ptg Using SQL Cache Dependencies Using Push SQL Cache Dependencies with Data Caching You can use Push SQL cache dependencies when working with the Cache object.. The page uses a data-bas
Trang 1CHAPTER 29 Caching Application Pages and Data
</body>
</html>
In Listing 29.47, the SqlDataSource control includes a Selecting event handler Because
this event is raised when the data cannot be retrieved from the cache, you can use this
event to determine when the data is retrieved from the cache or the database server (see
Figure 29.17)
FIGURE 29.17 Using Push SQL cache dependencies with a DataSource control
WARNING
The page in Listing 29.47 connects to a Server database named MyMovies You should
not use Push dependencies with a Local SQL Express database The page uses a
data-base table named Movies, which was created with the following SQL command:
CREATE TABLE Movies
(
Id int IDENTITY NOT NULL,
Title nvarchar(100) NOT NULL,
Director nvarchar(50) NOT NULL,
EntryDate datetime NOT NULL DEFAULT GetDate()
)
Trang 2ptg Using SQL Cache Dependencies
Using Push SQL Cache Dependencies with Data Caching
You can use Push SQL cache dependencies when working with the Cache object You
represent a Push SQL cache dependency with an instance of the SqlCacheDependency
class
For example, in the Page_Load() handler in Listing 29.48, a DataTable is added to the
cache that represents the contents of the Movies database table The DataTable displays in
a GridView control
LISTING 29.48 PushSQLDataCache.aspx
<%@ Page Language=”C#” Trace=”true” %>
<%@ Import Namespace=”System.Data” %>
<%@ Import Namespace=”System.Data.SqlClient” %>
<%@ Import Namespace=”System.Web.Configuration” %>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
<script runat=”server”>
void Page_Load()
{
DataTable movies = (DataTable)Cache[“Movies”];
if (movies == null)
{
Trace.Warn(“Retrieving data from database”);
string conString =
WebConfigurationManager.ConnectionStrings[“MyMovies”].ConnectionString;
SqlDataAdapter dad =
new SqlDataAdapter(“SELECT Title,Director FROM dbo.Movies”,
➥conString);
SqlCacheDependency sqlDepend = new SqlCacheDependency(dad.SelectCommand);
movies = new DataTable();
dad.Fill(movies);
Cache.Insert(“Movies”, movies, sqlDepend);
}
grdMovies.DataSource = movies;
grdMovies.DataBind();
}
</script>
<html xmlns=”http://www.w3.org/1999/xhtml” >
<head id=”Head1” runat=”server”>
<title>Push SQL Data Cache</title>
</head>
<body>
<form id=”form1” runat=”server”>
Trang 3CHAPTER 29 Caching Application Pages and Data
<div>
<asp:GridView
id=”grdMovies”
Runat=”server” />
</div>
</form>
</body>
</html>
An instance of the SqlCacheDependency class is created A SqlCommand object is passed to
the constructor for the SqlCacheDependency class If the results of the SqlCommand change,
the DataTable will be dropped automatically from the cache
The order of the commands here is important You need to create the SqlCacheDependency
object before you execute the command If you call the Fill() method before you create
the SqlCacheDependency object, the dependency is ignored
WARNING
The page in Listing 29.48 connects to a Server database named MyMovies You should
not use Push dependencies with a Local SQL Express database The page uses a
data-base table named Movies, which was created with the following SQL command:
CREATE TABLE Movies
(
Id int IDENTITY NOT NULL,
Title nvarchar(100) NOT NULL,
Director nvarchar(50) NOT NULL,
EntryDate datetime NOT NULL DEFAULT GetDate()
)
Summary
In this chapter, you learned how to improve the performance of your ASP.NET
applica-tions by taking advantage of caching In the first part of this chapter, you learned how to
use each of the different types of caching technologies supported by ASP.NET Framework
First, you learned how to use Page Output Caching to cache the entire rendered contents
of a page You learned how to create different cached versions of the same page when the
page is requested with different parameters, headers, and browsers You also learned how
Trang 4ptg Summary
to remove pages programmatically from the Page Output Cache Finally, we discussed how
you can define Cache Profiles in a web configuration file
Next, you learned how to use Partial Page Caching to apply different caching policies to
different regions in a page You learned how to use post-cache substitution to dynamically
inject content into a page that has been output cached You also learned how to use User
Controls to cache different areas of a page
We also discussed how you can cache data by using the different DataSource controls You
learned how to enable caching when working with the SqlDataSource, ObjectDataSource,
and XmlDataSource controls
Next, you learned how to use the Cache object to cache items programmatically You
learned how to add items to the cache with different expiration policies and
dependen-cies You also learned how to configure the maximum size of the cache in the web
configuration file
Finally, we discussed SQL cache dependencies You learned how to use SQL cache
depen-dencies to reload database data in the cache automatically when the data in the
under-lying database changes You learned how to use both Polling and Push SQL cache
dependencies with Page Output Caching, DataSource Caching, and the Cache object
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Trang 6CHAPTER 30
Localizing Applications
for Multiple Languages
IN THIS CHAPTER
Setting the Current Culture Using the CultureInfo Class Creating Local Resources Creating Global Resources Using the Localize Control Summary
You can localize an ASP.NET website so that it supports
multiple languages and cultures For example, you might
need to create both an English language and Spanish
language version of the same website
One approach to localization is to simply create multiple
copies of the same website and translate each copy into a
different language This was a common approach when
building ASP Classic (or even ASP.NET 1.1) websites The
problem with this approach is it creates a website
mainte-nance nightmare Whenever you need to make a change to
the website—no matter how simple—you must make the
change in each copy of the website
When building ASP.NET applications, you do not need to
