Please advise pattern for this situation

Hi all,
I plan to develop apps with thick client on the client side and using EJB on the server side, the EJB (Stateful Session Bean) will contain all the business logic and database connection.
The apps are divided into multiple modules. Those modules can be used independently, but they can also be used in an integrated manner.
So for example I develop Sales Invoicing module and Inventory module. If they're used together, each entry in Invoice will cut down the available Inventory automatically. But I also want to be able to sell Sales Invoicing module without dependency on Inventory module and vice versa.
Question :
1. Should I create separate Statefull Session Bean for each module (i.e EJBSalesInvoicing & EJBInventory) ?
2. How can I detect the presence of another modules so that I can call their methods ?
Any advice would be greatly appreciated
Setya

I am not sure if anybody can help you on designing the BUSINESS modules for Stateful SBs. But, we can suggest you the general overall architecture for THick Client Scenario.....
How do u plan to connect to the Server?....are yoou using BMPs /JDOs...or are writing the JDBC connectivity directly inside Stateful Session Bean( wrong Design)?

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Is there a design pattern for this situation?

Hi,
I'm making a survey engine. There is a Question class and a bunch of children of it (dropdown, checkbox, textbox, etc.). Now, correct me if i'm wrong, but I feel that this is a good case for inheritance. The problem I have is that Question needs to be initialized with parameters that the concrete question types have no business knowing about:
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As a result, I am forced to require this as a parameter for all the concrete types since the Question requires these to be initialized:
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Dan

tieTYT wrote:
Yes, there's a bad smell, and it's coming from your proposed design.
Separate the UI from your Survey and Question objects. Design the model and worry about the UI later.
%You're assuming I didn't. Just because I'm using the word Checkbox and Dropdown doesn't mean I'm talking about UI components.I hope you didn't. If you actually did some analysis and came up with names like that for non-UI objects, your design is even smellier than I first thought
A Checkbox has state like, "is box on right?" and "is checked". The Dropdown has state like, "currently selected option" and "list of options". The Question has state like, "am i invisible?", "what is my script", "am i enabled?". None of these classes have UI code in them. They just have names like this because, as you can see, there are fundamental differences between different question types that I use concrete children to sort out. With this setup I've already made a SWING and an AJAX frontend so I must be doing something right in the MVC department. No. I disagree that questions have states like "am I invisible?". That is irrelevant. A Question should not be aware that it is visible. Your design is very poor, I'm afraid, and it works by coincidence
I'm making the assumption that you thought I wasn't doing this but if you still think this is a bad design, let me know. If not, please help me with my original question.It is, most definately, a bad design. Classes named for UI widgets, but that are not UI widgets? Terrible idea. Really, sickeningly awful. No offence.
EDIT: And keep in mind this is a SURVEY engine. I specifically want to give the user of the library the power to specify whether their question is a Checkbox/Dropdown/RadioButtons/etc. In a normal application's code, the model wouldn't concern itself with details like, "Is this data going to be visualized as a checkbox?" But I feel that in this situation, the answer to that question actually does belong in the Model. But again, correct me if I'm wrong.
Edited by: tieTYT on Oct 22, 2007 10:53 AMThe model should be entirely unaware of how it will be rendered. Siure, in this instance, you've decided to render a question as,say, a checkbox. What if you're generating a report on what questions there are? Presentation logic doesn't belong in the model, at all. You say "in a normal application" here, but, like it or not, this is a normal application. Everyone goes through a phase of thinking their own code is special, and different, and new, but it isn't. It's a pretty straightforward app as far as I can tell.
Re-think your design. A class called Checkbox, that isn't a widget, stinks. Group UI concepts together, and use that as an abstraction. Dropdowns and radio buttons both present questions that can have exactly one correct answer out of a set. So you have a "MultipleChoice" question type. Then, in the UI layer, the decision can be made to render that question as a Dropdown or a bunch of radio buttons, without having to pollute your model with that.

Regex Pattern For this String ":=)"

Hello All
True, this isn't the place to ask this but here it is anyway, if you can help please do.
Can anybody tell me the regex pattern for this String:
":=)"
Thanks
John

Yep, cheers it's ":=\\)"
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ss[1] = {two}
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I'm looking for a solution to a design problem I have.
For a restaurant booking system I need a number of different opening times describing when you can and cannot book. These opening times are essentially Jodatime Period objects. There's a set of opening times spanning a week and these are repeated for every week (a default set of opening times) however it's possible to override these opening times say for a specific day.
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jduprez wrote:
But why do you put the logic in the database too (I'm no DB expert and I didn't know these concepts until I read your post, but that's what a dynamic view based on derived values looks like to me): performance (1 round-trip instead of two)?Hi jduprez. Long time no speakee.
I guess part of it is that I spent many years as a DBA and modeller, and really appreciate what it's taught me about design. Also, databases are (or should be) designed from the ground up to provide data-directed requests optimally, and include all sorts of nice stuff like transaction handling that aid consistency, as well as speed.
That said: I HATE SQL. Think Coliseum, with that emblazoned in 60-foot high letters around its walls, and it might come close to just how much I hate that so-called "language". I hate its form; I hate it's inconsistencies; I hate the fact that something like what OP is trying to do is NOT an easy task (and might involve the creation of a table that simply contains Dates, just in order to satisfy Boolean logic).
However, once you work it out, a database view (at least from the database's standpoint; JDBC I'm not so sure about) is just like any other Table - and that I DO like.
Programs are good at processing parameterized (ugh) temporal information; databases are good at persistence and high volume. Those two may meet at some point, but I reckon it's going to take another Codd (or Joda) before it does.
- that's clearer to 90% of the dev team (my biased numbers, based on 50% of Java developers having decent knowledge of SQL and much less than that having the advanced SQL knowledge which I rank your suggestion at)Sounds to me like you'll get the solution that matches the skills you have then. Is that what you really want, if a better one is available?
- that doesn't require investigating the if of your suggestion (JDBC support)Agreed, but only because my JDBC knowledge isn't what it could be. I'd also be surprised if it doesn't support access to a named view, since they were designed to be equivalent to Tables.
- the Op is using DAOs, so it's possible, if profiling does show this is hampering performances, to change that with no impact on the client code that calls the DAO.There's no doubt that a database solution is much higher level than a programming one; but, as I said, it's what they were designed to do. And tinkering around with program optimization has the feel of a "hacker's solution" to me. Not that there's any particular problem with that - I do it quite often when I have no control over my source - but I also try to keep in mind what the "actual" problem is.
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What is the best design pattern for this problem?

No code to go with the question. I am trying to settle on the best design pattern for the problem before I code. I want to use an Object Oriented approach.
I have included a basic UML diagram of what I was thinking so far.
Stated simply, I have three devices; Module, Wired Modem, and Wireless Modem.
In the Device Under Test parent class, I have put the attributes that are variable from device to device, but common to all of them.
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I haven't much idea of how override works and when you would use it and why. I'm the newest of the new here.
Good. At least you will not be smaking with a OPPer dOOPer hammer if I make some gramatical mistake.
You may want to look at this thread in the BreakPoint where i trie to help Cory get a handle on Dynamic Dispatching with an example of two classes that inherit from a common parent and invoke Over-ride VIs to do the same thing but with wildly varying results.
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It is dirt simple and Cory did a decent job of explaining it.
It just be the motivation you are looking for.
have fun!
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