Dynamic layout of data

Question

Hi,
I'm new to JSF, and would like to ask how to model my web interface, so it would meet the next challenge:
Imagine I have some very complex entities in my model, with lots of fields and relations. Now, I write a page that contains every bit of data to be read & submitted. How do I go about writing a framework for this in such a way so that if the web designer (who just knows how to write JSP & HTML) can split this page into several pages to his liking, without requiring the intervention of a developer.
The basic approach I'm thinking about is:
* Giving the designer an API for requesting whatever data he needs (i.e., something like 'get me entity A') - how do i do that in JSF? obviously, there should be some server side code for getting the entity, but how can I model the JSP api so that it will remain the same whatever API the server offers (so that i wouldn't need to, e.g., write new tags).
* Writing one monolithic action listener that will listen to whatever data is submitted and will know what entities to update. obviously, there should be some API to the submission, such as the ids of the entities to update. A more subtle point is that since not all pages will contain all fields, the action listener needs to somehow know what fields are in the submitted page (so that if, for example, a boolean (=checkbox) property isn't submitted, it is because it is not there and not because it is false (unchecked)).
Thanx,
Ittay

Answer 1

It's hard to answer such a general question without more detail, but here are some points:
Imagine I have some very complex entities in my model,
with lots of fields and relations. Now, I write a page
that contains every bit of data to be read &
submitted. How do I go about writing a framework for
this in such a way so that if the web designer (who
just knows how to write JSP & HTML) can split this
page into several pages to his liking, without
requiring the intervention of a developer.
The basic approach I'm thinking about is:
* Giving the designer an API for requesting whatever
data he needs (i.e., something like 'get me entity A')
- how do i do that in JSF? obviously, there should be
some server side code for getting the entity, but how
can I model the JSP api so that it will remain the
same whatever API the server offers (so that i
wouldn't need to, e.g., write new tags).JSF components are bound to bean properties, so the "get me entity A" method you're talking about would be a bean property getter method, e.g., getEntityA() bound to a component with through a value binding expression like "${myBean.entityA}". You can have as many beans as you like, typically one per logical set of data, all bound to by components in the same or multiple pages.
* Writing one monolithic action listener that will
listen to whatever data is submitted and will know
what entities to update. obviously, there should be
some API to the submission, such as the ids of the
entities to update. A more subtle point is that since
not all pages will contain all fields, the action
listener needs to somehow know what fields are in the
submitted page (so that if, for example, a boolean
(=checkbox) property isn't submitted, it is because it
is not there and not because it is false (unchecked)).JSF updates the properties the components are bound to, so unless I'm missing something, just make sure you define setter methods for the bean properties you bind to, e.g., setEntityA(String value). An event handler (e.g., an action method) bound to command button can then get all data saved in th beans and do whatever you want with it, e.g., save it in a database or use it to process an order.
I suggest you browser through the spec and the tutorial to get a feel for what JSF is and how it works. The sample chapters for my book may also help you get the Big Picture:
http://www.oreilly.com/catalog/jsvrfaces/chapter/