Introduction
A few years ago we started hearing new terms in economics
about globalization and integration of international markets. This made many
large business companies begin thinking of how to attract markets from all over
the world and not only from domestic markets. The first idea that might come
to the company is to have a Multilanguage website; clients from a set of
targeted countries can localize their website to their own native language.
ASP.NET 2.0 comes with a rich environment that makes
localization of web applications a very easy task to perform. There are two main
kinds of localization in ASP.NET 2.0: implicit localization and explicit
localization, each of which will be discussed in more detail throughout this
article.
Preliminary Steps
When you think of localizing a web application, some
preliminary steps should be taken into account. Those steps can be summarized
in two main points:
Globalization: The main strategy of the web application is
set in this step. The web application architect shall ask the following
questions: How many countries or languages are targeted in the application? What
sections are to be localized? Etc. In addition, gathering of resources for
all the predetermined languages should be collected before any implementation
starts.
Localization: The actual localization and implementation
through code is done in this step. The resources needed are supplied to the
web application and then it is the developer's role to allow the application being
worked on to support all the predetermined languages required by their
application.
Localization and Visual Studio 2005
Visual Studio 2005 now ships with a new resource editor that
allows you to easily add/remove/update any resource key in any ASP.NET resource
file (.resx).
In addition, Visual Studio 2005 makes generating resource
files an easy step to do by just going to Tools à
Generate Local Resource while your WebForm is in the Design view.
Moreover, Visual Studio 2005 provides two ways of localizing
a web application. The first is using Local Resources; a local resource is a
resource file attached to a WebForm. Or you could use Global Resources in
which you can combine all common resource keys used by several ASP.NET web
forms into a single resource file.
The above tools and concepts will be revisited throughout
this article while creating and manipulating resource files.
Working with Local Resources
In this section we are going to show how easy it is to
generate a local resource file for any ASP.NET web form. By local resource we
mean that a single resource file is in a many to 1 relationship with the
ASP.NET web form. In other words, if you have a Label server control and you
want to show some text in this label for each culture available in the web
application, then you place a resource key in an accompanying resource file for
a specific culture. At run time, the resource key will be looked up in the
culture-specific resource file, evaluated and replaced with the proper text
translation. You can have several resource files for the same ASP.NET web form,
each representing a specific culture.
To generate a local resource file in Visual Studio 2005,
start by creating a new web site. Open the default.aspx page and add few
controls, including the following:
Label Server Control, with an ID of lblName
TextBox Server Control, with an ID of txtName
Button Server Control with an Id of btnSubmit
The figure below shows what the default.aspx page looks
like.
Figure 1
Make sure your default.aspx page is in the design view.
Then go to Tools à click on the Generate
Local Resource command.
You will notice two changes to your web application and ASP.NET
page. First of all, a new "system" folder has been added in the web
application’s root folder called App_LocalResources. The App_LocalResources
folder has been newly added to the ASP.NET 2.0 web application. This folder
holds all the resource files for all the ASP.NET web forms. The ASP.NET
runtime uses the .NET framework, ResourceManager, to perform resource key
lookups. The ResourceManager will look at the App_LocalResources folder at all
times. This means that any resource file located outside this folder will be
ignored.
You can easily add a new resource file to that folder to
represent any additional language for your web application by simply copying
the default resource file of an ASP.NET form and pasting it with a new name.
For instance, if you have the default.aspx.resx resource file, which represents
the English language, then you have English set as the default language of your
machine. Now you want to add the Arabic-Lebanese language for your web
application. You simply copy the default.aspx.resx and rename it to
defaut.aspx.ar-LB.resx. This way you have added support for a new language.
The only thing left to do is to change the values of every resource key inside
the resource file added.
Next, open the source view of the default.aspx page and you
will notice new tags have been added to the controls that require localization.
Listing 1
<form id="form1"runat="server">
<div>
<asp:Label ID="lblName"runat="server"meta:resourcekey="lblNameResource1"></asp:Label>
<asp:TextBox ID="txtName"runat="server"meta:resourcekey="txtNameResource1"></asp:TextBox><br/>
<br />
<asp:Button ID="btnSubmit"runat="server" Text="Submit"meta:resourcekey="btnSubmitResource1" /></div>
</form>
As you can see, a “meta:” tag has been added to every server
control together with a resource key that corresponds to the resource key entry
in the default.aspx.resx resource file.
The snapshot of the default.aspx.resx is shown below.
Figure 2
For each server control a single resource key has been added
with multiple properties of .Text and .ToolTip.
As mentioned above, at runtime the resource key will be
evaluated and the corresponding text in the resource file will be displayed.
Now we can add the Text and ToolTip values for every control
in the resource file. However, before we can run this page and see how it is
being localized automatically, we have to specify the Culture and UICulture
properties in the Page directive. This way, the ASP.NET runtime will know the
culture used and apply the specific resource file for that chosen culture.
To do so, add the following to the Page directive:
Listing 2
Culture="auto:en-US" UICulture="auto"
We have set the Culture to be auto and have a default value
of en-US and the UICulture set to auto. Having an auto property means that the
request will automatically detect the culture specified on the client browser.
Run the application and you will see that the server mainly
controls the Label and that the Button Text property will be evaluated based on
the culture and the resource file of that culture.
To support an additional culture, copy the original resource
file as mentioned above and add your translation for the entire resource key
and test it in your browser. To test your application with other cultures,
refer to the following: Setting
a Preferred Language in Internet Explorer.
Working with Global Resources
As mentioned above, the Local Resources are in a many to 1
relationship with ASP.NET web forms. In some cases, your ASP.NET web forms in
an application might share a set of resource keys. Instead of having redundant
data in your resource files, ASP.NET 2.0 introduces the App_GlobalResources
folder which lets you place all the global resources, i.e. resources shared by
some ASP.NET web forms, in one location.
