Re: [equinox-dev] Equinox Aspects and OSGi Weaving Hook Service Specific

[Alexander Shutyaev <shutyaev@xxxxxxxxx>]

Hi Martin!

Ok, I now have a much more clearer view on all of the existing logic.
I agree that going the short way is just a workaround and not a
upgrade so I will take the long road and will reimplement all bundles
to use OSGi spec interfaces. Do I correctly understand that
o.e.e.weaving.hook bundle will therefore be obsoleted completely or
does it have any extra functions?

On Wed, May 11, 2011 at 11:36 PM, Martin Lippert <lippert@xxxxxxx> wrote:
> Hey Alexander!
>
> It wasn't clear to me if you would like to "just" change the existing
> implementation to use the new hook or if you would like to implement a
> completely new aspect weaving mechanism.
>
> So the existing structure of Equinox Weaving is:
>
> - org.eclipse.equinox.weaving.hook
> This uses the basic Equinox hooks to inject a general bytecode weaving and
> caching mechanism. There is nothing special here for aspect weaving. This
> hook provides a service interface that other bundles can implement to
> provide concrete bytecode modifications and a service hook for caching
> services.
>
> - org.eclipse.equinox.weaving.aspectj
> This implements the service interface from the hook mentioned above and uses
> the AspectJ weaver to weave aspects into bytecode.
>
> - org.eclipse.equinox.weaving.caching
> This implements the caching service from the hook mentioned above and
> implements an asynchronous cache storing on the hard drive.
>
> My understanding of the OSGi Weaving specification is that it partly
> implements what the weaving hook mentioned above implemented (so that
> another bundle can implement a service interface in order to inject the real
> bytecode modification). So in an ideal world, the
> org.eclipse.equinox.weaving.aspectj bundle would use that interface in the
> future to realize bytecode weaving instead of the old one from
> o.e.e.weaving.hook. But doing this would also mean that the caching would no
> longer work for that weaving (because the old o.e.e.weaving.hook is the glue
> between weaving and caching).
>
> The other way would be to re-implement the o.e.e.weaving.hook bundle to use
> the new OSGi Weaving spec hook instead of the old Equinox-specific ones
> while providing the same interface to the outside world as before (the one
> that the aspectj component uses). That would allow the caching to work with
> this. But from an design point of view, this wouldn't provide a big step
> forward, I think.
>
> Just some thoughts...
>
> Cheers,
> -Martin
>
>
>
>
>> I thought that the only thing this reimplementation would affect would
>> be how (using osgi weaving hook vs equinox internal mechanisms) the
>> aspects are woven, and would not affect other things such as which
>> aspects to weave, caching etc. But given your question it seems I
>> thought wrong.. Could you please clarify? Also I'm not quite sure what
>> is opt-in and opt-out.. Is this about which side initiates the weaving
>> (Eclipse-SupplementBundle vs Require-Bundle)?
>>
>> On Wed, May 11, 2011 at 10:49 AM, Martin Lippert<lippert@xxxxxxx>  wrote:
>>>
>>> Hey Alexander!
>>>
>>>> Thanks for your answer, Martin.
>>>>
>>>> I will indeed try to re-implement aspect weaving to comply to the
>>>> specification. If I succeed I'll send you my result so you could maybe
>>>> just review it and give it a go saving some of your development time..
>>>
>>> Any contributions are of course highly welcome. Please let me know when
>>> you
>>> have something working here. Would be glad to take a look.
>>>
>>> The CVS resources are at the RT repository:
>>>
>>>
>>> http://dev.eclipse.org/viewcvs/viewvc.cgi/org.eclipse.equinox/weaving/bundles/?root=RT_Project
>>>
>>>
