What WebLogic knows about GlassFish
WebLogic Server detects the presence of GlassFish web deployment descriptors in WAR files and parses them. Known entries are parsed into WebLogic server settings and applied at runtime via WebLogic MBeans (weblogic.j2ee.descriptor.wl.WeblogicWebAppBean).
WebLogic always will use an existing weblogic.xml instead of the GlassFish deployment descriptors if it is present and WebLogic applies the settings at runtime which means, that no weblogic.xml is actually generated.
If you deploy a GlassFish web-application to WebLogic you get some log messages with INFO level and you can follow what is happening:
<Info> <HTTP> <BEA-101392>...
<Glassfish Descriptor element <glassfish-web-app> is not supported>
<Glassfish Descriptor element <context-root> was successfully parsed and applied>
<Glassfish Descriptor element <idempotent-url-pattern> is not supported>
<Glassfish Descriptor element <property> is not supported>
<Glassfish Descriptor element <reapIntervalSeconds> was successfully parsed and applied>
<Glassfish Descriptor element <res-ref-name> was successfully parsed and applied>
<Glassfish Descriptor element <jndi-name> was successfully parsed and applied>
<Glassfish Descriptor element <delegate> was successfully parsed and applied>
<Glassfish Descriptor element <keepgenerated> was successfully parsed and applied>
Compared to what GlassFish knows about WebLogic, this is still a very limited set of parameters. But it covers the most needed ones. And we are still looking forward to even less xml configuration with further Java EE versions. But let's look at the other side.
What GlassFish knows about WebLogic
GlassFish Server offers limited support for the weblogic-application.xml, weblogic.xml, and weblogic-webservices.xml deployment descriptor files. The only element in weblogic-application.xml that GlassFish Server supports is security. The equivalent element in the glassfish-application.xml file is security-role-mapping.
But for what is all that good for?
Good question. There are some possible interpretations for what is happening.
1) GlassFish could be positioned as a certified, lightweight development platform for Oracle's FMW stack based on WebLogic server. If this would be the main goal, I wouldn't expect WebLogic to understand any of the GF DDs but GF knowing about all tweaks and settings of WLS.
2) Easy re-deployment of GF apps on WLS. This is what you find on the official launch slides. If you are running GF and you need to scale up to WLS you have a more easier migration path.
3) Both teams are trying to get hands on the concepts and switches of the other side. The GF roadmaps from the past highlight a "Common Server Platform" for WLS and GF. So knowing each other could be an easy and obvious first step for the teams.
As always, a bit of everything might be true. So there is nothing else left for now than simply to be happy about and watch how both excellent servers come closer together and to be open for future possibilities.