VS 2008 BeginReceive/EndReceive - Docs Incorrect?
Nov 2, 2009
This is the MSDN example for handling the BeginReceive callback.BeginReceive is called over and over until no more data is available, i.e. EndReceive returns 0. However I am finding that the callback is only fired when there is data available.
I'm guessing that the example is simply wrong or refers to expected behaviour in a previous version of .NET, although it says it is for 3.5.So how do I ensure I have received all of the available data?
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Jan 27, 2010
I'm reading a text doc from my hard drive. I'm reading it via a stream reader.
On a button click i'm reading it again, because the contence of the text doc may have been updated, what I want to do is show in one textbox the actual file and in another one just what is new. How can I compare them?
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Apr 15, 2010
I created a very simple program that organizes my various document and opens them when the button is clicked inside the program with the process.start method. The problem is that when i take the executable file and move it to another machine or cd to run the program the process.start filepath is no longer valid.
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Jul 6, 2011
I am using the following code to receive data from a Public Address Controller.the programme sends data...waits for a reply....send more data...waits for a reply..etc.
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is there some way of cancelling the BeginReceive after a delay so that the programme can carry on and inform the user that something is wrong and terminate gracefully?
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Sep 25, 2010
The following code waits for data over UDP. I have a test function that sends 1000 packets (datagrams?) of 500 bytes each. Each time I run the test function, the receiver gets only the first few dozen packets but drops the rest. I looked at the incoming network data using Wireshark and I see all 1000 packets are actually received, but just don't make it to may app's code.[code]If I add a small delay after each call to Send, more packets make it through; however since Wireshark says that they were all received anyways, it seems that the problem is in my receive code. I should mention that UdpListen is running on a separate thread.Any idea why I am dropping packets? I also tried UdpClient. BeginReceive/ EndReceive but had the same problem. A second issue that bothers me is the global nature of the receive buffer when using Sockets and I am not sure if I don't process incoming packets quickly enough that the buffer will be overwritten.
Based on the various, somewhat conflicting suggestions from replies to this and other posts, I made some changes to my code. Thanks to all who chimed in various bits; I now get all my packets from dial-up to Fast Ethernet. As you can see, it was my code at fault and not the fact that UDP drops packets (in fact I have not seen more than a tiny percentage of packets being dropped or out of order since my fixes). Differences:
1) Replaced BeginReceive()/EndReceive() with BeginReceiveFrom()/EndReceiveFrom(). By itself this had no notible effect though.
2) Chaining BeginReceiveFrom() calls instead of waiting for the async handle to set. Not sure if any benefit here.
3) Explicitly set the Socket.ReceiveBufferSize to 500000 which is enough for 1 second worth of my data at Fast Ethernet speed. Turns out this is a different buffer than the one passed to BeginReceiveFrom(). This had the biggest benefit.
4) I also modified my send routine to wait a couple of ms after having sent a certain number of bytes to throttle based on expected bandwidth. This had a big benefit for my receiving code even though Wireshark said all my data still made it across even without this delay.
I did NOT end up using a separate processing thread because, as I understand it, each call to BeginReceiveFrom will invoke my callback on a new worker thread. This means that I can have more than one callback running at the same time. It also means that once I call BeginReceiveFrom I have time to do my stuff (as long as I don't take too long and exaust the available worker threads).[code]What is not shown above is the error handling and dealing with UDP data being out of order or missing.I think this handles my issue, but if anybody still sees anything wrong with the above (or something I could do better) I would love to hear about it.
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Sep 15, 2009
The MSDN Documentation in question can be found here:[URL].. It offers the following code snippet example:
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Aug 13, 2010
i just want to make a program with first form to enter the serial if correct just continue to form2 if incorrect just a popup say like "Serial Incorrect" how i can make it ?
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Aug 31, 2011
Below is the code that I have while reading the DGV column and let me know what I'm doing wrong, here.
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Jul 28, 2010
I am trying to create a Datagrid at runtime. This I have done on other forms no problem yet on this I get a error:
"Incorrect syntax near the keyword 'FROM'." And the the following "In order to evaluate an indexed property, the property must be qualified and the arguments must be explicitly supplied by the user."
