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I have a client form that uses a remote object 'RemoteDataManager ' as follows:
RemoteDataManager r = new RemoteDataManager();
r.Test();
This works correctly, Test is executed like it should. However, this method takes a while to complete, so I'd like to make it a asynchronous call. So I tried:
RemoteDataManager r = new RemoteDataManager();
AsyncCallback RemoteCallback = new AsyncCallback(OurRemoteAsyncCallBack);
TestDelegate RemoteDel = new TestDelegate(r.Test);
IAsyncResult iar = RemoteDel.BeginInvoke(RemoteCallback, null);
This runs, but the Test method is never executed!
I don't know where to look for... does anyone have a clue?
Kind regards,
Ludwig
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If you're using .NET 1.1 and catching exceptions, it's possible you might have the same problem discussed earlier here[^]. Stepping through your code in the debugger might shed some light on your problem, too, because from what little you provided all I can say is that your code looks fine.
Microsoft MVP, Visual C#
My Articles
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Hi,
After two days I found out why it didn't work. Originally my config file contained:
<channels>
<channel ref="http">
</channels>
I changed it into:
<channels>
<channel ref="tcp">
</channels>
and all of a sudden the methods was also called asynchronously. I still don't know why, but it works now.
For your information, I wanted to use asynchronous calls because my remote method lasted 10 minutes to complete. I ran into another issue however, and I want to mention it here because it took me a while to find a solution. After 2 minutes or so, the thread was aborted on the server and my callback method was never called (the method was executed correctly though). So it worked, but I never got callback because the server thread ended. I solved this by dynamically increasing the script timeout that IIS uses:
System.Web.HttpContext.Current.Server.ScriptTimeout = 1800;
Now it works... but it was hard to find the solution 
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You realize that when you put the < and > characters into an HTML input field that they won't show up, right? Your XML for your .config file isn't visible. Please click "modify" on the bottom of your message and either escape these characters or click the "Do not treat <'s as HTML tags" check box right below the posting textarea. Note that any tags you use (like the <code> tag you put your last line between) will be escaped as well, so you'd best remove them.
Microsoft MVP, Visual C#
My Articles
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hi everyone,
i'm trying to create a small multiple choice quiz in a c# console application (within visual studio). has anyone done something similar and still has some of the code i could use to adapt to create mine?
thanks 
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(doesn't do any error checking)
<br />
class Question<br />
{<br />
string name;<br />
ArrayList choices;<br />
<br />
public Question(string name)<br />
{<br />
choices = new ArrayList();<br />
}<br />
<br />
public string Name<br />
{<br />
get { return name; }<br />
}<br />
<br />
pubic ArrayList Choices<br />
{<br />
get { return choices; }<br />
}<br />
}<br />
<br />
class Quiz<br />
{<br />
static void Main() <br />
{<br />
ArrayList questions = new ArrayList();<br />
Question q = new Question("What is your age?");<br />
q.Choices.Add("1-15");<br />
q.Choices.Add("16-50");<br />
q.Choices.Add("51-100");<br />
questions.Add(q);<br />
<br />
q = new Question("What is your sex?");<br />
q.Choices.Add("Male");<br />
q.Choices.Add("Female");<br />
<br />
foreach (Question qq in questions)<br />
{ <br />
Console.WriteLine(qq.Name);<br />
int pos=1;<br />
foreach (string choice in qq.Choices)<br />
{<br />
Console.WriteLine(pos.ToString() + ":" + choice);<br />
pos++;<br />
}<br />
<br />
string answer = Console.ReadLine();<br />
int answerNum = Int32.Parse(answer);<br />
<br />
Console.WriteLine("Your answer is: " + (string)qq.Choices[answerNum]);<br />
<br />
}<br />
}<br />
}<br />
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I followed your posts where you were looking for help with the C# code and this post on what you are trying to do.
First: you may find that your application is faster to develop and definitely much easier to use if you did it as a WindowsForm client or as a Web Client.
Second: you would want to write your application with the questions, multiple choices and the correct answer externalized. This way you can change questions, make question selection random, etc. without having to rewrite or rebuild your application.
Finally: present the data one question at a time with any other bells you want on your app.
So create a form and add a GroupBox to it from the tool box.
Decide the maximum number of choices (4?) then add that many radio button controls to the group box.
Above the group box put a label which will display the question.
Use the property pages to name everything.
Right click your project and Add New Item... and add a class named QuestionGetter.
In the class you will have the constructor code
public QuestionGetter()
{
}
In there you would establish your internal list of questions and choices. You may want to have an internal pattern to match your correct answers -- that way you calculate correct answers instead of having the correct answer laying around.
Then you need to add a button below the group box labelled Next and probably one for Exit.
