I finally started exploring google app engine. I'm planning on giving a knowledge session later this year as part of my goals for this year. I only spent a few days experimenting and with no prior knowledge I'm quite satisfied with my progress. Uptill now i created a new app engine project using JDO for persistence. I hope JPA does not turn out to be a better choice in the end.
Anyway, i was able to create a userform widget (composite) which enabled me to add a new user and another usersform widget which presented all users. It took me a while to understand how the Async interface worked since the return type can only be 'void'. Luckily a quick look at the AsyncCallback.java reveiled how it all works.
Below some screenshots of how it works:
Another thing which takes getting used to is page navigation with GWT. You only have one html page representing your EntryPoint. So what you basically do is dynamically adding and removing your widgets in the pagecontainer.
Next weeks I will write more about my findings.