Re: Asynchronous socket question - C# Discussion Boards

Re: interupting the loop with the button

Not Active3-Aug-06 5:14

Not Active

3-Aug-06 5:14

Use a seperate processing thread and a ManualResetEvent to trigger the stop/start

only two letters away from being an asset

Re: interupting the loop with the button

Stefan Troschuetz3-Aug-06 5:21

Stefan Troschuetz

3-Aug-06 5:21

The method you're looking for is Application.DoEvents.
Nevertheless I also think it would be a much nicer way to do the loop inside of a separate thread.

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning." - Rick Cook

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Re: interupting the loop with the button

Blubbo3-Aug-06 5:26

Blubbo

3-Aug-06 5:26

Yeah... seems that "Application.DoEvents()" in the while loop does the trick. Thanks!

Re: interupting the loop with the button

Nader Elshehabi3-Aug-06 5:31

Nader Elshehabi

3-Aug-06 5:31

Hello

There is a method that do the same thing as ProcessMessages in C#, it's called Application.DoEvent(). So it process all the messages in your queue including the Button.Click

Here is a simple class that will do what you wany. Note that Button1 starts the loop. Button2 ends it:

public partial class Form1 : Form
    {
        bool Go;
        public Form1()
        {
            InitializeComponent();
            Go = true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Go = true;
            int temp = 0;
            textBox1.Text = "0";
            while (Go)
            {
                temp++;
                textBox1.Text = temp.ToString();
                button1.Capture = false;  //This is present only in .NET 2.0
                Application.DoEvents();
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Go = false;
        }
    }

Regards

Asynchronous socket question

Madmaximus3-Aug-06 4:39

Madmaximus

3-Aug-06 4:39

Hi all,

I have a continuous stream of packet data going through my asynchronous socket connection. My question is how can I tell in the EndReceive callback method where one package of data ends and another begins? I coded the socket class in C# 1.1.

Thanks in an advance. Smile | :)

Ken

Re: Asynchronous socket question

Tim Kohler3-Aug-06 5:56

Tim Kohler

3-Aug-06 5:56

You have to have a delimiter in the data. And once you read in the delimiter in the callback, you'll know you got to the end of one message/stream and you're now reading for the next message/stream.

So a very simple protocol is needed to delimit your messages. You have to make sure you read all the message as it may/may not (certainly not guaranteed) to be send in a single socket.send.

Prefix

Ennis Ray Lynch, Jr.3-Aug-06 5:59

Ennis Ray Lynch, Jr.

3-Aug-06 5:59

I like to prefix my messages with a length rather than delimit them.

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

Re: Asynchronous socket question

RizwanSharp3-Aug-06 6:11

RizwanSharp

3-Aug-06 6:11

The more appealing and real world solution for all types of data transfer is to prefix each messaeg with its length.

Procedure is as follow.

Sending Part:

1) Calculate the Number of bytes produced by a message.
2) Store length as an integer value.
3) Convert the Length (integer) into bytes using BitConverter.GetBytes(messageLength) method.
4) Send these bytes on stream.
5) Send the original message.

Receiving Part:

1) Read 4 bytes from the stream Asynchronously.
2) Convert these bytes into integer value using BitConverter.ToInt32(buffer,0)
3) Now creat a Memory Stream and loop on it untill that message size is met.

Its the best technique in my knowledge and supports in Network delay situation for other type of data (Not String)

If you have further queries, feel free to conact me Wink | ;)

rizwansharp@hotmail.com

Best Regards,
Rizwan

Impersonation + Process.Start

Gonzalo Brusella3-Aug-06 4:12

Gonzalo Brusella

3-Aug-06 4:12

I have to run several secuential proceses, some of them impersonated from the main identity of the program.

Using .Net 2.0, the a "ProcessStartInfo" instance, can impersonate, but the password must be a "SecureString".

I have the Username and the Password on a encrypted file, but when I decrypt the tye file, password this make is readable (wich we all know is bad thing).

The constructor of "SecureString", does not take a String as parameter, so I mahe this (check the sample):

System.Diagnostics.ProcessStartInfo _ps = new System.Diagnostics.ProcessStartInfo();

_ps.FileName = _command;
_ps.CreateNoWindow = false;
_ps.Arguments = _arguments;
_ps.UseShellExecute = false;

//Load the SecureString (This can be worst way)
SecureString _psw = new SecureString();

string _password = "123456";
foreach (char Character in _password.ToCharArray())
{
    _psw.AppendChar(Character);
}

_psw.MakeReadOnly();

_ps.LoadUserProfile = false;
_ps.UserName = "User";
_ps.Password = _psw;

System.Diagnostics.Process _process = new System.Diagnostics.Process();
_process.Start(_ps);
_process.WaitForExit();

Now There is way to solve the clear-password-in-memory problem?

The user account is a restricted account, but with access to some processes wich we don't want to be publicaly accessed.

I'm on a Fuzzy State: Between 0 an 1

Re: Impersonation + Process.Start

Judah Gabriel Himango3-Aug-06 6:25

Judah Gabriel Himango

3-Aug-06 6:25

If you want to be secure, you can never store the password as a plain string. You'll need to read in the password character-by-character, decrypting each character. Once you've done this, you can clear out the contents of your character array.

The reason this is more secure is that strings, once created, cannot be cleared (since they are immutable). The .NET GC can even move strings around in memory, thus leaving your password in multiple places in memory. thus, there's a good chance someone inspecting your process's memory or the page file could discover your password. If you read your password in as a character array, you can construct a SecureString from it, after which you should immediately clear your character array. This makes it extremely difficult for someone to discover your password as the window of opportunity to intercept your password is very low. Here's[^] an excellent article on the purpose and uses of SecureString.

