8 Oracle Globalization Development Kit

Deploying a Monolingual Internet Application

Deploying a global Internet application with multiple instances of monolingual Internet applications is shown in Figure 8-1.

Figure 8-1 Monolingual Internet Application Architecture

Description of "Figure 8-1 Monolingual Internet Application Architecture"

Each application server is configured for the locale that it serves. This deployment model assumes that one instance of an Internet application runs in the same locale as the application in the middle tier.

The Internet applications access a back-end database in the native encoding used for the locale. The following are advantages of deploying monolingual Internet applications:

• The support of the individual locales is separated into different servers so that multiple locales can be supported independently in different locations and that the workload can be distributed accordingly. For example, customers may want to support Western European locales first and then support Asian locales such as Japanese (Japan) later.

• The complexity required to support multiple locales simultaneously is avoided. The amount of code to write is significantly less for a monolingual Internet application than for a multilingual Internet application.

The following are disadvantages of deploying monolingual Internet applications:

• Extra effort is required to maintain and manage multiple servers for different locales. Different configurations are required for different application servers.

• The minimum number of application servers required depends on the number of locales the application supports, regardless of whether the site traffic will reach the capacity provided by the application servers.

• Load balancing for application servers is limited to the group of application servers for the same locale.

• More QA resources, both human and machine, are required for multiple configurations of application servers. Internet applications running on different locales must be certified on the corresponding application server configuration.

• It is not designed to support multilingual content. For example, a web page containing Japanese and Arabic data cannot be easily supported in this model.

As more and more locales are supported, the disadvantages quickly outweigh the advantages. With the limitation and the maintenance overhead of the monolingual deployment model, this deployment architecture is suitable for applications that support only one or two locales.

Deploying a Multilingual Internet Application

Multilingual Internet applications are deployed to the application servers with a single application server configuration that works for all locales. Figure 8-2 shows the architecture of a multilingual Internet application.

Figure 8-2 Multilingual Internet Application Architecture

Description of "Figure 8-2 Multilingual Internet Application Architecture"

To support multiple locales in a single application instance, the application may need to do the following:

• Dynamically detect the locale of the users and adapt to the locale by constructing HTML pages in the language and cultural conventions of the locale

• Process character data in Unicode so that data in any language can be supported. Character data can be entered by users or retrieved from back-end databases.

• Dynamically determine the HTML page encoding (or character set) to be used for HTML pages and convert content from Unicode to the page encoding and the reverse.

The following are major advantages of deploying multilingual Internet application:

• Using a single application server configuration for all application servers simplifies the deployment configuration and hence reduces the cost of maintenance.

• Performance tuning and capacity planning do not depend on the number of locales supported by the Web site.

• Introducing additional locales is relatively easy. No extra machines are necessary for the new locales.

• Testing the application across different locales can be done in a single testing environment.

• This model can support multilingual content within the same instance of the application. For example, a web page containing Japanese, Chinese, English and Arabic data can be easily supported in this model.

The disadvantage of deploying multilingual Internet applications is that it requires extra coding during application development to handle dynamic locale detection and Unicode, which is costly when only one or two languages need to be supported.

Deploying multilingual Internet applications is more appropriate than deploying monolingual applications when Web sites support multiple locales.

Locale Determination

To be locale-aware or locale-sensitive, Internet applications need to be able to determine the preferred locale of the user.

Monolingual applications always serve users with the same locale, and that locale should be equivalent to the default runtime locale of the corresponding programming environment.

Multilingual applications can determine a user locale dynamically in three ways. Each method has advantages and disadvantages, but they can be used together in the applications to complement each other. The user locale can be determined in the following ways:

• Based on the user profile information from a LDAP directory server such as the Oracle Internet Directory or other user profile tables stored inside the database

  The schema for the user profile should include preferred locale attribute to indicate the locale of a user. This way of determining a locale user does not work if a user has not been logged on before.

• Based on the default locale of the browser

  Get the default ISO locale setting from a browser. The default ISO locale of the browser is sent through the Accept-Language HTTP header in every HTTP request. If the Accept-Language header is NULL, then the desired locale should default to English. The drawback of this approach is that the Accept-Language header may not be a reliable source of information for the locale of a user.

• Based on user selection

  Allow users to select a locale from a list box or from a menu, and switch the application locale to the one selected.

The Globalization Development Kit provides an application framework that enables you to use these locale determination methods declaratively.

Locale Awareness

To be locale-aware or locale-sensitive, Internet applications need to determine the locale of a user. After the locale of a user is determined, applications should:

• Construct HTML content in the language of the locale

• Use the cultural conventions implied by the locale

Locale-sensitive functions, such as date, time, and monetary formatting, are built into various programming environments such as Java and PL/SQL. Applications may use them to format the HTML pages according to the cultural conventions of the locale of a user. A locale is represented differently in different programming environments. For example, the French (Canada) locale is represented in different environments as follows:

• In the ISO standard, it is represented by fr-CA where fr is the language code defined in the ISO 639 standard and CA is the country code defined in the ISO 3166 standard.

• In Java, it is represented as a Java locale object constructed with fr, the ISO language code for French, as the language and CA, the ISO country code for Canada, as the country. The Java locale name is fr_CA.

• In PL/SQL and SQL, it is represented mainly by the NLS_LANGUAGE and NLS_TERRITORY session parameters where the value of the NLS_LANGUAGE parameter is equal to CANADIAN FRENCH and the value of the NLS_TERRITORY parameter is equal to CANADA.

If you write applications for more than one programming environment, then locales must be synchronized between environments. For example, Java applications that call PL/SQL procedures should map the Java locales to the corresponding NLS_LANGUAGE and NLS_TERRITORY values and change the parameter values to match the user's locale before calling the PL/SQL procedures.

The Globalization Development Kit for Java provides a set of Java classes to ensure consistency on locale-sensitive behaviors with Oracle databases.

Localizing the Content

For the application to support a multilingual environment, it must be able to present the content in the preferred language and in the locale convention of the user. Hard-coded user interface text must first be externalized from the application, together with any image files, so that they can be translated into the different languages supported by the application. The translation files then must be staged in separate directories, and the application must be able to locate the relevant content according to the user locale setting. Special application handling may also be required to support a fallback mechanism, so that if the user-preferred locale is not available, then the next most suitable content is presented. For example, if Canadian French content is not available, then it may be suitable for the application to switch to the French files instead.

Modifying the HelloWorld Application

This section explains how to modify the HelloWorld application to support globalization. The application will be modified to support three locales, Simplified Chinese (zh-CN), Swiss German (de-CH), and American English (en-US). The following rules will be used for the languages:

• If the client locale supports one of these languages, then that language will be used for the application.

• If the client locale does not support one of these languages, then American English will be used for the application.

In addition, the user will be able to change the language by selecting a supported locales from the locale selection list. The following tasks describe how to modify the application:

• Task 1: Enable the Hello World Application to use the GDK Framework

• Task 2: Configure the GDK Framework for Hello World

• Task 3: Enable the JSP or Java Servlet

• Task 4: Create the Locale Selection List

• Task 5: Build the Application

Task 1: Enable the Hello World Application to use the GDK Framework

In this task, the GDK filter and a listener are configured in the Web application deployment descriptor file, web.xml. This allows the GDK framework to be used with the HelloWorld application. Example 8-3 shows the GDK-enabled web.xml file.

