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From "Michael Delamere" <h...@michael-delamere.de>
Subject Re: Architecture advice....
Date Mon, 29 Jul 2002 20:22:03 GMT
Graham,

there´s just one more question that I have concerning your method.

Obviously there will be many different objects which make up the service
facade.  Does that mean that one has a "factory" for each object; i.e. each
"factory" returns it´s type of instance,  or do you pass a parameter to the
"factory" and return an instance accordingly?

Thanks for your time.

Michael


----- Original Message -----
From: "David Graham" <dgraham1980@hotmail.com>
To: <struts-user@jakarta.apache.org>
Sent: Monday, July 29, 2002 9:59 PM
Subject: Re: Architecture advice....


> I chose not to implement a session facade in my current project but have
> done it this way in other applications.  I really dislike bunches of
static
> method calls so this solution works nicely.  I mispoke when I mentioned
the
> factory method; it would only create the singleton instance on the first
> request, after that it would always return that instance.  You would use
> your service layer like this:
>
> // returns same instance every time
> ServiceFacade sf = ServiceFacade.getInstance();
> sf.doSomeServiceMethod();
>
> instead of
>
> ServiceFacade.doSomeServiceMethod();
>
> Sure, it's one more line of code but it is a cleaner design to me.
>
> >Yep, that´s exactly what it sounds like :-).  I would like to implement
> >something similar to the session facade used in EJB environments.
> >
> >I like the singleton idea.  Have you implemented this yourself.  What are
> >your experiences in doing it this way?
> >I take it that the factory would do the job of making sure that only the
> >existing instance is returned and if gone, create a new one.
> >
> >Have I got that right?  I certainly like the idea.
> >
> >Regards,
> >
> >Michael
> >
> >
> >----- Original Message -----
> >From: "David Graham" <dgraham1980@hotmail.com>
> >To: <struts-user@jakarta.apache.org>
> >Sent: Monday, July 29, 2002 8:59 PM
> >Subject: Re: Architecture advice....
> >
> >
> > > Sounds like a "how to implement a facade" problem.  I would make your
> > > service layer a singleton with a factory method to retrieve the
> >instance.
> > > That way you avoid the static method calls and maintain the symantics
of
> > > passing messages to objects (the singleton).  You also avoid creating
a
> >new
> > > object everytime you want to use a service method.
> > >
> > >
> > > >Hi,
> > > >
> > > >I had a discussion at work today concerning the best way to implement
> >our
> > > >application.  A very
> > > >basic discription of the framework would be the following:
> > > >
> > > >1. Struts + Velocity for the view
> > > >2. Struts ActionServlets for the controller
> > > >3. Service layer/methods for querying persistence layer
> > > >4. OJB persistence layer
> > > >
> > > >The main debate was actually about what the service layer would look
> >like.
> > > >We thought about the following options:
> > > >
> > > >1. The service layer consists of static methods
> > > >2. The service layer would consists of normal classes
> > > >3. The service layer could consist of servlets
> > > >
> > > >The idea is that (this is nothing new of course) the service layer
> >would
> > > >purely have methods such as addToShoppingBasket() or checkLogin();
> > > >basically
> > > >service methods which carry out the communication with the
persistense
> > > >layer
> > > >and returns the result to the controller.
> > > >
> > > >The question is though, should we create a new object every time we
> >want
> >to
> > > >access a stateless method?  Surely that would be a bit of an
overhead.
> >Go
> > > >with servlets?  This possibly ties it to the web-container too much
and
> > > >isn´t very elegant (?).  Another option would be just to use static
> > > >methods;
> > > >can this cause a problem when wanting to distribute to more than one
> > > >server?
> > > >Is it better in terms of performance?
> > > >
> > > >I would really appreciate some help and ideas on this.  It would make
> > > >things
> > > >easier in terms of deciding on the next step.
> > > >
> > > >Thanks in advance!
> > > >
> > > >Regards,
> > > >
> > > >Michael
> > > >
> > > >
> > > >--
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> > >
> > >
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