Re: [aspectj-users] LTW weaving with foreign code

[Andy Clement <andrew.clement@xxxxxxxxx>]

Hi

On 28 March 2012 11:58, trhouse <trhouse@xxxxxxxxx> wrote:
> It occurred to me that I can improve the quality of my question by putting
> it this way:
>
> Suppose I ( went crazy and ) wanted to have every method call in the JDK
>  report soemthing along the lines of
>
>  System.out.println(
>         "------------------- Aspect Advice Logic --------------------");
>      System.out.println(
>         "In the advice attached to the call point cut");
>      System.out.println("Captured target object for the method call: "
>         + myObject);
>      System.out.println(
>         "------------------------------------------------------------");
>
> I need just one aspect to do this, I'll call it the *.* aspect for obvious
> reasons.
>
> How would I invoke the VM and what System variables (if any) would I have
> had to define?

The loadtime weaver does not get called earlier enough to modify
system classes, so you can't typically use loadtime weaving for
changing those classes.  If you want to do this the best thing to do
is offline weave the system jar and then run with that modified jar.

First, call ajc to take a jar in, modify it, and produce a new one:

ajc -inpath systemclasses.jar MyAspect.java -outjar modifiedsystemclasses.jar

Then launch java using your modified jar:

java -Xbootclasspath/p:modifiedsystemclasses.jar SomeMainClass

> I am not having trouble with aspectJ conceptually, but setting up all the
> system bits with understanding what needs to be where on my machine and
> environment and what magic incantation needs to be used and where has me
> stumped.

Andy


> On 3/28/2012 2:27 PM, Andy Clement wrote:
>>
>> Hi,
>>
>> Best solution is to use the agent:
>>
>> java -javaagent:pathtoaspectj/lib/aspectjweaver.jar SomeMainClass
>>
>> The weaver will discover its configuration from the CLASSPATH.  It
>> will look out for a file META-INF/aop.xml (or META-INF/aop-ajc.xml)
>> and use that to configure the weaving.
>>
>> A typical aop xml might be
>>
>> <aspectj>
>> <aspects>
>>   <aspect name="SomeAspect"/>
>> </aspects>
>> </aspectj>
>>
>> But you can create one by passing -outxml when you compile the
>> aspects.  The one created will simply include entries for all aspects
>> it compiled.
>>
>> If you need to know about what is going on you can add a weaver
>> section into the aspectj section:
>>
>> <weaver options="-debug"/>
>>
>> cheers,
>> Andy
>>
>>
>> On 28 March 2012 11:16, trhouse<trhouse@xxxxxxxxx>  wrote:
>>>
>>> Hi all,
>>>
>>> I am attempting to set up some LTW with a foreign (.class files only)
>>> code
>>> base.
>>>
>>> After having read the documentation I am not sure what is required.
>>> Specifically
>>>
>>>
>>> If I provide
>>>
>>> -Djava.system.class.loader=org.aspectj.weaver.loadtime.WeavingURLClassLoader
>>> as a VM option, is this sufficient or do I also need to
>>>
>>> 1) have to set ASPECTPATH as a system variable or is this just for
>>> developing aspects?
>>> 2 have to set the ASPECTJ_HOME as a system variable or is this just for
>>> developing aspects when I compile with AJC?
>>> 3) add aspectjrt.jar  to my CLASSPATH system variable or is this just for
>>> developing aspects when I compile with AJC?
>>> 4) somehow include lib/aspectjrt.jar  and aspectjweaver.jar to the
>>> runtime?
>>>
>>>
>>> So the idea is clear, I have foreign code. I have aspects already
>>> compiled.
>>> I just want to run the foreign code as usual, but have the LTW apply
>>> itself
>>> and execute the aspects as appropriate.
>>>
>>>
>>> Many thanks...
>>>
>>>
>>>
>>> _______________________________________________
>>> aspectj-users mailing list
>>> aspectj-users@xxxxxxxxxxx
>>> https://dev.eclipse.org/mailman/listinfo/aspectj-users
>>
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>
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