Java 2 Platform, Enterprise Edition: Platform and Component Specifications

JSP.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 Chapter JSP.6 for more details.