Vaadin framework is very interesting and promising, and as a portlet developer, who uses GWT for UI, I’m excited to see you’re integrating with Liferay! I’m looking for using Vaadin for my next portlet and I want to clarify some important details before diving into.
I know there are plenty of problems, when trying to create portlet with UI using GWT and deploy it to Liferay through WSRP. GWT is designed to be used through Servlet API only and not through Portlet API.
Because you have all the UI written with GWT, I wonder if you plan to deal with such a case. Will decision to keep all GWT scripts in Liferay themes folder help to deal with this? Have anyone tried to deploy Vaadin portlet through WSRP and is it possible at all? Will all requests from the UI go through Portlet API only or I will still have an additional Servlet?
The current implementation (Vaadin 6.1.5) still uses an additional servlet. The next version (6.2) that will be released in three weeks (6.2.0-pre1 release will be next week) will include JSR-286 support with no extra servlets needed.
With Vaadin 6.2, the server and client parts of this communication engine were updated to support JSR-286, removing the servlet from the picture. Also JSR-168 portlets (with a servlet and a portlet both running on the portal) are still supported, though.
WSRP has not been tested with Vaadin as far as I know, and there might be some complications related to its use (e.g. serving themes to the browser - see below). Feedback would be welcome if you do try it.
GWT does have some limitations about running multiple GWT modules on a single page, and GWTs own client-server communication framework might have problems with portlet deployments. The latter is not a problem with Vaadin that uses its own communication engine.
As for the first issue, in practice, all Vaadin portlets on a page need to use the same widgetset. This is easiest achieved by selecting a single Vaadin version to use on the portal, building a widgetset with all the needed client-side widgets (if any custom GWT widgets are needed) and using the same widgetset in all portlets on the portal.
An additional issue when using JSR-286 is that all URLs to the portlet have to be generated by the portal. Therefore, the portal cannot in practice serve themes or widgetsets (both normally consisting of multiple non-Java files referring to each other with relative URLs) from the portlet. These resources need to be served statically by the portal, making it complicated to use WSRP portlets with their own custom themes.
JSR-168 portlets have less restrictions about serving themes and other files from the portlet, but have session management complications and other limitations.
We are looking into to running vaadin as WSRP portlets ontop of Weblogic portal 10.3.2 but would like to hear about the known challenges and limitations with this?