PATH Documentation > WebObjects 4.5 > EOF Developer's Guide

Behind the Scenes

Using Application Kit applications as examples, this chapter answers the following questions about what Enterprise Objects Framework does behind the scenes:

What is the sequence of events when objects are fetched from the database?
How does an EOEditingContext manage changes to its objects?
What happens when changes to objects are saved to the database?
How does Enterprise Objects Framework manage transactions?

Enterprise Objects Framework provides hooks so that your code can intervene in each of these scenarios. In addition to describing what happens behind the scenes in an Enterprise Objects Framework application, this chapter lists the delegate methods and notifications your code can use at every stage of an application to do custom processing.

Most of the information in this chapter can also be applied to other types of applications (command-line and web applications), but some of the details vary from what's illustrated here with Application Kit applications.

Fetching Objects

EODisplayGroup Receives a fetch Message

Inside EODatabaseContext

Inside EODatabaseChannel

Flow of Data During a Fetch

Uniquing, Snapshots, and Faults

How Changes are Distributed and Applied

How an EOEditingContext Manages Changes to Its Objects

Saving Changes

Locking and Update Strategies

Transactions

Transactions and Optimistic Locking

Transactions and Pessimistic Locking

Transactions and On-Demand Locking