The other exception classes should inherit it to describe a more specific error. A good practice is to create a base class for exceptions. Therefore, all specific exceptions must be caught, and all specific errors must be handled. If you decide to change the database type, the model implementation must guarantee that the other part of the software remains intact. However, if the lifetime of the model equals the lifetime of the application, you do not have to do it in most cases. The model wraps the code working with the database from the rest of the application.īecause the model holds a database object, it has to implement IDisposable interface to release it. The model must be implemented in accordance with the architecture designed. This is the way the model informs that its state was changed.Ĭomparison of User Mode and Kernel Mode Applications for Modifying HTTP Traffic Step 2. Similarly, the ContactRemovedEvent is called on removing a contact from the database. The ContactAddedEvent is called if a contact had been successfully added to the database. The RemoveContact method deletes a contact by its id, and Count method allows obtaining the number of contacts in the database. Besides, there are methods that allow us either to select a single contact with a specific id from the database or select a specific range of the contact entries. The methods of the model class accept a Contact object to add a contact data to the database. The class diagram in Figure 2 depicts two classes to manipulate with contact data. The model must have the methods to manipulate with the contact data. Thus, the solution of the demo-application will consist of the two following projects: PhoneBookGUI and PhoneBookModel. Such interaction provides loose coupling between the application components. In our demo-application, a user interacts with the model through the GUI, and the model updates the GUI through the events. It will allow you to modify each part of the software independently. To separate business logic from its presenter we suggest using MVC-like architecture.

We assume the application specification is ready before designing the application architecture. Accounts table in Contacts.db database Step 1.

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4 Steps to Create a Basic Windows Forms Application

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