Re: [aspectj-dev] Load Time Weaver Java 1.4 AJ.BAT

[Dennis Taylor <dwt@xxxxxxxxxxxxxxx>]

Thanks Andy,

I'm still digging into this.  I've found that the first level that
eliminates the exceptions is 1.7.0.  I found that the reason for "can't
determine superclass" error was due to a referenced, but unused, class
that wasn't in the classpath so that one is gone.  I'm starting to
wonder if the other exceptions could be due to certain classes in the
application being newer than java 1.4 since the application and its
supporting infrastructure are like aspectj and so many other things:
they run on older JVMs but also contain support for newer constructs if
running on a newer JVM.  Seems like aspectj may be analyzing unused
non-1.4 classes or something along those lines.

I'm currently trying to understand what changed in the aspectjweaver
source between 1.6.3 and 1.7.0 to see how bad it will be to bring the
necessary 1.7.0 code back to 1.4 source level.  I did take a quick look
at retroweaver and may come back to that. No matter what happens, its
all a pretty good learning experience for me and is applicable to the
kinds of things we do here. 

Dennis
919 719 8428 (w)

On 5/12/2015 12:00 PM, aspectj-dev-request@xxxxxxxxxxx wrote:
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>    1. Re: Load Time Weaver Java 1.4 AJ.BAT (Andy Clement)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Mon, 11 May 2015 12:11:19 -0700
> From: Andy Clement <andrew.clement@xxxxxxxxx>
> To: AspectJ developer discussions <aspectj-dev@xxxxxxxxxxx>
> Subject: Re: [aspectj-dev] Load Time Weaver Java 1.4 AJ.BAT
> Message-ID: <E723A335-E84E-43DE-BF1B-F9EC32EB9FA5@xxxxxxxxx>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Dennis,
>
> For a long time AspectJ was keeping the compatibility requirements as low as possible. The times it has been increased have typically been when the JDT compiler (upon which we are based) has increased its own requirements - and that doesn?t happen very often.
>
> The Readme for 1.6.6 ( https://eclipse.org/aspectj/doc/released/README-166.html <https://eclipse.org/aspectj/doc/released/README-166.html> ) mentioned that Java5 was now required to run the compiler/weaver. This doesn?t mean it couldn?t weave into older code but of course that is only true for compile time weaving or binary weaving (run AspectJ on Java5 but weave into Java1.4 or 1.3 code). With load-time weaving you are running the weaver on the same level of Java as the code being loaded - so if they are using a 1.4 VM to run their 1.4 code, it?ll be a problem.
>
> So 1.6.5 is the most recent you can probably get away with. Maybe I can help you with the ?can?t determine superclass of missing type? exceptions? Recall that weaving can need to do as much analysis to determine pointcut matches as a compiler would (in terms of resolving types) so you may need to put as many jars on the class path to weave something as were then when it was compiled. For some messages, if you are confident they are irrelevant you can turn them off (e.g. you *know* you don?t need to resolve the information related to the type it can?t find). The AbortExceptions are more worrying.
>
> There is a tool called retroweaver that allows the use of later JVM constructs on older VMs - possibly the aspectjweaver jar could be run through retroweaver but I?m not sure how it?ll behave. It is possible, given that Java5 requirement, that AspectJ will attempt to load classes like Annotation and fail horribly if they aren?t there (because they?d always be there on Java5 or higher).
>
> cheers,
> Andy
>
>> On May 8, 2015, at 8:36 AM, Dennis Taylor <dwt@xxxxxxxxxxxxxxx> wrote:
>>
>> We're incorporating some very simple aspects into some of the things we
>> do and have kind of a major problem.  We're good with Java 1.5 and later
>> but can't get load time weaving working on Java 1.4 with versions of
>> aspectj 1.6.9 and later. Versions 1.6.3 and earlier seem to have issues
>> with the java 1.4 code that we're trying to weave into.
>>
>> Unfortunately, we can't dictate what jvm versions our customers run on
>> and some very large installations need to run 1.4.  We are a very small
>> part of large java applications that they own/maintain.  All of their
>> application code is java 1.4 compatible and that is what we are weaving
>> into.  When we try to use AspectJ 1.6.3 and earlier, there are aspectj
>> related issues that we don't see with the latest version of the AspectJ
>> weaver (org.aspectj.bridge.AbortException's and "can't determine
>> superclass of missing type" exceptions).
>>
>> I'm hoping for some kind of guidance.  I can't find anything anywhere
>> about the LTW requiring a newer level of java.  The 1.4 JVM compatible
>> AJ.BAT still ships with even the latest versions and all the
>> documentation that refers to AJ.BAT still seems to be in place, yet
>> AJ.BAT doesn't work if the JVM is java 1.4.  Am I missing something?
>>
>> Thanks.
>>
>> -- 
>> Dennis
>> 919 719 8428 (w)
>>
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