On Apr 7, 2005 10:45 AM, Jonathan Eric Miller <[EMAIL PROTECTED]> wrote:
The way that I've been doing it is that I usually just have one bean named
something like CourseRegistrationHandler, if it was for an application that
handled registering for courses. I would make that bean a managed bean
stored in session scope. Then, I would have other data objects stored within
that bean and the JSF components would be bound to those. For example, I
might have an object respresenting a course called Course and then an object
in Course called Section, etc. I found that it definitely helps to get the
data objects modelled correctly and to get the relationships setup properly.
Otherwise, you could have to go back and make a lot of changes after the
fact if you try to do it in a more quick and dirty way. I'm using Hibernate
as a persistent service which helps keep the code nice and clean (no SQL all
over the place). So, basically, I have my application logic in the handler
bean which is the glue between the JSF UI and the data objects.
I have one application that is a little more complicated which is a
reservation system. There are three main types of objects that a user can
manipulate: items, reservations, and users. So, in that application I have
ItemHandler, ReservationHandler, and UserHandler managed beans that are
stored in session scope.
I don't know if this is really the recommended way of doing it. It's worked
OK for me so far, but, I don't know how it would hold up if you had a really
complicated application.
I've been wondering the same thing: if one should have a different bean for
each page for storing things like data that is put into drop-down lists and
the like.
I'm also not sure exactly what the recommended naming conventions are. I got
the idea of using the "Handler" naming convention from Hans Bergten's
JavaServer Faces book. To me, "Handler" makes more sense that "Bean."
Personally, I think suffixing anything with "Bean" is pretty pointless as it
doesn't say a lot.
One issue to watch out for if you have a wizard-like application is for
session expiration. I created a Servlet filter to handle this. It checks to
see if the browser provided a session ID that is invalid and if it's
present, it redirects to whatever page you configured it to go to. For
example, a page that notifies the user that their session has expired, or
make it go back to the first page of the wizard process. The filter that I
have is a little more complicated than that though because I made it so that
it works if you are using Tomcat integrated security too. In that case, I
had to make it so that the session expiration check was in the login page
and then set an attribute that the filter would look for and clear. Does
anyone know if this is the kind of thing that Shale does? When I first
started using JSF, I thought to myself, JSF should make this easier. It's
not that bad now that I have it working, but, it took me awhile to refine it
to the point where it works well.
Another issue to potentially watch out for if you have a wizard-like
application is what happens if a user skips pages? Originally, I had a
filter that did some checks on this, but, now, I just do validation at the
last step to make sure everything is filled in correctly at that point,
otherwise, it redirects to page 1. Sorry for rambling on so long. These are
just issues that I've run into. I don't know if how I've solved them is the
way everyone else has or not.
Jon
----- Original Message -----
From: "Ray Clark" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, April 06, 2005 8:41 PM
Subject: Managed Bean OO Design question
> I've been on this list for awhile now and I don't
> remember a discussion about how to architect managed
> beans for a page. (Please bear with me as this has
> turned into a rather long post.) I see 2 alternatives
> with how to set up the classes for my managed beans.
>
> First, for sake of discussion, here is my problem set.
> On my page I have 2 selectOneMenu lists and 1
> dataTable. The first selectOneMenu is a list of
> subjects, the second is a list of teachers, and the
> dataTable is a list of classes. Selecting the subject
> and teacher determines which classes will be displayed
> in the list of classes. The list of classes is
> displayed when the search commandButton is clicked.
>
> Now, the question is, do I have just 1 managed bean
> for the page? That bean would have as a class
> variables, a teachers list, a selected teacher String,
> a subjects list, a selected subject String, and a
> classes list. Then for methods it would have all of
> the getters and setters for these fields in addition
> to the method for the commandButton. The method for
> the commandButton would call the business layer to
> actually retrieve the list of classes from the data
> layer. The getter for the teacher list would call the
> business layer to actually retrieve the list of
> teachers, etc.
>
> I could have another page in my app (or another app),
> that needs an inputText field for a teacher, and
> possibly a method to validate the name entered to see
> if it was valid.
>
> So with this design managing of teacher information
> would be spread across multiple beans.
>
> Or, do I have 1 managed bean per object. So I would
> have a managed bean to manage teacher information, a
> managed bean to manage subject information, and a
> managed bean to manage class information.
>
> This would group all of the presentation for an object
> into 1 class, but it causes complexity when one class
> needs access to the information in another class in
> order to retrieve its data. It also seems to make the
> managed bean organized more like the data layer than
> the presentation layer.
>
> In either case, the managed bean would just be for
> passing the data to the JSF page and for calling the
> business layer to retrieve, maintain, etc, the data.
>
> I like aspects of both designs.
>
> Maybe there is another better solution. I have just
> been learning the tags and haven't given much thought
> to the design of the beans yet. But it's time for me
> to start thinking about how to set up my managed
> beans, hence I am asking for your advice.
>
>>From an OO perspective, which way do you experienced
> JSF programmers have things set up?
>
> Thanks,
> Ray
>
>
>
>
> __________________________________
> Do you Yahoo!?
> Yahoo! Mail - You care about security. So do we.
> http://promotions.yahoo.com/new_mail
>
--
-Heath Borders-Wing
[EMAIL PROTECTED]
