Hi
Firstly, our application has two kinds of clients. A browser client
(therefore we need to display the result after a particular transaction)
and a java stand alone application which listens over a message bus for
requests. Therefore the stand alone application is not interested in the
display of the result and hence the third servlet does not come into the
picture.
We also have many complex reports. When a user requests for a report,
the first servlet which talks to the EJBs and the result is stored in a
temporary table. The second servlet then talks to the group manager EJB
(See description below) to get the results from the temporary table and
puts it into a bean stored in the HttpSession object. The third servlet
forwards the request to the appropriate jsp which picks the information
from the session object and displays the report.
If the user wishes to see the next record in the report, the third
servlet is called which forwards the request to the appropriate jsp which
picks the information from the session object and displays the report. But
if the user wants to see the same report, but changes the filter, the
second servlet is called which talks to the group manager EJB to get the
required information from the temporary table and puts into a bean stored
in the HttpSession object. The third servlet then forwards the request to
the appropriate jsp which picks the information from the session object and
displays the report.
Regards
Pratima
"Vootla, Venkateswara-Prasad" <[EMAIL PROTECTED]> on
10/23/2000 02:35:08 PM
To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>
cc:
Subject: RE: Design Issue
Why do you think that the 3 servlet design is neat? I can understand a
servlet that handles a request and that which handles the response. Apart
from that a session/entity or data object should be enough to encapsulate
the retrieved information, be it LDAP/DB.
~Prasad
-----Original Message-----
From: [EMAIL PROTECTED]
[SMTP:[EMAIL PROTECTED]]
Sent: Friday, September 22, 2000 6:45 PM
To: [EMAIL PROTECTED]
Subject: Design Issue
Hi
Our application has been designed based on the J2EE design
guidelines.
To briefly explain :
We have a single controller servlet through which all requests are
routed from the Client (java application or browser). This servlet
routes
the requests to the respective module's controller servlets.
Each module has three servlets, one for initiating the logic, one for
getting the result and another for displaying the result. The first
servlet
converts the input into an event and sends the event to a group manager
EJB
(session bean). The group manager EJB in turn talks to the entity
beans/session beans in its module, to perform the task. The second
servlet
gets the results from the group manager EJB and the third servlet
displays
the result.
We follow this route whenever we need to perform any action. But
there
are many times when I need to get some information from the RDBMS
database
or LDAP in order to populate the input form to be displayed to the user.
(Say I need to get all the users in the system and the roles in the
system,
in order to populate an input form so that the administrator can assign
roles to users).
What I would like to know is whether I should bypass the above design
and
directly talk to the DB / LDAP to get such information, otherwise it
seems
like I am going to do a lot of work just to get this information.
or should I still go ahead and follow the design to keep this neat.'
Any ideas/suggestions would be greatly appreciated.
Regards
Pratima
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