Enterprise Services: InvalidCastException when calling a method - C# Discussion Boards

Ritesh Sompura2-Mar-04 7:01

2-Mar-04 7:01

Hi! Guys,

I am a learner and new to .NET Technologies. I am creating a small application and want to include a facility for Backup.

The problem is, how to create a wizard which will guide the user for creating backup of database. Like, it will ask for path to store backup, other filteration criteria for data to take backup etc.

One approach can be to create a frame for each step and display them as per the user's choice (Back / Next).

Is this approach proper? What are the other possible ways?

Please, send in your suggestions and / or comments regarding this problem.

Thanking you,

Ritesh.

Re: How To: Wizard for my Application

Heath Stewart2-Mar-04 9:16

Heath Stewart

2-Mar-04 9:16

The most common method is to use a form and swap controls. If you've done any decent Win32 programming with the provided property sheet interfaces, you could design your classes like that, so that each page can tell their parent what they support.

You should search CodeProject using the Search text box at the top, and even this forum using the "Search comments" link directly above the message area. This has been covered many times in the past and many solutions have been discussed.

Microsoft MVP, Visual C#
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Re: How To: Wizard for my Application

Nick Parker2-Mar-04 9:27

Nick Parker

2-Mar-04 9:27

riteshsompura@yahoo.com wrote:
The problem is, how to create a wizard which will guide the user for creating backup of database. Like, it will ask for path to store backup, other filteration criteria for data to take backup etc.

Read the following article: TSWizard - a wizard framework for .NET[^]

- Nick Parker
My Blog

Animation

hxxbin2-Mar-04 6:55

hxxbin

2-Mar-04 6:55

Hi
I need to put a animation into my app, but I was wonderind what it's better use single frames and swap them with a timer or use a gif or avi directly (it's possible with .NET?)

Thanks

----
hxxbin

Re: Animation

Heath Stewart2-Mar-04 9:13

Heath Stewart

2-Mar-04 9:13

Depends on the quality of the animation and whether or not you want to require additional dependencies.

You could use a PictureBox to show an animated GIF, but GIFs only display 256 colors and don't support an alpha channel.

If you want to display an AVI or other video file, you could host the Windows Media Player control and hide its UI. Windows also contains an older version of this control but you may have problems finding information about it.

Another option is to use DirectX, for which there is now a managed runtime (aptly named Managed DirectX (9.0b)).

Finally, you could always use a timer and loop frames (basically what a GIF does). You can use a higher quality image this way, but your FPS are limited by the relatively low resolution of the timer classes in the .NET Framework.

Again, it all depends on what you want and how many dependencies you're willing to require.

Microsoft MVP, Visual C#
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Re: Animation

hxxbin3-Mar-04 4:03

hxxbin

3-Mar-04 4:03

The animation is little, but needs 24-bits color and alpha. I think I'll use the timer cuz I don't know how to use DirectX, I imagine that with DirectDraw2D I could do it, but I don't know how, you know some good info about??.

Thanks

----
hxxbin

Re: Animation

Heath Stewart3-Mar-04 5:55

Heath Stewart

3-Mar-04 5:55

http://msdn.microsoft.com/directx[^]

Microsoft MVP, Visual C#
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Enterprise Services: InvalidCastException when calling a method

Le centriste2-Mar-04 5:45

Le centriste

2-Mar-04 5:45

When I call method from a custom ServicedComponent object from ASP.NET, I get the following exception:

? 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidCastException: ?

Note the question mark as the exception message.

Here is the stack trace:

InvalidCastException: ?]
   System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) +264
   System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) +877
   MyCOMPlusApp.MyInterface.MyMethod(String s1, String s2)
   Intermediary method calls
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +108
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +57
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +18
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33
   System.Web.UI.Page.ProcessRequestMain() +1277

The return value is a string.

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Re: Enterprise Services: InvalidCastException when calling a method

Heath Stewart2-Mar-04 6:55

Heath Stewart

2-Mar-04 6:55

This information doesn't help at all. Stack traces are only helpful if you know the code that adds to the call stack. Since you provided none, it's pretty hard to help you. Why don't you provide some code in your Click event handler or something?

