Moving to a new thread.
On Jan 21, 2010, at 3:02 PM, Jonathan Gallimore wrote:
I've signed up for the no-interface view (as long as no-one
objects ;-)),
sounds pretty interesting, and I'm sure I'll learn a fair bit from
it :-)
Great. So for this one the primary missing part we need is
essentially something that looks and feels like
java.lang.reflect.Proxy but allows for subclassing (i.e. the super
class to be passed in) instead of just interfaces.
The library cglib will do this, but I'd strongly prefer us not use
it. It generates one class per method of the subclass or interface
and in real world use it quickly eats away all your permgen space and
severely increases load time. To date, anytime we've needed to do
some dynamic class creation (CMP for example) we've just done it
ourselves using ASM directly and it works out pretty great with
usually just a couple classes to pull off rather than a whole library.
ASM is actually pretty easy to work with. Standard approach most
people take is just to hand code an example of the class you want to
generate, then use the ASMifier util to have it spit out the java code
that uses ASM to build that exact class. I have a little script like
this to make it easy to do from the command line:
http://gist.github.com/282865
So basically you'd create a test bean, then hand code a subclass of
that bean that accepts an InvocationHandler in the constructor and
where every method of the test bean is overridden in the subclass to
simply call the InvocationHandler and return the value the handler
gives (or the exception it throws). Get it working exactly the way
you want it, and only then start the ASM work. Where possible it's
best to move as much code off to utility methods or some other class
just to keep the subclass code (and therefore the ASM code) down to a
minimum.
This basic proxy class can go into org.apache.openejb.util as well and
just needs a really good test case to verify it works. Once we have
that we can start in on the more tedious process of weaving the
@LocalBean meta-data through the codebase -- far less of an isolated
task.
Anyway, hope that's enough to get things started. Fire questions at
will.
-David
