In a windows form application I have:
Private Sub ReadData(ByVal CodeId as String)'...reads SQL Table End Sub
Private Sub FileSystemWatcher_Created(ByVal Sender as Object, ByVal e as System.IO.FileSystemEventArgs)
'do some stuff 'Need CallBack to ReadData
I'm working on a Windows Service that watches a few folders for changes, creations, and deletions. It all works well with the exception of one watcher that watches a single file (XML File with Configuration Settings) for minor changes.
I tried taking the Windows Service code and putting it into a simple windows application with start/stop buttons for the filesystem watchers and stepped through it. It never detects the file change of the XML config file. The changes are indeed occurring and the "Date Modified" of the file is updating.
XmlEventReferences = New System.IO.FileSystemWatcher()
XmlEventReferences.Path = "C:XmlReferences"
XmlEventReferences.Filter = "*.xml"
[Code].....
I'm using FileSystemWatcher in an application.it monitors the files in a folder, then do some processing. I monitor FileCreate, Change, Rename, Delete event.the problem is: when I copy some images to that folder, it fired the create event, but the file is not actually ready, so, when I load the file in the event handler, it failed.how can deal with this correctly?
View 2 RepliesMy goal is to have the user be able to click the row and the row will be the selected row almost like having the select button but the entire row clickable to do the same thingthe error i get popups when i click the row, not when the webpage is loaded
this is the onrowdatabound portion i just added that causes the error
If e.Row.RowType = DataControlRowType.DataRow Then
' Get reference to button field in the gridview.
how to write below in vb.net??
Me.connection = New RAPI
connection.ActiveSync.Active += new ActiveHandler(ActiveSyncActive);
Private Sub ActiveSyncActive()
..................
End Sub
I need help with a month calendar. I want to write an If statement in a button_click event. I need an If statement that says if one date is selected then a label becomes visible. I cannot figure it out.
View 1 Repliestell way to get: KEYPRESS event in the cells of DataGrid ?If user enters numeric value in Quantity, it would calculate & give result in Rate.How can I fire KEYPRESS event in cell
View 3 RepliesCannot Consistently and Reliably Write to a Custom Event Log from DotNet
View 4 RepliesI am trying to write disk errors to the system event logs.I have a list of errors reported to the event logs if disk issues occur.So i just want to write dummie errors to the logs so I can do testing.I am able to write to the logs but the description comes up as follows:
[Code]...
I have 50 buttons on my form and have to write code for click of all that buttons. So my question is do I have to write separate codes for every button click event:
[code]...
I need to declare a directory, create a file in the form_load event. I need to write the value from an array in the file when during Button_click event Is there any way to use the object declared in the form_load to be used in the Button_click event????
[Code]....
I'm trying to use a .DLL which Callbacks a Function of my project, but I can't get it to work.
Declaration from .h file of .DLL
void DLL_EXPORT SetEntity_CallBack(bool Active, _
void (*Entity_Callback)(int Site, int Application, int ID, _
[Code].....
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].....
I have a C++ dll that contains a callback. The callback has one parameter that is passed in and one parameter that is passed out. The parameter that is passed from C++ is a variant. So, we are going from a variant in C++ to an object in VB.NET. The function works. However, It seems that there is a memory leak on the VB.Net side. This must be a Marshaling issue. I have tried to use the MarshalAs Functions, but to no avail.
VB.NET
Declare
Function EnableWriteNotification
Lib
[code]....
there is error when i use callback function A callback was made on a garbage collected delegate of type 'skynet1!skynet1.Form1+myCallBack::Invoke'. This may cause application crashes, corruption and data loss. When passing delegates to unmanaged code, they must be kept alive by the managed application until it is guaranteed that they will never be called.
View 6 RepliesI am working on a Twitter application and with the authentication process, Twitter returns Two Tokens with a Callback URL, For example: [URL]. How do I extract each token and put them into separate strings?
View 5 RepliesI am writing classes in VB.Net (both managed). The main class "A" creates an instance of "B". Class "B" must call a method of Class "A". I need to know two things (syntax, etc...):
1. How does class "A" tell class "B" what method to call?
2. How does class "B" call the method?
The method must pass back an array of Shorts (in this particular example), either as a return value, or as a ByRef argument.I don't want to use an event if I don't have to. The execution is timing critical. (I assume event handling involves a lot of overhead by the operating system, but I may be wrong.)
I do not know Why I am recieving a TimeOutException in my code:
Dim Uri2 As New Uri("http://localhost:8733/Design_Time_Addresses/ssWcfService/Service1/")
Dim binding2 As New WSDualHttpBinding()
Dim callback = New MyCallBackClient()
[Code].....
