I'm going to be migrating an application to JSF during the course of this year and I am starting to think about some of the particular design issues. Any feedback would be appreciated.
The problem is that I need a list of changes from a form. The current way I'm doing this is to clone the "document" object that is bound to these values in my Struts form and then compare the two objects using some of the commons BeanUtils stuff. This works pretty well and in the end, I get a list of changes that I can pass through a "chain of responsibility" pattern where each element of the chain can inspect the list of changes for ones they are interested in. I love the value change listener option in JSF and I think this will be a big improvement for me. I don't have to implement clone methods on my document bean (and the many properties that are also document beans). What I'm trying to avoid is adding a listener manually through the JSF page to every element (since I'm basically interested in all changes so I need them all.) I had an idea that I could have a request scope bean that could be the listener for all changes. That bean would compile the master list of changes as it received that value change events from all of the components its listening to. Then I could have a request-level bean that would listen for the end of the "update model values" phase. That bean could take the list of changes and call some business logic methods through a facade. Since the model would be updated at this point, I could pass references to those beans to the facade depending on the nature of the change (ex. change in document owner). What do you guys think about this general approach? sean