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Dec 30, 2010
just trying to decode my signed request.. I've done a bit of searching and haven't found a VB alternative..The signed_request parameter is a concatenation of a HMAC SHA-256 signature string, a period (.) and a base64url encoded JSON object.
signed_request:vlXgu64BQGFSQrY0ZcJBZASMvYvTHu9GQ0YM9rjPSso
eyJhbGdvcml0aG0iOiJITUFDLVNIQTI1NiIsIjAiOiJwYXlsb2FkIn0
PHP function to decode request:
<?php
define('FACEBOOK_APP_ID', 'your_app_id');
define('FACEBOOK_SECRET', 'your_app_secret');
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Aug 2, 2011
I've got a a simple database setup with a parent child relationship.Imagine one expense report can have many line items associated with it.Now inside of this line items table I have a column that stores the link / pathof an attachment on our local storage server. Some example values could be:
\myserverattachments1.pdf
\myserverattachments2.jpg
\myserverattachmentssomeDoc.docx
[code].....
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Nov 14, 2009
I have several docs in a folder in iPads dir (Help Files). When the user selects help it shows a dialog which has a listbox, richtextbox, and three buttons ( open, close, update < to launch the updater)
When the form loads its supposed to add all the files in the dir. It does but the full path and name. This is the code I have>>>If System.IO.Directory.Exists(Application.StartupPath & "Help Files") = True Then
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Jun 29, 2011
The programs runs fine for about 10 seconds but then I get this error message: ArgumentException was unhandled. Message: The parameter is incorrect. Here's my
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Jun 9, 2011
I'm having trouble with a Stopwatch one one of the user's machines. I'm using the Stopwatch class to track time elapsed on one of my applications, and it seems to work fine on everyone else's machine, but on one machine it goes really slow. It's probably 1/3 or 1/4 of the actual time elapsed.
Here's the
I'm using the timer to update the textbox that displays the time elapsed of the stopwatch every second.
Partial Public Class
Private WithEvents breakTimer As New Timer
Private breakSW As New Stopwatch
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Sep 27, 2011
I have a folder that contains multiple word documents. I need to monitor this folder for any changes in these word documents. I am facing the following problems.
File system watcher never reports the exact name of file being changed. For example for file abc.doc, it reports "~$abc.doc is changed" on first save.For all subsequent saves to that file, OnChanged event in the following code is not called. When I changed the filter to watcher.Filter = ".", I found that for subsequent saves, it reports "~WRL0001.tmp is changed".
So the bottom line is that I never know the exact name of the file changed.[code]...
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Jun 14, 2010
I want to be able to code a small system that reads a set directory, for new PDF or Word DOC file types.
Then i want to print them.
I understand, with reference to this thread, - [URL]
and this one - [URL]
that i can use MS Word automation to print the document, but i would like the application to read the folder constantly in real time and then print what ever is 'new' in the folder.
Would there be any advantage to code my own print driver?
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Sep 11, 2009
I've been searching the web in general (and this forum specifically) for information on setting up Help documentation on a project - but the 'help' in the search just seems to give too much.I've never set up help documentation and was wondering if there is a good primer anywhere on the web or in a book - I've looked through VB books and none cover this topic also the I've so far been unable to absorb the official MS docs.
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May 6, 2009
Look at the code. all i need to do is take all notes from orders table.
The connection is openned
Private Sub Load_History()
Dim myCnt As Integer
Dim myStr As String
Dim totalrows As Integer
Dim myDataset As New DataSet
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Apr 30, 2009
Is it possible to build a search engine to use on a DVD that contains Word documents, text documents, etc.? Say I wanted to find all documents with the name "James" in them. In the search box I would type "James", and it would return the results of everywhere James is found. Or suppose I wanted to find all Land Deeds where James is found, is that possible? All search engine examples that I have seen on VB Help has to do with databases, and I guess to an extent, my DVD would be the database.
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Jan 18, 2011
I need help in coding VB 2008 so that it can combine several word document into one to be used for a mail merge template.I need to:
1) combine the word doc (does not work see note 1)
2) use this new doc a for the mail merge (works, only for the rewrite doc)
3) create a pdf. (works, only for the rewrite doc)[code]
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Dec 17, 2009
I know there is a lot of forums out there regarding this, but I haven't been able to find what I need and I am somewhat new to this. I would like the simple openfiledialog code button click to attach a word document or PDF and upload it to a SQL server table to be saved. I would like to use my current datasets and controls without creating another SQL query within my project as I have seen in other forums, unless that is the only method. I know that the data needs to be saved as an image type with the file name and extension but I just need the code for this. I would then like to download the doc or pdf to view it within a form.
