Handling Task Factory Exceptions?
Apr 18, 2011
I have set up a process to create new tasks to handle file processing. A problem arised where I received and unhandled exception error and just clicking on the continue button, the main process continued to run. Now I also found that within the child task I was having a file conflict error and as the tasks run as separate .exe i was under the impression that everything would have been thread safe. So for the first issue here is the task creation in the main process..GProcess is a complete project on its own consisting of 6 classes. This is added as a class library reference to the main process class form1
Public Class Form1
..Private parser as GProcess.module = new GProcess.module()
dim factory as new taskfactory
[code].....
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Feb 2, 2010
Using vs2008, vb.net, C#, fw 3.5
I am consuming my service in my client
Service is hosted in IIS
Client(winforms MDI) is generated using svcutil using /l, /r, /ct, & /n switches
Service and client both use a MyEntities.dll
I am using nettcp with TransportWithMessageCredential. I cache the proxy in the main form
if Membership.ValidateUser(UsernameTextBox.Text, PasswordTextBox.Text)
_proxy = new MyServiceClient
_proxy.ClientCredentials.UserName.UserName = "username"[code].....
Could I subscribe to the _proxy.InnerChannel.Faulted and do that clean up there?
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Jun 13, 2011
I am trying to start a new thread in VB.Net and having syntax problems.In C# this is we can do the same task using
var manualResetEvent = new ManualResetEvent(false);
waitHandles.Add(manualResetEvent);
var taskOne = Task.Factory.StartNew(() => new Thread(TaskToRun).Start(manualResetEvent));[code]....
where TaskToRun is a void method with a single object parameter.All online converters generate similar code to this
Dim manualResetEvent = New ManualResetEvent(False)
waitHandles.Add(manualResetEvent)
Dim taskOne = Task.Factory.StartNew(Function() New Thread(AddressOf TaskToRun).Start(manualResetEvent))
taskOne.Wait()
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Jun 2, 2009
All of us use the try catch blocks. But what is the best way of handling errors within custom functions?Display a messagebox to the user when the exception is thrown (if possible within the function), or return a value indicating that an error was found within the function?
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Aug 29, 2011
How does one handle unhandled exceptions in a DLL? VS doesn't give me the option to add Application Events, I'm guessing because it's a DLL. Do I just have to do it in the main app?
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Sep 29, 2010
This was a difficult question to google. I have an Order class with a couple of dozen properties such as ClientReference, ShipMethod, etc. I use databinding to bind this class to an Order form. If a user enters an invalid shipping method, an exception is raised in the ShipMethod property and a validation error is displayed to the user. But I'm trying to use the same Order class within an OrderImport class whose job it is to take a flat file and create multiple orders. The problem occurs if I'm assigning to a dozen of the order fields consecutively, and say the first one causes a validation exception. If I have all dozen assignments occuring within a single try-catch block, the next 11 assignments will be skipped and I'll only be able to record one validation error. I could solve the problem by doing a dozen separate try-catch statements, but that doesn't seem very elegant.
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May 21, 2010
What are some of the most common mistakes you've seen made when handling exceptions?It seems like exception handling can be one of the hardest things to learn how to do "right" in .Net. Especially considering the currently #1 ranked answer to Common programming mistakes for .NET developers to avoid? is related to exception handling.
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Apr 28, 2012
When two computers are connected through TCP, and one of them closes and breaks the connection, it throws error 10054 "Remote host forcibly closed the connection".I want to handle this error because I know it will happen more often than not with the application I'm building. In System.Net.Sockets.SocketException, there is an on the error code. But when I run the program, the exception that is being thrown is System.IO.IOException, and the GetType for IOException is the socket exception. I don't know how to handle the socket exception if it's not the root cause of the exception.
Here is the code for my Try Catch block:
For infiniteCounter = 1 To 2
infiniteCounter = 1
[code].....
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May 18, 2010
If any directory within a set being searched by the [URL] or [URL] methods contains a junction point, the entire method fails and returns zero results on my tests under VB 2008. I would like to make the call more robust: to return the folders or files not blocked by access restrictions and to note the folders which were blocked. Do those methods offer a means to do this, or is a recursive folder-by-folder call necessary?
