On Aug 4, 2009, at 1:22 PM, Costin Manolache wrote:
Thanks - so objectweb instead of BCEL.
I'll try it out - it's a bit different from what I had in mind, it
looks
like xbean-finder first finds all classes and
than reads the files using the class loader ( but not Class.forName,
which
is good ) and keeps track of all annotations.
I was thinking of a simple File/zip based scanning, without any
class loader
- and just select the few
annotations we need and write a web.xml fragment as it goes, without
keeping
anything in memory.
I've been thinking about adding in a sort of "filter" for the
scanning. Something that could be supplied in the constructor.
Something simple like:
public interface Filter {
boolean accept(String annotationName);
}
Then you would implement that and be guaranteed to only have metadata
for the annotations you cared about. In this case @Filter and
@Servlet. I actually already experimented with it in a little copy
of the ClassFinder, would only take like 10 minutes to integrate the
change in.
In terms of keeping things in memory, there really isn't that much in
memory, especially if you filter out the annotations you don't care
about. As far as needing a classloader, that is only there so we can
return a list of classes (or methods, or fields, etc.) when you ask
for things that have a specific annotation. Someone has to load the
class to get the annotation data so it's just in the API for
convenience.
Another thing I've been experimenting with is some additional byte
code reading optimizations. Basically if you know your annotations
are class-level annotations only, you can get a boost in scan time by
just reading the top of the class def and skipping the rest. The
technique is proven, just need to think of an elegant way to specify
that is the behavior you want.
I guess in 3.0 a deploy tool / phase is absolutely needed - we can't
have
tomcat scan all files
each time it starts up, so the user will have to do something to re-
initiate
the scanning. Like touch
web.xml, or run a re-deploy tool.
I'm curious - why objectweb and not BCEL ?
We (OpenEJB) already had a bunch of code using ASM so that's what I
went with -- I wrote it OpenEJB and moved it over into XBean later so
others could use it. I also know a couple ASM guys and find it's good
getting direct tips for best performance as well as getting any
features in we need.
-David
On Tue, Aug 4, 2009 at 12:50 PM, David Jencks
<david_jen...@yahoo.com>wrote:
We use xbean-finder for this in geronimo/openejb/etc.
http://repo2.maven.org/maven2/org/apache/xbean/xbean-finder/3.5/
https://svn.apache.org/repos/asf/geronimo/xbean/trunk/xbean-finder
We also have a servlet 3.0 spec jar I've been trying to keep up to
date
with the glassfish javadocs.
https://repository.apache.org/content/repositories/snapshots/org/apache/geronimo/specs/geronimo-servlet_3.0_spec/1.0-EA-SNAPSHOT/
https://svn.apache.org/repos/asf/geronimo/specs/trunk/geronimo-servlet_3.0_spec
thanks
david jencks
On Aug 4, 2009, at 11:11 AM, Costin Manolache wrote:
Hi, anyone working on the @Filter, @Servlet annotation scanner for
tomcat-trunk ?
If I'm understanding it correctly, tomcat will have to read all
files in
classes and lib and look for the
annotation - and I would guess the only reasonable option is
looking at
bytecode.
I checked BCEL - seems reasonably easy, but if anyone has
different code -
I
would rather reuse it in
tomcat-lite :-)
BTW - there is a typo in javax.servlet.ServletRegistration -
should be
Dynamic, not Dynmaic.
I can fix it next time I get some free time...
Costin
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