Annotations scanning nightmare

[obrien]

Hi Ales,

having currently some performance problems in development environment due to the annotation scanning (multiple different frameworks, components, etc.) I'm wondering if there is any idea (or better ongoing work) how to facilitate handling existing of annotations only once?

I've been wondering how complicated it would be to integrate it into Microcontainer. Given fact VFS is handling all deployments, it should be difficult to create class visitor to collect matrix about available classes and included annotations. This information (as some kind of repository - attached to classloading domain) would then be available through MC extension of some sort.

Obviously on the client side there would be a requirement to have some kind of stub, to be able to switch from this implementation between MC powered version and good-old find all URLs and scan them.

This would also allow to come-up with some universal XML (or other format) override of annotations.

Cheers

Radim

[alesj]

This is all already done. ;-)
- http://anonsvn.jboss.org/repos/jbossas/projects/jboss-deployers/trunk/deployers-vfs/src/main/java/org/jboss/deployers/vfs/plugins/annotations/

The entry point to this is
- http://anonsvn.jboss.org/repos/jbossas/projects/jboss-deployers/trunk/deployers-vfs/src/main/java/org/jboss/deployers/vfs/plugins/annotations/AnnotationEnvironmentDeployer.java
where you can then access the information via
- http://anonsvn.jboss.org/repos/jbossas/projects/jboss-deployers/trunk/deployers-spi/src/main/java/org/jboss/deployers/spi/annotations/AnnotationEnvironment.java

There is one AnnotationEnvironment instance per Module (classloading info) instance in deployment.

AnnotationEnvironment instance is kept in DeploymentUnit,
so, if you can get access to DeploymentUnit, you have an access to annotations info.
See how Seam-int gets access to DeploymentUnit/AnnotationEnvironment:
- http://anonsvn.jboss.org/repos/jbossas/projects/jboss-seam-int/trunk/jbossas/src/main/java/org/jboss/seam/integration/jbossas/vdf/AnnotationEnvironmentVDFConnector.java
- http://anonsvn.jboss.org/repos/jbossas/projects/jboss-seam-int/trunk/jbossas/src/main/java/org/jboss/seam/integration/jbossas/vdf/VFSDeploymentUnitVDFConnector.java

The nice part about this annotation scanning is, that it's Javassist based, meaning it doesn't actually load classes until really needed.
And doing this over Module means you already follow all the import/export classloading rules.
e.g. you won't have access to 'hidden' resources

In JBossAS this is already used for EJB3 annotation scanning.
And there are already plans to use this more tightly in Seam/JSR299.

[obrien]

Wicked! That will keep me busy for some time.

Thanks

Radim