<?xml version = '1.0' encoding = 'windows-1252'?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
  <description>web.xml file for Hello World</description>
   <!-- Enable the application to use the GDK Application Framework.-->
  <filter> 
    <filter-name>GDKFilter</filter-name>
    <filter-class>oracle.i18n.servlet.filter.ServletFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>GDKFilter</filter-name>
    <url-pattern>*.jsp</url-pattern>
  </filter-mapping>
 
  <listener> 
    <listener-class>oracle.i18n.servlet.listener.ContextListener</listener-class>
  </listener> 
 
  <session-config>
    <session-timeout>35</session-timeout>
  </session-config>
  <mime-mapping>
    <extension>html</extension>
    <mime-type>text/html</mime-type>
  </mime-mapping>
  <mime-mapping>
    <extension>txt</extension>
    <mime-type>text/plain</mime-type>
  </mime-mapping>
</web-app>

The following tags were added to the file:

• <filter>

  The filter name is GDKFilter, and the filter class is oracle.i18n.servlet.filter.ServletFilter.

• <filter-mapping>

  The GDKFilter is specified in the tag, as well as the URL pattern.

• <listener>

  The listener class is oracle.i18n.servlet.listener.ContextListener. The default GDK listener is configured to instantiate GDK ApplicationContext, which controls application scope operations for the framework.

Task 2: Configure the GDK Framework for Hello World

The GDK application framework is configured with the application configuration file gdkapp.xml. The configuration file is located in the same directory as the web.xml file. Example 8-4 shows the gdkapp.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<gdkapp xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="gdkapp.xsd">  
  
  <!-- The Hello World GDK Configuration -->
  <page-charset default="yes">UTF-8</page-charset>
 
  <!-- The supported application locales for the Hello World Application -->

  <application-locales>
    <locale>de-CH</locale>
    <locale default="yes">en-US</locale>
    <locale>zh-CN</locale>
  </application-locales>
  
  <locale-determine-rule>
    <locale-source>oracle.i18n.servlet.localesource.UserInput</locale-source>
    <locale-source>oracle.i18n.servlet.localesource.HttpAcceptLanguage</locale-source>
  </locale-determine-rule>
  
  <message-bundles> 
    <resource-bundle name="default">com.oracle.demo.Messages</resource-bundle>
  </message-bundles> 
</gdkapp>

The file must be configured for J2EE applications. The following tags are used in the file:

• <page-charset>

  The page encoding tag specifies the character set used for HTTP requests and responses. The UTF-8 encoding is used as the default because many languages can be represented by this encoding.

• <application-locales>

  Configuring the application locales in the gdkapp.xml file makes a central place to define locales. This makes it easier to add and remove locales without changing source code. The locale list can be retrieved using the GDK API call ApplicationContext.getSupportedLocales.

• <locale-determine-rule>

  The language of the initial page is determined by the language setting of the browser. The user can override this language by choosing from the list. The locale-determine-rule is used by GDK to first try the Accept-Language HTTP header as the source of the locale. If the user selects a locale from the list, then the JSP posts a locale parameter value containing the selected locale. The GDK then sends a response with the contents in the selected language.

• <message-bundles>

  The message resource bundles allow an application access to localized static content that may be displayed on a Web page. The GDK framework configuration file allows an application to define a default resource bundle for translated text for various languages. In the HelloWorld example, the localized string messages are stored in the Java ListResourceBundle bundle named Messages. The Messages bundle consists of base resources for the application which are in the default locale. Two more resource bundles provide the Chinese and German translations. These resource bundles are named Messages_zh_CN.java and Messages_de.java respectively. The HelloWorld application will select the right translation for "Hello World!" from the resource bundle based on the locale determined by the GDK framework. The <message-bundles> tag is used to configure the resource bundles that the application will use.

Task 3: Enable the JSP or Java Servlet

JSPs and Java servlets must be enabled to use the GDK API. Example 8-5 shows a JSP that has been modified to enable to use the GDK API and services. This JSP can accommodate any language and locale.

. . .
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title><%= localizer.getMessage("helloWorldTitle") %></title>
  </head>
  
  <body>
  <div style="color: blue;" align="right">
    <% Date currDate= new Date(System.currentTimeMillis()); %>
    <%=localizer.formatDateTime(currDate, OraDateFormat.LONG)%>
  </div>
  <hr/>
  
  <div align="left">
  <form>
    <select name="locale" size="1">
      <%= getCountryDropDown(request)%>
    </select>
    <input  type="submit" value="<%= localizer.getMessage("changeLocale") %>">
  </input>
  </form>
  </div>
  <h1><%= localizer.getMessage("helloWorld") %></h1>
  </body>
</html>

Figure 8-5 shows the HelloWorld application that has been configured with the zh-CN locale as the primary locale for the browser preference. The HelloWorld string and page title are displayed in Simplified Chinese. In addition, the date is formatted in the zh-CN locale convention. This example allows the user to override the locale from the locale selection list.

Figure 8-5 HelloWorld Localized for the zh-CN Locale

Description of "Figure 8-5 HelloWorld Localized for the zh-CN Locale"

When the locale changes or is initialized using the HTTP Request Accept-Language header or the locale selection list, the GUI behaves appropriately for that locale. This means the date and time value in the upper right corner is localized properly. In addition, the strings are localized and displayed on the HelloWorld page.

The GDK Java Localizer class provides capabilities to localize the contents of a Web page based on the automatic detection of the locale by the GDK framework.

The following code retrieves an instance of the localizer based on the current HTTPServletRequest object. In addition, several imports are declared for use of the GDK API within the JSP page. The localizer retrieves localized strings in a locale-sensitive manner with fallback behavior, and formats the date and time.

<%@page contentType="text/html;charset=UTF-8"%>
<%@page import="java.util.*, oracle.i18n.servlet.*" %>
<%@page import="oracle.i18n.util.*, oracle.i18n.text.*" %>
 
<%
    Localizer localizer = ServletHelper.getLocalizerInstance(request);
%>

The following code retrieves the current date and time value stored in the currDate variable. The value is formatted by the localizer formatDateTime method. The OraDateFormat.LONG parameter in the formatDateTime method instructs the localizer to format the date using the locale's long formatting style. If the locale of the incoming request is changed to a different locale with the locale selection list, then the date and time value will be formatted according to the conventions of the new locale. No code changes need to be made to support newly-introduced locales.

div style="color: blue;" align="right">
 
    <% Date currDate= new Date(System.currentTimeMillis()); %>
    <%=localizer.formatDateTime(currDate, OraDateFormat.LONG)%>
  </div>

The HelloWorld JSP can be reused for any locale because the HelloWorld string and title are selected in a locale-sensitive manner. The translated strings are selected from a resource bundle.

The GDK uses the OraResourceBundle class for implementing the resource bundle fallback behavior. The following code shows how the Localizer picks the HelloWorld message from the resource bundle.

The default application resource bundle Messages is declared in the gdkapp.xml file. The localizer uses the message resource bundle to pick the message and apply the locale-specific logic. For example, if the current locale for the incoming request is "de-CH", then the message will first be looked for in the messages_de_CH bundle. If it does not exist, then it will look up in the Messages_de resource bundle.

<h1><%= localizer.getMessage("helloWorld") %></h1>

Task 4: Create the Locale Selection List

The locale selection list is used to override the selected locale based on the HTTP Request Accept-Language header. The GDK framework checks the locale parameter passed in as part of the HTTP POST request as a value for the new locale. A locale selected with the locale selection list is posted as the locale parameter value. GDK uses this value for the request locale. All this happens implicitly within the GDK code.

