do this in 2008 Express? Or something similar I could read up on?
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Nov 24, 2009
I have a console app that is supposed to async call a web service...i don't get any errors but the completed handler doesn't seem to complete correctly. I have a subroutine with a loop that is supposed to fire off say 6 seperate calls to another routine that calls the service. The completed event handler routine puts data into the database..If i put a thread.sleep under the call to the routine calling the web service. The completed event handler fires but only one record is put in the database instead of the hundreds expected and only that one webservice call appears to fire.I should mention that this works as expected when calling the sync method of the web service within a console app and the asyc calls work as expected from a windows forms app. I just need it to work async within a console app..
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Mar 16, 2010
My app is basically talking to a device via RS232. I need to 'listen' to the data received and do certain things based on it, update labels, etc. When I started, I only had a couple cross-thread calls and I used JMC's example to get by that. Now my app is bigger and I am calling the ThreadProcSafe all the time. I am hoping there is an easier way so I don't have to create sub routines for every control. Here's the relevant parts of my code.
Private Sub StepperSerialPort_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles StepperSerialPort.DataReceived
Dim ReceiveBuffer As String
[Code].....
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