Advanced Web Application Features

This section includes summaries of the following topics:

• Internationalization Issues

• Virtual Servers

• Default Web Modules

• Class Loader Delegation

• Using the default-web.xml File

• Configuring Logging and Monitoring in the Web Container

• Header Management

• Redirecting URLs

Internationalization Issues

This section covers internationalization as it applies to the following:

• The Server's Default Locale

• Servlet Character Encoding

The Server's Default Locale

To set the default locale of the entire Application Server, which determines the locale of the Admin Console, the logs, and so on, use the Admin Console. Select the Application Server component, the Advanced tab, and the Domain Attributes tab, then type a value in the Locale field. For details, click the Help button in the Admin Console.

Servlet Character Encoding

This section explains how the Application Server determines the character encoding for the servlet request and the servlet response. For encodings you can use, see http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html.

Servlet Request

When processing a servlet request, the server uses the following order of precedence, first to last, to determine the request character encoding:

• The getCharacterEncoding() method

• A hidden field in the form, specified by the form-hint-field attribute of the parameter-encoding element in the sun-web.xml file

• The default-charset attribute of the parameter-encoding element in the sun-web.xml file

• The default, which is ISO-8859-1

For details about the parameter-encoding element, see parameter-encoding in Sun Java System Application Server Platform Edition 9 Application Deployment Guide.

Servlet Response

When processing a servlet response, the server uses the following order of precedence, first to last, to determine the response character encoding:

• The setCharacterEncoding() or setContentType() method

• The setLocale() method

• The default, which is ISO-8859-1

Virtual Servers

A virtual server, also called a virtual host, is a virtual web server that serves content targeted for a specific URL. Multiple virtual servers can serve content using the same or different host names, port numbers, or IP addresses. The HTTP service directs incoming web requests to different virtual servers based on the URL.

When you first install the Application Server, a default virtual server is created. You can also assign a default virtual server to each new HTTP listener you create. Open the HTTP Service component under the relevant configuration in the Admin Console, select HTTP Listeners, and select or create an HTTP listener. Then select from the Default Virtual Server drop-down list. For details, click the Help button in the Admin Console.

Web applications and Java EE applications containing web components can be assigned to virtual servers.

To Assign Virtual Servers

1. Deploy the application or web module and assign the desired virtual server to it.

   For more information, see Sun Java System Application Server Platform Edition 9 Application Deployment Guide.

2. In the Admin Console, open the HTTP Service component under the relevant configuration.

3. Open the Virtual Servers component under the HTTP Service component.

4. Select the virtual server to which you want to assign a default web module.

5. Select the application or web module from the Default Web Module drop-down list.

   For more information, see Default Web Modules.

See Also

For details, click the Help button in the Admin Console from the Virtual Servers page.

Default Web Modules

A default web module can be assigned to the default virtual server and to each new virtual server. For details, see Virtual Servers. To access the default web module for a virtual server, point the browser to the URL for the virtual server, but do not supply a context root. For example:

http://myvserver:3184/

A virtual server with no default web module assigned serves HTML or JavaServer Pages^TM (JSP^TM) content from its document root, which is usually domain-dir/docroot. To access this HTML or JSP content, point your browser to the URL for the virtual server, do not supply a context root, but specify the target file.

For example:

http://myvserver:3184/hellothere.jsp

Class Loader Delegation

The Servlet specification recommends that the Web class loader look in the local class loader before delegating to its parent. To make the Web class loader follow the delegation model in the Servlet specification, set delegate="false" in the class-loader element of the sun-web.xml file. It’s safe to do this only for a web module that does not interact with any other modules.

The default value is delegate="true", which causes the Web class loader to delegate in the same manner as the other class loaders. Use delegate="true" for a web application that accesses EJB components or that acts as a web service client or endpoint. For details about sun-web.xml, see The sun-web.xml File in Sun Java System Application Server Platform Edition 9 Application Deployment Guide.

For general information about class loaders, see Chapter 2, Class Loaders.

Using the default-web.xml File

You can use the default-web.xml file to define features such as filters and security constraints that apply to all web applications.

The mime-mapping elements in default-web.xml are global and inherited by all web applications. You can override these mappings or define your own using mime-mapping elements in your web application's web.xml file. For more information about mime-mapping elements, see the Servlet specification.

To Use the default-web.xml File

1. Place the JAR file for the filter, security constraint, or other feature in the domain-dir/lib directory.

2. Edit the domain-dir/config/default-web.xml file to refer to the JAR file.

3. Restart the server.

Configuring Logging and Monitoring in the Web Container

For information about configuring logging and monitoring in the web container using the Admin Console, click the Help button in the Admin Console from the Logging or Monitor tab on the Application Server page.

Header Management

In all Editions of the Application Server, the Enumeration from request.getHeaders() contains multiple elements (one element per request header) instead of a single, aggregated value.

The header names used in HttpServletResponse.addXXXHeader() and HttpServletResponse.setXXXHeader() are returned as they were created.

Redirecting URLs

You can specify that a request for an old URL is treated as a request for a new URL. This is called redirecting a URL.

To specify a redirected URL for a virtual server, use the redirect_n property, where n is a positive integer that allows specification of more than one. This property is a subelement of a virtual-server element in the domain.xml file. For more information about this element, see virtual-server in Sun Java System Application Server Platform Edition 9 Administration Reference. Each of these redirect_n properties is inherited by all web applications deployed on the virtual server.

The value of each redirect_n property has two components, which may be specified in any order:

The first component, from, specifies the prefix of the requested URI to match.

The second component, url-prefix, specifies the new URL prefix to return to the client. The from prefix is simply replaced by this URL prefix.

For example:

<property name="redirect_1" value="from=/dummy url-prefix=http://etude"/>