VL - GWT to Appengine

A new experience i wanted to make was wether it would be possible to create a gwt application based on an appengine server, which is capable of being deployed to "offline servers".

More exactly: I want to create an application which natively runs on the appengine server with multiple users but also offers to option to create "deliverables" of the datastore and an additonal jar which could be integrated into a "normal" appserver like a jboss for situations where an internet connection is either not possible or where it would be too risky too depend on both the internet and the appengine to be reachable.

The application is question is a re-implementation of a very old program dos, VL (VolksLauf). The program in question should be able to register data and participants for various running competitions taking place at the same day. For this task, a humble worker has to enter all participant registrations (currently manually) into the system about 1 week before the event starts. During the event, the program is used to retrieve the time lists and calculate the rankings as well as printing the records.

What I want is a gwt-based frontend (just a simple java gui) with powerful data input mechanisms, import filters and exports in the form of a record printer. The backend should be an appengine application with mandate-separated datablocks. In other words, multiple users can use the app at once with completely independent data. However, since the google accounts do not work offline, there must also be an offline solution usable on a "normal" webserver. This offline solution is just an export of the database with the user data only (no data from the others) and a much simpler account management (if any). This could be used for events where either internet is not possible or to reduce the dependence no both a good connection AND the appengine. It would be a catastrophe if there would be no connection at the critical day.

After the event, the data could be restored on appengine by re-importing the deliverable and overwriting all former data of the user that way.

Well.. we will see wether i have the endurance to finish the entire application or if just create some gwt widgets and then give up. Currently, I am taking care mostly of the application skeleton on the client.