The following code sample displays the locale selection list as an HTML select tag with the name locale. The submit tag causes the new value to be posted to the server. The GDK framework retrieves the correct selection.

<form>
    <select name="locale" size="1">
      <%= getCountryDropDown(request)%>
    </select>
    <input type="submit" value="<%= localizer.getMessage("changeLocale") %>">
    </input>
</form>

The locale selection list is constructed from the HTML code generated by the getCountryDropDown method. The method converts the configured application locales into localized country names.

A call is made to the ServletHelper class to get the ApplicationContext object associated with the current request. This object provides the globalization context for an application, which includes information such as supported locales and configuration information. The getSupportedLocales call retrieves the list of locales in the gdkapp.xml file. The configured application locale list is displayed as options of the HTML select. The OraDisplayLocaleInfo class is responsible for providing localization methods of locale-specific elements such as country and language names.

An instance of this class is created by passing in the current locale automatically determined by the GDK framework. GDK creates requests and response wrappers for HTTP request and responses. The request.getLocale() method returns the GDK determined locale based on the locale determination rules.

The OraDsiplayLocaleInfo.getDisplayCountry method retrieves the localized country names of the application locales. An HTML option list is created in the ddOptBuffer string buffer. The getCountryDropDown call returns a string containing the following HTML values:

<option value="en_US" selected>United States [en_US]</option>
   <option value="zh_CN">China [zh_CN]</option>
   <option value="de_CH">Switzerland [de_CH]</option>

In the preceding values, the en-US locale is selected for the locale. Country names are generated are based on the current locale.

Example 8-6 shows the code for constructing the locale selection list.

<%!
    public String getCountryDropDown(HttpServletRequest request)
    {
        StringBuffer ddOptBuffer=new StringBuffer();
        ApplicationContext ctx = ServletHelper.getApplicationContextInstance(request);
        Locale[] appLocales = ctx.getSupportedLocales();
        Locale currentLocale = request.getLocale();
        
        if (currentLocale.getCountry().equals(""))
        {
             // Since the Country was not specified get the Default Locale 
             // (with Country) from the GDK
             OraLocaleInfo oli = OraLocaleInfo.getInstance(currentLocale);
             currentLocale = oli.getLocale(); 
        }
         
        OraDisplayLocaleInfo odli = OraDisplayLocaleInfo.getInstance(currentLocale);
        for (int i=0;i<appLocales.length; i++)
        {
            ddOptBuffer.append("<option value=\"" + appLocales[i] + "\"" +  
            (appLocales[i].getLanguage().equals(currentLocale.getLanguage()) ? " selected" : "") +
                    ">" + odli.getDisplayCountry(appLocales[i]) +
                " [" +  appLocales[i] + "]</option>\n");
        }
       
        return ddOptBuffer.toString();
    }
%>

Task 5: Build the Application

In order to build the application, the following files must be specified in the classpath:

• orai18n.jar

• regexp.jar

The orai18n.jar file contains the GDK framework and the API. The regexp.jar file contains the regular expression library. The GDK API also has locale determination capabilities. The classes are supplied by the ora18n-lcsd.jar file.

Making the GDK Framework Available to J2EE Applications

The behavior of the GDK application framework for J2EE is controlled by the GDK application configuration file, gdkapp.xml. The application configuration file allows developers to specify the behaviors of globalized applications in one centralized place. One application configuration file is required for each J2EE application using the GDK. The gdkapp.xml file should be placed in the ./WEB-INF directory of the J2EE environment of the application. The file dictates the behavior and the properties of the GDK framework and the application that is using it. It contains locale mapping tables, character sets of content files, and globalization parameters for the configuration of the application. The application administrator can modify the application configuration file to change the globalization behavior in the application, without needing to change the programs and to recompile them.

For a J2EE application to use the GDK application framework defined by the corresponding GDK application configuration file, the GDK Servlet filter and the GDK context listener must be defined in the web.xml file of the application. The web.xml file should be modified to include the following at the beginning of the file:

<web-app>
<!-- Add GDK filter that is called after the authentication -->

<filter>
    <filter-name>gdkfilter</filter-name>
    <filter-class>oracle.i18n.servlet.filter.ServletFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>gdkfilter</filter-name>
    <url-pattern>*.jsp</url-pattern>
</filter-mapping>

<!-- Include the GDK context listener -->

 <listener>
<listener-class>oracle.i18n.servlet.listener.ContextListener</listener-class>
 </listener>
</web-app>

Examples of the gdkapp.xml and web.xml files can be found in the $ORACLE_HOME/nls/gdk/demo directory.

The GDK application framework supports Servlet container version 2.3 and later. It uses the Servlet filter facility for transparent globalization operations such as determining the user locale and specifying the character set for content files. The ContextListener instantiates GDK application parameters described in the GDK application configuration file. The ServletFilter overrides the request and response objects with a GDK request (ServletRequestWrapper) and response (ServletResponseWrapper) objects, respectively.

If other application filters are used in the application to also override the same methods, then the filter in the GDK framework may return incorrect results. For example, if getLocale returns en_US, but the result is overridden by other filters, then the result of the GDK locale detection mechanism is affected. All of the methods that are being overridden in the filter of the GDK framework are documented in Oracle Globalization Development Kit Java API Reference. Be aware of potential conflicts when using other filters together with the GDK framework.

Integrating Locale Sources into the GDK Framework

Determining the user's preferred locale is the first step in making an application global-ready. The locale detection offered by the J2EE application framework is primitive. It lacks the method that transparently retrieves the most appropriate user locale among locale sources. It provides locale detection by the HTTP language preference only, and it cannot support a multilevel locale fallback mechanism. The GDK application framework provides support for predefined locale sources to complement J2EE. In a web application, several locale sources are available. Table 8-1 summarizes locale sources that are provided by the GDK.

The GDK application framework provides seamless support for predefined locale sources, such as user input locale, HTTP language preference, user profile locale preference in the database, and the application default locale. You can incorporate the locale sources to the framework by defining them under the <locale-determine-rule> tag in the GDK application configuration file as follows:

<locale-determine-rule>
    <locale-source>oracle.i18n.servlet.localesource.UserInput</locale-source>
    <locale-source>oracle.i18n.servlet.localesource.HTTPAcceptLanguage</locale-source>
</locale-determine-rule>

The GDK framework uses the locale source declaration order and determines whether a particular locale source is available. If it is available, then it is used as the source, otherwise, it tries to find the next available locale source for the list. In the preceding example, if the UserInput locale source is available, it is used first, otherwise, the HTTPAcceptLanguage locale source will be used.

Custom locale sources, such as locale preference from an LDAP server, can be easily implemented and integrated into the GDK framework. You need to implement the LocaleSource interface and specify the corresponding implementation class under the <locale-determine-rule> tag in the same way as the predefined locale sources were specified.

The LocaleSource implementation not only retrieves the locale information from the corresponding source to the framework but also updates the locale information to the corresponding source when the framework tells it to do so. Locale sources can be read-only or read/write, and they can be cacheable or noncacheable. The GDK framework initiates updates only to read/write locale sources and caches the locale information from cacheable locale sources. Examples of custom locale sources can be found in the $ORACLE_HOME/nls/gdk/demo directory.

