I am about to start my newest project, it is basicly an application that gets some data from a database and then display that data a graph!
now even though that this may seem simple it is important to me that this is done in a very correct way when it comes to object orientated programming.
Now my idea was the following:
I wanted to create the following four classes:
Adapter:
The class that connects the application to the database and recives the data
CallQueue:
This is an object that differences depending on what type of data is recived from the database and what type of data you wish to show on your graph. An example of this would be Cheese and fruits. both of them are food but they are very different types of food.
Statistics
This would be a tool class used to calculate the information recived from the database (for example changeing it to percentage instead of raw data)
Graph
This would be the class that gets the information from the statistic class and turns the numbers into a graph
GUI
This is ofcourse the GUI class where i will post the graph on!
Now i want to make the project as object orientated as possible. But my problem is that the information from the database is not always the same. For example if get the data from a day to day basis it will be different than from month to month. This means that the information is always going to change depending on what the user need.
How would i make this program object orientated ? and what type of connections should my classes have to eachother to make it most accessible. Do i have to create subclasses in order to simplify it?
should i add all information from the datbase directly into the CallQueue Class or should that object be created later on?
Update – Elaboration
The name callQueue is not a streaming implementation it is marely an object that should contain values of the data recived from the database (note that this is still in the idea phase and nothing is implemented). The idea is that a user opens the program and then chooses a day from and then a day to for instance: 04/11/2012 to 10/11/2012. The reason the objects value changes is when the day changes for instance to the following: 04/11/2012 – 04/12/2012 then a new graph will be created new information from the database will be calculated ect ect.
One thing that i am confused about aswell is the following:
When you have an object that is created from the database (adapater Note this could be optimized if you guys have a better idea) then how would you calculate statistics from that? would it be better that the statistic class called the adapter for data then worked with the data and then created the objects contain the calculated data?
Then the Graph class would need to get the objects data and insert into the graph.
From experience designing large systems and even smaller, the best approach is to think in terms of components rather than classes. This will allow you to break down your problems into smaller (and mostly independent) pieces.
So for example, you will have a component which sole responsibility will be to bring the data to your application for processing. That component will need to be able to deal with the multiple data sources, etc… That then becomes a sub-system that you can design independently from the rest of the application and deals with a specific problem, smaller than the whole.
If the sub-problems are still larger than they should, keep breaking them down into sub-compoennts, until the implementation of the components becomes almost trivial. At that point, you can start bringing in the notion of classes because you have enough visibility on the protagonists in your system.
In short, I put a lot of emphasis on separation of concerns. By isolating sub-problems into sub-components, you also isolate the solutions which makes it easier to correct your design mistakes or replace implementations without impacting the entire system.
Just my two cents…