AppEngine : Java development using Spring 3.0.6 on Mac OS X

Today, I was setting up a demo portal to demonstrate hosting of a Java/Spring web application on Google AppEngine.  Cleancode NZ has a useful blog on using Springsource with AppEngine.  I recommend reading the blog entry. I ran into a few errors, which could have been avoided if I had followed the instructions to the letter. Here are some issues I faced and what I did to solve them.

1.  Deploying the war file to Tomcat works, but on appengine (even local demo) it returned 404 Not found. 
1. Go to command line and enter the project folder where the pom.xml file is
2. run mvn:clean, to clean up the code
3. run mvn:package to generate the expanded war file in 'target' folder.
4. Now make sure appengine deploys the application from the 'target' folder.
1. The lastWarOutDir  property in .settings/com.google.gdt.eclipse.core.prefs  file of the project folder gives you a clue as to where the previous version was deployed from.