Microsoft MVP, Visual C#
My Articles

Re: Enterprise Services: InvalidCastException when calling a method

Le centriste2-Mar-04 8:05

Le centriste

2-Mar-04 8:05

I thought this information could ring a bell on what may be a well-known issue. The problem is that I cannot post code because it is proprietary code. I will try to make an example with which i can reproduce this problem.

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Re: Enterprise Services: InvalidCastException when calling a method

Le centriste2-Mar-04 8:40

Le centriste

2-Mar-04 8:40

I have more information, now I have a message instead of the question mark:

System.InvalidCastException: QueryInterface for interface MyApplication.IMyInterface failed

Here is how the Serviced component object is declared:

namespace MyApplication
{
	[SecurityRole("MyAppClients")]
	public interface IMyInterface
	{
		string MyMethod(string s1, string s2);
	}

	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	[ConstructionEnabled(true, Default="Server=(local);trusted connection=yes")]
	[Transaction(TransactionOption.Supported)]
	[ComponentAccessControl(true)]
	[SecurityRole("MyAppClients")]
	//[SecureMethod]
	public class MyClass: ServicedComponent, IMyInterface
	{
		private string connectionString = String.Empty;

		public MyClass()
		{
			//
			// TODO: Add constructor logic here
			//
		}
	
		protected override void Construct(string s)
		{
			this.connectionString = s;

			base.Construct(s);
		}
	
		#region IMyInterfaceimplementation

		public string MyMethod(string s1, string s2)
		{
			// TODO:  Add DataAccess.GetLogonToken implementation
			return "My String";
		}

		#endregion
	}

When the application is registered in COM+, I add the MYMACHINE\ASPNET user to the role.

Here is how it is called from the Asp.NET client:

IMyInterface myInterface = new MyClass();

string aString = myInterface.MyMethod("s1", "s2"));

The exception is thrown at the second line.

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Re: Enterprise Services: InvalidCastException when calling a method

Heath Stewart2-Mar-04 8:57

Heath Stewart

2-Mar-04 8:57

It's just a hunch since I don't have a lot of experience writing serviced components in .NET, but I have and do work a lot with COM interoperability. When exposing types to COM (as CCWs), you should follow the "rules" of COM, such as attributing your interfaces and classes with the GuidAttribute to give them specific IIDs and CLSIDs. These GUIDs and the interface declarations should never change after being published.

Since your QI is failing to get the interface, I'm figuring it's because the IID can't be resolved. When registering, this GUID is generated automatically unless explicitly specified.

I hope this helps.

Microsoft MVP, Visual C#
My Articles

Re: Enterprise Services: InvalidCastException when calling a method

Nick Parker2-Mar-04 9:14

Nick Parker

2-Mar-04 9:14

Michel Prévost wrote:
IMyInterface myInterface = new MyClass();string aString = myInterface.MyMethod("s1", "s2"));

You should make sure you your cast were successful. I am not sure why it is failing but you definitely want to perform some error checking:

IMyInterface myInterface = new MyClass();
if(myInterface != null)
   string aString = myInterface.MyMethod("s1", "s2");

- Nick Parker
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TextBox for number

Amirjalaly2-Mar-04 5:31

Amirjalaly

2-Mar-04 5:31

Hi I want to create a text box only for number
i create a user control that inherits from textbox
and override onkeypress to enter only number
but i can't do it . I try with processKeyMessage but i can't again

is nobody can help me.

Regards' Amirjalaly

Re: TextBox for number

Heath Stewart2-Mar-04 6:52

Heath Stewart

2-Mar-04 6:52

What can't you do? Please be more specific. A simple example using OnKeyPress would look like:

public class NumericTextBox : TextBox
{
  // ...
  protected override void OnKeyPress(KeyEventArgs e)
  {
    if (e.KeyCode < Keys.D0 || e.KeyCode > D9 ||
        e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
      e.Handled = true;

    base.OnKeyPress(e);
  }
}

You can do this by overriding ProcessDialogChar or ProcessDialogKey as well.

