Google Eclipse Plugin: Autogenerated files

Question

I just installed the Google plugin for Eclipse and created a new GWT/GAE app using the Web Application Project wizard.

Among the plethora of files it generated for me, three caught my eye:

• META-INF/jdoconfig.xml
• META-INF/persistence.xml
• log4j.properties

With regards to the 2 META-INF/* files, what are these and what purpose do they serve? I can't find any references to them inside the official GAE docs.

Also, my understanding was that GAE uses JUL for logging by default, so my plan was to have my application log using SLF4J and then throw slf4j-jdk14, log4j-over-slf4j.jar, and jcl-over-slf4j.jar on the runtime classpath (forcing everything to log using JUL and thus complying with what GAE wants).

Why is this log4j.properties file even there in the first place? If I place log4j-over-slf4j.jar on the classpath, am I guaranteed that anything using log4j (and hence being congfigured via this properties file) will eventually be bridged over to JUL? Thanks in advance!

Answer 1

1. jdoconfig.xml is obviously a JDO config file.

2. persistence.xml is a JPA config file. Thay are both there by default even if you don't use JDO/JPA.

3. AFAIK, you can not force GAE services to go through SLF4J, but you can combine slf4j and JUL: Using logback-access with Google App Engine (GAE)