Chapter 7: New Features in EAServer 4.0
EAServer 4.0 supports the Servlet 2.3 and JSP 1.2 specifications, and adds support to connect Web applications hosted in EAServer to popular Web servers such as Apache and Netscape.
EAServer 4.0 supports servlet filters. Using servlet filters, you can preprocess servlet requests and postprocess servlet responses. You can install code that executes in response to changes in the servlet context or HTTP sessions associated with your Web application. For details on these features, see Chapter 23, “Using Filters and Event Listeners,” in the EAServer Programmer’s Guide.
EAServer 4.0 supports the JSP 1.2 specification. JSP 1.2 extends JSP 1.1 in a number of ways:
Uses Servlet 2.3 as the foundation for its semantics.
Defines the XML syntax for JSP pages.
Provides for translation-time validation of JSP pages. A new compilation phase has been added that gives custom tag libraries the opportunity to examine an XML view of the parsed page, and throw a translation time exception if problems are detected.
The ability for tag libraries to include event listener
classes. The listeners are listed in the tag library descriptor
and the JSP container automatically instantiates the listener classes
and registers them in a similar way to web.xml.
Essentially, the mechanism locates the type-library descriptors (TLDs)
in the Web Application (either in WEB-INF/classes or WEB-INF/lib),
and regards them as an extension of those listed in web.xml.
Better specification of the tag handler contract – tag handlers are Java classes that implement specific servlet interfaces. JSP 1.2 introduces some new interfaces and changes some existing interfaces to provide better support.
Improvements on authoring support – extends tag library functionality.
Better I18N support – implements the
to provide support for dynamic content-type.
Fixes the “flush before you include” limitation in JSP 1.1.
For information on creating JSPs in EAServer, see Chapter 24, “Creating JavaServer Pages,” in the EAServer Programmer’s Guide.
In accord with the Servlet 2.3 specification, EAServer allows you to install extensions and define the extensions required by a Web application. If you import a Web application (in WAR format) that requires extensions that are not installed, EAServer Manager warns you of the unfulfilled dependencies. For more information, see Chapter 21, “Creating Web Applications,” in the EAServer Programmer’s Guide
The Web server redirector plug-in allows communication between the Web server and the EAServer HTTP protocol listener. You can integrate a Web server and EAServer by installing the redirector plug-in on the Web server host. Client requests are sent directly to the Web server, which forwards requests to EAServer that need to access EAServer resources. EAServer processes the requests and returns the results back to the Web server. For details, see the EAServer Installation Guide.
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