RE: [aspectwerkz-user] Hot deployment questions

Thanks you very much Mihir, that's very helpful. I have found that it works
without any aop.xml and without Deployment Scope. However, I'm suspecting
that it's required in some cases so your example will prove useful.

Any idea when it's required and when it wouldn't work without it? The docs
says:

"They are needed due to the fact that no JVMs today support schema
redefinition when redefining your classes."

This does not seem to be true as it's working for me without one. It seems
they are not *always* needed. I would love to know more...

Thanks
-Vincent

> -----Original Message-----
> From: Mihir Mehta [mailto:[email protected]]
> Sent: dimanche 10 avril 2005 17:49
> To: [email protected]; [email protected]
> Subject: RE: [aspectwerkz-user] Hot deployment questions
> 
> 
> Here is what I have found through some help and investigation:
> 
> Getting deployment scope:
>         	SystemDefinition sysDef =
> SystemDefinitionContainer.getDefinitionFor(this.getClass().getClassLoade
> r(),"webapp");
> 
> Where "webapp" is the systemid from aop.xml.
> 
> Am not sure about which classloader, but in a web application the
> webappclassloader seems to work when the aop.xml is in META-INF dir of
> one of the jars in WEB-INF/lib dir.
> 
> 
> The deployment scope defines all the possible join points where you want
> the aspect to be deployed. So if you have planned to provide hot
> deployment capability for all your code and it resides in org.mycode.*,
> then you would define a deployment scope as such.
> 
> You also have to have all your aspects defined (am not too sure about
> this).
> 
> Now, when you want to instrument some part of your code and apply some
> aspect to it using hot deployment, you would have something in the
> application that can take the xmldefinition and aspect classname as
> argument and then do the following:
> 
> - assume your aop.xml is
> <aspectwerkz>
>     <system id="webapp">
>             <deployment-scope name="myscope"
> expression="execution(public * org.mypackage..*.*(..))"/>
>     </system>
> </aspectwerkz>
> 
> - to get system definition:
>         	SystemDefinition sysDef =
> SystemDefinitionContainer.getDefinitionFor(this.getClass().getClassLoade
> r(),"webapp");
> 
> - to get deployment scope (e.g. if your aop.xml was
>              DeploymentScope scope =
> sysDef.getDeploymentScope("name_of_your_scope_from_aop.xml i.e.
> myscope");
>                 System.out.println("Scope is: "+scope.getExpression());
> 
> - now deploy the aspect you want
> 
>      DeploymentHandle handle =
>      	    	Deployer.deploy(YOUR_ASPECT_CLASS.class,
> "<aspect name='measureTime'>" +
>       "<pointcut name='usermanager' " +
> "expression='execution(public *
> org.mypackage.subpackage_to_instrument.*.*(..))'/> " +
> 	"<advice name='trace' type='around' bind-to='usermanager'/> " +
> 
> "</aspect>",
> 	scope);
> 
> 
> 
> 
> 
> 
> -----Original Message-----
> From: Vincent Massol [mailto:[email protected]]
> Sent: Sunday, April 10, 2005 2:00 AM
> To: [email protected]
> Subject: [aspectwerkz-user] Hot deployment questions
> 
> Hi,
> 
> I'm still trying to get hot deployment to work for Cactus2... I have now
> decided to try using JDK 5.0 to get started.
> 
> I have some questions:
> 
> 1/ On http://aspectwerkz.codehaus.org/dynamic_aop.html it says to use
> the
> following to get a deployment scope:
> 
> DeploymentScope scope = SystemDefinition.getDefinitionFor(loader,
> systemId).getDeploymentScope("toString");
> 
> However the SystemDefinition object does not have a static
> getDefinition()
> method. It does have a non-static method of this name though. How do I
> get a
> SystemDefinition object? Do I need to create one using "new"? If so what
> string should I pass? The same as the systemId defined in aop.xml?
> 
> 2/ In
> http://blogs.codehaus.org/people/jboner/archives/000913_aspect_hot_deplo
> ymen
> t_in_practice_implementing_a_jmx_monitoring_aspect_.html, Jonas says, in
> the
> "Define a deployment scope" section:
> 
> "This can be done either in the META-INF/aop.xml file or using
> annotations
> in the aspect class"
> 
> Thus it seems possible not to have anything defined in aop.xml. Thus
> something like this would work, right?
> 
> <aspectwerkz>
>   <system id="cactus2"/>
> </aspectwerkz>
> 
> 3/ Would it also work if I have a generic deployment scope such as:
> 
> <aspectwerkz>
>   <system id="cactus2">
>     <deployment-scope name="allcode" expression="within(..)"/>
>   </system>
> </aspectwerkz>
> 
> 4/ If I use the Deployer.deploy(class, xmlDef) method, do I also need to
> define the xmlDef in the aop.xml file or can it be empty.
> 
> 5/ If the aop.xml file is empty, do I still need one?
> 
> Thanks and sorry for all those newbie questions but I really have a hard
> time understanding all this even though I have read and re-read at least
> 5
> times the docs on the web site ;-) I should probably read the source
> code to
> try to understand how it all works but then this is a bigger task which
> I
> would prefer not to start now :-)
> 
> Thanks
> -Vincent
> 
> 
> 
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