Microsoft MVP, Visual C#
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Re: TextBox for number

Werdna3-Mar-04 5:18

Werdna

3-Mar-04 5:18

The problem with this approach is that it doesn't stop anyone from pasting a string, and this will block Backspace key as well. It will also not accept decimal numbers.

I needed a numeric text field control a while ago, and I thought it would be as simple as overriding OnKeyPress, but there is more to it.

Re: TextBox for number

Heath Stewart3-Mar-04 5:58

Heath Stewart

3-Mar-04 5:58

You can change the sample to accept backspace, delete, and the decimal point. In order to validate pasted text, override OnTextChanged or OnValidating. It's possible to do what you need, you just have to override the right methods as necessary.

Microsoft MVP, Visual C#
My Articles

Re: TextBox for number

Stefan Troschuetz3-Mar-04 8:29

Stefan Troschuetz

3-Mar-04 8:29

Try this one:

private void textBox_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
this.validValue = this.Text;
}

private void textBox_TextChanged(object sender, System.EventArgs e)
{
try
{
int.Parse(this.Text);
}
catch (System.FormatException)
{
this.Text = this.validValue;
}
}

Re: TextBox for number

indranilbanerjee31-Mar-04 4:45

indranilbanerjee

31-Mar-04 4:45

Almost...

private void textBox_TextChanged(object sender, System.EventArgs e)
{
try
{
if(this.Text.Length > 0)
int.Parse(this.Text);
this.validValue = this.Text
}
catch (System.FormatException)
{
this.Text = this.validValue;
}
}

Re: TextBox for number

Stefan Troschuetz31-Mar-04 5:20

Stefan Troschuetz

31-Mar-04 5:20

Interesting, I will consider this in my application.
Never needed to look for an empty string, because all my TextBoxes, i use this for, have default values. But better be prepared for all cases Smile | :)

By the way, what happens, if the Parse method is called with a string with Length = 0?

Re: TextBox for number

indranilbanerjee31-Mar-04 22:02

indranilbanerjee

31-Mar-04 22:02

int.Parse throws a FormatException when given a zero length string so that check is definitely necessary (at least it is for my application)

how to assigning a Drive to a Share ?

zoltix2-Mar-04 5:22

zoltix

2-Mar-04 5:22

how to assigning a Drive to a Share in c#?

Currently, i try the API for make that but he don't run....
Could you help me ?

public enum ResourceScope
{
RESOURCE_CONNECTED = 1,
RESOURCE_GLOBALNET,
RESOURCE_REMEMBERED,
RESOURCE_RECENT,
RESOURCE_CONTEXT
};

public enum ResourceType
{
RESOURCETYPE_ANY,
RESOURCETYPE_DISK,
RESOURCETYPE_PRINT,
RESOURCETYPE_RESERVED
};

public enum ResourceUsage
{
RESOURCEUSAGE_CONNECTABLE = 0x00000001,
RESOURCEUSAGE_CONTAINER = 0x00000002,
RESOURCEUSAGE_NOLOCALDEVICE = 0x00000004,
RESOURCEUSAGE_SIBLING = 0x00000008,
RESOURCEUSAGE_ATTACHED = 0x00000010,
RESOURCEUSAGE_ALL = (RESOURCEUSAGE_CONNECTABLE | RESOURCEUSAGE_CONTAINER | RESOURCEUSAGE_ATTACHED),
};

public enum ResourceDisplayType
{
RESOURCEDISPLAYTYPE_GENERIC,
RESOURCEDISPLAYTYPE_DOMAIN,
RESOURCEDISPLAYTYPE_SERVER,
RESOURCEDISPLAYTYPE_SHARE,
RESOURCEDISPLAYTYPE_FILE,
RESOURCEDISPLAYTYPE_GROUP,
RESOURCEDISPLAYTYPE_NETWORK,
RESOURCEDISPLAYTYPE_ROOT,
RESOURCEDISPLAYTYPE_SHAREADMIN,
RESOURCEDISPLAYTYPE_DIRECTORY,
RESOURCEDISPLAYTYPE_TREE,
RESOURCEDISPLAYTYPE_NDSCONTAINER
};

public class ServerEnum : IEnumerable
{
enum ErrorCodes
{
NO_ERROR = 0,
ERROR_NO_MORE_ITEMS = 259
};

public class ServerEnum : IEnumerable
{
enum ErrorCodes
{
NO_ERROR = 0,
ERROR_NO_MORE_ITEMS = 259
};

