Programming the Object Model

The next few sections discuss the overall approach to programming the database interface, business objects and back end systems. For a second iteration, we are considering the following technologies to clean up the implementation:

• SQLExpress is now and for the forseable future what we are using.

• EntityFramework or NHibernate (http://nhforge.org/Default.aspx) and possibly Fluent NHibernate (http://fluentnhibernate.org/) for database business objects instead of hand coding the ObjectRelationalMapping.

• SpecExpress framework for specifying property rules validation (http://specexpress.codeplex.com/). Quite frankly, the validation is happening now! As in post Alpha stage, we are now implementing this. See how at SpecExpressImplementation

For now we have the Main Form instantiating the Controller Logic, the Controller Logic instantiating the UI as needed and gluing it to the Model. Our implementation blurs the Controller and ORM functions which sit on top of the Dataset object.

Visual Design Elements

We are using Windows Forms to create an interface with Menus and multiple layers of embedded tabbed panels. When the application starts the UI loads the following information:

Site is loaded from app.config

Fields are loaded from the database based on app.config setting and are stored in a UI local Dictionary<int,FieldData> object that maps the Field Identifier to an object for the specified field. This Dictionary object is the top controller object in the UI and may be used to initiate control functionality from the UI directly. NOTE: For items that are bound (using a BindingSource) it is not always necessary to traverse the controller hierarchy via the fields Dictionary Object to initiate a some control functionality. Basically we bind three types of UI objects (click on each one to see documentation about binding the UI object to business object properties): TextBox, ComboBox and DataGridView objects.

Object to Database Integration Model

We are building a Model View Controller (MVC) application.

Our model is contained in a Dataset object ArchDataset.xsd along with the ancillary host of helper objects. Although these are very complex, they are standard elements and perform in expected ways. We will not cover them in detail. To find out more information about this particular model, see the ArchaeologyProject/DataModel.

The view is contained in [Name]Controls.cs and Forms files. These are organized under the directories Forms, FormControls, and Controls. These hold the visual components that display data and contain visual elements that allows the user to interact with that data. Currently we are using windows forms. In the future we would like to move to WPF.

The controller components glue the underlying model to the views and make extensive use of the Dataset paradigm to speed the development process. This is the most complicated part to be programmed. And deserves the greatest attention. In a moment of weakness these were seen to work more with the model than the view and are organized under the Data folder.

Controller

The controller interacts with both the Model and the View in the following ways: Creating new forms, Loading Filled Forms and Saving Changes to forms.

Creating New Locus Forms

New forms are created by menu selection while viewing a square. The menu creates a LocusDataEarth, LocusDataArchitecture or LocusDataInstallation object. These are controller objects that both interact with the Database and generate and control the view of that data. The tab control is acquired and a tab page added with the appropriate labels. Then the controller object provides a ctrlPanel that is placed on the Tab. The control panel provided by the controller object is linked in such a way that interaction with it, is reflected in the controller object and as needed back to the database. The LocusDataX object is added to the controller hierarchy in the squares squareLoci Dictionary.

For a general description of how these objects work see the base object from which they inherit much of their functionality: LocusDataBase.