JVM Process Status Tool

jps - Java Virtual Machine Process Status Tool

http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jps.html

JMap - Memory Map Tool for Java

JMap tool is very useful to capture process state while debugging remote java applications. Refer to the following link for details.
http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jmap.html

Debugging J2EE Applications in Sun App Server

The following link provides guidelines for debugging applications in Sun Java System Application Server.
http://docs.sun.com/source/819-0217-10/dgdebug.html