In addition, in an error page, you can access the 

exception

 implicit object, described in 

TABLE 2 3

.

TABLE 2 3 

Implicit Objects Available in Error Pages

Implicit Variable

Of Type

What It Represents

scope

exception

java.lang.Throwable

The uncaught 

Throwable

 that 

page

resulted in the error page being 

invoked.

Object names with prefixes 

jsp

, 

_jsp

, 

jspx

 and 

_jspx

, in any combination of upper and 

lower case, are reserved by the JSP specification.

See Section 5.8.1 for some non normative conventions for the introduction of new implicit 

objects.

2.9

The pageContext Object

A 

PageContext

 provides an object that encapsulates implementation dependent features 

and provides convenience methods. A JSP page implementation class can use a 

PageContext

 to run unmodified in any compliant JSP container while taking advantage of 

implementation specific improvements like high performance 

JspWriter

s. Generating such 

an implementation is not a requirement of JSP 1.1 compliant containers, although providing 

the 

pageContext

 implicit object is.

See Appendix 6 for more details.

2.10

Scripting Elements

The JSP 1.1 specification describes three scripting language elements declarations, 

scriptlets, and expressions. A scripting language precisely defines the semantics for these 

elements but, informally, a declaration declares elements, a scriptlet is a statement fragment, 

and an expression is a complete language expression. The scripting language used in the 

current page is given by the value of the 

language

 directive (see Section 2.7.1,  The page 

Directive ). In JSP 1.1, the only value defined is 

 java 

.

Each scripting element has a  <%  based syntax as follows:

Chapter 2

Standard Syntax and Semantics

54