create multiple copies of a website to support multiple
languages Instead, you can take advantage of resource files
A resource file contains language-specific content For
example, one resource file might contain a Spanish version
of all the text in your website, and a second resource file
might contain the Indonesian version of all the text in
your website
In this chapter, you learn how to localize ASP.NET
applica-tions First, you learn how to set the culture of the current
page You learn how to use both the Culture and UICulture
properties You also learn how to detect users’ preferred
languages automatically through their browser settings
Next, local resources are explored A local resource contains
content scoped to a particular file such as an ASP.NET page
You learn how to use both implicit and explicit resource
expressions
Trang 7CHAPTER 30 Localizing Applications for Multiple Languages
This chapter also examines global resources, which contain content that can be used in
any page within an application For example, you can place the title of your website in a
global resource file
Finally, the ASP.NET Localize control is discussed You learn how to use this control in
your pages to localize big chunks of page text
Setting the Current Culture
Two main properties of the Page class have an effect on localization:
UICulture
Culture
The UICulture property specifies which resource files are loaded for the page The resource
files can contain all the text content of your pages translated into a particular language
You can set this property to any standard culture name This property is discussed in detail
during the discussion of using local and global resources later in this chapter
The Culture property, on the other hand, determines how strings such as dates, numerals,
and currency amounts are formatted It also determines how values are compared and
sorted For example, by modifying the Culture property, you can display dates with
language-specific month names such as January (English), Januar (German), or Enero
(Spanish)
Both the UICulture and Culture properties accept standard culture names for their values
Culture names follow the RFC 1766 and RFC 3066 standards maintained by the Internet
Engineering Task Force (IETF) The IETF website is located at www.IETF.org
Following are some common culture names:
de-DE = German (Germany)
en-US = English (United States)
en-GB = English (United Kingdom)
es-MX = Spanish (Mexico)
id-ID = Indonesian (Indonesia)
zh-CN = Chinese (China)
Each culture name consists of two parts The first part represents the language code, and
the second part represents the country/region code If you specify a culture name and do
not provide a country/region code—for example, en—you have specified something called
a neutral culture If you provide both a language code and a country/region code—for
example, en-US—you have specified something called a specific culture.
Trang 8Setting the Current Culture
NOTE
You can view the culture names supported by NET Framework by looking up the entry
for the CultureInfo class in the Microsoft NET Framework SDK documentation It’s a
really long list
The Culture property must always be set to a specific culture This makes sense because,
for example, different English speakers use different currency symbols The UICulture
property, on the other hand, can be set to either a neutral or specific culture name Text
written in Canadian English is pretty much the same as text written in U.S English
You can set the UICulture and Culture properties to the same value or different values For
example, if you create an online store, you might want to set the UICulture property to the
value de-DE to display German product descriptions However, you might want to set the
Culture property to the value en-US to display product prices in U.S currency amounts
Setting a Culture Manually
You can set either the UICulture or Culture properties by using the <%@ Page %>
direc-tive For example, the page in Listing 30.1 sets both properties to the value id-ID
(Indonesian)
LISTING 30.1 Bagus.aspx
<%@ Page Language=”C#” Culture=”id-ID” UICulture=”id-ID” %>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”
“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>
<script runat=”server”>
void Page_Load()
{
lblDate.Text = DateTime.Now.ToString(“D”);
lblPrice.Text = (512.33m).ToString(“c”);
}
</script>
<html xmlns=”http://www.w3.org/1999/xhtml” >
<head id=”Head1” runat=”server”>
<title>Bagus</title>
</head>
<body>
<form id=”form1” runat=”server”>
<div>
Today’s date is:
<br />
<asp:Label
Trang 9ptg CHAPTER 30 Localizing Applications for Multiple Languages
FIGURE 30.1 Displaying a localized date and price
id=”lblDate”
Runat=”server” />
<hr />
The price of the product is:
<br />
<asp:Label
id=”lblPrice”
Runat=”server” />
</div>
</form>
</body>
</html>
The page in Listing 30.1 displays a date and a currency amount Because the Culture
property is set to the value id-ID in the <%@ Page %> directive, both the date and
currency amount are formatted with Indonesian cultural conventions (see Figure 30.1)
The date is displayed like this:
05 March 2010
Trang 10ptg Setting the Current Culture
The currency amount is displayed as an Indonesian Rupiah amount like this:
Rp512
NOTE
Setting the Culture does not actually convert a currency amount Setting a particular
culture formats only the currency as appropriate for a particular culture If you need to
convert currency amounts, you need to use a Web service: Conversion rates change
minute by minute See, for example, www.xmethods.com
Instead of using the <%@ Page %> directive to set the Culture or UICulture properties, you
can set these properties programmatically For example, the page in Listing 30.2 enables
you to select a particular culture from a drop-down list of cultures (see Figure 30.2)
LISTING 30.2 SelectCulture.aspx
<%@ Page Language=”C#” %>
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”
“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>
<script runat=”server”>
protected void btnSelect_Click(object sender, EventArgs e)
{
Culture = ddlCulture.SelectedValue;
FIGURE 30.2 Selecting a culture from a DropDownList control