I don't know if this is the right forum, but I had the following question.
I want to build an application that dynamically updates its GUIs (Google Web Toolkit) whenever the underlying relational database is changed. In this application database updates might be done about every 20 seconds.
How might a Java application listen for changes in a database?
I presume that a persistence layer would have to do the listening? Can, for example, a JPA EntityManager listen for changes?
There would not be any way do notify from the database itself, would there be? (Triggers remain solely in SQL, I think). I would not think so.