To create a new global resource, right click your web
application root, add an ASP.NET Folder and choose App_GlobalResources. Then
right click this folder and add a new Resource file. The structure of this
resource file is the same as the structure of the resource files placed inside
the App_LocalResources. However, the name of this file can be any meaningful
name and is not limited to the name of the ASP.NET web form. This file, as
mentioned above, will hold shared resource keys for several ASP.NET web forms.
To have the same resource file available for several
languages, you need to follow the same steps mentioned while discussing the
local resources. The default global resource file is named resource.resx and
the French version is written as resource.fr.resx.
Add a new Label Server control to the default.aspx page as:
Listing 3
<asp:Label ID="lblwelcome" runat="server"/>
Inside the resource.resx and resource.fr.resx files add one resource
key called “welcome.”
English:
Key: welcome
Value: Welcome to our website
French:
Key: welcome
Value: Bienvenue à notre site Web
To link the global resource to the above label, we need to
do the following:
Right click on the label in Design view, click on properties
and then choose Expressions. A pop-up window is then opened for you so choose
from the Bindable properties, Text property and form the Expression Type,
Resources. In the Expression Properties you set the ClassKey to be
resource.resx and the ResourceKey to be welcome.
You can see now how the label server control looks.
Listing 4
<asp:Label ID="lblwelcome"runat="server" Text="<%$ Resources:resource, welcome%>"></asp:Label>
Instead of having implicit localization as the case of local
resources, the explicit localization in global localization is done by
evaluating an expression and giving this expression the original resource name
and the resource key in that resource file.
Now, run your application in a browser and try to change the
default culture of your browser from English to French and see how the text
inside the label changes as specified in the two resource files mentioned
above.
CurrentCulture and CurrentUICulture
Before going on with this article, let us stop and discuss
the two main properties of concern, mainly the CurrentCulture and
CurrentUICulture.
CurrentCulture and CurrentUICulture are both of the type
CultureInfo which belongs to the System.Globalization.
CurrentCulture and CurrentUICulture are both properties of
the current thread represented by
System.Threading.Thread.CurrentThread.CurrentCulture and
System.Threading.Thread.CurrentThread.CurrentUICulture
CurrentCulture is used mainly to format the Dates,
Currencies, etc. For that reason, it should be set as specific and not left as
neutral. For instance, you need to set the CurrentCulture as:
Listing 5
System.Threading.Thread.CurrentThread.CurrentCulture= newCultureInfo("ar-LB");We have set the current culture to be a specific culture,
Arabic - Lebanese. So make sure to always be specific in specifying the
CurrentCulture.
CurrentUICulture is mainly used for language/text
translations. The ResourceManager is based upon the CurrentUICulture. It does
not matter whether the culture set here is specific or neutral. For instance,
either ar or ar-lb works fine with the CurrentUICulture.
Listing 6
System.Threading.Thread.CurrentThread.CurrentCulture= newCultureInfo("ar");Programmatically Setting Culture and UICulture
In the above discussion, we have seen that the Culture and
UICulture properties inside the Page directive were set to "auto." In
this section we will learn how to set both properties programmatically inside
our Visual Basic .NET or C# code.
Create a new ASP.NET web form and add the following code:
Listing 7
<asp:DropDownList ID="ddlLanguage"runat="server" AutoPostBack="True">
<asp:ListItem Selected="True"Value="auto">Auto</asp:ListItem>
<asp:ListItemValue="en-US">English (US)</asp:ListItem>
<asp:ListItemValue="en-GB">English (UK)</asp:ListItem>
<asp:ListItemValue="ar">Arabic</asp:ListItem>
<asp:ListItemValue="fr">French</asp:ListItem>
</asp:DropDownList>
This DropDownList lists a few options to change the default
culture. One of the methods of the Page class is called InitializeCulture(). This
method is being executed in the early stages of the page creation. It is the
responsibility of this method to set the Culture and UICulture of the current
request. We will override this method to build our own logic in setting the
above two mentioned properties based on the selection from the DropDownList.
Copy this code and paste it inside your code behind class.
Listing 8
protected override void InitializeCulture()
{
string lang =Request["DropDownList1"];
if ((lang != null))
{
if (lang != "")
{
Thread.CurrentThread.CurrentUICulture =new CultureInfo(lang);
Thread.CurrentThread.CurrentCulture =CultureInfo.CreateSpecificCulture
(lang);
}
}
}In this piece of code, we are first getting the selection
from the language DropDownList. Notice that we did not use the DropDownList properties
to access the selected option; this is done on purpose, since the first time
the page is visited the DropDownList will not be created. We use the Request
object to access the form's controls.
The CurrentUICulture property is set to the language
selected.
The CurrentCulture, as mentioned above, should always be set
to a specific culture. Keeping that in mind, we have to use the static method
of CultureInfo object, CreateSpecificCulture(). This takes as an input a
parameter specifying the culture and returns a CultureInfo instance having a
specific culture set.
Once a culture is chosen from the DropDownList, the current
Culture and UICulture will be set accordingly.
Conclusion
We have presented the new localization features in ASP.NET
2.0. Visual Studio 2005 has been improved to give a better experience in many
aspects, mainly the Localization of web applications. Two new features in
ASP.NET 2.0 Localization, Implicit and Explicit localization, have been
discussed. A distinction between CurrentCulture and CurrentUICulture was given
showing the similarities/differences and the effect of each of them. Finally,
a programmatic way of setting the CurrentCulture and CurrentUICulture was
shown.
Hope you enjoyed this article.
Happy Dot Netting!!