Getting the User Locale From the GDK Framework

The GDK offers automatic locale detection to determine the current locale of the user. For example, the following code retrieves the current user locale in Java. It uses a Locale object explicitly.

Locale loc = request.getLocale();

The getLocale() method returns the Locale that represents the current locale. This is similar to invoking the HttpServletRequest.getLocale() method in JSP or Java Servlet code. However, the logic in determining the user locale is different, because multiple locale sources are being considered in the GDK framework.

Alternatively, you can get a Localizer object that encapsulates the Locale object determined by the GDK framework. For the benefits of using the Localizer object, see "Implementing Locale Awareness Using the GDK Localizer".

Localizer localizer = ServletHelper.getLocalizerInstance(request);
Locale loc = localizer.getLocale();

The locale detection logic of the GDK framework depends on the locale sources defined in the GDK application configuration file. The names of the locale sources are registered in the application configuration file. The following example shows the locale determination rule section of the application configuration file. It indicates that the user-preferred locale can be determined from either the LDAP server or from the HTTP Accept-Language header. The LDAPUserSchema locale source class should be provided by the application. Note that all of the locale source classes have to be extended from the LocaleSource abstract class.

<locale-determine-rule>
    <locale-source>LDAPUserSchema</locale-source>
    <locale-source>oracle.i18n.localesource.HTTPAcceptLanguage</locale-source>
</locale-determine-rule>

For example, when the user is authenticated in the application and the user locale preference is stored in an LDAP server, then the LDAPUserSchema class connects to the LDAP server to retrieve the user locale preference. When the user is anonymous, then the HttpAcceptLanguage class returns the language preference of the web browser.

The cache is maintained for the duration of a HTTP session. If the locale source is obtained from the HTTP language preference, then the locale information is passed to the application in the HTTP Accept-Language header and not cached. This enables flexibility so that the locale preference can change between requests. The cache is available in the HTTP session.

The GDK framework exposes a method for the application to overwrite the locale preference information persistently stored in locale sources such as the LDAP server or the user profile table in the database. This method also resets the current locale information stored inside the cache for the current HTTP session. The following is an example of overwriting the preferred locale using the store command.

<input type="hidden" 
name="<%=appctx.getParameterName(LocaleSource.Parameter.COMMAND)%>" 
value="store">

To discard the current locale information stored inside the cache, the clean command can be specified as the input parameter. The following table shows the list of commands supported by the GDK:

Note that the GDK parameter names can be customized in the application configuration file to avoid name conflicts with other parameters used in the application.

Implementing Locale Awareness Using the GDK Localizer

The Localizer object obtained from the GDK application framework is an all-in-one globalization object that provides access to functions that are commonly used in building locale awareness in your applications. In addition, it provides functions to get information about the application context, such as the list of supported locales. The Localizer object simplifies and centralizes the code required to build consistent locale awareness behavior in your applications.

The oracle.i18n.servlet package contains the Localizer class. You can get the Localizer instance as follows:

Localizer lc = ServletHelper.getLocalizerInstance(request);

The Localizer object encapsulates the most commonly used locale-sensitive information determined by the GDK framework and exposes it as locale-sensitive methods. This object includes the following functionalities pertaining to the user locale:

• Format date in long and short formats

• Format numbers and currencies

• Get collation key value of a string

• Get locale data such as language, country and currency names

• Get locale data to be used for constructing user interface

• Get a translated message from resource bundles

• Get text formatting information such as writing direction

• Encode and decode URLs

• Get the common list of time zones and linguistic sorts

For example, when you want to display a date in your application, you may want to call the Localizer.formatDate() or Localizer.formateDateTime() methods. When you want to determine the writing direction of the current locale, you can call the Localizer.getWritingDirection() and Localizer.getAlignment() to determine the value used in the <DIR> tag and <ALIGN> tag respectively.

The Localizer object also exposes methods to enumerate the list of supported locales and their corresponding languages and countries in your applications.

The Localizer object actually makes use of the classes in the GDK Java API to accomplish its tasks. These classes include, but are not limited to, the following: OraDateFormat, OraNumberFormat, OraCollator, OraLocaleInfo, oracle.i18n.util.LocaleMapper, oracle.i18n.net.URLEncoder, and oracle.i18n.net.URLDecoder.

The Localizer object simplifies the code you need to write for locale awareness. It maintains caches of the corresponding objects created from the GDK Java API so that the calling application does not need to maintain these objects for subsequent calls to the same objects. If you require more than the functionality the Localizer object can provide, then you can always call the corresponding methods in the GDK Java API directly.

Defining the Supported Application Locales in the GDK

The number of locales and the names of the locales that an application needs to support are based on the business requirements of the application. The names of the locales that are supported by the application are registered in the application configuration file. The following example shows the application locales section of the application configuration file. It indicates that the application supports German (de), Japanese (ja), and English for the US (en-US), with English defined as the default fallback application locale. Note that the locale names are based on the IANA convention.

<application-locales>
    <locale>de</locale>
    <locale>ja</locale>
    <locale default="yes">en-US</locale>
</application-locales>

When the GDK framework detects the user locale, it verifies whether the locale that is returned is one of the supported locales in the application configuration file. The verification algorithm is as follows:

1. Retrieve the list of supported application locales from the application configuration file.

2. Check whether the locale that was detected is included in the list. If it is included in the list, then use this locale as the current client's locale.

3. If there is a variant in the locale that was detected, then remove the variant and check whether the resulting locale is in the list. For example, the Java locale de_DE_EURO has a EURO variant. Remove the variant so that the resulting locale is de_DE.

4. If the locale includes a country code, then remove the country code and check whether the resulting locale is in the list. For example, the Java locale de_DE has a country code of DE. Remove the country code so that the resulting locale is de.

5. If the detected locale does not match any of the locales in the list, then use the default locale that is defined in the application configuration file as the client locale.

By performing steps 3 and 4, the application can support users with the same language requirements but with different locale settings than those defined in the application configuration file. For example, the GDK can support de-AT (the Austrian variant of German), de-CH (the Swiss variant of German), and de-LU (the Luxembourgian variant of German) locales.

The locale fallback detection in the GDK framework is similar to that of the Java Resource Bundle, except that it is not affected by the default locale of the Java VM. This exception occurs because the Application Default Locale can be used during the GDK locale fallback operations.

If the application-locales section is omitted from the application configuration file, then the GDK assumes that the common locales, which can be returned from the OraLocaleInfo.getCommonLocales method, are supported by the application.

Handling Non-ASCII Input and Output in the GDK Framework

The character set (or character encoding) of an HTML page is a very important piece of information to a browser and an Internet application. The browser needs to interpret this information so that it can use correct fonts and character set mapping tables for displaying pages. The Internet applications need to know so they can safely process input data from a HTML form based on the specified encoding.

The page encoding can be translated as the character set used for the locale to which an Internet application is serving.

In order to correctly specify the page encoding for HTML pages without using the GDK framework, Internet applications must:

1. Determine the desired page input data character set encoding for a given locale.

2. Specify the corresponding encoding name for each HTTP request and HTTP response.

Applications using the GDK framework can ignore these steps. No application code change is required. The character set information is specified in the GDK application configuration file. At runtime, the GDK automatically sets the character sets for the request and response objects. The GDK framework does not support the scenario where the incoming character set is different from that of the outgoing character set.

