PetStore: correct design?

Question

Just recently I reviewed Pet Store 1.3.1 application by Sun Microsystem, and I found that Sun model the catalog, item, category, and product using combination of Stateless SB, DAO, and simple java bean..
I was quite surprised.. Then I found their reason in their documentation :
The catalog is a stateless session bean.
If the catalog were implemented as a Web-tier component like a servlet, it would be
limited to Web-only clients. If the catalog were written as a conventional class, it might
have to manage connection pooling and concurrent access to achieve adequate
performance and scalability. Choosing a stateless session bean provides catalog
access to any type of enterprise beans client, while meeting the resource sharing
and scalability goals of the component. The component is stateless because it
requires the highest possible performance and scalability.
Catalog entries are modelled as conventional classes.
In this application, catalog entries provide an excellent example of when not to use
enterprise beans. Catalog entries are simple, tabular data with little or no behavior.
They do not need the services enterprise beans provide. For example, because they
are read-only, they don?t require concurrent update management or transactions.
Modelling catalog entries as entity beans would create unnecessary overhead.
Modelling them as conventional classes meets all of their requirements
in the simplest, most efficient way.
Well, true that it is simple to use DAO, but this design is not very scallable. Imagine that pet store host thousands category with 10,000 items, and imagine if each items has its own availability (eg: the number of parrots to sell are only 8), etc.
I personally will model the entities (catalog, product, items, category) with Local Entity Bean for caching benefit.
My opinion, this design assumes that Database (through DAO) must be robust in order the application to be scallable. We know how limited is DAO without application caching mechanism (such as Entity Bean) when application get hundred hits per seconds.
I know that some database cache the sql queries and its result implicitly so same query won't be processed again and again. We can also use PrepareStatement in DAO class to optimize the query further. But I still think that this design is too much on delegating the overhead to database. They should use EB instead of Stateless SB.
What do you think guys?
Dukes will be awarded to person(s) who able to say that the design is correct / unproper, by giving valuable input / design consideration (aside of my statement above)
Alex

Answer 1

We can try to create a Dynamic layout:
http://msdn.microsoft.com/en-us/library/windows/apps/jj207042(v=vs.105).aspx#BKMK_DynamicLayout .
Vote if help you