I'm publishing a session bean a WebService and it works just fine.
The problem is that some methods returns or receives instances of an EntityBean. The problem arises when I add some mapped relations that involve such a bean.
In my "Hello World" example I'm using the WS to retrieve, create and modify UserBean (login / password). WHen I add a many2one relation "friend" that maps users to users WebService stop working.
any idea if there is any limitation on the type of WS parameters?
Please rethink your design. Webservices is about the exchange of comples business documents defined by xml schema.
An entity bean is an implementation detail of some persistence aspect.
BTW, XML schema can only express object trees - no graphs.