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Update Strategies

The applications you build with Enterprise Objects will likely be used simultaneously by many different users. These users usually can access the same set of data and probably have the rights to update all or part of that data set. But what happens when multiple users try to update the same data simultaneously? How do you prevent users from overwriting other user’s work? This realm of database application development is referred to as update conflicts.

This chapter discusses the update strategies available in Enterprise Objects. It is divided into the following sections:

• “Choosing a Strategy” discusses the available strategies for dealing with update conflicts.

• “Inside Optimistic Locking” provides details on the mechanics of Enterprise Object’s optimistic locking mechanism.

• “Multiple Coordinators and Optimistic Locking” discusses how optimistic locking is affected when you use multiple object store coordinators.

• “Using Optimistic Locking” discusses what you need to do to use optimistic locking in an Enterprise Objects application.

• “Prevention” discusses how to instrument your applications to prevent update conflicts.

• “Recovery” discusses how to instrument your applications to recover from update conflicts, specifically optimistic locking conflicts.

• “Recovering and Refaulting” shows you one way to recover from an optimistic locking failure.

• “Recovering and Last Write Wins” shows you an advanced way to recover from an optimistic locking failure.

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