Optionally, you could read the password in as a string, then use unsafe code to clear the string in-place. I don't recommend doing this, but if you're up to it, here's an article[^] that will get you started in the right direction.

Tech, life, family, faith: Give me a visit.
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The apostle Paul, modernly speaking: Epistles of Paul

Judah Himango

Re: Impersonation + Process.Start

Judah Gabriel Himango3-Aug-06 6:37

Judah Gabriel Himango

3-Aug-06 6:37

I should also mention that you could remove any heap allocations by creating a character array allocated on the stack. You can do this using unsafe code and the stackalloc C# keyword.

char* password = stackalloc char[200];
// read in your password, character-by-character, placing it into the password variable
...
//Now create a secure string from the stack allocated password char*.
SecureString securePassword = new SecureString(password, passwordLength);

The above has the added benefit of the password never touching the heap, which makes it even more difficult to intercept.

Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Messianic Instrumentals (with audio)
The apostle Paul, modernly speaking: Epistles of Paul

Judah Himango

Re: Impersonation + Process.Start

Gonzalo Brusella3-Aug-06 7:05

Gonzalo Brusella

3-Aug-06 7:05

This is much better code than the one i've made...

Thanks!

I'm on a Fuzzy State: Between 0 an 1

Combobox problem

ZeinaBaG3-Aug-06 3:37

ZeinaBaG

3-Aug-06 3:37

Hi;

Does anyone know how to programtically let a combobox display its dropdown portion?
The reason is that the application fills up the combobox programtically when the user clicks on it. But ones it is populated it will automatically choose the first item and close the dropdown. So i want to force it to stay open.

Thanx

Re: Combobox problem

stancrm3-Aug-06 3:44

stancrm

3-Aug-06 3:44

this.comboBox1.DroppedDown = true;

speed up application

V.3-Aug-06 3:19

3-Aug-06 3:19

Hi guys,

Our application takes some time to load.
I already tried some tricks like the suspend layout when loading combo boxes and only loading them when necessary etc. but it's still slow. Especially the first time. (because of JIT compiler)

A while ago there was a link here on CP to some article on the web that enables you to leave the JIT compilation, but I can't find it anymore. If somebody could point me out to that one, that would be great.

Any tricks you know to speed up the application is helpful, but we don't want too many code changes.

Thanks for your help!

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Re: speed up application

yueue3-Aug-06 3:27

yueue

3-Aug-06 3:27

Make a form that print 'loading...' and show it before your application run Laugh | :laugh:

Re: speed up application

V.3-Aug-06 3:33

3-Aug-06 3:33

I thought of that Laugh | :laugh:

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Re: speed up application

WillemM3-Aug-06 3:29

WillemM

3-Aug-06 3:29

I recommend precompiling the application using NGen. This creates a native image of the application, this makes the application start a little faster and run a little faster.

Quick question: How many controls do you use on the form and is the form databound to a lot of datasources? Having a lot of controls on a form makes the application slower, especially when layering them using groupboxes and panels.

Also loading from a database the first time (and often after that too) makes the application slow. You can fake the user by loading the data using async methods. This makes the application more responsive.

There could be more tricks, but this is what I know at the moment.

WM.

What about weapons of mass-construction?

Re: speed up application

V.3-Aug-06 3:33

3-Aug-06 3:33

WillemM wrote:
I recommend precompiling the application using NGen

That was the thing I lost. Thank you so much.

We don't have that many controls, but a lot of data is in them. The entire logic seems simple at the outside, but is very complex at the inside. That's why we loose so much time. Furthermore, on my laptop, speed is acceptable, but the client works on old(er) machines.

thanks for your help !!

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Re: speed up application

V.3-Aug-06 4:09

3-Aug-06 4:09

Can I ask you a little question: I've found this article -> Ngen[^].

As I understand correctly it doesn't change anything in your exe, it just has a compiled 'image' in a service. this would mean I need to use ngen again if I install on another cpu. Here's my problem: The NGen tool comes with VS2005 and on the client machine we only have the framework installed.

So what did I miss?

again, tnx for your help!

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Re: speed up application

Dave Kreskowiak3-Aug-06 5:31

Dave Kreskowiak

3-Aug-06 5:31

NGen is part of the .NET Framework, not Visual Studio. For 1.1, you'll find it in C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Re: speed up application

V.3-Aug-06 6:52

3-Aug-06 6:52

that's why I couldn't find it, I was searching under program files D'Oh! | :doh:

.

Tnx a lot for your help.

I've found a living worth working for, but I haven't found work worth living for.

<marquee> Beer | [beer]

Re: speed up application

RizwanSharp3-Aug-06 20:02

RizwanSharp

3-Aug-06 20:02

I also have a question abour pre compilation. Doesnot we need to precompile on different hardware Configuration? A best Precompiled Image of assembly may not even good at your hardware?

Am I right? Or please give me some more info.

Best regards,
Rizwan Ahmed

Re: speed up application

Dave Kreskowiak4-Aug-06 2:02

Dave Kreskowiak

4-Aug-06 2:02

NGen generates binaries that are VERY processor specific. If you use NGen on a Pentium IV, the code won't work on a Pentium III.

NGen is best used during application installation. After the app is installed, you can have a Custom Action precompile any/all of your assemblies so as to reduce the startup time as much as possible.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Re: speed up application

RizwanSharp4-Aug-06 2:34

RizwanSharp

4-Aug-06 2:34

Exactly this is what I was thinking of. Can you point any article that uses acustom action? Do I have to make a seperate application for precompiling it using System.Diagnostics.Process.Start()???
Best Regards,
Rizwan

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