>>> http://dev.eclipse.org/viewcvs/viewvc.cgi/org.eclipse.equinox/weaving/features/?root=RT_Project
>>>
>>> Hope that helps!
>>>
>>> Are you planning on implementing just pure aspect weaving for AspectJ, or
>>> are you also looking at the different aspect resolving mechanisms (opt-in
>>> vs. opt-out) and the caching for woven classes?
>>>
>>> Cheers,
>>> -Martin
>>>
>>>
>>>
>>>
>>>
>>>> Therefore could you confirm that these are correct links for latest
>>>> source of Equinox Aspects (I got them from the same web site which as
>>>> you said is a little outdated):
>>>>
>>>>
>>>>
>>>> http://dev.eclipse.org/viewcvs/viewvc.cgi/equinox-incubator/aspects/org.eclipse.equinox.weaving.hook/
>>>>
>>>>
>>>> http://dev.eclipse.org/viewcvs/viewvc.cgi/equinox-incubator/aspects/org.eclipse.equinox.weaving.aspectj/
>>>>
>>>>
>>>> http://dev.eclipse.org/viewcvs/viewvc.cgi/equinox-incubator/aspects/org.eclipse.equinox.weaving.caching/
>>>>
>>>>
>>>> http://dev.eclipse.org/viewcvs/viewvc.cgi/equinox-incubator/aspects/org.eclipse.equinox.weaving.caching.j9/
>>>>
>>>> I was confused by 'equinox-incubator' part. You told me that the
>>>> project has graduated to the main SDK so maybe it now resides
>>>> somewhere else?
>>>>
>>>> On Tue, May 10, 2011 at 8:28 PM, Martin Lippert<lippert@xxxxxxx>
>>>>  wrote:
>>>>>
>>>>> Hi Alexander!
>>>>>
>>>>> Equinox Aspects is not the implementation of the OSGi Weaving Hook
>>>>> Service
>>>>> Specification. That specification is implemented as part of Equinox
>>>>> 3.7,
>>>>> I
>>>>> think. So if you use Equinox 3.7, you already have that specification
>>>>> implementation at hand.
>>>>>
>>>>> Equinox Aspects (now called Equinox Weaving) has graduated and ins now
>>>>> part
>>>>> of the Equinox SDK, so regularily updated by nightly builds, etc.
>>>>> Nevertheless there isn't much activity in this area over the past
>>>>> month,
>>>>> but
>>>>> its pretty stable and usable.
>>>>>
>>>>> The relationship between these two things are:
>>>>> - Equinox Weaving was implemented before the weaving spec came out, to
>>>>> it
>>>>> is
>>>>> still based on some Equinox-specific hooks deep inside of Equinox and
>>>>> is
>>>>> currently build mostly to weave aspects into OSGi bundles.
>>>>> - The OSGi Weaving spec was done to allow all kinds of bytecode weaving
>>>>> on a
>>>>> general level, so you should be able to re-implement the aspect-weaving
>>>>> part
>>>>> of Equinox Weaving on top of the new OSGi spec right now. I haven't
>>>>> done
>>>>> that (haven't found the time), but its on my list.
>>>>>
>>>>> The web will be updated soon to reflect all this...
>>>>>
>>>>> Hope this answers your questions!
>>>>> -Martin
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Could you please clarify for me whether the Equinox Aspects is the
>>>>>> implementation of OSGi Weaving Hook Service Specification? The thing
>>>>>> that confuses me is that Equinox Aspects was last update May 1 2009
>>>>>> (according to it's home page
>>>>>> http://www.eclipse.org/equinox/incubator/aspects/index.php) and is
>>>>>> still in incubator state with Milestone 7 as the latest version while
>>>>>> OSGi Weaving Hook Service Specification (56) was added to the
>>>>>> specification starting with version 4.3 which was released about a
>>>>>> month ago.
>>>>>>
>>>>>> If the Equinox Aspects really is the implementation of this
>>>>>> specification then what is the current status of this project, what is
>>>>>> it's latest version and is it stable?
>>>>>>
>>>>>> If the Equinox Aspects is NOT the implementation of the specification
>>>>>> mentioned then what are the differences between the two and what can
>>>>>> help me in choosing between them.
>>>>>>
>>>>>> Thanks in advance...
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