Best Practices for Developing World-Ready Applications
This section describes the best practices to follow when developing world-ready applications.
Globalization Best Practices
- Make your application Unicode internally.
- Use the culture-aware classes provided by the System.Globalization namespace to manipulate and format data.
- For sorting, use the SortKey class and the CompareInfo class.
- For string comparisons, use the CompareInfo class.
- For date and time formatting, use the DateTimeFormatInfo class.
- For numeric formatting, use the NumberFormatInfo class.
- For Gregorian and non-Gregorian calendars, use the Calendar class or one of the specific Calendar implementations.
- Use the culture property settings provided by the System.Globalization.CultureInfo class in the appropriate situations. Use the CultureInfo.CurrentCulture property for formatting tasks, such as date and time or numeric formatting. Use the CultureInfo.CurrentUICulture property to retrieve resources. Note that the CurrentCulture and CurrentUICulture properties can be set per thread.
- Enable your application to read and write data to and from a variety of encodings by using the encoding classes in the System.Text namespace. Do not assume ASCII data. Assume that international characters will be supplied anywhere a user can enter text. For example, accept international characters in server names, directories, file names, user names, and URLs.
- When using the UTF8Encoding class, for security reasons, it is recommended that you use the error detection feature offered by this class. To turn on the error detection feature, create an instance of the class using the constructor that takes a throwOnInvalidBytes parameter and set the value of throwOnInvalidBytes to true.
- Whenever possible, handle strings as entire strings instead of as a series of individual characters. This is especially important when sorting or searching for substrings. This will prevent problems associated with parsing combined characters.
- Display text using the classes provided by the System.Drawing namespace.
- For consistency across operating systems, do not allow user settings to override CultureInfo. Use the CultureInfo constructor that accepts a useUserOverride parameter and set it to false.
- Test your application's functionality on international operating system versions, using international data.
- If a security decision is based on the result of a string comparison or case change operation, perform a culture-insensitive operation by explicitly specifying the CultureInfo.InvariantCulture property. This practice ensures that the result is not affected by the value of CultureInfo.CurrentCulture. See Custom Case Mappings and Sorting Rules for an example that demonstrates how culture-sensitive string comparisons can produce inconsistent results.
Localization Best Practices
- Move all localizable resources to separate resource-only DLLs. Localizable resources include user interface elements such as strings, error messages, dialog boxes, menus, and embedded object resources.
- Do not hardcode strings or user interface resources.
- Do not put nonlocalizable resources into the resource-only DLLs. This causes confusion for translators.
- Do not use composite strings that are built at run time from concatenated phrases. Composite strings are difficult to localize because they often assume an English grammatical order that does not apply to all languages.
- Avoid ambiguous constructs such as "Empty Folder" where the strings can be translated differently depending on the grammatical roles of the strings' components. For example, "empty" can be either a verb or an adjective, and this can lead to different translations in languages such as Italian or French.
- Avoid using images and icons that contain text in your application. They are expensive to localize.
- Allow plenty of room for the length of strings to expand in the user interface. In some languages, phrases can require 50-75 percent more space.
- Use the System.Resources.ResourceManager class to retrieve resources based on culture.
- Use Microsoft Visual Studio .NET to create Windows Forms dialog boxes, so they can be localized using the Windows Forms Resource Editor (Winres.exe). Do not code Windows Forms dialog boxes by hand.
- Arrange for professional localization (translation).
- For a complete description of creating and localizing resources, see Resources in Applications and Resources and Localization Using the .NET Framework SDK Tutorial.
Globalization Best Practices for ASP.NET Applications
- Explicitly set the CurrentUICulture and CurrentCulture properties in your application. Do not rely on defaults.
- Note that ASP.NET applications are managed applications and therefore can use the same classes as other managed applications for retrieving, displaying, and manipulating information based on culture.
- Be aware that you can specify the following three types of encodings in ASP.NET:
- requestEncoding specifies the encoding received from the client's browser.
- responseEncoding specifies the encoding to send to the client browser. In most situations, this should be the same as requestEncoding.
- fileEncoding specifies the default encoding for .aspx, .asmx, and .asax file parsing.
- Specify the values for the requestEncoding, responseEncoding, fileEncoding, culture, and uiCulture attributes in the following three places in an ASP.NET application:
- In the globalization section of a Web.config file. This file is external to the ASP.NET application. For more information, see <globalization> Element.
- In a page directive. Note that when an application is in a page, the file has already been read. Therefore, it is too late to specify fileEncoding and requestEncoding. Only uiCulture, Culture, and responseEncoding can be specified in a page directive.
- Programmatically in application code. This setting can vary per request. As with a page directive, by the time the application's code is reached it is too late to specify fileEncoding and requestEncoding. Only uiCulture, Culture, and responseEncoding can be specified in application code.
- Note that the uiCulture can be set to the browser accept language. For details, see the ASP.NET QuickStart Working With Resources sample.