Appligenics White Paper (page 4)

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The Entity Relationship Diagram is a critical picture of the scope of the project. Because of Appligenics' inherent concepts, you can deduce relative impact from the diagram. If more entities are added, for instance, they have a direct impact on the overall project, whereas if more enquiry or maintenance programs are added they will have minimum impact on the overall project.

High level Entity Relationship Diagram showing static, variable and transaction entities

This is also the first pass where the user gets involved. Leading questions elicit a great deal of information that often is not asked. For example, a user that requests multiple currencies in a financial application could mean "we have many currencies but each customer trades in only one" or "some of our customers have many currencies."

The difference is stark but only a Business Analyst can answer the direct question as it is diagrammatically represented on the ERD.

Step 3: Entities, Elements, and Rules

The entities and elements are now defined. This effectively gives us the physical file layouts.

In Appligenics the element name is unique. An element can be one of four types - Information, Base, Derived or Transient. The type then determines which rules are allowed and thus how the element will behave in programs. Here are some examples:

Element Type	Characteristics	Example
Information	Over 80% of a commercial database is informational.	Name, address, voucher number, journal reference, invoice code, price
Derived	This is the result of a calculation.	Inventory on hand, customer balance, statistical elements
Base	This triggers the calculation that updates the Derived element.	Inventory receipt quantity, deposit value, order quantity
Transient	This element is not on the database. The value is calculated and output to a screen or report.	Inventory value (price multiplied by unit cost), local value (foreign value divided by exchange rate)

Defining and maintaining an element is a simple process :

Screenshot of the Element Properties Dialog Box in Designer

Rules, help text and table values are all defined at the element level. They are defined once only and at the lowest level of detail. Therefore, there can be no redundancy in the design.

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