C# Discussion Boards - CodeProject

18-Feb-03 16:20

I'm just starting out with C# and I'm following one of the Microsoft walkthroughs for creating a distributed application.

It involves IIS, SQL server and a windows client and a web client.

The windows client works fine, but the web client just times out so I was poking around trying to find out what's going on because there are no obvious problems (aka I don't know really what to look for Big Grin | :-D

).

Anyway, the question I have is when I switch to HTML view for my web form, the first line of xml code is highlighted in yellow, the line is (not broken in the original, just one line):
<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="WebApplication1.WebForm1" %>

Is this to indicate an error or parsing problem of some kind or....?

The full code for the form is this:

<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="WebApplication1.WebForm1" %><br />
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" ><br />
<HTML><br />
	<HEAD><br />
		<title>WebForm1</title><br />
		<meta name="GENERATOR" Content="Microsoft Visual Studio 7.0"><br />
		<meta name="CODE_LANGUAGE" Content="C#"><br />
		<meta name="vs_defaultClientScript" content="JavaScript"><br />
		<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5"><br />
	</HEAD><br />
	<body MS_POSITIONING="GridLayout"><br />
		<form id="Form1" method="post" runat="server"><br />
		</form><br />
	</body><br />
</HTML>

Furty18-Feb-03 16:27

Furty

18-Feb-03 16:27

It's 100% normal for it to be highlighted yellow. The yellow highlighted lines in asp.net pages are lines that specify the backend library for the page.

Member 9618-Feb-03 16:40

18-Feb-03 16:40

Thank you Furty. That rules that out as pointing to the problem.

I guess I'm going to have to do some digging to figure out how to debug a web application.

Thanks again

Atul Kale19-Feb-03 7:19

Atul Kale

19-Feb-03 7:19

Hi there,
I just thought this information might be useful to u! Though from ur mail it sounded like u r just beginning ASP.NET, I would not try and offend u by giving some information that u already know! If it helps, GREAT!

Debugging a web Application fortunately is much better in VS.NET than it was in InterDEV with ASP.

A process named ASPNET_WP.exe runs on the machine within which your ASP.NET (C# or VB.NET) code is debuged.

If your solution contains several projects, just set up any of the desired projects as a Startup Project from the Context menu, and any of the aspx pages as the startup page.

If your machine's config is very good, you will go for this traditional debugging approach which is good too!
But, there is a better approach wherein, you just open any desired page in the Browser, and at any point of time Go into Debug mode by Attaching to the ASPNET_WP.exe process from Tools->Debug Processes menu option. just go ahead with the default options while doing this.

Hope htis helps a bit! Smile | :)

Atul kale
Sr. Software Engineer
XcelVision Technologies Ltd.

Member 9619-Feb-03 12:12

19-Feb-03 12:12

Hi Atul, that information is extremely helpful, thank you very much!

Cheers!

David Stone19-Feb-03 12:02

David Stone

19-Feb-03 12:02

Are you debugging remotely or locally?

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Member 9619-Feb-03 12:16

Re: cryptography question

19-Feb-03 12:16

Hi David, I'm debugging remotely if you consider the computer sitting 6 inches to the left of my development system remote.

From what I understand (and have done) since reading Atul's message is that you can debug locally if you have installed VS.NET after you installed IIS etc as it adds debugging support, however, as in my case, you need to run the STEP 1 of the vs.net setup on the remote IIS server, then do STEP 2 of the VS.NET setup selecting only the server / remote debugging components which takes care of all that. (it's in the readme file for VS.NET installation).

(Although you may already know all this;))

cryptography question

jtmtv1818-Feb-03 14:23

jtmtv18

18-Feb-03 14:23

i have set up a new member of the RC2CryptoServiceProvider. im trying to enhance the security of my program further by generating a random saltbyte using the RNGCryptoServiceProvider class. it works fine to generate the random file in a byte using the following code :

byte[] random = new Byte[100];<br />
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();<br />
rng.GetBytes(random);

my question is...i can encrypt with this method and random salt bytes...but since they are random how can i call apon them when decrypting ? if you dont decrypt with the same bytes then you get a encryptiong "bad data" error. how can i safely get the bytes used for encrypting to my decryptiong method.

im trying my best to make a clear question out of this problem if it wasnt clear enough let me know and ill try to clearify.

thanks alot,

Jesse M

P.s furty i know you know the awnser...

The Code Project Is Your Friend...

Furty18-Feb-03 16:09

Furty

18-Feb-03 16:09

The simplest way would be to have a fixed salt byte array of course, however the next easiest option would be to write the salt bytes to your filestream when encrypting, and read them back when decrypting.

Encryption:

FileStream fs = File.Create(filename);<br />
byte[] salt = new byte[16];<br />
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();<br />
rng.GetBytes(salt);<br />
fs.Write(salt, 0, salt.Length)<br />
<br />
// PasswordDeriveBytes and do your encrypting..

