Sorry for the long message, but I'm a bit unclear on some Tag related
spec details. I need to make sure I have a clear understanding before
I start thinking about tag handler reuse implementation.
My original understanding of Tag.release was that it was always called after
a tag handler was used -- after doEndTag. After calling release, the JSP
container could then put the tag handler back into a pool for reuse. So,
I was under the impression that a tag handler could be treated simply as
a pooled resource.
Based on my understanding, all of our code simply set tag handler attributes
to their default values in the release method. By doing this we set the tag
handler to a "default" or "initialized" state. Subsequently, setPageContext,
various setters, etc. could be called and the whole tag use process would
proceed again.
But, after a more careful reading of the tag sections of the JSP 1.2 spec, it
appears that tag reuse can only occur when tags have the same set of
attributes that are initialized in the JSP. Specifically, in section 10.1.1
under the "Lifecycle" section, bullet [3] states:
Note that since there are no guarantees on the state of the properties,
a tag handler that had some optional properties set can only be reused
if those properties are set to a new (known) value. This means that
tag handlers can only be reused within the same "Att-Set" (set of
attributes that have been set).
This part of the spec could be interpreted to mean that tag handlers
should only be reused if they have the same set of attributes. For example,
given the following JSP fragment, two different tag1 handlers would
have to be used (instead of reusing the handler):
<X:tag1 attr1="A" attr2="B"/>
<X:tag1 attr1="A"/>
I hope that I'm misunderstanding something. I'd much prefer that the
JSP container can rely on the handler's release method to reset the
handler to a known state and simply start the tag process over again
(setPageContext, setters, etc.) Such an assumption would greatly
simplify a pooling strategy.
Can anyone provide clarification?
-Casey
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