In the Next button code
int i = 0;
foreach (RadioButton item in myGroupBox.Controls)
{
if (item.Checked == true) //user chose this answer
{
... calculate correct answer value
correctAnswer = recordNumber/4+1; //don't use this...too easy to break pattern
if (i == correctAnswer)
correct++;
else
wrong++;
break;
}
}
...read next question
if (GetQuestion()) // method returns true if all questions processed
{
string msg = String.Format("You got {0} answers correct.", correct);
string msg += correct>75?" You passed the exame.": " You failed.";
MessageBox.Show(this, msg);
Application.End();
}
question.Text = current.Question;
int i=0;
foreach (RadioButton item in myGroupBox.Controls)
{
item.Text = current.Choice[i];
item.Checked = false;
}
return;
_____________________________________________
Of all the senses I could possibly lose,
It is most often the one called 'common' that gets lost.
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My application uses sharpziplib to compress a directory, the system sits in the system tray awaiting another use.
If the applicaiton is restarted, no problems.
If the application is not shutdown and restarted, the application will double up on all of the files.
I have tried to debug this and found that most or all of the variables used in the creation of the ZIP file and reset.
Is there any other way to clear out the memory used and a funtion is performed ?
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OK, I am an official dumb@$$.
This had nothing todo with sharpziplib, I had an arraylist that was not getting cleared.
Although it took me all day, problem solved.
Thanks anyway if you were gonna try and help me out.
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In the future, if you believe a certain problem is with a product, you'd be better off asking in their forums (if possible). You can find more targetted advice and help with a particular product that way.
Microsoft MVP, Visual C#
My Articles
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I have figured out how to open a JPG file and then resize it. However, I cannot find out how to save the resized image to a different File.
Can someone give me an idea where to start? (I'm using C#)
Mr Mike
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Image.Save() method.
Mazy
You're face to face,
With the man who sold the world - David Bowie
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I've donwloaded the cool CheckBoxItem control discussed here:
http://www.codeproject.com/aspnet/DataGridCheckBox.asp
It works fine when I bind to a DataTable, but when I bind to one of my custom objects (A collection of type ProcessMap), which has a boolean property of Exists, I get the error: "Specified cast is not valid"
I tracked it to this line in the CheckBoxItem:
<br />
string data = ((DataRowView) container.DataItem)[dataField].ToString();<br />
Basicaly it is expecting a DataRow to bind to. I know that the usual datagrid columns can bind to a custom object, no matter what it is. Anybody have any idea how to do this?
Thanks eveyone!
Also, when I figure it out, how do I re-submit the code? Just email him a new version?
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The easiest way is to use the TypeDescriptor to get the properties and bind against the collection.
If want specific details of how the DataGridTextBoxColumn and DataGridBoolColumn work, you can use ildasm.exe (the IL Disassembler) that comes with .NET and view the IL (helps to understand Intermediate Language that is contained in assemblies), or use a good decompiler like .NET Reflector[^] to view the decompiled code (it's alright, but not always exact).
There's always good tips and tricks that the .NET developers use that can be handy to know.
Microsoft MVP, Visual C#
My Articles
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Excuse my ignorance, i'm quite a novice to programming
my problem is i can't get my program to find the appropriate window handle for it to hide/minimize when the game is in fullscreen.... it will do it fine in windowed mode (i use process.mainWindowHandle property), but after i fullscreen it (Even if i go back) it won't find the right handle again...
i've seen pieces of code using the FindWindow(string window class, string window name) method from the Windows API (user32.dll) but it will return something well out of the bounds of a window handle (way out of the bounds of an integer :p )
so i made a class that is derived from a process.. i added a method called ToggleState()
(note, hWND is also set to "this.MainWindowHandle" in the constructor of the class)
<br />
public void ToggleState()<br />
{<br />
<br />
if ( IsWindowVisible(hWND) != 0 )<br />
{<br />
this.hWND = (int) this.MainWindowHandle;<br />
ShowWindow(this.hWND, SW_HIDE );<br />
}<br />
<br />
else if ( IsWindowVisible(hWND ) == 0 )<br />
{<br />
ShowWindow(hWND, SW_RESTORE );<br />
SetForegroundWindow(hWND);<br />
}<br />
}<br />
In summary: if i launch the game in windowed mode, it will work indefinately, but then if i fullscreen it (or start in fullscreen) it will cease to function (even if i go back to windowed)
i've tried other alternatives, like creating a new process object and doing GetProcessByName and then getting the main handle of THAT (still no luck)
Thanks for your time anybody who reads this
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You really should read the .NET Framework SDK documentation, especially if you're just starting out. All controls in System.Windows.Forms already expose their window handles through the Handle property. And you don't need to P/Invoke ShowWindow - you just use Show and Hide (or set the Visible property accordingly). You can also control the full-screen behavior - as well as maximized, minimized, and normal states - all through the .NET Framework. Most of these classes just encapsulate the Windows APIs anyway.