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Oct 21, 2009
So I've made this control that inherits from the treeview control and basically loads objects from active directory into a treeview (url...).All working fine, but as this is the first custom control I have made that I have intended for other people to use, I'm not quite sure how I should approach error handling.I mean, obviously I shouldnt do something like show any exceptions in a messagebox because that might not be what the person that is using the control wants to happen. So do I just write out exception messages to the debug window? Do I swallow exceptions (guessing not)? Do I just totally ignore them so that they are thrown in the user's project?
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Jun 8, 2010
i created a Class library (.dll) and loaded it as reference into a main project. In the code for the class i've handled exceptions using try..catch subs, however when debugging the main project exceptions that are handled in the DLL still get thrown! (the class ".vb" file gets loaded into the debugger and the line of the exception shows up)
Up till now i've found it useful that when an unhandled error occurs in the imported reference, it shows up in the main project with tracing back to the referenced class. But i dont want the exceptions that are handled in the reference class to be thrown when debugging the main project!
As you can see the exception thrown was handled with try...catch this class exception.vb belongs to the project that created the class library (.DLL that i referenced). i didnt even load the project that built the reference so it amazes me that it could find the coding class to begin with.
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May 24, 2010
I'm using task.factory to make threads and start having the "Cross-thread operation not valid" error when trying to update the main form.I search for this error and tried some examples of code, using delegate for example, but all result in some deadlock.
[Code]...
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Sep 28, 2011
I am writing a class library that envelopes an USB device driver. This device has its own class library, provided by the hardware vendor.
Very often, especially if you handle with old DLL or COM assemblies, there are methods (functions to be correct) that return TRUE if all was OK, or FALSE if any error happen. Often these methods return information about the error in one of their parameters or separately in a GetLastError method or even if in an OnError event.
Now, normally I handle all native .NET exceptions in my class libray handling locally or re-throwing to the client if the error is useful to know. But what to do with all other errors that are hidden in the vendor's methods? (in the true I have no exceptions, but only returned TRUE or FALSE values).
Let's make an example with the method "CONNECT" that connect the client to the USB device.
I envelope the method in this way:
Public Sub Connect()
oVendorDevice.connect()
End Sub
now if any connection error happen, the vendor's connect method return FALSE. But I do not know why the connection failed. To know why the connection failed I have to call (for example) the method GetLastError that gives me information about the error. (but do not forget that other vendors use other strategies like returning the error in a method's parameter or in a OnError events.
Now, in order to follow a good .NET exception handling strategy I could write something like this:
Public Sub Connect()
Dim res As Boolean = oVendorDevice.connect()
If res = False Then
[Code].....
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Jun 3, 2011
So I wrote a VB.net project in Visual studio.I have a scheduled task that is set to run the program every morning at 10AM. If I use windows explorer and double click the application, it runs fine.If I open task scheduler, open the task properties, and browse to the application, then choose run, the program fails, due to Runtime exceptions.I know I have the path entered correctly, since I can debug the instance when it crashes from the task scheduler. VS2010 pulls up my source code.The exception is System.IO.FileNotFoundException, remember, it works fine when I double click the app. If attach a debugger to the process after it is executed from the task scheduler, I can then restart the debugger, and Voila!, The application runs fine.
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Sep 23, 2010
Part of my assignment is to check if input to Group Number and Number of Units are correct input by making error handling exceptions...
I have to check the following:
a) group number is neither 501 nor 062
b) number of units are NOT numbers
c) number of units is NOT a positive number
So my first question is, am I checking correctly? 2nd question is, How do I make sure my Exceptions will pertain to their correct respective things (a, b, and c.. above)?
[Code]...
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Dec 26, 2009
I've just skipped around a few inbuilt VB classes' methods which throws exception. of all that i've came across, methods may throw multiple exceptions but ALL of them are exclusive, meaning there is no way 2 exceptions will ever occur simultaneously, yea and i was trying to make my class throw 2 exceptions simultaneously, hence this question, must all exceptions be exclusive?
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Nov 24, 2010
is it guaranted that a task A started before TaskB will be completed before task B assuming the task do the same level of operatons?or in other words is there a chance that a task B will finish before tast A in the assumption that the task calls the same procedure?
