Business model - how to handle properly?

I think reports shouldn't generate business classes, just fill an array with data from the Business Layer.
These arrays are passed to the presentation layer to be displayed as a report.
Report arrays can be made of pure string, or other fundamental types by declaring an array of objects.
The presentation layer can interpret array types for proper formatting and alignment.

Hi Goran,

First, if I can suggests some terminology clarity...

I was originally confused by your use of Business Model and this being cross-posted in the Project Management area.  A Business Model is typically a description or concept for how an organization (or an initiative) expects to generate revenue or value.

A Business Process Model is the definition for how the various functions within an organization interact with each other and process inputs to add value within the enterprise activities to satisfy customers and generate revenue.

Now, what you seem to be describing is an Application Data Model, and you seem to be seeking advice as to whether these metrics about the financial transactions should be stored in tables or generated at run time from procedures and calculations.

Assuming this is the case, my suggestion is to keep them as real-time calculations unless:
*  The complexity of the calculations and/or quantity of data (considering data growth) would produce exceedingly long execution times, or
* You intend to provide some sort of business intelligence reporting, in which case the calculations might need to be trended over time or sliced-and-diced like a pivot table.

The two conditions, however, could have different approaches.  For the first, you need to figure out how to pre-cache the calculations or perhaps store running figures and then just increment the calculations by-request.  This might result in relatively simple data tables to store partial, current results.

The second scenario, however, will require more thought into how to dimension the tables so that you have the proper trends and drill-down categories.

And in either case, you'll need to figure out how the processing is initiated to populate the data: manual update by the user, automatic launch or termination processing of the client, or completely separate scheduled batch processing, or...

As for classes and programming structure, you seem to have really two paths to consider: first, what is the functionality needed by the user to interact with this data?  Is it a static report, or an interactive pivot table-like thing?  What types of filters and sorts will be allowed?

Then that will drive considerations of the data needed to support these use cases.  As Jaime suggested, then this becomes a relatively simple processes of Model-View-Controller to give the user what they need.

However, that doesn't address the logic and rules needed to get the data into the proper shape to feed the reports.  If you take a fully automated, batch route - or some real-time caching scheme - then you don't really need a "View" to manage the data - just your Model and Controller.

So, without knowing your existing app and your requirements, I can't make more detailed suggestions on what classes you need - but as I see it, these are the broad categories of classes you'll need to design.

Hello all, thanks for the response.

@jaime_olivares
You say I should store generated data in arrays - ok, what about classes that generate data? Where is their place in business model? Is it factory method involved for retrieving data?

@cdbosh
I appologize if my terminology is confusing, theory is my weaker side, I have just started digging into this area. Considering the cross-posting, I usually add different areas which I find that can be fitted in. Since Business Model is part of Project Management as a wider area, and my first thought was to post this question in Business Model section, then Project Management section was just added as a "bonus"

So far I have read several books about modeling (intended for programmers mostly), and I have never met with the term Business process model. Usually the authors call it business model.

[quote]Now, what you seem to be describing is an Application Data Model, and you seem to be seeking advice as to whether these metrics about the financial transactions should be stored in tables or generated at run time from procedures and calculations.[/quote]

No, I am not interested in designing RDBMS, I agree with you that most of the times calculated values should not be stored in database.

I will try to explain a little more about the things that confuse me: generally speaking, user interface (UI) should interact with the business layer (BL), which interacts with the data layer (DL). There could be some in-between layers, but I will not include them for the sake of simplicity. When displaying some statistical data, which could be a static report, or can be filtered by user (like per day, month, year, etc), UI should call some method on BL (possibly some factory method), which will call DL to retrieve data. Now, my question is where do these classes fir in the model? I dont see them as some entity, so what is the method used in these situations?

As far as the existing application requirements, it is an accounting software, so if you have ever done something similar, you will know what I am talking about. I am not 100% sure what are the terms used in english language areas, but its about keeping tracks of things like: supply, stock, sale, tracking payment on time, calculating workers pays, and many other things. I could have reports like:

1) show me the supplier bills that should be payed on this day
2) show me the customer bills that should be payed on this day
3) show me the stock movement per year
4) show me sum of all invoices from particular customer per month, quarte of year, year, etc

Now, dont get me wrong, I am not asking you how to make this reports, I already have this working for several years. As I have said, I am not recoding my whole software to support n-layer architecture, in order to make it available to different platforms that windows (like web, for example).

Up to now I did it simply by executing some stored procedure from the UI and storing data in some array. Now I would like towhere to fit all this classes in business model, that should provide me all this statistical data, which could be the source from different entities (like sum of invoices from suppliers, sum of invoices to customers).

I hope I have made myself more clearer now.

I have made a typing mustake, it should have been

As I have said, I am now re-coding my whole software...

Thanks you guys, much appreciated. But (I think) I still didnt get the answer to the implementation method? Is it a Static report class with like 50 static methods, or...? Or the answer is to use MVC model (I will be reading about it today)?