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no.... to be honest, I haven't used the command
pattern much, and not recently, so someone might need to correct me on details,
but.....
you have a CommandExecutor that has a
method
void execute(Command cmd) throws
CommandException;
or similar. then, when you want something
done, you would do something like:
// to view cart contents
ViewCartContentsCommand cmd =
CommandFactory.createViewCartContentsCommand();
CommandExecutor.getInstance().execute(cmd); //
note that there are difference approaches to doing this line
... = cmd.getCartContents();
does that help?
cheers
dim
----- Original Message -----
Sent: Thursday, September 12, 2002 3:55
PM
Subject: Re: Stateful Session Beans
Thanks, This can be one alternative. Do
We have to store the command object in session ?
----- Original Message -----
Sent: Thursday, September 12, 2002
11:07 AM
Subject: Re: Stateful Session
Beans
there's no reason why the command pattern
couldn't be used to hide the SFSB from the web tier.
just have the command executor as the sfsb....
the web tier creates the command, uses the command executor, that extracts
the sfsb from the session, and passes the command to it for
execution.
hth
dim
----- Original Message -----
Sent: Thursday, September 12, 2002
3:33 PM
Subject: Re: Stateful Session
Beans
Normally it is said that access to ejb should
be hidden by using business delegate, facade, service locator. But for
SFSB there is no such solution as Glenn tried to find out. This is becuase
maintaining reference to the SFSB would be difficult if we use any
of therse. So SFSB is exception ?
Comment ??
Ashwani
----- Original Message -----
Sent: Thursday, September 12, 2002
10:40 AM
Subject: Re: Stateful Session
Beans
Thanks Juan for your comments they very
much in line with Dmitri's and it really helps
So it seems that it normal practice to
store a SFSB in a session class for the during of client's
session.
So if may paint a picture here in summation
in regard to my architecture I described:
1. the user logs in and WEB Tier controller
creates a SFSB and adds this reference to the session object of the
request.
2. the client and other class may
references this SFSB at any time
Therefore the SFSB is not hidden by any
facade such the CustomerService?
Glenn
----- Original Message -----
Sent: Thursday, September 12,
2002 12:55 PM
Subject: RE: Stateful Session
Beans
Handles... check out javax.ejb.Handle and
javax.ejb.HomeHandle.
to get the handle of an instance i, you use
i.getHandle(); this is defined in javax.ejb.EJBObject. Section 6.5 of
the spec refers to EJBObject in a Session Bean.
Handles are serializable and network
transparent.
Basically, SFSB hold state, but you need to
keep track of the reference to the SFSB... that's what the handle
is for
example (in jsp):
page1.jsp:
<%
....
mySFSB s =
sHome.create();
s.setUsername("jpl");
session.setAttribute("CustomerSession",
s.getHandle() ) ;
...
%>
page2.jsp
<%
....
mySFSB s = (SFSB) ((Handle)
session.getAttribute("CustomerSession")).getEJBObject();
String username =
s.getUsername();
....
%>
HTH,
Juan Pablo
Lorandi
Chief Software
Architect
Code Foundry
Ltd.
Barberstown, Straffan, Co. Kildare,
Ireland.
Tel: +353-1-6012050 Fax: +353-1-6012051
Mobile:
+353-86-2157900
www.codefoundry.com
Disclaimer:
Opinions expressed are
entirely personal and bear no relevance to opinions held by my
employer.
Code Foundry Ltd.'s opinion
is that I should get back to work.
Hey thanks for your comments I would
like to ask then:
I do have this structure :
action class(struts)
<---->webTier Controller (class) <-------> EJB Business
Delegate(SLSB) <--------> Customer Service (SLSB)
<------> Customer (Entity Bean)
1. Where would be an appropriate
in this structure to place a bean that holds the customers login
details and session state ? Would you create another bean called
CustomerSession (SFSB) or make the Customer Service a
SFSB?
2. How would this SFSB be referenced ?
I don't understand how the SFSB can be retrieve at some time later
to use the session details.
TIA
Glenn
----- Original Message -----
Sent: Wednesday, September
11, 2002 4:58 PM
Subject: RE: Stateful Session
Beans
Answers
in line
? Ramesh
Kesavanarayanan
? [EMAIL PROTECTED]
Anger results in delusion, delusion leads to loss in
memory,
memory loss leads to knowledge loss, If knowledge is lost
you perish
Can
anyone tell me the following about stateful session beans ?
1.
Who
calls them, I am to understand that these beans should be called
by the specific client (stub-client)?
Yes if
you do not have any other design pattern like session fa�ade(SLSB)
or Business Pattern
2.
Can a
facade call these and hide its use?
Yes
obviously you can refer any design pattern books for
these.
3.
Do they
have to be called from the client and if not, what are the common
ways in which these are used.
Yes if
you do not have any other layer between them and the client. These
are basically to hold the state of your bean in handles. Refer
mastering EJB by Ed Roman for further studies on
EJB.
4. Who exactly calls these (client side apps etc) and how I
structure they use properly (according to how that are to be used
correctly!)
I do not understand your question can you come again
please.
As I said earlier refer to
the book by Ed Roman from www.theserverside.com
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