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Dec 11, 2009
I'm starting a new project; trying to be more strict than previous ones. I've set warnings as errors in the build I've added FxCop to PostBuild. The one last thing on my list os require people to add inline docs for all classes/non-private methods/properties.
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Feb 22, 2011
when saving am getting this error"undiscclosed quotation mark after the character string')'.incorrect syntax near ')'.I used the command in other codes which working perfectly. [code]...
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Feb 27, 2009
i am creating a quiz which would be 20 questions for software design students and may use alot of code.my first problem is the score for the test, i know a friend of mine can add up the score but he cant move onto the next thread until you have got the question correct which is sort of cheating, i want to know how you create a variable and make that variable stay in all the forms and add up the score of correct and incorrect answers and come up with a final score for the user in the end.
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Apr 18, 2012
I've given a job to convert old data in table format to new format.Old dummy data is as follows:
<table>
<tr>
<td>Some text 1.</td>
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Apr 7, 2011
I used to have this one
Dt = MyMod.GetDataTable("SELECT TOP " & QuestionsPerCats(i) & " * From Questions WHERE CategoriesID ='" & Cats(i) & "' ORDER BY NEWID()")
but now i decided to use sqlparameters like
Dim cmd As New SqlCommand("SELECT TOP @QuestionsPerCats * From Questions WHERE CategoriesID = @CategoriesID ORDER BY NEWID()", conn)
Dim sqlParam As SqlParameter = Nothing
sqlParam = cmd.Parameters.Add("@QuestionsPerCats", SqlDbType.SmallInt)
[code]....
and returns the following error
Incorrect syntax near '@QuestionsPerCats'.
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Dec 14, 2009
It was suggested that I use xmldocument.load to do a sql insert statement instead of BULK INSERT.However when I run the Sub I am getting this error: "Incorrect syntax near '<'. "Here is my code, I have no clue what is causing this error, or how to fix it.
Sub AO()
Dim Z As String = Microsoft.VisualBasic.Format(Today.AddDays(-1), "MMddyyyy")
Dim AO_Name As New String("\NetImportAO-M_" & (Z) & ".xml")
Console.WriteLine(AO_Name)
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Apr 23, 2009
I have dll and exe files which have assebly version numbers different from the values stored in AssemblyInfo.vb.If I look at the information displayed in the Details tab of File properties in Windows, the File version and Product version values are identical with the values of AssemblyInfo.vb. But when I use My.Application.Info.Version to display the version number at runtime, the value displayed is incorrect. Also when I add a reference to a dll file, the referenced version is incorrect. The incorrect value is the same as the value last time AssemblyInfo.vb was edited on the local machine. If the AssemblyInfo.vb file is edited on another machine, the value won't be updated on other machines.
Typical example: On a nightly build the build server increments the build number of all AssemblyInfo.vb files. When developer workstations are updated in the morning (get latest) the build number isn't updated at runtime - even though the AssemblyInfo.vb file is updated and compiled into a new dll or exe file. But file properties in Windows displays the updated build number as described above. I've been looking for other places where a version number might be stored (in case there are more than one place to update the version number), but I can't find any reference to the displayed build number when I search the source files.
If a developer workstation edits the build number, compiles, and edits it back to the correct value and builds again, the displayed value at runtime is equal to the value in the source file. It's like the AssemblyInfo.vb files must be edited on the machine that builds the solution, or the result is not reliable..
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Sep 20, 2011
I've added a DataGridView and on a MouseDown event I'm invoking a ContextMenuStrip on the right mouse button. But for somereason the context menu always appears at the top center of my DataGrid.When I look at the value of e.Location it is always the same regardless of where I click in the grid. I'm at a loss as to what is going on. Below is the code for the MouseDown event:
Private Sub dgvTreename_CellMouseDown(sender As Object, e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles dgvTreename.CellMouseDown
If e.Button = Windows.Forms.MouseButtons.Right Then
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Mar 10, 2011
i am having a problem with my date format. i want the format to be MM/DD/YYYY for example 02/28/2011 . i have put custom format in my event. but when i change my setting in regional settings it changes the format
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim Myconnection As OleDbConnection
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