Planning an Application
Good application design begins by understanding the problem you are trying to solve and the different pieces of information associated with the problem. You don't have to know everything right away. Iterative feedback loops give you the opportunity to modify your solution. As you think about your application, ask yourself a few questions:

• What functions will my application accomplish?
• What pieces of information are important in my application?
• How are these pieces of information related to each other?

The sample sales order application helps a sales team take orders in the field. Rather than using paper order forms, reps capture orders directly on their PalmPilots, and synchronize this information with the corporate database. This application tracks three significant pieces of information: Customers, Orders, and Line Items. These become tables.

Each table stores different pieces of information. The Customers table tracks the customer number, name, address, and credit limit. These become columns. Similarly, the Orders table tracks the order number, order date, purchase order number, and whether or not it is a rush order. The Line Items table tracks the product ordered, the quantity, and the price.

As discussed earlier, each order references the customer who placed the order. Thus, the Orders table contains a foreign key column referencing the Customers table. Similarly, the Line Items table contains a foreign key to the Orders table.

Now that we have an outline of our application, we can begin building our prototype.

Creating tables in Satellite Forms
Creating tables is straightforward. Begin by starting the Satellite Forms App Designer and then select New from the File menu to create a new application, shown in Figure B.

FIGURE B


The App Designer manages the application development process. Roll over picture for a larger image.

To start the table editor, select Insert Table from the Edit menu, and then select the New or Edit button to bring up the column editor, shown in Figure C. The column editor lets you specify a column's name, data type, and size. Specifying the correct data type helps ensure accurate data entry, preventing, for example, end-users from typing characters in a numeric field.

FIGURE C


The column editor defines database columns. Roll over picture for a larger image.

Use the column editor to create two numeric columns, ORD_NO and CUST_NO, a character column, PO_NO, a date column, DATE, and a true/false column, RUSH. Figure D shows the completed table. The Editor tab lets you enter sample data for testing. At this point, you can also create the Line Items and Customers tables.

FIGURE D


The layout view of the table editor displays the completed Orders table. Roll over picture for a larger image.

Creating PalmPilot screens
End-users interact with PalmPilot applications through one or more forms, each containing GUI controls. Satellite Forms supports standard controls, including edit fields, drop lists, check boxes, and buttons. It also supports PalmPilot-specific controls like the title bar and Graffiti shift indicator, and special controls like ink fields, bitmaps, and timestamps. Forms and controls can link directly to tables and columns, or can be unbound (not linked), and populated through scripts.