Decryption:

FileStream fs = File.OpenRead(filename);<br />
byte[] salt = new byte[16];<br />
fs.Read(salt, 0, salt.Length)<br />
<br />
// PasswordDeriveBytes and do your decrypting..

While this is certainly not the best method of doing it, it will work fine. Ideally your salt bytes would also be encrypted, so as not to weaken the basic thing they're about. But then again, your IV should be unique and encrypted too, and you should be using a keyed checksum, and etc etc.. OK, I'll write an article and put together a wrapper for it all *when* I get a few hours free time.. For now this will get you by Smile | :)

Re: cryptography question

jtmtv1818-Feb-03 16:57

jtmtv18

18-Feb-03 16:57

thanks alot for the help...i will use a filestream...write the salt bytes...then encrypt the salt bytes....so on so forth.....or i guess i could just make a dll to do it for my program too....

The Code Project Is Your Friend...

Passing various Controls by ref

draco_iii18-Feb-03 10:56

draco_iii

18-Feb-03 10:56

How can Controls(Buttons, Panels, etc..) be passed by referenece without making an overload for each type of Control. When trying to pass a button control an error is recieved of :

cannot convert from 'ref System.Windows.Forms.Button' to 'ref System.Windows.Forms.Control'

Trying to cast this does not work, and as said before making an overload for each control type seems a little massive. Every control made after this will have to be added to the code and then recompiled.

Nnamdi Onyeyiri18-Feb-03 11:29

Nnamdi Onyeyiri

18-Feb-03 11:29

have you tried boxing the button to a control when you call the method?

MyMethod(ref (Control)myButton);

1001111111011101111100111100101011110011110100101110010011010010
Sonork | 100.21142 | TheEclypse

Kannan Kalyanaraman18-Feb-03 19:00

Kannan Kalyanaraman

18-Feb-03 19:00

There should be someother way of doing it(something seems to be wrong here, but I couldn't figure out), but did you try passing ref Object

Cheers,
Kannan

leppie18-Feb-03 23:14

leppie

18-Feb-03 23:14

Why why why? object is by ref all ready!

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Richard Deeming19-Feb-03 0:49

Richard Deeming

19-Feb-03 0:49

First, you only need to pass an object by reference if you are changing the object reference. If you're only changing properties or calling methods on the object, you should pass it by value.

When you pass a variable by reference (ref Parameter or out Parameter), the variable type has to match precisely. For example, the following code would attempt to assign a Textbox to a Button variable:

void Test(ref Control c)
{
    // Change the object reference
    c = new Textbox();
}
...
Button b = myButton;
Test(ref b);

The simplest way to pass an object by reference to a function which expects a base class is to use a temporary variable of the correct type. Downcast the actual object, call the function, and then try to upcast the variable back to the object:

Control temp = (Control)myButton;
Test(ref temp);
myButton = (Button)temp;

In this case, if anything other than a Button (or a class derived from Button) has been assigned to the reference variable, you will get a runtime error.

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A tough design decision

Chris Austin18-Feb-03 8:28

Chris Austin

18-Feb-03 8:28

Hey folks,

I am working on a multi-threaded windows app and I have run into a bit of a design snag. I’d like to follow a MVC type of design as much as possible; so I want to separate all of the business and event handling logic from the form.

To do this without passing references to controls and forms all over the place, it looks like a Mediator is the sure fire way to go. But, the downside of the classical Mediator is that all the controls must extend (or implement) a “Colleague” base class in order to be aware of the Mediator. I really don’t want to have to subclass every possible control that I might use.

Does anybody have some insight to share on this one? Is there another approach that I am missing?

[edit]
An idea I have is to implement the Mediator using an Observer to force the UI to update in response to events.
[/edit]

TIA
Chris

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I have spread my dreams under your feet;
Tread softly, because you tread on my dreams.
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Philip Fitzsimons19-Feb-03 1:55

Philip Fitzsimons

19-Feb-03 1:55

try using an interface.... IColleague

"When the only tool you have is a hammer, a sore thumb you will have."

Chris Austin19-Feb-03 3:59

Chris Austin

19-Feb-03 3:59

try using an interface.... IColleague

Thanks for the input Philip.

I was actualy trying to avoid implementing an interface as I was hoping to be able to just use "any old" control. But, it looks like using an interface or reflecting the controls may be the two most reasonable approachs. I'll probably whip up a little test app today and see how I like the two approaches.

Thanks again.

But I, being poor, have only my dreams.
I have spread my dreams under your feet;
Tread softly, because you tread on my dreams.
- Yeats

Stephane Rodriguez.19-Feb-03 3:05

Stephane Rodriguez.

19-Feb-03 3:05

Chris Austin wrote:
To do this without passing references to controls and forms all over the place

IMHO interfaces, reflection, virtual methods and event subscriptions are helpful in this area. And quite honestly there is nothing new compared to what we already have with C/C++.