The GDK application framework supports the following scenarios for setting the character sets of the HTML pages:

• A single local character set is dedicated to the whole application. This is appropriate for a monolingual Internet application. Depending on the properties of the character set, it may be able to support more than one language. For example, most Western European languages can be served by ISO-8859-1.

• Unicode UTF-8 is used for all contents regardless of the language. This is appropriate for a multilingual application that uses Unicode for deployment.

• The native character set for each language is used. For example, English contents are represented in ISO-8859-1, and Japanese contents are represented in Shift_JIS. This is appropriate for a multilingual Internet application that uses a default character set mapping for each locale. This is useful for applications that need to support different character sets based on the user locales. For example, for mobile applications that lack Unicode fonts or Internet browsers that cannot fully support Unicode, the character sets must to be determined for each request.

The character set information is specified in the GDK application configuration file. The following is an example of setting UTF-8 as the character set for all the application pages.

<page-charset>UTF-8</page-charset>

The page character set information is used by the ServletRequestWrapper class, which sets the proper character set for the request object. It is also used by the ContentType HTTP header specified in the ServletResponseWrapper class for output when instantiated. If page-charset is set to AUTO-CHARSET, then the character set is assumed to be the default character set for the current user locale. Set page-charset to AUTO-CHARSET as follows:

<page-charset>AUTO-CHARSET</page-charset>

The default mappings are derived from the LocaleMapper class, which provides the default IANA character set for the locale name in the GDK Java API.

Table 8-2 lists the mappings between the common ISO locales and their IANA character sets.

The locale to character set mapping in the GDK can also be customized. To override the default mapping defined in the GDK Java API, a locale-to-character-set mapping table can be specified in the application configuration file.

<locale-charset-maps>
   <locale-charset>
      <locale>ja</locale><charset>EUC-JP</charset>
   </locale-charset>
</locale-charset-maps>

The previous example shows that for locale Japanese (ja), the GDK changes the default character set from SHIFT_JIS to EUC-JP.

Managing Localized Content in the GDK

This section includes the following topics:

• Managing Localized Content in JSPs and Java Servlets

• Managing Localized Content in Static Files

<% Locale user_locale=request.getLocale();
   ResourceBundle rb=ResourceBundle.getBundle("resource",user_locale); %>
<%= rb.getString("Welcome") %> 

<% Localizer.getMessage ("Welcome") %>

<message-bundles>
  <resource-bundle name="default">resource</resource-bundle>
</message-bundles>

/fr/index.html
/ja/index.html

<img src="<%="ServletHelper.rewriteURL("image/welcome.jpg", request)%>">
<a href="<%="ServletHelper.rewriteURL("html/welcome.html", request)%>">

<url-rewrite-rule fallback="yes">
    <pattern>(.*)/(a-zA-Z0-9_\]+.)$</pattern>
    <result>$1/$A/$2</result>
  </url-rewrite-rule>

Oracle Locale Information in the GDK

Oracle locale definitions, which include languages, territories, linguistic sorts, and character sets, are exposed in the GDK Java API. The naming convention that Oracle uses may be different from other vendors. Although many of these names and definitions follow industry standards, some are Oracle-specific, tailored to meet special customer requirements.

OraLocaleInfo is an Oracle locale class that includes language, territory, and collator objects. It provides a method for applications to retrieve a collection of locale-related objects for a given locale. Examples include: a full list of the Oracle linguistic sorts available in the GDK, the local time zones defined for a given territory, or the common languages used in a particular territory.

Following are examples of using the OraLocaleInfo class:

// All Territories supported by GDK 
String[] avterr = OraLocaleInfo.getAvailableTerritories();

// Local TimeZones for a given Territory

OraLocaleInfo oloc = OraLocaleInfo.getInstance("English", "Canada");
TimeZone[] loctz = oloc.getLocalTimeZones();

Oracle Locale Mapping in the GDK

The GDK Java API provides the LocaleMapper class. It maps equivalent locales and character sets between Java, IANA, ISO, and Oracle. A Java application may receive locale information from the client that is specified in an Oracle Database locale name or an IANA character set name. The Java application must be able to map to an equivalent Java locale or Java encoding before it can process the information correctly.

The follow example shows using the LocaleMapper class.

// Mapping from Java locale to Oracle language and Oracle territory

Locale locale = new Locale("it", "IT");
String oraLang = LocaleMapper.getOraLanguage(locale);
String oraTerr = LocaleMapper.getOraTerritory(locale);

// From Oracle language and Oracle territory to Java Locale

locale = LocaleMapper.getJavaLocale("AMERICAN","AMERICA");
locale = LocaleMapper.getJavaLocale("TRADITONAL CHINESE", "");

// From IANA & Java to Oracle Character set

String ocs1     = LocaleMapper.getOraCharacterSet(
                               LocaleMapper.IANA, "ISO-8859-1");
String ocs2     = LocaleMapper.getOraCharacterSet(
                               LocaleMapper.JAVA, "ISO8859_1");

The LocaleMapper class can also return the most commonly used e-mail character set for a specific locale on both Windows and UNIX platforms. This is useful when developing Java applications that need to process e-mail messages.

Oracle Character Set Conversion in the GDK

The GDK Java API contains a set of character set conversion classes APIs that enable users to perform Oracle character set conversions. Although Java JDK is already equipped with classes that can perform conversions for many of the standard character sets, they do not support Oracle-specific character sets and Oracle's user-defined character sets.

In JDK 1.4, J2SE introduced an interface for developers to extend Java's character sets. The GDK Java API provides implicit support for Oracle's character sets by using this plug-in feature. You can access the J2SE API to obtain Oracle-specific behaviors.

Figure 8-7 shows that the GDK character set conversion tables are plugged into J2SE in the same way as the Java character set tables. With this pluggable framework of J2SE, the Oracle character set conversions can be used in the same way as other Java character set conversions.

Figure 8-7 Oracle Character Set Plug-In

Description of "Figure 8-7 Oracle Character Set Plug-In"

Because the java.nio.charset Java package is not available in JDK versions before 1.4, you must install JDK 1.4 or later to use Oracle's character set plug-in feature.

The GDK character conversion classes support all Oracle character sets including user-defined characters sets. It can be used by Java applications to properly convert to and from Java's internal character set, UTF-16.

Oracle's character set names are proprietary. To avoid potential conflicts with Java's own character sets, all Oracle character set names have an X-ORACLE- prefix for all implicit usage through Java's API.

The following is an example of Oracle character set conversion:

// Converts the Chinese character "three" from UCS2 to JA16SJIS 

String str = "\u4e09"; 
byte[] barr = str.getBytes("x-oracle-JA16SJIS");

Just as with other Java character sets, the character set facility in java.nio.charset.Charset is applicable to all of the Oracle character sets. For example, if you want to check whether the specified character set is a superset of another character set, then you can use the Charset.contains method as follows:

Charset cs1 = Charset.forName("x-oracle-US7ASCII");
Charset cs2 = Charset.forName("x-oracle-WE8WINDOWS1252");
// true if WE8WINDOWS1252 is the superset of US7ASCII, otherwise false.
boolean osc = cs2.contains(cs1);

For a Java application that is using the JDBC driver to communicate with the database, the JDBC driver provides the necessary character set conversion between the application and the database. Calling the GDK character set conversion methods explicitly within the application is not required. A Java application that interprets and generates text files based on Oracle's character set encoding format is an example of using Oracle character set conversion classes.

