SkipPageException -- where?

[debedb]

Hi all,

So I was trying to look at the *_jsp.java sources created
by Tomcat 5.0 (so I can step through them for debugging),
and I couldn't compile those because they had SkipPageException,
which was not in my compile-time classpath.

Now, a search for it gave me a Javadoc page
on sun.com:
http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/jsp/SkipPageException.html
but it was nowhere to be found in any of the servlet.jar
files around (maybe I am wrong and I have no servlet.jar
from 1.4). I eventually found it in jsp-api.jar in
common/lib of my tomcat installation.

So the question is -- is it Tomcat's own extension (even
though it's javax.servlet...) or it is a part of Sun's
distribution?

 

[John C. Bollinger]

Hi all,

So I was trying to look at the *_jsp.java sources created
by Tomcat 5.0 (so I can step through them for debugging),
and I couldn't compile those because they had SkipPageException,
which was not in my compile-time classpath.

Now, a search for it gave me a Javadoc page
on sun.com:
http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/jsp/SkipPageException.html
but it was nowhere to be found in any of the servlet.jar
files around (maybe I am wrong and I have no servlet.jar
from 1.4). I eventually found it in jsp-api.jar in
common/lib of my tomcat installation.

So the question is -- is it Tomcat's own extension (even
though it's javax.servlet...) or it is a part of Sun's
distribution?

It is a documented part of the JSP branch of the servlet API. The
implementation you found is provided by Tomcat, just like the rest of
Tomcat's implementation of the servlet API. In version 5 Tomcat broke
up its servlet API implementation among two (or is it three?) different
jars. Sun provides the specs and an API. Application servers provide
their own API implementations.

 

[debedb]

It is a documented part of the JSP branch of the servlet API. The

implementation you found is provided by Tomcat, just like the rest of

So, is this interpretation of your statement correct: it's
"documented", but there's no code
to be found for it by Sun (either in EE or SE editions of JDK)? Or am I
utterly confused now...
servlet.jar from Sun (that's for 1.3) has some implementations, now,
why not
implementation of this new SkipPageException (I compared Javadoc pages
on
java.sun.com, it is new with 1.4).

 

[debedb]

Actually, never mind. I found it in j2ee.jar of J2EE SDK 1.4. Oooof...

 

[John C. Bollinger]

So, is this interpretation of your statement correct: it's
"documented", but there's no code
to be found for it by Sun (either in EE or SE editions of JDK)? Or am I
utterly confused now...

Sun defines the J2SE and J2EE standard API. These definitions include
the names, contracts, and externally-visible characteristics of of all
the standard classes, but not implementations.

Sun also distributes implementations of the J2SE and J2EE API, the
former in all its JDK and JRE releases, and the latter in its J2EE
reference implementation. There are few alternative implementations of
J2SE, and Sun's is by far the most commonly used, so it is easy there to
confuse the API definition with the API implementation. Every
application server must provide its own J2EE implementation, however, so
there are as many J2EE implementations as there are application servers,
and it is important to not confuse the API definition with its
implementation.

The whole situation with respect to J2EE is even more muddied by the
existence of API-only jars, which contain only the externally visible
classes and interfaces of J2EE or one of its components (such as
servlets). Because many J2EE components are defined in terms of
interfaces, such jars can and do contain everything needed to compile a
J2EE client or application, but none of the underlying implementation to
actually run it. The program gets the appropriate implementations from
its execution environment (typically an application server) at runtime.

servlet.jar from Sun (that's for 1.3) has some implementations, now,
why not
implementation of this new SkipPageException (I compared Javadoc pages
on
java.sun.com, it is new with 1.4).

The J2EE 1.4 API definition defines and specifies the SkipPageException
class. Sun's J2EE 1.4 reference implementation contains an
implementation, as does Tomcat 5's servlet API implementation. (The
servlet API being one part of the J2EE API.) Since the class is new in
1.4, you will not find it in the 1.3 jars.