2.2

Error Handling

There are two logical phases in the lifecycle/processing of a JavaServer Page source file:

Translation (or compilation) from JSP page source into a JSP page implementation class 

file.

Per client request processing by an instance of the JSP page implementation class.

Errors may occur at any point during processing of either phase. This section describes how 

such errors are treated by a compliant implementation.

2.2.1

Translation Time Processing Errors

The translation of a JSP page source into a corresponding JSP page implementation class 

using the Java technology by a JSP container can occur at any time between initial 

deployment of the JSP page into the runtime environment of a JSP container, and the receipt 

and processing of a client request for the target JSP page. If translation occurs prior to the 

JSP container receiving a client request for the target (untranslated) JSP page then error 

processing and notification is implementation dependent. Fatal translation failures shall result 

in subsequent client requests for the translation target to also be failed with the appropriate 

error; for HTTP protocols, error status code 500 (Server Error).

2.2.2

Client Request Time Processing Errors

During the processing of client requests, arbitrary runtime errors can occur in either the body 

of the JSP page implementation class or in some other code (Java or other implementation 

programming language) called from the body of the JSP page implementation class. Such 

errors are realized in the page implementation using the Java programming language 

exception mechanism to signal their occurrence to caller(s) of the offending behavior

1

. 

These exceptions may be caught and handled (as appropriate) in the body of the JSP page 

implementation class. 

However, any uncaught exceptions thrown from the body of the JSP page implementation 

class result in the forwarding of the client request and uncaught exception to the 

errorPage

 URL specified by the offending JSP page (or the implementation default 

behavior, if none is specified).

1. Note that this is independent of scripting language; this requires that unhandled errors occurring in a scripting language 

environment used in a JSP container implementation to be signalled to the JSP page implementation class via the Java 

programming language exception mechanism.

37

JavaServer Pages 1.1 Specification  

November 30, 1999