Oracle Date, Number, and Monetary Formats in the GDK

The GDK Java API provides formatting classes that support date, number, and monetary formats using Oracle conventions for Java applications in the oracle.i18n.text package.

New locale formats introduced in Oracle Database 10g, such as the short and long date, number, and monetary formats, are also exposed in these format classes.

The following are examples of Oracle date, Oracle number, and Oracle monetary formatting:

// Obtain the current date and time in the default Oracle LONG format for
// the locale de_DE (German_Germany)

Locale locale = new Locale("de", "DE");
OraDateFormat odf =
  OraDateFormat.getDateTimeInstance(OraDateFormat.LONG, locale);

// Obtain the numeric value 1234567.89 using the default number format
// for the Locale en_IN (English_India)

locale = new Locale("en", "IN");
OraNumberFormat onf = OraNumberFormat.getNumberInstance(locale);
String nm = onf.format(new Double(1234567.89));

// Obtain the monetary value 1234567.89 using the default currency 
// format for the Locale en_US (American_America)

locale = new Locale("en", "US");

onf = OraNumberFormat.getCurrencyInstance(locale);
nm = onf.format(new Double(1234567.89));

Oracle Binary and Linguistic Sorts in the GDK

Oracle provides support for binary, monolingual, and multilingual linguistic sorts in the database. In Oracle Database, these sorts provide case-insensitive and accent-insensitive sorting and searching capabilities inside the database. By using the OraCollator class, the GDK Java API enables Java applications to sort and search for information based on the latest Oracle binary and linguistic sorting features, including case-insensitive and accent-insensitive options.

Normalization can be an important part of sorting. The composition and decomposition of characters are based on the Unicode standard; therefore, sorting also depends on the Unicode standard. The GDK contains methods to perform composition.

The sorting order of a binary sort is based on the Oracle character set that is being used. Except for the UTFE character set, the binary sorts of all Oracle character sets are supported in the GDK Java API. The only linguistic sort that is not supported in the GDK Java API is JAPANESE, but a similar and more accurate sorting result can be achieved by using JAPANESE_M.

The following example shows string comparisons and string sorting.

// compares strings using XGERMAN

private static String s1 = "abcSS";     
private static String s2 = "abc\u00DF"; 

String cname = "XGERMAN";
OraCollator ocol = OraCollator.getInstance(cname);
int c = ocol.compare(s1, s2);


// sorts strings using GENERIC_M 

private static String[] source =
  new String[]
  {
    "Hochgeschwindigkeitsdrucker",
    "Bildschirmfu\u00DF",
    "Skjermhengsel",
    "DIMM de Mem\u00F3ria",
    "M\u00F3dulo SDRAM com ECC",
  };


  cname = "GENERIC_M";
  ocol = OraCollator.getInstance(cname);
  List result = getCollationKeys(source, ocol);
 

private static List getCollationKeys(String[] source, OraCollator ocol)
{
  List karr = new ArrayList(source.length);
  for (int i = 0; i < source.length; ++i)
  {
    karr.add(ocol.getCollationKey(source[i]));
  }
  Collections.sort(karr); // sorting operation
  return karr;
}

Oracle Language and Character Set Detection in the GDK

The Oracle Language and Character Set Detection Java classes in the GDK Java API provide a high performance, statistically based engine for determining the character set and language for unspecified text. It can automatically identify language and character set pairs from throughout the world. With each text, the language and character set detection engine sets up a series of probabilities, each probability corresponding to a language and character set pair. The most probable pair statistically identifies the dominant language and character set.

The purity of the text submitted affects the accuracy of the language and character set detection. Only plain text strings are accepted, so any tagging needs to be stripped before hand. The ideal case is literary text with almost no foreign words or grammatical errors. Text strings that contain a mix of languages or character sets, or nonnatural language text like addresses, phone numbers, and programming language code may yield poor results.

The LCSDetector class can detect the language and character set of a byte array, a character array, a string, and an InputStream class. It supports both plain text and HTML file detection. It can take the entire input for sampling or only portions of the input for sampling, when the length or both the offset and the length are supplied. For each input, up to three potential language and character set pairs can be returned by the LCSDetector class. They are always ranked in sequence, with the pair with the highest probability returned first.

The following are examples of using the LCSDetector class to enable language and character set detection:

// This example detects the character set of a plain text file "foo.txt" and
// then appends the detected ISO character set name to the name of the text file

LCSDetector         lcsd = new LCSDetector();
File             oldfile = new File("foo.txt");
FileInputStream      in = new FileInputStream(oldfile);
lcsd.detect(in);
String          charset = lcsd.getResult().getIANACharacterSet();
File            newfile = new File("foo."+charset+".txt");
oldfile.renameTo(newfile);

// This example shows how to use the LCSDector class to detect the language and 
// character set of a byte array

int          offset = 0;
LCSDetector     led = new LCSDetector();
/* loop through the entire byte array */
while ( true )
{
    bytes_read = led.detect(byte_input, offset, 1024);
    if ( bytes_read == -1 )
        break;
    offset += bytes_read;
}
LCSDResultSet    res = led.getResult();

/* print the detection results with close ratios */
System.out.println("the best guess "  );
System.out.println("Langauge " + res.getOraLanguage() );
System.out.println("CharacterSet " + res.getOraCharacterSet() );
int     high_hit = res.getHiHitPairs();
if ( high_hit >= 2 )
{
        System.out.println("the second best guess  " );
        System.out.println("Langauge " + res.getOraLanguage(2) );
        System.out.println("CharacterSet " +res.getOraCharacterSet(2) );
}
if ( high_hit >= 3 )
{
         System.out.println("the third best guess  ");
         System.out.println("Langauge " + res.getOraLanguage(3) );
         System.out.println("CharacterSet " +res.getOraCharacterSet(3) );
}

Oracle Translated Locale and Time Zone Names in the GDK

All of the Oracle language names, territory names, character set names, linguistic sort names, and time zone names have been translated into 27 languages including English. They are readily available for inclusion into the user applications, and they provide consistency for the display names across user applications in different languages. OraDisplayLocaleInfo is a utility class that provides the translations of locale and attributes. The translated names are useful for presentation in user interface text and for drop-down selection boxes. For example, a native French speaker prefers to select from a list of time zones displayed in French than in English.

The following example shows using OraDisplayLocaleInfo to return a list of time zones supported in Canada, using the French translation names.

OraLocaleInfo oloc = OraLocaleInfo.getInstance("CANADIAN FRENCH", "CANADA");
OraDisplayLocaleInfo odloc = OraDisplayLocaleInfo.getInstance(oloc);
TimeZone[] loctzs = oloc.getLocaleTimeZones();
String []  disptz = new string [loctzs.length];
for (int i=0; i<loctzs.length; ++i)
{
  disptz [i]= odloc.getDisplayTimeZone(loctzs[i]);
  ...
}

Using the GDK with E-Mail Programs

You can use the GDK LocaleMapper class to retrieve the most commonly used e-mail character set. Call LocaleMapper.getIANACharSetFromLocale, passing in the locale object. The return value is an array of character set names. The first character set returned is the most commonly used e-mail character set.

