Case Study:
Decision Support System
(DSS)

Introduction

In the corporate world, you often need to create decision support systems that allow employees to query the company database, and determine the current state of sales, orders, etc. You can create applications like this using Rapid Applications Development (RAD) tools like Oracle Power Objects, PowerBuilder, JAM, and others. Better yet, with the right set of OpenDoc parts, an ordinary user can assemble simple decision support systems, as illustrated below.

Theta Group Example

dtF Americas, Inc. is the US arm of theta group in Germany. Hans Martin Kern and his co-workers have developed a high-performance "dtF"database management system for the Macintosh. They have also developed an elegant set of OpenDoc parts to illustrate how easy it can be to develop customized decision support solutions.

An end-user can assemble a database query solution using the simple OpenDoc documents shown below. A screen shot of a typical part in use follows.

Parts, database, and query files.

Screen shot

The solution uses ODF Container as a simple container for the database parts. All the parts embedded in the container were developed by theta group. These include:

- TablePart displays the results of the database queries. The relational database itself is populated by dropping a "database.dtf"document on the TablePart that contains sales and product data.

- ButtonPart. A ButtonPart can be customized by simply dropping a text file on it. It then uses the name of the text file for the button label, and stores the text from the file inside the button part as its main content. In this case, the text will represent SQL queries into the database, such as "select * from customers".

- PopupPart initially contains an empty popup menu. Menu items are added by again simply dropping text files containing SQL queries on the popup menu part.

Linking is used to connect the buttons and popup menus to the table part, so the user can press a button or choose a popup menu item to start a SQL query. How do you create a link? In this example, you can option-click on the button part to activate it. You then select "Copy"from the "Edit" menu. You can then click on the table part to activate it, and then select "Paste As..." from the "Edit" menu to construct the link. Whenever the user presses the source of the link (the button), the text in the button will be sent as an SQL query to the database for which the table is the front end.

What must a developer do to create a solution like this? You do not necessarily have to create a container. You could use an existing one like ODFContainer, as we did here. You would have to find or create parts that can be the link source, such as the button and popup parts used here. You would have to find or create parts that can be the link destination, such as the table part used here.