Nat Luengnaruemitchai

Peril of FileMode.OpenOrCreate

Nat Luengnaruemitchai — Sat, 24 Oct 2009 04:00:12 GMT

Many people use .NET framework library without reading documentation. Sometimes, it just like taking medicine without reading its label. Today, I found that there is a piece of code trying to read AssemblyInfo.cs and change the version of the .NET assembly based on the input. The code seems to work quite well for most of the files except for certain files. In each of those files, there is an extra "]" at the end. It took a while to see that it's using FileMode.OpenOrCreate instead of FileMode.Create. This will cause the FileStream to open that file at position 0 but it will keep the rest of the file intact. Therefore, if the program overwrite the file with shorter content, you will still see some of the old content at the end of the file!

Java Plugin Problem with Google Chrome

Nat Luengnaruemitchai — Wed, 07 Oct 2009 00:04:52 GMT

I have been fiddled with Java Plugin on Google Chrome for a while but having a problem getting it to work even though I follow the steps on many websites. I finally tracked down the issue. It seems that Google Chrome searches for installed JRE plugin by querying

HKLM/SOFTWARE/JavaSoft/Java Runtime Environment/BrowserJavaVersion

If the value in there refers to the version older than 1.6.0_10, it will not work. To fix it, you need to install JRE with version 1.6.0_10 or later then modify this registry key to point to the version that you just install.. then Voila!

Oracle Express Installation Problem

Nat Luengnaruemitchai — Fri, 19 Jun 2009 00:01:12 GMT

If…

1. You installed Oracle XE but you cannot launch APEX or start up oracle.exe process

2. Your computer joined Windows domain

3. You installed it using Domain account

Very likely, it will try to install it using domain authentication which it may not work.

Therefore, the solution is to:

1. Create a local user with admin right

2. Log in using that local user and set regional setting to en-US

3. Install Oracle XE

4. Go to c:\Oracle\app\oracle\product\10.2.0\server\NETWORK\ADMIN\sqlnet.ora and remove the line that said SQLNET.AUTHENTICATION_SERVICES = (NTS)

SQL Server 2008 Installation Problem

Nat Luengnaruemitchai — Thu, 18 Jun 2009 23:46:37 GMT

Many times, I installed SQL Server 2008 and failed with just the error message “Access Denied”. One of the cases I found is that my Administrator account doesn’t have SeDebugPrivilege especially when GPO policy is in effect. I still don’t understand why anyone should be admin but cannot debug things :(

Check out the following links for more information:

http://blogs.msdn.com/joaol/archive/2008/12/02/sql-server-2008-installation-aborts-due-an-access-denied.aspx

http://social.msdn.microsoft.com/Forums/en-US/sqlreportingservices/thread/94f373ae-bb3e-4664-b0fd-95121d09f7de

TCP/IP Connection Limit in XP and Vista

Nat Luengnaruemitchai — Wed, 18 Feb 2009 05:35:07 GMT

The other day I ran into a page here. It mentioned that XP SP2 and Vista have an updated TCP/IP stack where it was designed to reduce the risk of your PCs to spread out the worm in case it gets affected. Some people found a way to work around it by manually editing the TCPIP.sys file. You might need this if you have to write an application where it attempts to connect to multiple PCs concurrently such as web crawlers, peer-to-peer application, system monitor where the remote hosts cannot be expected to be up all the time.

Maximum Concurrent HttpWebRequest

Nat Luengnaruemitchai — Tue, 17 Feb 2009 05:09:22 GMT

Many people have a problem when spawning multiple requests to get content from a server where only 2 requests can be processed concurrently. This is because the HTTP protocol standard suggests that HTTP client should not make more than 2 calls to a server at one time. However, in many cases, you have a need to make more than 2 requests at the same time by adding the following configuration in App.config.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.net>
    <connectionManagement>
      <add address="*" maxconnection="10"/>
    </connectionManagement>
  </system.net>
</configuration>

Java applet problem with Firefox 3.0

Nat Luengnaruemitchai — Wed, 22 Oct 2008 23:25:05 GMT

Some people may experience a problem with Java applet in Mozilla Firefox 3.0. For me, I noticed that after upgrading from Firefox 2.0 to Firefox 3.0, some of my applets don't work anymore. This happens when I have network.cookie.cookieBehavior setting = 1. This will disallow access to 3rd party cookies. However, it also has a side effect where it disallow cookie from the same site when fetching for Java applet codebase as well. Changing it back to 0 (Allow all cookies" fixes it.

http://kb.mozillazine.org/Network.cookie.cookieBehavior

WPF: Transform trigger into event

Nat Luengnaruemitchai — Thu, 20 Sep 2007 12:55:38 GMT

Yesterday, I had a problem where I need to hook up an event to a certain data condition. I first thought about EventTrigger. However, it does the other way around. This class is responsible for convert event into trigger. So I digged around WPF architecture to see what I can do and bingo. I found that I can create an attached property with the following construct

and then in XAML, you can register for this event by

public static readonly DependencyProperty SomethingHappenedProperty = DependencyProperty.RegisterAttached("SomethingHappened",typeof(bool),typeof(Window1),new PropertyMetadata(false,new PropertyChangedCallback(SomethingHappened)));public bool GetSomethingHappened(DependencyObject d)
{
    return (bool)d.GetValue(SomethingHappenedProperty);
}public void SetSomethingHappened(DependencyObject d, bool value)
{
    d.SetValue(SomethingHappenedProperty, value);
}private void SomethingHappened(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    // do something here
}

Free WPF DataGrid from Infragistics

Nat Luengnaruemitchai — Wed, 19 Sep 2007 02:25:59 GMT

Andrew Flick announced that Infragistics WPF Express Edition will be free as well. Before this release, xamDataGrid suffered a lot of performance problem. It seems that they have fixed various performance problem. So I think I will give it a try again later. To try it out visit http://blogs.infragistics.com/blogs/andrew_flick/archive/2007/09/13/infragistics-netadvantage-for-wpf-express-aka-free-grid.aspx for more information.