The following example illustrates sending an e-mail message containing Simplified Chinese data in the GBK character set encoding.

import oracle.i18n.util.LocaleMapper;
import java.util.Date;
import java.util.Locale;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeUtility;
/**
 * Email send operation sample
 *
 * javac -classpath orai18n.jar:j2ee.jar EmailSampleText.java
 * java  -classpath .:orai18n.jar:j2ee.jar EmailSampleText
 */
public class EmailSampleText
{
  public static void main(String[] args)
  {
    send("localhost",                    // smtp host name
      "your.address@your-company.com",        // from email address
      "You",                            // from display email
      "somebody@some-company.com",           // to email address
      "Subject test zh CN",             // subject
      "Content ˘4E02 from Text email", // body
      new Locale("zh", "CN")            // user locale
    );
  }
  public static void send(String smtp, String fromEmail, String fromDispName,
    String toEmail, String subject, String content, Locale locale
  )
  {
    // get the list of common email character sets
    final String[] charset = LocaleMapper.getIANACharSetFromLocale(LocaleMapper.
EMAIL_WINDOWS,
locale
      );
    // pick the first one for the email encoding
    final String contentType = "text/plain; charset=" + charset[0];
    try
    {
      Properties props = System.getProperties();
      props.put("mail.smtp.host", smtp);
      //  here, set username / password if necessary
      Session session = Session.getDefaultInstance(props, null);
      MimeMessage mimeMessage = new MimeMessage(session);
      mimeMessage.setFrom(new InternetAddress(fromEmail, fromDispName,
          charset[0]
        )
      );
      mimeMessage.setRecipients(Message.RecipientType.TO, toEmail);
      mimeMessage.setSubject(MimeUtility.encodeText(subject, charset[0], "Q"));
      // body
      mimeMessage.setContent(content, contentType);
      mimeMessage.setHeader("Content-Type", contentType);
      mimeMessage.setHeader("Content-Transfer-Encoding", "8bit");
      mimeMessage.setSentDate(new Date());
      Transport.send(mimeMessage);
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
  }
}

locale-charset-maps

This section enables applications to override the mapping from the language to the default character set provided by the GDK. This mapping is used when the page-charset is set to AUTO-CHARSET.

For example, for the en locale, the default GDK character set is windows-1252. However, if the application requires ISO-8859-1, this can be specified as follows:

<locale-charset-maps>
    <locale-charset>
      <locale>en</locale>
      <charset>ISO_8859-1</charset>
    </locale-charset>
  </locale-charset-maps>

The locale name is comprised of the language code and the country code, and they should follow the ISO naming convention as defined in ISO 639 and ISO 3166, respectively. The character set name follows the IANA convention.

Optionally, the user-agent parameter can be specified in the mapping table to distinguish different clients as follows:

<locale-charset>
  <locale>en,de</locale>
  <user-agent>^Mozilla⁄4.0</user-agent>
  <charset>ISO-8859-1</charset>
</locale-charset>

The previous example shows that if the user-agent value in the HTTP header starts with Mozilla/4.0 (which indicates an older version of Web clients) for English (en) and German (de) locales, then the GDK sets the character set to ISO-8859-1.

Multiple locales can be specified in a comma-delimited list.

page-charset

This tag section defines the character set of the application pages. If this is explicitly set to a given character set, then all pages use this character set. The character set name must follow the IANA character set convention, for example:

<page-charset>UTF-8</page-charset>

However, if the page-charset is set to AUTO-CHARSET, then the character set is based on the default character set of the current user locale. The default character set is derived from the locale to character set mapping table specified in the application configuration file.

If the character set mapping table in the application configuration file is not available, then the character set is based on the default locale name to IANA character set mapping table in the GDK. Default mappings are derived from OraLocaleInfo class.

application-locales

This tag section defines a list of the locales supported by the application. For example:

<application-locales>
  <locale default="yes">en-US</locale>
  <locale>de</locale>
  <locale>zh-CN</locale>
</application-locales>

If the language component is specified with the * country code, then all locale names with this language code qualify. For example, if de-* (the language code for German) is defined as one of the application locales, then this supports de-AT (German- Austria), de (German-Germany), de-LU (German-Luxembourg), de-CH (German-Switzerland), and even irregular locale combination such as de-CN (German-China). However, the application can be restricted to support a predefined set of locales.

It is recommended to set one of the application locales as the default application locale (by specifying default="yes") so that it can be used as a fall back locale for customers who are connecting to the application with an unsupported locale.

locale-determine-rule

This section defines the order in which the preferred user locale is determined. The locale sources should be specified based on the scenario in the application. This section includes the following scenarios:

• Scenario 1: The GDK framework uses the accept language at all times.

<locale-source>oracle.i18n.servlet.localesource.HTTPAcceptLanguage</locale-source>

• Scenario 2: By default, the GDK framework uses the accept language. After the user specifies the locale, the locale is used for further operations.

<locale-source>oracle.i18n.servlet.localesource.UserInput</locale-source>
    <locale-source>oracle.i18n.servlet.localesource.HTTPAcceptLanguage</locale-source>

• Scenario 3: By default, the GDK framework uses the accept language. After the user is authenticated, the GDK framework uses the database locale source. The database locale source is cached until the user logs out. After the user logs out, the accept language is used again.

<db-locale-source
        data-source-name="jdbc/OracleCoreDS"
        locale-source-table="customer" 
        user-column="customer_email" 
        user-key="userid" 
        language-column="nls_language" 
        territory-column="nls_territory" 
        timezone-column="timezone" 
        >oracle.i18n.servlet.localesource.DBLocaleSource</db-locale-source>
     <locale-source>oracle.i18n.servlet.localesource.HttpAcceptLanguage</locale-source>

Note that Scenario 3 includes the predefined database locale source, DBLocaleSource. It enables the user profile information to be specified in the configuration file without writing a custom database locale source. In the example, the user profile table is called "customer". The columns are "customer_email", "nls_language", "nls_territory", and "timezone". They store the unique e-mail address, the Oracle name of the preferred language, the Oracle name of the preferred territory, and the time zone ID of a customer. The user-key is a mandatory attribute that specifies the attribute name used to pass the user ID from the application to the GDK framework.

• Scenario 4: The GDK framework uses the accept language in the first page. When the user inputs a locale, it is cached and used until the user logs into the application. After the user is authenticated, the GDK framework uses the database locale source. The database locale source is cached until the user logs out. After the user logs out, the accept language is used again or the user input is used if the user inputs a locale.

<locale-source>demo.DatabaseLocaleSource</locale-source> 
    <locale-source>oracle.i18n.servlet.localesource.UserInput</locale-source>    
    <locale-source>oracle.i18n.servlet.localesource.HttpAcceptLanguage</locale-source>

Note that Scenario 4 uses the custom database locale source. If the user profile schema is complex, such as user profile information separated into multiple tables, then the custom locale source should be provided by the application. Examples of custom locale sources can be found in the $ORACLE_HOME/nls/gdk/demo directory.

locale-parameter-name

This tag defines the name of the locale parameters that are used in the user input so that the current user locale can be passed between requests.

Table 8-3 shows the parameters used in the GDK framework.

The parameter names are used in either the parameter in the HTML form or in the URL.

message-bundles

This tag defines the base class names of the resource bundles used in the application. The mapping is used in the Localizer.getMessage method for locating translated text in the resource bundles.

<message-bundles>
  <resource-bundle>Messages</resource-bundle>
  <resource-bundle name="newresource">NewMessages</resource-bundle>
</message-bundles>

If the name attribute is not specified or if it is specified as name="default" to the <resource-bundle> tag, then the corresponding resource bundle is used as the default message bundle. To support more than one resource bundle in an application, resource bundle names must be assigned to the nondefault resource bundles. The nondefault bundle names must be passed as a parameter of the getMessage method.

