Demo Question

I see quite a few few demo source code in this directory:

  1. Are these projects guaranteed to compile successfully?

  2. Is there a location where the demo’s are running so we can see them in action?

I only see 4 demo’s listed on vaadin site.


No, unfortunately the “incubator” projects are not all guaranteed to compile. Probably most of them are maintained reasonably often, while some others not so well.

Most of them are not “demo” projects as such. It’s an “incubator” for personal “Community Friday” projects of mostly Vaadin employees and some Vaadin community members. Most of the incubator projects are Vaadin add-ons, which you can find in the Vaadin Directory. Probably most of them have a live demo site. Some of the projects are experimental or under work and not at least yet released in Directory or elsewhere.

One of the few actual demo/example projects in Incubator is the
Gas Diary
, which has its own
live demo
. Can’t promise that it compiles with the latest version of Vaadin. It’s also under work and not yet quite complete, but demonstrates many very typical tasks for applications.

hi Marko,
Thanks for your reply. I have looked at the gas diary, as a starting point. I’m interested in looking at demo’s for a site which contains user login/registration action along with some CRUD operations.

Do you have a preference to using SpringSource Roo or Hibernate for CRUD operations? Why?

Do you know how many concurrent users vaadin can support if deployed with Google App Engine?

thank you.

As far I see it, Roo is just a rapid development environment that supports Hibernate, among other persistence solutions. You can use Hibernate directly, or with Roo. If you are not in a hurry and don’t like to do it in such a rapid manner, you can just use Hibernate and forget all about Roo.

Regarding the question about GAE, as far as I know, it’s pretty scalable and I can’t really say about a practical limit. Depends on the application I guess. Perhaps someone else knows better.

If I remember correctly, Vaadin application scalability on GAE is only limited by the occasional session cleanup (in Vaadin) and GAE itself. Single-user performance is not very good, but scalability should be.

hi Henri,

Would you please elaborate on why single user is not good? What other frameworks would you recommend?

Single-user performance is not good in most Vaadin applications on GAE because GAE always serializes the session at the end of every request and deserializes it at the beginning of every request - even when you have told GAE to keep your application running all the time on a certain number of servers. This causes a variable but significant latency on every request other than those for static resources.

This is not specific just to Vaadin but applies to all systems running on GAE that keep a significant amount of data in the session - GAE has been designed primarily for stateless or almost stateless applications.

Furthermore, at least in the past, there have been some occasional reliability issues in GAE itself - I’m not sure if some of those have been resolved as I haven’t used GAE much, and not at all recently.

AppFoundation add-on
might be a suitable starting point as well.

Thanks Henri. So which platform instead of GAE do you recommend for deploying a Vaadin SAAS application?

I don’t really have experience with such platforms - others can probably say much more about these - and a lot also depends on the usage of your application. However, while still in beta, at least Cloud Foundry looks quite promising to me.