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Designing Enterprise Objects

The Enterprise Objects Framework and the applications you build with it revolve around the enterprise objects that you design. Designing these objects, then, is in many ways the essence of creating an Enterprise Objects Framework application. This chapter explains the mechanics of designing enterprise objects, describes their structure and interaction with the Framework, and explains how you can take advantage of features provided by the Framework.

Designing an enterprise object entails three major steps:

Designing your schema
Modeling the enterprise object
Implementing the enterprise object

This chapter describes the activities that occur during each. The EOModeler application plays a part in all stages of enterprise object design, so this chapter refers frequently to Enterprise Objects Framework Tools and Techniques, where using EOModeler is documented.

This chapter uses selections from the Enterprise Objects Framework on-line examples to explain the principles of designing an enterprise object. In particular, the chapter focuses on the Customer entity in the Rentals database. A customer is a video store member who is authorized to rent videos.

Designing Your Schema Defining the Model

EOGenericRecord or Custom Class?

Which Attributes Should Be Class Properties?

What Data Types Should Your Properties Be?

How Should Your Enterprise Object Manage Relationships with Other Objects?

What About Inheritance?

Implementing an Enterprise Object

Generating Source Files

Instance Variables

Writing Accessor Methods

Writing Derived Methods

Performing Validation

Creating and Inserting Objects

Setting Defaults for New Enterprise Objects

Writing Business Logic

Constructor for Creating Enterprise Objects

Numeric Values and NULL

Cautions in Implementing Accessor Methods

Don't Override equals