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Jun 22, 2009
when should a trigger in your head go off signifying "Aha! I should use the factory pattern here!"? I find these moments will occur with many other design patterns, but never do I stop myself and think about this pattern.
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Jul 3, 2009
First the requirements: By management requirements, I can't use open source code. I need the users to define their own formulas for a project. My users don't know how to code. The formulas need to be saved somehow, and being read later. I need to debug the formulas written, so I need to be able to see and understand them. The formulas used are quite specialized and specific (actuarial formulas). Adding new formulas (functionality) must be done in fast and maintainable way.
[Code].....
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Sep 20, 2011
In Motorola MC55, I'd like to get the factory or unique id or serial no of the scanner. How to code it in vb.net?
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Feb 22, 2011
I have integrated the innovative gateway (third party payment gateway) into our asp.net ( language vb.net) web application. while doing transation we are getting the following error in server.
Server Error in '/' Application.
Retrieving the COM class factory for component with CLSID {7A1284E2-7E00-46B5-8440-FC28305E6A27} failed due to the following error: 80040154.
But in my localhost am getting the failure transaction without getting any error.
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Mar 30, 2012
I have written a base class from which I wish to derive several child classes (in this case Windows Form classes), and I'm using a Factory pattern in order to maintain a collection of the child instances, so that a form can only have one instance per primary key value. (sort of a mash-up of Factory and Singleton patterns.)
I'm using the following code in the base form class[code]...
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May 6, 2011
I tried this one...but its not working.[code]...
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Feb 12, 2011
How would I change this code to make the factory dynamic. I believe I was close with remoting. I don't want any hardcoding of the factory, nor do I want to have to recompile. The database drives it.
Dim genericRule As Rule
Dim factoryObject As String
factoryObject = _dal.GetFactoryObject(ruleId)
[code]....
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Sep 26, 2006
I have a VB.NET application that references a 3rd party Com component. The file is Interop.WINTSRRLIB.dll. My VB.NET application has a project reference to the COM comonent which lives in the directory: C:WaveTracker. The application runs fine. When I sent it to my customer, he installed in on his desktop machine. It runs fine. Then he copied all of the application files (which live in C:WaveTracker) to his laptop. However, on his laptop, he gets the error:
"System.Runtime.InteropServices.COMException (0x80040154). Retrieving the COM class factory for component xxxx failed due to the following error: 80040154" The customer swears he has the .NET 2.0 Framework installed properly on his laptop. Any ideas on how I can get over this problem???
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Jan 27, 2010
Whenever I try to create a new CD object I get a stack overflow. I want a parameter to be passed into mediaFactory so that it could be determined what type of media is created. Why I might be having problems with this when I do this
"Dim media As CD = New CD()"
Public MustInherit Class MediaFactory
Inherits MediaContext
Implements IMedia
Public Sub New(ByVal typeId As Integer)
[Code] .....
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Feb 4, 2011
I am having a problem with a SQL server query giving a timeout error. I read about setting the timeout value of the command object but in my DAL, I do not see how to do that. Here is how I create the command object
Public Sub Init()
If ConnString = "" Then
Select Case ConnStringID
[Code]....
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Apr 30, 2009
Is it possible to prevent compiler warning caused by a static factory method returning an instance of an obsolete class? For example if an instance of an obsolete class (Foo) is created through a static method (Create) a compiler warning is caused by the factory method.
<Obsolete()> _
Public Class Foo
Public Shared Function Create() As Foo
[code]....
In C# the warning could be suppressed using "#pragma warning..." but I don't think that this exists within VB.Net. Migrating to C# is not an option due to business requirements.
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Jan 21, 2011
Is it possible to prevent compiler warning caused by a static factory method returning an instance of an obsolete class? For example if an instance of an obsolete class (Foo) is created through a static method (Create) a compiler warning is caused by the factory method.
<Obsolete()> _
Public Class Foo
Public Shared Function Create() As Foo
[code]....
In C# the warning could be suppressed using "#pragma warning..." but I don't think that this exists within VB.Net. Migrating to C# is not an option due to business requirements.
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Aug 12, 2009
I found a lot of information about how to make a database factory or how to deal with connection pooling but i nowhere found a complete solution.I have always used my own solutions, but they're not complete i think or could be improved.Are there some good designed classes any of you use that i can find on the net?
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