Check whether the application is in DesignMode in WPF

Nat Luengnaruemitchai — Mon, 17 Sep 2007 03:25:28 GMT

In Windows Forms application, we can use Control.IsInDesignMode or LicenseManager.UsageMode == LicenseUsageMode.Designtime to check whether your code is executing in DesignMode or not. You might wonder how would you do the same in WPF. Fortunately, Cider and Blend offers a similar functionality. You can test the following condition DesignerProperties.GetIsInDesignMode(new DependencyObject()).

WPF XBAP Application requires proxy authentication

Nat Luengnaruemitchai — Mon, 17 Sep 2007 03:03:22 GMT

ClickOnce deployment has problem with Proxy that requires authentication. You might get the following error:

(407) Proxy Authentication Required

If so, you would need to get a hotfix at http://support.microsoft.com/kb/917952/en-us.

For more detail, you can check out at http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=294738&SiteID=1

WPF XBAP Application failed to work with ISS Proventia Buffer Overflow (vpatch.exe)

Nat Luengnaruemitchai — Mon, 17 Sep 2007 02:56:45 GMT

If you try to run any XBAP application on the machine that has ISS Proventia Buffer Overflow Protection (vpatch.exe) installed, you might experience COMException with HRESULT 0xFFFFFFFF. The workaround is to stop vpatch.exe. I hope Microsoft and ISS work together to fix this issue.

Handle leaks in svchost.exe

Nat Luengnaruemitchai — Mon, 17 Sep 2007 02:33:43 GMT

If you experience bad handle leaks in svchost.exe process like I did, what happened was a bug in a dll that leaks handles when you have some antivirus software installed. It might worth to get a hotfix from Microsoft. It is detailed at KB892489.

WPF ComboBox with LimitToList feature: Part I

Nat Luengnaruemitchai — Wed, 08 Aug 2007 01:37:47 GMT

Sometimes, you would like to get a combobox where a user can type. This can be done by turning on IsEditable property to true. However, it opens another can of worm, it means the user can type anything in the combobox even text that is not in the ItemsSource.

To provide LimitToList feature, you can hook up an event to PreviewLostKeyboardFocus as follows:

private void ComboBox_PreviewLostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)

{

if (!e.Handled)

{

TextBox textBox = e.OldFocus as TextBox;

ComboBox comboBox = sender as ComboBox;

if (textBox != null && comboBox!=null)

{

DependencyObject common = comboBox.FindCommonVisualAncestor(e.NewFocus as DependencyObject);

// validate only the case when user step out of this control

if (common != comboBox)

{

bool invalid = !string.IsNullOrEmpty(textBox.Text) && comboBox.SelectedIndex < 0;

if (invalid)

{

e.Handled = true;

}

Later, I will show you how to create a visual clue to indicate that the combobox is invalid

WPF Nested Template Bug

Nat Luengnaruemitchai — Sun, 29 Jul 2007 13:17:54 GMT

I posted in MSDN Forum a while ago that I ran into a WPF bug that occurs when you put one template inside another template like

The above code won't fail during the compilation. However,during the run, you will notice that only the first item of the outer listbox will show up but not the rest. Sam Bent, WPF/WinFX Dev Lead answered that this is a nested template bug. If template is used nestedly, the result will be unexpected. To workaround, the template should be defined as a separated template in Resources section like:

<Window.Resources>
    <DataTemplate x:Key="InnerTemplate">
        <StackPanel>
            <ComboBox ItemsSource="{Binding Source={StaticResource CategoryData}, XPath=Category}"
            SelectedValue="{Binding XPath=Category}"/>
            <TextBlock Text="{Binding XPath=Title}" />
            <TextBlock Text="{Binding XPath=Summary}" />
        </StackPanel>
    </DataTemplate>
    <DataTemplate x:Key="OuterTemplate">
        <StackPanel>
            <ListBox HorizontalContentAlignment="Stretch" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
                ItemTemplate="{StaticResource InnerTemplate}" Background="Honeydew" ItemsSource="{Binding XPath=.}">
            </ListBox>
        </StackPanel>
    </DataTemplate>
</Window.Resources>

<Grid VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
    <ListBox HorizontalContentAlignment="Stretch" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
            ItemTemplate="{StaticResource OuterTemplate}" Background="Honeydew">
        <ListBox.ItemsSource>
            <Binding Source="{StaticResource InventoryData}"
                    XPath="*[@Stock='out'] | *[@Number>=8 or @Number=3]"/>
        </ListBox.ItemsSource>
    </ListBox>
</Grid>