I am a relative newcomer to Windows programming and VB.net. What we are trying to do is call a function in an existing, 3rd party COM dll. This function requires a callback parameter, whose type is an interface also defined in the dll.In our VB.net application, we have added the dll as a COM reference, and created a class that implements the interface in the DLL. We then send an object of that type as the callback parameter. This compiles fine. However, when we run the application, we receive an error stating that the program is unable to cast the object from our existing type to the interface type.
I suspect that there is a simple fix, but so far, my efforts to find a solution have come up short. If anyone could point me in the right direction,
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.
View 5 RepliesI 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]....
Situation: i've created several forms with a datagrid:formwithdatagrid1formwithdatagrid2formwithdatagrid3.... These datagrid can be filled manually or with a selection list. I've written this selection list a a new form (frmSelectionList), witch is called with a SQL instruction, now this selectionlist calls a funtion in formwithdatagrid1 to return the selected value. Question:How can the same selectionform being used for all datagridforms?
[Code]...
I'm trying to convert C++ API to VB.Net, but this function is too hard and i don't know how make it work.
Here is the API doc for this function:
void RemoteDllSetReceiver(void *inst, on_received_buffer_t received_buf_cb);
Sets a callback function to receive notifications from the DLL. The prototype of the callback is:
typedef bool (*on_received_buffer_t)(void* inst, const unsigned char *buffer, unsigned int size);
Where inst is the pointer originally passed to RemoteDllSetReceiver buffer & size contain the notification text as defined in the Remote Protocol. Note: notifications may arrive in different threads (e.g. network, timer, audio).
I can't imagine what i mus do with on_received_buffer_t, must it be a delegate? Like you can read, this functions returns notifications from the DLL like connection status, user id...
I've used the async classes in the .NET framework several times but I've never tried to do something like that myself - I mean I've used background threads and made them invoke other methods on the UI thread loads of times but they have always been hard coded method names, not something where you can specify what method is invoked when the background thread is finished.
I'm writing the data access layer for my current project and I want to have all of the methods be asynchronous, so these methods in the DAL need to be able to 'call back' any method that is specified, rather than a specific method in the same project as I would normally do. This is how I have done it, and it seems to work, but I'm not sure that this is the best way or even close... Here is the signature of public method in my DAL that my programs call:
[Code]...
why my mciSendString callback isn't working?the app is a console app, with a nativeWindow msgHandler class.
here's the code:
Imports System.Windows.Forms
Public Class msgHandler
Inherits NativeWindow
[code].....
I have my application watching my desktop, pictures, music, and document folders.[code]What would I need to put into logrename() in order for it to automatically upload the renamed file onto my server?
View 5 RepliesI have been reading the async design patterns on MSDN and the general idea makes sense to me but in practice it is proving to be more difficult. I am working on a project utilizing VMWARE VIX.
HTML Code: [url]. Each function such as connecting to a host server, retrieving properties, etc. can be executed in two different ways.
Connecting to a host using a blocking Wait:
Code:
Dim m_lib As New VixLib
Dim m_hostJob As VixCOM.IJob
[CODE]...
Code:
Dim m_lib As New VixLib
Dim m_hostJob As VixCOM.IJob
dim m_callback as VixCOM.ICallback
[CODE]...
The problem with the VIX SDK is that sometimes the functions never return, hanging the application. dblock.
HTML Code:[URL] came up with a library that specifies a timeout value. When the timeout runs out the method aborts and returns regardless whether it finished or not.
The callback method is an active wait where the code continues to execute. What I want to implement is a blocking wait with a timeout. The ICallback interface has one sub OnVixEvent(IJob,Integer,IVixHandle). This method is fired at least twice, first when some progress is posted and second when it is complete. The first call to this method can be one second after registering the callback or 30 seconds, so I can not rely on this method to block the main thread. how to create some kind of async result class that would block the main thread from executing until either a timer runs out or the OnVixEvent method returns an Operation Complete signal that also implements ICallback.
I am creating a class ("Class B") which is used by another class ("Class A") which instantiates it in VB.NET 3.5.I would like Class B to read a value assigned to one of its properties by Class A every time an event happens in Class B.However, I would like this property value to be dynamically assigned to the property by Class A when the event is fired in Class B.I was thinking about somehow creating a delegate function in Class A that is linked to the property in Class B so that when the event is fired in Class B it would eventually invoke the delegate in Class A so that it returns a value to Class B.I've been reading around delegates (that's how I arrived at the idea), but I am stuck on how to code this up - could someone please help with some skeleton code?
View 1 RepliesI 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.
My thoughts are:
Private Function BeginConnect(ByVal URl As String, ByVal callback As AsyncCallback, ByVal state As Object) As IAsyncResult
'Some Code
[Code].....
I am using a function from a dll in unmanaged code that requires a callback to my managed code in Visual Basic 2010. The callback is asynchronous and is called continuously over the life of the application. What's the best way to protect the callback function from the garbage collector? Right now it is being collected after several dozen calls from the dll.
View 11 Replies