For example:

Localizer loc = ServletHelper.getLocalizerInstance(request);
 String translatedMessage = loc.getMessage("Hello");
 String translatedMessage2 = loc.getMessage("World", "newresource");

url-rewrite-rule

This tag is used to control the behavior of the URL rewrite operations. The rewriting rule is a regular expression.

<url-rewrite-rule fallback="no">
  <pattern>(.*)/([^/]+)$</pattern>
  <result>$1/$L/$2</result>
</url-rewrite-rule>

If the localized content for the requested locale is not available, then it is possible for the GDK framework to trigger the locale fallback mechanism by mapping it to the closest translation locale. By default, the fallback option is turned off. This can be turned on by specifying fallback="yes".

For example, suppose an application supports only the following translations: en, de, and ja, and en is the default locale of the application. If the current application locale is de-US, then it falls back to de. If the user selects zh-TW as its application locale, then it falls back to en.

A fallback mechanism is often necessary if the number of supported application locales is greater than the number of the translation locales. This usually happens if multiple locales share one translation. One example is Spanish. The application may need to support multiple Spanish-speaking countries and not just Spain, with one set of translation files.

Multiple URL rewrite rules can be specified by assigning the name attribute to nondefault URL rewrite rules. To use the nondefault URL rewrite rules, the name must be passed as a parameter of the rewrite URL method. For example:

<img src="<%=ServletHelper.rewriteURL("images/welcome.gif", request) %>">
<img src="<%=ServletHelper.rewriteURL("US.gif", "flag", request) %>">

The first rule changes the "images/welcome.gif" URL to the localized welcome image file. The second rule named "flag" changes the "US.gif" URL to the user's country flag image file. The rule definition should be as follows:

<url-rewrite-rule fallback="yes">
  <pattern>(.*)/([^/]+)$</pattern>
  <result>$1/$L/$2</result>
</url-rewrite-rule>
<url-rewrite-rule name="flag">
  <pattern>US.gif/pattern> 
  <result>$C.gif</result>
</url-rewrite-rule>

Example: GDK Application Configuration File

This section contains an example of an application configuration file with the following application properties:

• The application supports the following locales: Arabic (ar), Greek (el), English (en), German (de), French (fr), Japanese (ja) and Simplified Chinese for China (zh-CN).

• English is the default application locale.

• The page character set for the ja locale is always UTF-8.

• The page character set for the en and de locales when using an Internet Explorer client is windows-1252.

• The page character set for the en, de, and fr locales on other web browser clients is iso-8859-1.

• The page character sets for all other locales are the default character set for the locale.

• The user locale is determined by the following order: user input locale and then Accept-Language.

• The localized contents are stored in their appropriate language subfolders. The folder names are derived from the ISO 639 language code. The folders are located in the root directory of the application. For example, the Japanese file for /shop/welcome.jpg is stored in /ja/shop/welcome.jpg.

<?xml version="1.0" encoding="utf-8"?>
<gdkapp
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="gdkapp.xsd">
  <!-- Language to Character set mapping -->
  <locale-charset-maps>
    <locale-charset>
      <locale>ja</locale>
      <charset>UTF-8</charset>
    </locale-charset>
    <locale-charset>
      <locale>en,de</locale>
      <user-agent>^Mozilla\/[0-9\. ]+\(compatible; MSIE [^;]+; \)</user-agent>
      <charset>WINDOWS-1252</charset>
    </locale-charset>
    <locale-charset>
      <locale>en,de,fr</locale>
      <charset>ISO-8859-1</charset>
    </locale-charset>
  </locale-charset-maps>
 
  <!-- Application Configurations -->
  <page-charset>AUTO-CHARSET</page-charset>
  <application-locales>
    <locale>ar</locale>
    <locale>de</locale>
    <locale>fr</locale>
    <locale>ja</locale>
    <locale>el</locale>
    <locale default="yes">en</locale>
    <locale>zh-CN</locale>
  </application-locales>
  <locale-determine-rule>
    <locale-source>oracle.i18n.servlet.localesource.UserInput</locale-source>
    <locale-source>oracle.i18n.servlet.localesource.HttpAcceptLanguage</locale-source>
  </locale-determine-rule>
  <!-- URL rewriting rule -->
  <url-rewrite-rule fallback="no">
    <pattern>(.*)/([^/]+)$</pattern>
    <result>/$L/$1/$2</result>
  </url-rewrite-rule>
</gdkapp>

oracle.i18n.lcsd

Package oracle.i18n.lcsd provides classes to automatically detect and recognize language and character set based on text input. It supports the detection of both plain text and HTML files. Language is based on ISO; encoding is based on IANA or Oracle character sets. It includes the following classes:

• LCSDetector: Contains methods to automatically detect and recognize language and character set based on text input.

• LCSDResultSet: The LCSDResultSet class is for storing the result generated by LCSDetector. Methods in this class can be used to retrieve specific information from the result.

• LCSDetectionInputStream: Transparently detects the language and encoding for the stream object.

• LCSDetectionReader: Transparently detects the language and encoding and converts the input data to Unicode.

• LCSDetectionHTMLInputStream: Extends the LCSDetectionInputStream class to support the language and encoding detection for input in HTML format.

• LCSDetectionHTMLReader: Extends the LCSDetectionReader class to support the language and encoding detection for input in HTML format.

oracle.i18n.net

Package oracle.i18n.net provides Internet-related data conversions for globalization. It includes the following classes:

• CharEntityReference: A utility class to escape or unescape a string into character reference or entity reference form.

• CharEntityReference.Form: A form parameter class that specifies the escaped form.

oracle.i18n.servlet

Package oracle.i18n.Servlet enables JSP and JavaServlet to have automatic locale support and also returns the localized contents to the application. It includes the following classes:

• ApplicationContext: An application context class that governs application scope operation in the framework.

• Localizer: An all-in-one object class that enables access to the most commonly used globalization information.

• ServletHelper: A delegate class that bridges between Java servlets and globalization objects.

oracle.i18n.text

Package oracle.i18n.text provides general text data globalization support. It includes the following classes:

• OraCollationKey: A class which represents a String under certain rules of a specific OraCollator object.

• OraCollator: A class to perform locale-sensitive string comparison, including linguistic collation and binary sorting.

• OraDateFormat: An abstract class to do formatting and parsing between datetime and string locale. It supports Oracle datetime formatting behavior.

• OraDecimalFormat: A concrete class to do formatting and parsing between number and string locale. It supports Oracle number formatting behavior.

• OraDecimalFormatSymbol: A class to maintain Oracle format symbols used by Oracle number and currency formatting.

• OraNumberFormat: An abstract class to do formatting and parsing between number and string locale. It supports Oracle number formatting behavior.

• OraSimpleDateFormat: A concrete class to do formatting and parsing between datetime and string locale. It supports Oracle datetime formatting behavior.

oracle.i18n.util

Package oracle.i18n.util provides general utilities for globalization support. It includes the following classes:

• LocaleMapper: Provides mappings between Oracle locale elements and equivalent locale elements in other vendors and standards.

• OraDisplayLocaleInfo: A translation utility class that provides the translations of locale and attributes.

• OraLocaleInfo: An Oracle locale class that includes the language, territory, and collator objects.

• OraSQLUtil: An Oracle SQL Utility class that includes some useful methods of dealing with SQL.