If you're trying to do this for a separate process, things change. But judging by your code fragments, you're trying to do this to your own window. Is that correct?
Microsoft MVP, Visual C#
My Articles
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I used an ActiveX Object in my VB6 project like this:
obj = CreateObject("AAA.BBB");
When I tried to do the same thing in C# .Net project, I can't not find this object in "Add reference" dialog.
Does anyone know why?
Thanks in advance!
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Choose Add Reference and find it through COM tab, then you can create it like this:
yourobject obj = bew yourobject();
Mazy
You're face to face,
With the man who sold the world - David Bowie
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When you add an assembly reference (an interop assembly is created automatically for COM libraries), you must know in which library the COM object is contained.
To generate an ActiveX wrapper (known as a Runtime Callable Wrapper, or RCW) for this specific object, right-click on the toolbox and select Customize (or similar). Click the COM tab and find the control you're looking for. This generates a wrapper, which you can then use the new operator to instantiate. The typelib for that ActiveX control is converted to an interop assembly and automatically added to your project references.
.NET isn't VB6 - far from it. It's a type-safe runtime that manages memory and provides code access security, among many other things.
For more information on COM interoperability in .NET, see Interoperating with Unmanaged Code[^] in the .NET Framework SDK on MSDN Online, specifically the section Exposing COM Components to the .NET Framework[^].
Microsoft MVP, Visual C#
My Articles
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Thank you both very much, this is very helpful.
However I don't know which com dll I am using. Because this com dll is not provided for development purpose. It's registered by installing a specific software. I just happen to know this back door.
When I tried to find the same com in the COM tab in VS.Net, I can not find it. Then I went to my registry table, it didn't tell me which dll it's, it just showed like this under the CLSID folder: 'C:\program files\AAA\aaa.exe Automation'.
According to my understanding, VS.Net should be able to pick up the registered COM and show them in the COM tab.
Now I don't understand why in VB6 it is ok, but doesn't work in VS.Net. Is it because this COM doesn't register correctly?
Thanks in advance!
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That's a not a back door. Going into your registry and finding out which executable contains the component is what COM does anyway. That's how it works.
It appears that this COM component you want is actually an out-of-proc automation server. You should still have no problems using it, but you first need to use the write "COM tab", or just create it manually using tlbimp.exe. If you're looking to add a COM component, you need to use the toolbox customization dialog, not the project references dialog. That would be to add an entire typelib.
It would help if you knew where the typelib for this automation server is located. Sometimes they are embedded in the executable itself, and sometimes they are external files. You can easily use tlbimp.exe on that to create an interop assembly.
You should also read the links I gave you. Again, .NET is not VB6 and works a little differently under the covers when dealing with COM.
Microsoft MVP, Visual C#
My Articles
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Thanks again! I work it out with your help. It's a late-binding COM.
However another thing is I found late-binding in VS.Net is a bit more complicated than in VB6.
In VB6:
if com_obj.State.Result = com_obj.SUCCESS<br />
then<br />
.....
But In C#.Net, I have to do this:
object success = t.InvokeMember("SUCCESS", <br />
BindingFlags.Public |BindingFlags.GetProperty | BindingFlags.GetField, <br />
null, com_obj, null);<br />
<br />
object state = t.InvokeMember("State", <br />
BindingFlags.Public |BindingFlags.GetProperty | BindingFlags.GetField, <br />
null, com_obj, null);<br />
object result = result.GetType().InvokeMember("Result", <br />
BindingFlags.Public |BindingFlags.GetProperty | BindingFlags.GetField, <br />
null, state, null);<br />
if ( state.Equals(success) )<br />
....
Is it there any more convenient way in VS.Net to do the same thing?
Thanks in advance!
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Because of the fundamental architecture of COM and .NET interoperability. The code you're doing is essentially what the VB virtual machine does in the background using the IDispatch implementation of automation classes (it finds the method by the DISPID and invokes it with the specified parameters).
You shouldn't have to do this, though. If you create your interop assembly correctly, you just use the classes and methods from that. That's what the interop assembly is for - wrapping the COM control in a runtime-callable wrapper (RCW).
Again, read that link about exposing COM components to the .NET Framework I posted before. It's important to truly understand and not just accept the first thing that works. If you keep doing what you're doing, it'll take you forever to finish! Do it right and create and use the interop assembly.
Microsoft MVP, Visual C#
My Articles
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Hi,
I am working on an application which enumerates the shares from a remote computer and open it in explorer.
I have successfully got the names of the shares and now I am trying to open a directory lets say //station1/eBooks on the remote station1.
The behavior would be the same as typing //station1/eBooks on Run in Start Menu Or any other share scaner like shed. I have tried a new process for "explorer.exe" and passing the path as argument. It works fine for local shares but access denied instead of giving the login prompt for remote folders.
Anyone knows how to do it Plz reply. Thanks in advance.
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