This chapter summarizes most of the capabilities of the JSP 2.0 expression language. However, there are two capabilities that we did not discuss here: the use of the expression language in tag libraries and the use of expression language functions. We postpone coverage of these two capabilities to Volume 2 because they require techniques covered only in the second volume of the book.
Quick preview: expression language elements can be used in any custom tag attribute that allows request time expressions (i.e., whose attribute element specifies true for rtexprvalue ). Functions correspond to public static methods in regular Java classes and are defined with the function element of the Tag Library Descriptor (TLD) file.