[StructLayout(LayoutKind.Sequential)]
private class NETRESOURCE
{
public ResourceScope dwScope = 0;
public ResourceType dwType = 0;
public ResourceDisplayType dwDisplayType = 0;
public ResourceUsage dwUsage = 0;
public string lpLocalName = null;
public string lpRemoteName = null;
public string lpComment = null;
public string lpProvider = null;
};

[DllImport("Mpr.dll", EntryPoint="WNetAddConnection2", CallingConvention=CallingConvention.Winapi)]
private static extern ErrorCodes WNetAddConnection2(NETRESOURCE lpNetResource,ref string lpPassword,ref string lpUsername, System.UInt32 dwFlags );

public void connectMapDrive(){
NETRESOURCE lpNetResource = new NETRESOURCE();

lpNetResource.dwType =ResourceType.RESOURCETYPE_ANY;
lpNetResource.lpLocalName="O:";
lpNetResource.lpRemoteName= @"\\Bruxptest\Fichiers" ;
lpNetResource.lpProvider = "";

string lpPassword ="PASSWORD**" ;
string lpLocalName =@"bruxptest\ll2";

ErrorCodes rc = WNetAddConnection2(lpNetResource,ref lpPassword,ref lpLocalName,0x01);

}
}

-=zoltx=-

Re: how to assigning a Drive to a Share ?

Heath Stewart2-Mar-04 6:47

Heath Stewart

2-Mar-04 6:47

First, you didn't describe any errors or what exactly the problem was. It's very hard to help you when you don't mention specific problems.

Second, why not make this easier:

string drive = "X"; // Or whatever
string share = @"\\machine\share"; // Or whatever
Process.Start("net.exe", string.Format("use {0}: {1}", drive, share));

You could easily add switches for a username and password, too. Type "net use /?" in the command prompt for more information.

If you'd rather do this programmatically, then please be more specific about the nature of your problem.

Microsoft MVP, Visual C#
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Re: how to assigning a Drive to a Share ?

zoltix2-Mar-04 12:44

zoltix

2-Mar-04 12:44

sorry,
I would like to make a windows service which able to check and map the shared drive automatically. When i launch my api for that, I receive a error message 2202: ERROR_INVALID_WINDOW_STYLE

the equivalence in c++ is :

#include <windows.h>
#include <stdio.h>
#include <winnetwk.h>

void main()
{
NETRESOURCE nr;
DWORD res;
TCHAR szUserName[32] = "MyUserName",
szPassword[32] = "MyPassword",
szLocalName[32] = "Q:",
szRemoteName[MAX_PATH] = "\\\\products2\\relsys";
//
// Assign values to the NETRESOURCE structure.
//
nr.dwType = RESOURCETYPE_ANY;
nr.lpLocalName = szLocalName;
nr.lpRemoteName = szRemoteName;
nr.lpProvider = NULL;
//
// Call the WNetAddConnection2 function to assign
// a drive letter to the share.
//
res = WNetAddConnection2(&nr, szPassword, szUserName, FALSE);
//
// If the call succeeds, inform the user; otherwise,
// print the error.
//
if(res == NO_ERROR)
printf("Connection added \n", szRemoteName);
else
printf("Error: %ld\n", res);
return;
}

and it is work?

-=zoltx=-

Re: how to assigning a Drive to a Share ?

Dave Kreskowiak2-Mar-04 13:25

Dave Kreskowiak

2-Mar-04 13:25

Are you running the app as the LOCAL SYSTEM account or as a user? Also, you have to tag the service as able to interact with the desktop.

RageInTheMachine9532

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