In the <jsp:useBean> tag, JSP specifications define that class attribute is the implementation class name of the object. Complying with these specifications, the following checks are implemented during the JSP translation for the classes specified in the class attribute, with the version 07-00 and later versions:

• The class modifier is public.
• The class modifier is not an interface.
• The class modifier is not abstract.
• The method modifier is public and a constructor that is not an argument exists.

Therefore, when a class that does not meet these check items is specified in the class attribute, the JSP compilation results are different with the versions prior to 07-00 and with version 07-00 and later versions.

The following is an example of JSP wherein the implementation class is specified in the include source and an interface is specified in the include destination:

• test1.jsp (include source)
  

  <jsp:useBean id="bean" scope="request" class="test.TestBean"/> <jsp:include page="test1_included.jsp"/>

• test1_included.jsp (include destination)
  

  <jsp:useBean id="bean" scope="request" class="test.TestBeanIF"/>

Note:

test.TestBean specified in the class attribute is an implementation class compliant with the JSP specifications and test.TestBeanIF becomes the interface of test.TestBean.

The operations for each Application Server version in this example are as follows:

• With versions prior to 07-00
  Since the check is not implemented during JSP translation, the servlet generated from the JSP file is executed.
  In the servlet generated from the JSP file, the existing script variables are searched with "bean" specified in the id attribute. In the above description, since the same script variables are already defined in the include source (test1.jsp), the existing object (instance of the test.TestBean class) is used without being instantiated from the class (test.TestBeanIF interface) specified in the class attribute. Therefore, the operations are executed normally.
  
• With version 07-00 and later versions
  The checks for the class specified in the class attribute are implemented for test1_included.jsp during JSP translation, therefore, an error occurs in JSP translation.
  

The differences in the compilation operations when the JSP translation backward compatibility function is used and when the function is not used with version 07-00 and later versions are as follows:

When a class name that cannot be instantiated is specified in the class attribute

• Use the JSP translation backward compatibility function
  Bean can be acquired without the id attribute value specified in the <jsp:useBean> tag from the second time onwards without resulting in an error.
  
• Do not use the JSP translation backward compatibility function
  An error occurs during JSP translation.
  

To define the JSP translation backward compatibility function, specify the following parameter in the <configuration> tag of the logical J2EE server (j2ee-server) in the Easy Setup definition file:

webserver.jsp.translation.backcompat.taglib.noCheckPrefix

Specifies whether or not to check the class property value of the <jsp:useBean> tag during JSP translation.

For details on the Easy Setup definition file and the parameters to be specified, see the uCosminexus Application Server Definition Reference Guide.