Part 2 - Design for Web & GUI clients

[aders thomas]

My part 2 assignment indicates a requirement for a GUI application, in addition to the web application.
My key assumption here is that the GUI is stand alone, and it communicates directly with the application
server - not via the web server.
So - I would like to create a generic design pattern for client-side, which I can express on the UML diagrams
without drawing separate class and sequence diagrams specifically for servlets & JSPs (in the web application)
and MVC (in the GUI), so interested to hear if anyone has tried anything similar ?

[Darryl A. J. Staflund]

> So - I would like to create a generic design
> pattern for client-side, which I can express on
> the UML diagrams without drawing separate class
> and sequence diagrams specifically for servlets
> & JSPs (in the web application) and MVC (in the
> GUI), so interested to hear if anyone has tried
> anything similar ?
Hi there,
I have been asking myself this same question off and on for the past month or two. Grrr. The issue I find most difficult in Part II is not drawing the class or component or deployment diagrams, but rather drawing the sequence diagrams for the reasons you mention (i.e. although the client (the client application) and presentation (the customer web application) tiers both interact with the business tier, I am not sure how to draw a single set of sequence diagrams to cover both cases.) Pretty frustrating.
Here is where I am at in terms of reasoning right now:
1. Although the client and presentation tiers are both MVC in design (with the model residing in the business tier), the client tier most likely exposes V to the client if it is an AWT or Swing application. The presentation tier, on the other hand, most likely exposes C to the customer. As a result, even if we limit the scope of our sequence diagrams to MVC interaction between the client/presentation and business tiers, we'd still have to handle the client and presentation tiers differently.
2. However, both the client and presentation tiers interact with the business tier -- presumably through a shared set of exposed remote interfaces. This suggests that maybe we should forego details VC and concern ourself strictly with the details of M. At least this way we know that the client and travel interact with the business subsystem by way of a VC application of some sort.
Well, I am talked out. Hope this lets you know that others are raising the same issues.
Darryl

[Darryl A. J. Staflund]

Hi again.
Oh! I forgot. There is a third alternative I have been thinking as well, i.e. limit the scope of the sequence diagrams to interaction between the presentation and business tiers and leave the client tier out of it. After all, little specification has been provided for it.
Darryl

[James Ward]

Here is what i have thought :
Leave the Swing part completely out of Sequence diagrams. Do the sequence diagrams only for Web application. After all sequence diagram is only 12 points, and there is maximum work there.
In addition, if we include swing interaction in sequence diags., we will have to have 2 sequence diagrams for every use case (one for web, one for swing)... i don't think we can omit MVC part from sequence diags....

In addition a related thought is :
Could there be a separate Componenent diagram for the Swing App interaction with EJB layer ?

[Torsten Schippel]

If you communicate direct with EJB Layer how does it support SSL.
You can use custom secure socket factories but I think that's not fully EJB spec conform.
Torsten

[aders thomas]

> If you communicate direct with EJB Layer how does it support SSL.
> You can use custom secure socket factories but I think that's not fully EJB spec conform.
Torsten, I'm assuming also the GUI is to be used internally within the organisation -
the requirements seem to imply this - so hence communication (over RMI) with EJBs
on the application server - SSL is only a specific requirement for the external
browser to web server communication. This ties in quite nicely with network security / topology, since it supports deployment of the GUI inside an internal firewall,
and the web servers in a DMZ.

[James Ward]

>Torsten
>>>If you communicate direct with EJB Layer how does it support SSL.
>>>You can use custom secure socket factories but I think that's not fully EJB spec conform.
>>>
Why wud there be a custom secure socket factory, why not jsse ? That's j2ee or not ?

[aders thomas]

Darryl, Jitender
I agree two sets of sequence diagrams seems frustrating,
but my feeling they should support both the web and GUI clients
(in fact, the assigment grading guide states this!), hence the question... I'm thinking along the lines of defining something like abstract factory, which I can use to create mvc and/or servlet
controller components... I'll let you know how I get on with this !

[Torsten Schippel]

Originally posted by Jitender Bhatia:
>Torsten
>>>If you communicate direct with EJB Layer how does it support SSL.
>>>You can use custom secure socket factories but I think that's not fully EJB spec conform.
>>>
Why wud there be a custom secure socket factory, why not jsse ? That's j2ee or not ?

Of course the custum socket factory is based on JSSE. But the server doesn't need to support this SSL factory. Only JRMP, IIOP and T3 are supported by EJB Spec.

[James Ward]

In that case jsse is indeed not part of j2ee...