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From Costin Manolache <cos...@gmail.com>
Subject Re: 3.0 annotations ?
Date Fri, 07 Aug 2009 19:55:18 GMT
So far ASM looks good - the size of the jar is amazing. For tomcat-lite I'll
probably use it instead of bcel - I'll first try directly, if I get confused
by the callback style I'll use xbean-finder or the tree model.

Costin

On Fri, Aug 7, 2009 at 12:49 PM, David Blevins <david.blevins@visi.com>wrote:

> Cool.  Feel free to ping me in freenode if you want; dblevins in #openejb,
> #geronimo and #asfinfra.
>
> -David
>
>
> On Aug 7, 2009, at 9:30 AM, Filip Hanik - Dev Lists wrote:
>
>  I'll take a look at this after I'm done with the async stuff
>>
>> On 08/04/2009 03:28 PM, David Blevins wrote:
>>
>>>
>>> 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_jencks@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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>>>>>
>>>>>
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>>>
>>
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>>
>
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